CYTOSKELETON, Issue 2 2008
Ryota Uehara
Abstract Phosphorylation of myosin regulatory light chain (RLC) at Ser19 (mono-phosphorylation) promotes filament assembly and enhances actin-activated ATPase activity of non-muscle myosin, while phosphorylation at both Ser19 and Thr18 (di-phosphorylation) further enhances the ATPase activity. However, it has not well been addressed which type of phosphorylation is important in regulating myosin during cytokinesis. Here, we investigated subcellular localization in sea urchin eggs of mono-phosphorylated and di-phosphorylated RLC by both quantitative biochemical and spatiotemporal cytological approaches. Mono-phosphorylated RLC was dominant in the equatorial cortex throughout the whole process of cytokinesis. Inhibition of myosin light chain kinase (MLCK) decreased mono-phosphorylated RLC both in the cortex and in the cleavage furrow, and blocked both formation and contraction of the contractile ring. Two different types of ROCK inhibitor gave inconsistent results: H1152 blocked both RLC mono-phosphorylation in the cleavage furrow and contraction of the contractile ring, while Y27632 affected neither the mono-phosphorylation nor cell division. These results suggest that there may be other targets of H1152 than ROCK, which is involved in the RLC phosphorylation in the cleavage furrow. Furthermore, it was revealed that localization of myosin heavy chain in the cleavage furrow, but not in the cortex, was perturbed by inhibition of RLC mono-phosphorylation. These results suggested that RLC mono-phosphorylation by more than two RLC kinases play a main role in regulation and localization of myosin in the dividing sea urchin eggs. Cell Motil. Cytoskeleton 2007. © 2007 Wiley-Liss, Inc. [source]

Role of myosin II activity and the regulation of myosin light chain phosphorylation in astrocytomas

CYTOSKELETON, Issue 1 2008
Bodour Salhia
Abstract The generation of contractile force mediated by actin-myosin interactions is essential for cell motility. Myosin activity is promoted by phosphorylation of myosin light chain (MLC). MLC phosphorylation in large part is controlled by kinases that are effectors of Rho family GTPases. Accordingly, in this study we examined the effects of ROCK and Rac1 inhibition on MLC phosphorylation in astrocytoma cells. We found that low concentrations of the ROCK inhibitor Y27632 increased the phosphorylation state of the Triton X-100 soluble fraction of MLC, whereas higher concentrations of Y27632 decreased soluble phospho-MLC. These effects of Y27632 were dependent on Rac1. The soluble form of phospho-MLC comprises about 10% of total phospho-MLC in control cells. Interestingly, ROCK inhibition led to a decrease in the phosphorylation state of total MLC, whereas Rac1 inhibition had little effect. Thus, the soluble form of MLC is differentially regulated by ROCK and Rac1 compared with MLC examined in a total cell extract. We also observed that astrocytoma migration is stimulated by low concentrations of the myosin II inhibitor blebbistatin. However, higher concentrations of blebbistatin inhibit migration leading us to believe that migration has a biphasic dependence on myosin II activity. Taken together, our data show that modulation of myosin II activity is important in determining optimal astrocytoma migration. In addition, these findings suggest that there are at least two populations of MLC that are differentially regulated. Cell Motil. Cytoskeleton 2008. © 2007 Wiley-Liss, Inc. [source]

Myosin-mediated cytoskeleton contraction and Rho GTPases regulate laminin-5 matrix assembly

CYTOSKELETON, Issue 2 2004
Gregory W. deHart
Abstract Laminin-5 is a major structural element of epithelial tissue basement membranes. In the matrix of cultured epithelial cells, laminin-5 is arranged into intricate patterns. Here we tested a hypothesis that myosin II-mediated actin contraction is necessary for the proper assembly of a laminin-5 matrix by cultured SCC12 epithelial cells. To do so, the cells were treated with ML-7, a myosin II light chain kinase inhibitor, or Y-27632, an inhibitor of Rho-kinase (ROCK), both of which block actomyosin contraction. Under these conditions, laminin-5 shows an aberrant localization in dense patches at the cell periphery. Since ROCK activity is regulated by the small GTPase Rho, this suggests that members of the Rho family of GTPases may also be important for laminin-5 matrix assembly by SCC12 cells. We confirmed this hypothesis since SCC12 cells expressing mutant proteins that inhibit RhoA, Rac, and Cdc42 assemble the same aberrant laminin-5 protein arrays as drug-treated cells. We have also evaluated the organization of the laminin-5 receptors ,3,1 and ,6,4 integrin and hemidesmosome proteins in ML-7- and Y-27632-treated cells or in cells in which RhoA, Rac, and Cdc42 activity were inhibited. In all instances, ,3,1 and ,6,4 integrin heterodimers, as well as hemidesmosome proteins, localize precisely with laminin-5 in the matrix of the cells. In summary, our results provide evidence that myosin II-mediated actin contraction and the activity of Rho GTPases are necessary for the proper organization of a laminin-5 matrix and localization of hemidesmosome protein arrays in epithelial cells. Cell Motil. Cytoskeleton 57:107,117, 2004. © 2004 Wiley-Liss, Inc. [source]

ROCK inhibitor (Y27632) increases apoptosis and disrupts the actin cortical mat in embryonic avian corneal epithelium

DEVELOPMENTAL DYNAMICS, Issue 3 2004
Kathy K.H. Svoboda
Abstract The embryonic chicken corneal epithelium is a unique tissue that has been used as an in vitro epithelial sheet organ culture model for over 30 years (Hay and Revel [1969] Fine structure of the developing Avian cornea. Basel, Switzerland: S. Karger A.G.). This tissue was used to establish that epithelial cells could produce extracellular matrix (ECM) proteins such as collagen and proteoglycans (Dodson and Hay [1971] Exp Cell Res 65:215,220; Meier and Hay [1973] Dev Biol 35:318,331; Linsenmayer et al. [1977] Proc Natl Acad Sci U S A 74:39,43; Hendrix et al. [1982] Invest Ophthalmol Vis Sci 22:359,375). This historic model was also used to establish that ECM proteins could stimulate actin reorganization and increase collagen synthesis (Sugrue and Hay [1981] J Cell Biol 91:45,54; Sugrue and Hay [1982] Dev Biol 92:97,106; Sugrue and Hay [1986] J Cell Biol 102:1907,1916). Our laboratory has used the model to establish the signal transduction pathways involved in ECM-stimulated actin reorganization (Svoboda et al. [1999] Anat Rec 254:348,359; Chu et al. [2000] Invest Ophthalmol Vis Sci 41:3374,3382; Reenstra et al. [2002] Invest Ophthalmol Vis Sci 43:3181,3189). The goal of the current study was to investigate the role of ECM in epithelial cell survival and the role of Rho-associated kinase (p160 ROCK, ROCK-1, ROCK-2, referred to as ROCK), in ECM and lysophosphatidic acid (LPA) -mediated actin reorganization. Whole sheets of avian embryonic corneal epithelium were cultured in the presence of the ROCK inhibitor, Y27632 at 0, 0.03, 0.3, 3, or 10 ,M before stimulating the cells with either collagen (COL) or LPA. Apoptosis was assessed by Caspase-3 activity assays and visualized with annexin V binding. The ROCK inhibitor blocked actin cortical mat reformation and disrupted the basal cell lateral membranes in a dose-dependent manner and increased the apoptosis marker annexin V. In addition, an in vitro caspase-3 activity assay was used to determine that caspase-3 activity was higher in epithelia treated with 10 ,M Y-27632 than in those isolated without the basal lamina or epithelia stimulated with fibronectin, COL, or LPA. In conclusion, ECM molecules decreased apoptosis markers and inhibiting the ROCK pathway blocked ECM stimulated actin cortical mat reformation and increased apoptosis in embryonic corneal epithelial cells. Developmental Dynamics 229:579,590, 2004. © 2004 Wiley-Liss, Inc. [source]

Myosin-II negatively regulates minor process extension and the temporal development of neuronal polarity

DEVELOPMENTAL NEUROBIOLOGY, Issue 5 2009
K.M. Kollins
Abstract The earliest stage in the development of neuronal polarity is characterized by extension of undifferentiated "minor processes" (MPs), which subsequently differentiate into the axon and dendrites. We investigated the role of the myosin II motor protein in MP extension using forebrain and hippocampal neuron cultures. Chronic treatment of neurons with the myosin II ATPase inhibitor blebbistatin increased MP length, which was also seen in myosin IIB knockouts. Through live-cell imaging, we demonstrate that myosin II inhibition triggers rapid minor process extension to a maximum length range. Myosin II activity is determined by phosphorylation of its regulatory light chains (rMLC) and mediated by myosin light chain kinase (MLCK) or RhoA-kinase (ROCK). Pharmacological inhibition of MLCK or ROCK increased MP length moderately, with combined inhibition of these kinases resulting in an additive increase in MP length similar to the effect of direct inhibition of myosin II. Selective inhibition of RhoA signaling upstream of ROCK, with cell-permeable C3 transferase, increased both the length and number of MPs. To determine whether myosin II affected development of neuronal polarity, MP differentiation was examined in cultures treated with direct or indirect myosin II inhibitors. Significantly, inhibition of myosin II, MLCK, or ROCK accelerated the development of neuronal polarity. Increased myosin II activity, through constitutively active MLCK or RhoA, decreased both the length and number of MPs and, consequently, delayed or abolished the development of neuronal polarity. Together, these data indicate that myosin II negatively regulates MP extension, and the developmental time course for axonogenesis. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2009 [source]

RhoA/ROCK and Cdc42 regulate cell-cell contact and N-cadherin protein level during neurodetermination of P19 embryonal stem cells

DEVELOPMENTAL NEUROBIOLOGY, Issue 3 2004
Isabel Laplante
Abstract RhoGTPases regulate actin-based signaling cascades and cellular contacts. In neurogenesis, their action modulates cell migration, neuritogenesis, and synaptogenesis. Murine P19 embryonal stem cells differentiate to neurons upon aggregation in the presence of retinoic acid, and we previously showed that RhoA and Cdc42 RhoGTPases are sequentially up-regulated during neuroinduction, suggesting a role at this very early developmental stage. In this work, incubation of differentiating P19 cells with C3 toxin resulted in decreased aggregate cohesion and cadherin protein level. In contrast, C3 effects were not observed in cells overexpressing recombinant dominant active RhoA. On the other hand, C3 did not affect cadherin in uninduced cells and their postmitotic neuronal derivatives, respectively expressing E- and N-cadherin. RhoA is thus influential on cell aggregation and cadherin expression during a sensitive time window that corresponds to the switch of E- to N-cadherin. Cell treatment with Y27632 inhibitor of Rho-associated-kinase ROCK, or advanced overexpression of Cdc42 by gene transfer of a constitutively active form of the protein reproduced C3 effects. RhoA-antisense RNA also reduced cadherin level and the size of cell aggregates, and increased the generation of fibroblast-like cells relative to neurons following neuroinduction. Colchicin, a microtubule disrupter, but not cytochalasin B actin poison, importantly decreased cadherin in neurodifferentiating cells. Overall, our results indicate that the RhoA/ROCK pathway regulates cadherin protein level and cell-cell interactions during neurodetermination, with an impact on the efficiency of the process. The effect on cadherin seems to involve microtubules. The importance of correct timing of RhoA and Cdc42 functional expression in neurogenesis is also raised. © 2004 Wiley Periodicals, Inc. J Neurobiol 60: 289,307, 2004 [source]

Simvastatin regulates oligodendroglial process dynamics and survival

GLIA, Issue 2 2007
Veronique E. Miron
Abstract Simvastatin, a lipophilic statin that crosses the blood-brain barrier, is being evaluated as a potential therapy for multiple sclerosis (MS) due to its anti-inflammatory properties. We assessed the effects of simvastatin on cultures of rat newborn and human fetal oligodendrocyte progenitor cells (OPCs) and human adult mature oligodendrocytes (OLGs) with respect to cellular events pertaining to myelin maintenance and repair. Short-term simvastatin treatment of OPCs (1 day) induced robust process extension, enhanced differentiation to a mature phenotype, and decreased spontaneous migration. These effects were reversed by isoprenoid products and mimicked with an inhibitor of Rho kinase (ROCK), the downstream effector of the isoprenylated protein RhoA GTPase. Prolonged treatment (2 days) caused process retraction that was rescued by cholesterol, and increased cell death (4 days) partially rescued by either cholesterol or isoprenoid co-treatment. In comparison, simvastatin treatment of human mature OLGs required a longer initial time course (2 days) to induce significant process outgrowth, mimicked by inhibiting ROCK. Prolonged treatment of mature OLGs was associated with process retraction (6 days) and increased cell death (8 days). Human-derived OPCs and mature OLGs demonstrated an increased sensitivity to simvastatin relative to the rodent cells, responding to nanomolar versus micromolar concentrations. Our findings indicate the importance of considering the short- and long-term effects of systemic immunomodulatory therapies on neural cells affected by the MS disease process. © 2006 Wiley-Liss, Inc. [source]

PHOSPHATE ROCK: North Africa

AFRICA RESEARCH BULLETIN: ECONOMIC, FINANCIAL AND TECHNICAL SERIES, Issue 11 2010
Article first published online: 18 DEC 200
No abstract is available for this article. [source]

Implication of Rho-associated kinase in the elevation of extracellular dopamine levels and its related behaviors induced by methamphetamine in rats

JOURNAL OF NEUROCHEMISTRY, Issue 2 2003
Minoru Narita
Abstract A growing body of evidence suggests that several protein kinases are involved in the expression of pharmacological actions induced by a psychostimulant methamphetamine. The present study was designed to investigate the role of the Rho/Rho-associated kinase (ROCK)-dependent pathway in the expression of the increase in extracellular levels of dopamine in the nucleus accumbens and its related behaviors induced by methamphetamine in rats. Methamphetamine (1 mg/kg, subcutaneously) produced a substantial increase in extracellular levels of dopamine in the nucleus accumbens, with a progressive augmentation of dopamine-related behaviors including rearing and sniffing. Methamphetamine also induced the decrease in levels of its major metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanilic acid (HVA). Both the increase in extracellular levels of dopamine and the induction of dopamine-related behaviors by methamphetamine were significantly suppressed by pretreatment with an intranucleus accumbens injection of a selective ROCK inhibitor Y-27632. In contrast, Y-27632 had no effect on the decrease in levels of DOPAC and HVA induced by methamphetamine. Under these conditions, there were no changes in protein levels of membrane-bound RhoA in the nucleus accumbens following methamphetamine treatment. It is of interest to note that the microinjection of Y-27632 into the nucleus accumbens failed to suppress the increases in extracellular levels of dopamine, DOPAC, and HVA in the nucleus accumbens induced by subcutaneous injection of a prototype of µ-opioid receptor agonist morphine (10 mg/kg). Furthermore, perfusion of a selective blocker of voltage-dependent Na+ channels, tetrodotoxin (TTx) into the rat nucleus accumbens did not affect the increase in extracellular levels of dopamine in the rat nucleus accumbens by methamphetamine, whereas the morphine-induced dopamine elevation was eliminated by this application of TTx. The extracellular level of dopamine in the nucleus accumbens was also increased by perfusion of a selective dopamine re-uptake inhibitor 1-[2-[bis(4-fluorophenyl)methoxy]-4-(3-phenylpropyl)piperazine (GBR-12909) in the nucleus accumbens. This effect was not affected by pretreatment with intranucleus accumbens injection of Y-27632. These findings provide first evidence that Rho/ROCK pathway in the nucleus accumbens may contribute to the increase in extracellular levels of dopamine in the nucleus accumbens evoked by a single subcutaneous injection of methamphetamine. In contrast, this pathway is not essential for the increased level of dopamine in this region induced by morphine, providing further evidence for the different mechanisms of dopamine release by methamphetamine and morphine in rats. [source]

Rho-associated kinase (ROCK) inhibitor, Y27632, promotes neurite outgrowth in PC12 cells in the absence of NGF

JOURNAL OF NEUROCHEMISTRY, Issue 2002
R. Nath
Neurite extension and retraction are very important processes in the formation of neuronal networks. A strategy for fostering axonal regrowth/regeneration of injured adult neurons is attractive therapeutically for various diseases such as traumatic brain injury, stroke and Alzheimer's disease. The Rho family of small GTPases, including Rac and Cdc42 have been shown to be involved in promoting neurite outgrowth. On the other hand, activation of RhoA induces collapse of growth cone and retraction of neurites. Rho-associated kinase (ROCK) an effector molecule of RhoA, is downstream of a number of axonal outgrowth and growth cone collapse inhibition mechanisms. In the present study, we sought to identify the role of ROCK in neurite outgrowth in PC12 cells. Y27632, a specific inhibitor of ROCK, induced a robust increase in neurite outgrowth in these cells within 24,48 h as visualized by phase contrast microscopy. Staining with FITC-tubulin or phalloidin show extended neurites in PC12 cells treated with Y27632, comparable to that with 100 ng/mL of NGF. Assessment of other biochemical markers of neurite outgrowth such as GAP43, neurofilament and tyrosine hydroxylase phosphorylation further indicates that inhibition of ROCK in PC12 cells causes differentiation of these cells to a neuronal phenotype. [source]

Contribution of ROCK in contraction of trabecular meshwork: Proposed mechanism for regulating aqueous outflow in monkey and human eyes

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 4 2005
Emi Nakajima
Abstract Aqueous outflow in the conventional outflow pathway is regulated by the contraction and relaxation of the ciliary muscle (CM) and the trabecular meshwork (TM). Rho-associated coiled coil-forming protein kinase (ROCK) is thought to regulate actomyosin-based contractility in many types of cells by phosphorylation of ROCK substrates. In animal models, ROCK inhibitor Y-39983 relaxed CM and TM and decreased intraocular pressure (IOP). Thus, ROCK is implicated in the regulation of aqueous outflow and IOP. However, the site of action of ROCK in monkey and man is unknown. In the present communication, RT-PCR analysis of monkey tissues showed higher levels of mRNAs for ROCK and ROCK substrates in TM compared to CM. Human TM also showed higher levels of mRNAs for ROCK and ROCK substrates compared to CM. Differences between TM and CM in human were not as high as in monkey. ROCK inhibitor Y-39983 led to a dose-dependent relaxation of carbachol-induced, contracted TM from monkey. In contrast, Y-39983 was only slightly effective in relaxing CM. Our results suggested that TM was one of the major sites for regulating IOP by ROCK. ROCK inhibitor Y-39983 might be a candidate drug for lowering IOP by increasing conventional outflow and producing fewer side effects on accommodation and miosis. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:701,708, 2005 [source]

Acute and Chronic Alcohol Exposure Impair the Phagocytosis of Apoptotic Cells and Enhance the Pulmonary Inflammatory Response

ALCOHOLISM, Issue 10 2010
Darren M. Boé
Background:, Alcohol abuse increases the risk for acute respiratory distress syndrome (ARDS). Efferocytosis, the clearance of apoptotic cells, is important in the resolution of inflammation and is regulated by RhoA and rho kinase (ROCK) activation. The effects of alcohol on pulmonary Rho pathway activation and efferocytosis have not been determined. We hypothesize that acute and chronic alcohol exposure impair pulmonary efferocytosis, leading to heightened inflammation during ARDS. Methods:, For in vivo experiments, C57BL/6 mice received either a single intraperitoneal injection of alcohol or chronic ethanol-in-water for 8 weeks prior to intratracheal instillation of apoptotic cells or lipopolysaccharide (LPS). Bronchoalveolar lavage (BAL) was performed for cells counts, calculation of the phagocytic index (PI), and Rho activity measurements. For in vitro studies, primary alveolar macrophages were cultured in alcohol (25,100 mM) and then co-cultured with apoptotic cells. RhoA activity was determined following alcohol exposure, and the PI was determined before and after treatment with the ROCK inhibitor, Y27632. Results:, Acute alcohol exposure was associated with impaired efferocytosis. Following LPS exposure, acute alcohol exposure was also associated with increased BAL neutrophils. Chronic alcohol exposure alone did not alter efferocytosis. However, following exposure to LPS, chronic alcohol exposure was associated with both impaired efferocytosis and increased BAL neutrophils. In vitro alcohol exposure caused a dose-dependent decrease in efferocytosis. Despite the fact that RhoA activity was decreased by alcohol exposure and RhoA inhibition did not alter the effects of alcohol on efferocytosis, treatment with the Rho kinase inhibitor, Y27632, reversed the effects of alcohol on efferocytosis. Conclusions:, Acute alcohol exposure impairs pulmonary efferocytosis, whereas exposure to chronic alcohol is only associated with impaired efferocytosis following LPS-induced lung injury. Both forms of alcohol exposure are associated with increased alveolar neutrophil numbers in response to LPS. The acute effects of alcohol on efferocytosis appear to be mediated, at least in part, by RhoA-independent activation of ROCK. Further studies are needed to dissect the differences between the effects of acute and chronic alcohol exposure on efferocytosis and to determine the effects of alcohol on alternative activators of ROCK. [source]

Melatonin induces neuritogenesis at early stages in N1E-115 cells through actin rearrangements via activation of protein kinase C and Rho-associated kinase

JOURNAL OF PINEAL RESEARCH, Issue 3 2007
Alfredo Bellon
Abstract:, Melatonin increases neurite formation in N1E-115 cells through microtubule enlargement elicited by calmodulin antagonism and vimentin intermediate filament reorganization caused by protein kinase C (PKC) activation. Microfilament rearrangement is also a necessary process in growth cone formation during neurite outgrowth. In this work, we studied the effect of melatonin on microfilament rearrangements present at early stages of neurite formation and the possible participation of PKC and the Rho-associated kinase (ROCK), which is a downstream kinase in the PKC signaling pathway. The results showed that 1 nm melatonin increased both the number of cells with filopodia and with long neurites. Similar results were obtained with the PKC activator phorbol 12-myristate 13-acetate (PMA). Both melatonin and PMA increased the quantity of filamentous actin. In contrast, the PKC inhibitor bisindolylmaleimide abolished microfilament organization elicited by either melatonin or PMA, while the Rho inhibitor C3, or the ROCK inhibitor Y27632, abolished the bipolar neurite morphology of N1E-115 cells. Instead, these inhibitors prompted neurite ramification. ROCK activity measured in whole cell extracts and in N1E-115 cells was increased in the presence of melatonin and PMA. The results indicate that melatonin increases the number of cells with immature neurites and suggest that these neurites can be susceptible to differentiation by incoming extracellular signals. Data also indicate that PKC and ROCK are involved at initial stages of neurite formation in the mechanism by which melatonin recruits cells for later differentiation. [source]

Melatonin increases stress fibers and focal adhesions in MDCK cells: participation of Rho-associated kinase and protein kinase C

JOURNAL OF PINEAL RESEARCH, Issue 2 2007
Gerardo Ramírez-Rodríguez
Abstract:, Melatonin cyclically modifies water transport measured as dome formation in MDCK cells. An optimal increase in water transport, concomitant with elevated stress fiber (SF) formation, occurs at nocturnal plasma melatonin concentrations (1 nm) after 6 hr of incubation. Blockage in melatonin-elicited dome formation was observed with protein kinase C (PKC) inhibitors. Despite, this information on the precise mechanism by which melatonin increases SF formation involved in water transport is not known. Focal adhesion contacts (FAC) are cytoskeletal structures, which participate in MDCK membrane polarization. SF organization and vinculin phosphorylation are involved in FAC assembly and both processes are mediated by PKC, an enzyme stimulated by melatonin; in these processes also involved is Rho-associated kinase (ROCK). Thus, we studied FAC formation and the ROCK/PKC pathway as the mechanism by which melatonin increases SF formation and water transport. The results showed that 1 nM melatonin and the PKC agonist phorbol-12-miristate-13-acetate increased FAC. The PKC inhibitor GF109203x, and the ROCK inhibitor Y27632, blocked increased FAC caused by melatonin. ROCK and PKC activities, vinculin phosphorylation and FAC formation were increased with melatonin. The PKC inhibitor, GF109203x, abolished both melatonin stimulated FAC in whole cells and ROCK activity, indicating that ROCK is a downstream kinase in the melatonin-stimulated PKC pathway in MDCK cultured cells that causes an increase in SF and FAC formation. Data also document that melatonin modulates water transport through modifications of the cytoskeletal structure. [source]

LIM kinase-2 targeting as a possible anti-metastasis therapy

THE JOURNAL OF GENE MEDICINE, Issue 3 2004
Eigo Suyama
Abstract Background Metastatic properties of tumors involve movement of cancerous cells from one place to another and tissue invasion. Metastatic cells have altered cell adhesion and movement that can be examined by in vitro chemotaxis assays. The Rho/ROCK/LIM kinase pathway is one of the major signaling pathways involved in tumor metastasis. It is involved in the regulation of the actin cytoskeleton. Using the randomized ribozyme library, we initially found that metastatic human fibrosarcoma cells harboring ribozyme specific for ROCK lose their metastatic properties. In this study, we have determined the effect of ribozymes specific for LIM kinase-2 on metastatic and proliferative phenotypes of human fibrosarcoma cells. Methods We attempted to target LIM kinase-2 (LIMK-2) expression by hammerhead ribozymes (Rz) in human metastatic fibrosarcoma cells. An effective ribozyme was selected based on the expression analysis. Cells were stably transfected with Rz specifically effective for LIMK-2 and were examined for metastatic and proliferative properties. Results Analyses of cellular phenotypes such as cell proliferation, cell migration and colony-forming efficiency revealed that the suppression of LIMK-2 expression in human fibrosarcoma cells limits their migration and dense colony-forming efficiency without affecting cell proliferation rate or viability. Conclusions Specific targeting of metastatic and malignant properties of tumor cells by LIMK-2 ribozyme may serve as an effective therapy for invasive tumors with minimum effect on the surrounding normal cells. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Cortistatin,A is a High-Affinity Ligand of Protein Kinases ROCK, CDK8, and CDK11,

ANGEWANDTE CHEMIE, Issue 47 2009
Victor
Antiproliferatives Alkaloid: Cortistatin,A ist ein hochaffiner Ligand für einen kleinen Satz von Proteinkinasen, einschließlich der Rho-assoziierten Proteinkinase (ROCK), der Cyclin-abhängigen Kinase,8 (CDK8) und der Cyclin-abhängigen Kinase,11 (CDK11). Modelle von Cortistatin,A im Komplex mit einer kristallographischen Struktur von ROCK (siehe Bild) und ein Homologiemodell von CDK8 werden präsentiert. [source]

Rho kinase,dependent activation of SOX9 in chondrocytes

ARTHRITIS & RHEUMATISM, Issue 1 2010
Dominik R. Haudenschild
Objective The transcription factor SOX9 directly regulates the expression of the major proteoglycans and collagens comprising the cartilage extracellular matrix. The DNA binding activity and cellular localization of SOX9 is controlled through posttranslational modifications, including phosphorylation. The activity of Rho kinase (ROCK) has profound effects on the actin cytoskeleton, and these effects are instrumental in determining the phenotype and differentiation of chondrocytes. However, the mechanisms linking ROCK to altered chondrocyte gene expression remain unknown. The purpose of the present study was to test for a direct interaction between ROCK and SOX9. Methods Human SW1353 chondrosarcoma cells were transfected with constructs coding for RhoA, ROCK, Lim kinase, and SOX9. The interaction between ROCK and SOX9 was tested on purified proteins, and was verified within a cellular context using induced overexpression and activation of the Rho pathway. The effects of SOX9 transcriptional activation were quantified with a luciferase reporter plasmid containing SOX9 binding sites from the COL2A1 enhancer element. Results SOX9 was found to contain a consensus phosphorylation site for ROCK. In vitro, ROCK directly phosphorylated SOX9 at Ser181, and the overexpression of ROCK or the activation of the RhoA pathway in SW1353 chondrosarcoma cells increased SOX9Ser181 phosphorylation. ROCK caused a dose-dependent increase in the transcription of a SOX9-luciferase reporter construct, and increased phosphorylation and nuclear accumulation of SOX9 protein in response to transforming growth factor , treatment and mechanical compression. Conclusion These results demonstrate a new interaction that directly links ROCK to increased cartilage matrix production via activation of SOX9 in response to mechanical and growth factor stimulation. [source]

Enhancement of cell recovery for dissociated human embryonic stem cells after cryopreservation

BIOTECHNOLOGY PROGRESS, Issue 3 2010
Xia Xu
Abstract Due to widespread applications of human embryonic stem (hES) cells, it is essential to establish effective protocols for cryopreservation and subsequent culture of hES cells to improve cell recovery. We have developed a new protocol for cryopreservation of dissociated hES cells and subsequent culture. We examined the effects of new formula of freezing solution containing 7.5% dimethylsulfoxide (DMSO) (v/v %) and 2.5% polyethylene glycol (PEG) (w/v %) on cell survival and recovery of hES cells after cryopreservation, and further investigated the role of the combination of Rho-associated kinase (ROCK) inhibitor and p53 inhibitor on cell recovery during the subsequent culture. Compared with the conventional slow-freezing method which uses 10% DMSO as a freezing solution and then cultured in the presence of ROCK inhibitor at the first day of culture, we found out that hES cell recovery was significantly enhanced by around 30 % (P < 0.05) by the new freezing solution. Moreover, at the first day of post-thaw culture, the presence of 10 ,M ROCK inhibitor (Y-27632) and 1 ,M pifithrin-, together further significantly improved cell recovery by around 20% (P < 0.05) either for feeder-dependent or feeder-independent culture. hES cells remained their undifferentiated status after using this novel protocol for cryopreservation and subsequent culture. Furthermore, this protocol is a scalable cryopreservation method for handling large quantities of hES cells. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source]

Characterization of G proteins involved in activation of nonselective cation channels by endothelinB receptor

BRITISH JOURNAL OF PHARMACOLOGY, Issue 7 2002
Yoshifumi Kawanabe
We recently demonstrated that endothelin-1 (ET-1) activates two types of Ca2+ -permeable nonselective cation channels (NSCC-1 and NSCC-2) in Chinese hamster ovary cells expressing endothelinB receptors (CHO-ETBR) that couple with Gq and Gi. The purpose of the present study was to identify the G proteins involved in the activation of these Ca2+ channels by ET-1. For this purpose, we constructed CHO cells expressing an unpalmitoylated (Cys402Cys403 Cys405,Ser402Ser403Ser405) ETBR (CHO-SerETBR) and ETBR truncated at the cytoplasmic tail downstream of Cys403 (CHO-ETBR,403). Based on the data obtained from actin stress fibre formation, CHO-ETBR couple with G13. Therefore, CHO-ETBR couple with Gq, Gi and G13. CHO-SerETBR and CHO-ETBR,403 couple with G13 and Gq, respectively. ET-1 activated NSCC-1 in CHO-ETBR preincubated with phospholipase C (PLC) inhibitor, U73122, and in CHO-SerETBR. On the other hand, ET-1 failed to activate Ca2+ channels in CHO-ETBR,403. Microinjection of dominant negative mutants of G13 (G13G225A) abolished activation of NSCC-1 and NSCC-2 in CHO-ETBR and that of NSCC-1 in CHO-SerETBR. Y-27632, a specific Rho-associated kinase (ROCK) inhibitor, did not affect the ET-1-induced transient and sustained increase in [Ca2+]i in CHO-ETBR. These results indicate that (1) the cytoplasmic tail downstream of the palmitoylation sites of ETBR, but not the palmitoylation site itself, is essential for coupling with G13, (2) the activation mechanism of each Ca2+ channel by ET-1 is different in CHO-ETBR. NSCC-1 activation depends on G13 -dependent cascade, and NSCC-2 activation depends on both Gq/PLC- and G13 -dependent cascades. Moreover, ROCK-dependent cascade is not involved in the activation of these channels. British Journal of Pharmacology (2002) 136, 1015,1022. doi:10.1038/sj.bjp.0704805 [source]

Interleukin-1 receptor phosphorylation activates Rho kinase to disrupt human gastric tight junctional claudin-4 during Helicobacter pylori infection

CELLULAR MICROBIOLOGY, Issue 5 2010
Tamia K. Lapointe
Summary Helicobacter pylori infects more than half of the human population worldwide. In the absence of treatment, this persistent infection leads to asymptomatic gastritis, which in some cases can progress into gastric ulcers and adenocarcinomas. The host,microbial interactions that govern the clinical outcome of infection remain incompletely understood. H. pylori is known to disrupt gastric epithelial tight junctions, which may represent a significant component of disease pathogenesis. The present study demonstrates that H. pylori disrupt epithelial tight junctional claudin-4 in a Rho kinase (ROCK)-dependent manner in human gastric epithelial (HGE-20) cell monolayers, independently of the virulence factors CagA and VacA, and without altering claudin-4 transcription. In the same epithelial cell model, interleukin (IL)-1,, mediated a similar ROCK-dependent pattern of tight junction disruption. Further experiments revealed that H. pylori infection induced IL-1 receptor type I (IL-1RI) phosphorylation, independently of epithelial secretion of its endogenous ligands IL-1,, IL-1, or IL-18. Finally, inhibition of IL-1RI activation prevented H. pylori -induced ROCK activation and claudin-4 disruption. Taken together, these findings identify a novel pathophysiological mechanism by which H. pylori disrupts gastric epithelial barrier structure via IL-1RI-dependent activation of ROCK, which in turn mediates tight junctional claudin-4 disruption. [source]

AN EVALUATION OF SURFACE HARDNESS OF NATURAL AND MODIFIED ROCKS USING SCHMIDT HAMMER: STUDY FROM NORTHWESTERN HIMALAYA, INDIA

GEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 3 2009
VIKRAM GUPTA
ABSTRACT. Four rock types (quartz mica gneiss, schist, quartzite and calc-silicate) located in the Satluj and Alaknanda valleys were used to test whether a Schmidt hammer can be used to distinguish rock surfaces affected by various natural and man-induced processes like manual smoothing of rock surfaces by grindstone, surface weathering, deep weathering, fluvial polishing and blasting during road construction. Surfaces polished by fluvial process yielded the highest Schmidt hammer rebound (R-) values and the blast-affected surfaces yielded the lowest R-values for the same rock type. Variations in R-value also reflect the degree of weathering of the rock surfaces. It has been further observed that, for all the rock types, the strength of relationship between R-values for the treated surfaces (manual smoothing of rock surface by grindstone) and the unconfined compressive strength (UCS) is higher than for the fresh natural surfaces. [source]

VARIATIONS IN COMPOSITION, PETROLEUM POTENTIAL AND KINETICS OF ORDOVICIAN , MIOCENE TYPE I AND TYPE I-II SOURCE ROCKS (OIL SHALES): IMPLICATIONS FOR HYDROCARBON GENERATION CHARACTERISTICS

JOURNAL OF PETROLEUM GEOLOGY, Issue 1 2010
H. I. Petersen
Lacustrine and marine oil shales with Type I and Type I-II kerogen constitute significant petroleum source rocks around the world. Contrary to common belief, such rocks show considerable compositional variability which influences their hydrocarbon generation characteristics. A global set of 23 Ordovician , Miocene freshwater and brackish water lacustrine and marine oil shales has been studied with regard to their organic composition, petroleum potential and generation kinetics. In addition their petroleum generation characteristics have been modelled. The oil shales can be classified as lacosite, torbanite, tasmanite and kukersite. They are thermally immature. Most of the shales contain >10 wt% TOC and the highest sulphur contents are recorded in the brackish water and marine oil shales. The kerogen is sapropelic and is principally composed of a complex of algal-derived organic matter in the form of: (i) telalginite (Botryococcus-, Prasinophyte- (Tasmanites?) or Gloeocapsomorpha-type); (ii) lamalginite (laminated, filamentous or network structure derived from Pediastrum- or Tetraedron-type algae, from dinoflagellate/acritarch cysts or from thin-walled Prasinophyte-type algae); (iii) fluorescing amorphous organic matter (AOM) and (iv) liptodetrinite. High atomic H/C ratios reflect the hydrogen-rich Type I and Type I-II kerogen, and Hydrogen Index values generally >300 mg HC/g TOC and reaching nearly 800 mg HC/g TOC emphasise the oil-prone nature of the oil shales. The kerogen type and source rock quality appear not to be related to age, depositional environment or oil shale type. Therefore, a unique, global activation energy (Ea) distribution and frequency factor (A) for these source rocks cannot be expected. The differences in kerogen composition result in considerable variations in Ea -distributions and A-factors. Generation modelling using custom kinetics and the known subsidence history of the Malay-Cho Thu Basin (Gulf of Thailand/South China Sea), combined with established and hypothetical temperature histories, show that the oil shales decompose at different rates during maturation. At a maximum temperature of ,120°C reached during burial, only limited kerogen conversion has taken place. However, oil shales characterised by broader Ea -distributions with low Ea -values (and a single approximated A-factor) show increased decomposition rates. Where more deeply buried (maximum temperature ,150°C), some of the brackish water and marine oil shales have realised the major part of their generation potential, whereas the freshwater oil shales and other brackish water oil shales are only ,30,40% converted. At still higher temperatures between ,165°C and 180°C all oil shales reach 90% conversion. Most hydrocarbons from these source rocks will be generated within narrow oil windows (,20,80% kerogen conversion). Although the brackish water and marine oil shales appear to decompose faster than the freshwater oil shales, this suggests that with increasing heatflow the influence of kerogen heterogeneity on modelling of hydrocarbon generation declines. It may thus be critical to understand the organic facies of Type I and Type I-II source rocks, particularly in basins with moderate heatflows and restricted burial depths. Measurement of custom kinetics is recommended, if possible, to increase the accuracy of any computed hydrocarbon generation models. [source]

PETROPHYSICAL CHARACTERISTICS OF SOURCE AND RESERVOIR ROCKS IN THE HISTRIA BASIN, WESTERN BLACK SEA

JOURNAL OF PETROLEUM GEOLOGY, Issue 4 2009
C. Cranganu
The petroleum system in the Histria Basin, Western Black Sea, includes Oligocene source rocks and Upper Cretaceous , Eocene reservoir rocks. Here we report on the petrophysical characteristics of these source and reservoir rocks using mercury intrusion porosimetry data from 14 core samples collected from five wells drilled on the East Lebada, West Lebada and Pescarus structures. Samples were in general dominated by carbonate lithologies with minor shales. Petrophysical parameters analyzed were: median pore-throat radius, average pore-throat radius, apparent porosity, pore-throat size distribution, pore-throat type, pore-throat sorting, maximum threshold entry radius, pore-throat radius at 35% mercury saturation (R35), and air permeability. Reservoir rock quality was estimated using a permeability / porosity / pore-throat type plot. The Oligocene samples showed little petrophysical variation. Samples were relatively homogenous and had the same pore-throat type (nano), were well sorted, had unimodal pore-throat distribution (suggesting the existence of a single fluid phase), had similar values for median and average pore-throat radius, and similar values for R35 and maximum threshold entry radius. Upper Cretaceous , Eocene samples were more heterogeneous in terms of petrophysical properties, and reservoir quality was in general higher than in the Oligocene interval. Average porosity and calculated air-permeability values were 18.4% and 0.37 mD, respectively for Upper Cretaceous samples; and 11.8% and 27.11 mD, respectively for Eocene samples. A case study of Oligocene and Cretaceous , Eocene samples from well West Lebada 817 is presented. This paper represents the first petrophysical study of source and reservoir rocks in the Histria Basin, Western Black Sea. The results will help to establish the links between petrophysical characteristics, age and depositional environment for source and reservoir rocks in other basins bordering the Black Sea. [source]

HYDROTHERMALLY FLUORITIZED ORDOVICIAN CARBONATES AS RESERVOIR ROCKS IN THE TAZHONG AREA, CENTRALTARIM BASIN, NW CHINA

JOURNAL OF PETROLEUM GEOLOGY, Issue 1 2006
Zhijun Jin
Reservoir rocks at the Tazhong 45 oil pool, central Tarim Basin, consist of fluoritized carbonate strata of Middle - Late Ordovician age. Petrological observations indicate that the fluorite replaces calcite. Several other hydrothermal minerals including pyrite, quartz, sphalerite and chlorite accompany the fluorite. Two generations of fluid inclusions are present in the fluorite. Homogenization temperatures (Th) for primary inclusions are mostly between 260°C and 310°C and represent the temperature of the hydrothermal fluid responsible for fluorite precipitation. Th for secondary inclusions range from 100°C to 130°C, and represent the hydrocarbon charging temperature as shown by the presence of hydrocarbons trapped in some secondary inclusions. The mineral assemblage and the homogenization temperatures of the primary fluid inclusions indicate that the precipitation of fluorite is related to hydrothermal activity in the Tazhong area. Strontium isotope analyses imply that the hydrothermal fluids responsible for fluorite precipitation are related to late-stage magmatic activity, and felsic magmas were generated by mixing of mafic magma and crustal materials during the Permian. Theoretical calculations show that the molecular volume of a carbonate rock decreases by 33.5% when calcite is replaced by fluorite, and the volume shrinkage can greatly enhance reservoir porosity by the formation of abundant intercrystalline pores. Fluoritization has thus greatly enhanced the reservoir quality of Ordovician carbonates in the Tazhong 45 area, so that the fluorite and limestone host rocks have become an efficient hydrocarbon reservoir. According to the modelled burial and thermal history of the Tazhong 45 well, and the homogenization temperatures of secondary fluid inclusions in the fluorite, hydrocarbon charging at the Tazhong 45 reservoir took place in the Tertiary. [source]

EVALUATION OF THE CONTROLS ON FRACTURING IN RESERVOIR ROCKS

JOURNAL OF PETROLEUM GEOLOGY, Issue 4 2005
D.C.P. Peacock
The style, geometry and distribution of fractures within reservoir rocks can be controlled by numerous factors, including: rock characteristics and diagenesis (lithology, sedimentary structures, bed thickness, mechanical stratigraphy, the mechanics of bedding planes); structural geology (tectonic setting, palaeostresses, subsidence and uplift history, proximity to faults, position in a fold, timing of structural events, mineralisation, the angle between bedding and fractures); and present-day factors, such as orientations of in situ stresses, fluid pressure, perturbation of in situ stresses and depth. The relative timing of events plays a crucial role in determining the geometry and distribution of fractures. For example, open fractures are commonly clustered around faults if the open fractures and faults formed at the same time, but clustering does not tend to occur if the open fractures pre-date or post-date the faults. Understanding these factors requires traditional geological skills, including the analysis of one-dimensional (line-sampling) data from core, borehole images and exposed analogues. This paper reviews the factors that control fractures within reservoir rocks and discusses methods to assess those controls. Examples are presented from Mesozoic limestones in southern England. It is shown that traditional geological skills are of vital importance in determining the rock characteristics, structural and present-day factors that control fractures. [source]

DISTRIBUTION OF SOURCE ROCKS AND MATURITY MODELLING IN THE NORTHERN CENOZOIC SONG HONG BASIN (GULF OF TONKIN), VIETNAM

JOURNAL OF PETROLEUM GEOLOGY, Issue 2 2005
C. Andersen
The northern offshore part of the Cenozoic Song Hong Basin in the Gulf of Tonkin (East Vietnam Sea) is at an early stage of exploration with only a few wells drilled. Oil to source rock correlation indicates that coals are responsible for the sub-commercial oil and gas accumulations in sandstones in two of the four wells which have been drilled on faulted anticlines and flower structures. The wells are located in a narrow, structurally inverted zone with a thick predominantly deltaic Miocene succession between the Song Chay and Vinh Ninh/Song Lo fault zones. These faults are splays belonging to the offshore extension of the Red River Fault Zone. Access to a database of 3,500 km of 2D seismic data has allowed a detailed and consistent break-down of the geological record of the northern part of the basin into chronostratigraphic events which were used as inputs to model the hydrocarbon generation history. In addition, seismic facies mapping, using the internal reflection characteristics of selected seismic sequences, has been applied to predict the lateral distribution of source rock intervals. The results based on Yükler ID basin modelling are presented as profiles and maturity maps. The robustness of the results are analysed by testing different heat flow scenarios and by transfer of the model concept to IES Petromod software to obtain a more acceptable temperature history reconstruction using the Easy%R0 algorithm. Miocene coals in the wells located in the inverted zone between the fault splays are present in separate intervals. Seismic facies analysis suggests that the upper interval is of limited areal extent. The lower interval, of more widespread occurrence, is presently in the oil and condensate generating zones in deep synclines between inversion ridges. The Yükler modelling indicates, however, that the coaly source rock interval entered the main window prior to formation of traps as a result of Late Miocene inversion. Lacustrine mudstones, similar to the highly oil-prone Oligocene mudstones and coals which are exposed in the Dong Ho area at the northern margin of the Song Hong Basin and on Bach Long Vi Island in Gulf of Tonkin, are interpreted to be preserved in a system of undrilled NW,SE Paleogene half-grabens NE of the Song Lo Fault Zone. This is based on the presence of intervals with distinct, continuous, high reflection seismic amplitudes. Considerable overlap exists between the shale-prone seismic facies and the modelled extent of the present-day oil and condensate generating zones, suggesting that active source kitchens also exist in this part of the basin. Recently reported oil in a well located onshore (BIO-STB-IX) at the margin of the basin, which is sourced mainly from "Dong Ho type" lacustrine mudstones supports the presence of an additional Paleogene sourced petroleum system. [source]

HYDROCARBON POTENTIAL OF JURASSIC SOURCE ROCKS IN THE JUNGGAR BASIN, NW CHINA

JOURNAL OF PETROLEUM GEOLOGY, Issue 3 2003
A. N. Ding
Jurassic source rocks in the Junggar Basin (NW China) include coal swamp and freshwater lacustrine deposits. Hydrocarbon-generating macerals in the coal swamp deposits are dominated by desmocollinite and exinite of higher-plant origin. In lacustrine facies, macerals consists of bacterially-altered amorphinite, algal- amorphinite, alginite, exinite and vitrinite. Coals and coaly mudstones in the Lower Jurassic Badaowan Formation generate oil at the Qigu oilfield on the southern margin of the basin. Lacustrine source rocks generate oil at the Cainan oilfield in the centre of the basin. The vitrinite reflectance (Ro) of coal swamp deposits ranges from 0.5% to 0.9%, and that of lacustrine source rocks from 0.4% to 1.2%. Biomarker compositions likewise indicate that thermal maturities are variable. These variations cause those with lighter compositions to have matured earlier. Our data indicate that oil and gas generation has occurred at different stages of source-rock maturation, an "early" stage and a "mature" stage. Ro values are 0.4%,0.7% in the former and 0.8%,1.2% in the latter. [source]

THE RESERVOIR POTENTIAL OF MIOCENE CARBONATE ROCKS IN THE ASKALE AND HINIS-MUS-VAN SUB-BASINS, EAST ANATOLIA, TURKEY

JOURNAL OF PETROLEUM GEOLOGY, Issue 2 2003
A. G. Büyükutku
Lower-middle Miocene limestones in East Anatolia (eastern Turkey) assigned to the Adilcevaz Formation were studied using core and cuttings data from eight wells in the Tertiary Askale and Hinis-Mus-Van sub-basins. Their depositional environment, diagenetic characteristics and reservoir quality are reviewed. The Adilcevaz Formation carbonates are up to 225m thick. Abundant bioclasts are dominated by corals, encrusting red algae, bryozoans, and benthonic and planktonic foraminifera. Reef-core, fore-reef and back-reef facies were recognized. The preservation of primary porosity is generally poor as a result of late calcite cementation. Porosity is mainly present as moulds, vugs and interparticle types, which are best developed in the fore-reef and reef-core facies. However these pores are poorly connected and permeability is generally less than 0.1 mD. In contrast to coeval limestones of similiar facies in Iran, Iraq and other parts of the Middle East, the Adilcevaz Formation has little reservoir potential. [source]

FAULT-RELATED SOLUTION CLEAVAGE IN EXPOSED CARBONATE RESERVOIR ROCKS IN THE SOUTHERN APENNINES, ITALY

JOURNAL OF PETROLEUM GEOLOGY, Issue 2 2001
A. Billi
The deformation associated with a number of kilometre-scale strike-slip fault zones which cut through outcropping carbonate rocks in the Southern Apennines was investigated at regional and outcrop scales. These faults trend roughly east-west and were studied at the Gargano Promontory on the Adriatic Coast (in the Apulian foreland) and in the Matese Mountains, about 120 km to the west (within the Apenninic fold-and-thrust belt). The fault zones are 200,300 m wide and typically comprise a core surrounded by a damage zone. Within fault cores, fault rocks (gouges and cataclasites) typically occur along master slip planes; in damage zones, secondary slip planes and solution cleavage are the most important planar discontinuities. The protolith carbonates surrounding the fault zone at Gargano show little deformation, but they are fractured in the Matese Mountains as a result of an earlier thrust phase. Cleavage surfaces in the damage zone of the studied faults are interpreted to be fault-propagation structures. Our field data indicate that cleavage-fault intersection lines are parallel to the normals of fault slip-vectors. The angle between a fault plane and the associated cleavage was found to be fairly constant (c. 40") at different scales of observation. Finally, the spacing of the solution cleavage surfaces appeared in general to be regular (with a mean of about 22 mm), although it was found to decrease slightly near a fault plane. These results are intended to provide a basis for predicting the architecture of fault zones in buried carbonate reservoirs using seismic reflection and borehole data. [source]

THE EVOLUTION OF A MODEL TRAP IN THE CENTRAL APENNINES, ITALY: FRACTURE PATTERNS, FAULT REACTIVATION AND DEVELOPMENT OF CATACLASTIC ROCKS IN CARBONATES AT THE NARNI ANTICLINE

JOURNAL OF PETROLEUM GEOLOGY, Issue 2 2001
F. Storti
Recent hydrocarbon discoveries in the Southern Apennines of Italy have focussed attention on the importance of studying fracturing and cataclasis in carbonate rocks because of their fundamental impact on reservoir permeability and connectivity. The Narni Anticline in the central Apennines consists of a stack of easterly-verging carbonate thrust sheets compartmentalized by extensional and strike-slip fault zones. The structure provides afield analogue for studying the evolution of superimposed fold- and fault-related fractures in carbonate reservoir rocks. The fracture pattern at the Narni Anticline developed as a result of three mechanisms: (a) layer-parallel shortening predating folding and faulting; (b) thrust-related folding and further thrust breakthrough; and (c) extensional and strike-slip faulting. Along-strike (longitudinal) fractures developed during progressive rollover fault-propagation folding, and their intensity depends on the precise structural position within the fold: fracture intensity is high in the forelimb and low in the crest. The 3-D architecture of the mechanical anisotropy associated with thrusting, folding, and related fracturing constrained the location and geometry of subsequent extensional and strike-slip faulting. The superimposition in damage zones of a fault-related cleavage on the pre-existing fracture pattern, which is associated with layer-parallel shortening and thrust-related folding, resulted in rock fragmentation and comminution, and the development of cataclastic bands. The evolution of fracturing in the Narni Anticline, its role in constraining thrust breakthrough trajectories and the location of extensional and strike-slip faults, and the final development of low-permeability cataclastic bands, will be relevant to studies of known oilfields in the Southern Apennines, as well as for future exploration. [source]