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Molecular Mechanisms Underlying (molecular + mechanism_underlying)
Selected AbstractsCalorie restriction alters mitochondrial protein acetylationAGING CELL, Issue 5 2009Bjoern Schwer Summary Calorie restriction (CR) increases lifespan in organisms ranging from budding yeast through mammals. Mitochondrial adaptation represents a key component of the response to CR. Molecular mechanisms underlying this adaptation are largely unknown. Here we show that lysine acetylation of mitochondrial proteins is altered during CR in a tissue-specific fashion. Via large-scale mass spectrometry screening, we identify 72 candidate proteins involved in a variety of metabolic pathways with altered acetylation during CR. Mitochondrial acetylation changes may play an important role in the pro-longevity CR response. [source] Potential attenuation of p38 signaling by DDB2 as a factor in acquired TNF resistanceINTERNATIONAL JOURNAL OF CANCER, Issue 3 2005Chun-Ling Sun Abstract Our previous study demonstrated that DDB2, a DNA repair protein, attenuates cell surface membrane-associated death signal induced by UV or FasAb; DDB2 is overexpressed in cisplatin-selected cells. However, the molecular mechanism underlying the protective role of DDB2 along the apoptotic pathway remains unknown. Our study identified the cross-resistance of the cisplatin-selected cells to tumor necrosis factor-, (TNF-,). Since knock-down of the DDB2 level rendered cells (HR18) sensitive to the treatment, the cell sensitivity to TNF-, appears inversely proportional to the cellular level of DDB2. Treatment of HeLa cells with TNF-, transiently induced activation of p38MAPK signal, but this induction was significantly reduced in the resistant cells. Overexpression of DDB2 attenuated the activation of p38 in cells. TNF-,-induced apoptotic signals, represented by caspase-8 and downstream substrate cleavage, were reduced in resistant cells compared to their sensitive counterparts. Inhibition of p38 signal by SB202190 clearly attenuated TNF-,-induced apoptotic signals. Moreover, overexpression of DDB2 in HR18 cells also attenuated TNF-, induced caspase activation. These results suggest that p38MAPK activation may be a key upstream signal of TNF-,-induced apoptosis and that attenuation of p38 signal by DDB2 overexpression may be responsible for acquired TNF-, resistance. © 2005 Wiley-Liss, Inc. [source] The combination of polymorphisms within MCP-1 and IL-1, associated with ulcerative colitisINTERNATIONAL JOURNAL OF IMMUNOGENETICS, Issue 3 2009K.-S. Li Summary Monocyte chemoattractant protein-1 (MCP-1) is a chemokine involved in monocyte recruitment to sites of inflammation. Raised level of MCP-1 has been widely demonstrated in the intestinal mucosa of patients with ulcerative colitis (UC), suggesting an important role of MCP-1 in the pathogenesis of UC. The ,2518A/G polymorphism in the promoter region of MCP-1 gene affecting its transcriptional activation has been reported recently. In order to assess the potential role of this polymorphism in UC, we examined its distribution in 162 unrelated UC patients and 203 healthy controls. In addition, considering the gene regulatory association between interleukin-1, (IL-1,) and MCP-1, we further examined whether the gene polymorphisms between MCP-1 and IL-1, exert synergetic effects on risk of UC. Our results show that the distribution of MCP-1 genotype or allele frequencies between UC patients and controls was not significantly different; however, the association between the polymorphism of MCP-1 ,2518 GG and the polymorphism of IL-1,,511 T in UC patients is significant (OR 2.062, 95% CI 1.034,4.113, P = 0.038). This is the first report describing the association between MCP-1 polymorphism and UC, and our data suggest that the MCP-1 ,2518 polymorphism itself does not represent an independent genetic risk factor for UC. In contrast, the combination polymorphisms between MCP-1 and IL-1, can increase UC risk significantly, which might help us understand the molecular mechanism underlying the development of UC. [source] Lycopene Inhibits LPS-Induced Proinflammatory Mediator Inducible Nitric Oxide Synthase in Mouse Macrophage CellsJOURNAL OF FOOD SCIENCE, Issue 1 2007Mohamed M. Rafi ABSTRACT:, Lycopene is a fat-soluble red-orange carotenoid found primarily in tomatoes and tomato-derived products, including tomato sauce, tomato paste, and ketchup, and other dietary sources, including dried apricots, guava, watermelon, papaya, and pink grapefruit. In this study, we have demonstrated the molecular mechanism underlying the anti-inflammatory properties of lycopene using a mouse macrophage cell line (RAW 264.7). Treatment with lycopene (10 ,M) inhibited lipopolysaccharide (LPS)-stimulated nitric oxide (NO) production (40% compared with the control). Western blotting and reverse transcription-polymerase chain reaction (RT-PCR) analysis showed that lycopene treatment decreased LPS-induced inducible nitric oxide synthase (iNOS) protein and mRNA expression in RAW 264.7 cells, respectively. These results suggest that lycopene has anti-inflammatory activity by inhibiting iNOS proteins and mRNA expressions in mouse macrophage cell lines. Furthermore, cyclooxygenase-2 (COX-2) protein and mRNA expression were not affected by treatment with lycopene. [source] Tubulin and CRMP-2 complex is transported via Kinesin-1JOURNAL OF NEUROCHEMISTRY, Issue 6 2005Nariko, Toshihide, Yuko Kimura Arimura Fukata Abstract The transport of tubulin and microtubules in a growing axon is essential for axonal growth and maintenance. However, the molecular mechanism underlying the linkage of tubulin and microtubules to motor proteins is not yet clear. Collapsin response mediator protein-2 (CRMP-2) is enriched at the distal part of growing axons in primary hippocampal neurons and plays a critical role in axon differentiation through its interaction with tubulin dimer and Numb. In this study, we show that CRMP-2 regulates tubulin transport by linking tubulin and Kinesin-1. The C-terminal region of CRMP-2 directly binds to the tetratricopeptide repeat domain of kinesin light chain 1 (KLC1). Soluble tubulin binds to the middle of CRMP-2 and forms a trimeric complex with CRMP-2/KLC1. Furthermore, the movement of GFP,tubulin in the photobleached area is weakened by knockdown of KLCs or CRMP-2. These results indicate that the CRMP-2/Kinesin-1 complex regulates soluble tubulin transport to the distal part of the growing axon. [source] Transcriptional regulation of mesencephalic dopaminergic neurons: The full circle of life and deathMOVEMENT DISORDERS, Issue 3 2008Kambiz N. Alavian PhD Abstract Since mesencephalic dopaminergic neurons are associated to one of the most prominent human neurodegenerative ailments, Parkinson's disease, the molecular mechanism underlying their development and adult cellular properties has been the subject of intense investigations. Throughout life, transcription factors determine the fate of this neuronal population and control essential processes such as localization in the ventral midbrain, their neurotransmitter phenotype, their target innervations and synapse formation. Studies of transcription factors, such as Nurr1, Pitx3, Engrailed-1/2, and Lmx1a/b, have not only revealed importance of these genes during development, but also roles in the long-term survival and maintenance of these neurons. In this review, we will discuss the function of these transcription factors throughout the life of mesencephalic dopaminergic neurons and their value in the study of the disease mechanism. © 2007 Movement Disorder Society [source] Effects of 4-week Treatment with Lithium and Olanzapine on Levels of Brain-derived Neurotrophic Factor, B-Cell CLL/Lymphoma 2 and Phosphorylated Cyclic Adenosine Monophosphate Response Element-binding Protein in the Sub-regions of the HippocampusBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 2 2009Michael D. Hammonds It has been suggested that up-regulation of neurotrophic and neuroprotective factors including brain-derived neurotrophic factor (BDNF) and B-cell CLL/lymphoma 2 (Bcl-2) may underlie these neuroplastic actions of the drug. Olanzapine, an atypical anti-psychotic drug, has been shown to be an effective mood stabilizer. Olanzapine also has neurotrophic and neuroprotective actions, and these actions may underlie the efficacy of the drug for bipolar disorder and schizophrenia. However, the molecular mechanism by which the drug produces the neuroplastic actions is poorly understood. To understand a common molecular mechanism underlying the neuroplastic actions of lithium and olanzapine, we assessed the effect of 4-week lithium and olanzapine treatment on the levels of BDNF, Bcl-2 and cyclic adenosine monophosphate response element-binding protein (CREB), a transcription factor involved in expression of BDNF and Bcl-2, in the dentate gyrus and hippocampal area CA1. Our results show that 4-week treatment with both olanzapine and lithium increases the levels of Bcl-2 and CREB in the dentate gyrus and hippocampal area CA1. Four-week lithium treatment up-regulates BDNF in the dentate gyrus, and 4-week olanzapine treatment marginally did so. Neither drug altered BDNF levels in area CA1. These results suggest that the up-regulation of Bcl-2 and CREB may underlie the neuroplastic actions of olanzapine and lithium. [source] Cell death induction by isothiocyanates and their underlying molecular mechanismsBIOFACTORS, Issue 2 2006Yoshimasa Nakamura Abstract An important and promising group of compounds that have a chemopreventive property are organosulfur compounds, such as isothiocyanates (ITCs). In recent years, it has been shown that ITCs induce apoptosis in various cancer cell lines and experimental rodents. During the course of apoptosis induction by ITC, multiple signal-transduction pathways and apoptosis intermediates are modulated. We have also clarified the molecular mechanism underlying the relationship between cell cycle arrest and apoptosis induced by benzyl isothiocyanate (BITC), a major ITC compound isolated from papaya. The exposure of cells to BITC resulted in the inhibition of the G2/M progression that coincided with not only the up-regulated expression of the G2/M cell cycle arrest-regulating genes but also the apoptosis induction. The experiment using the phase-specific synchronized cells demonstrated that the G2/M phase-arrested cells are more sensitive to undergoing apoptotic stimulation by BITC than the cells in other phases. We identified the phosphorylated Bcl-2 as a key molecule linking the p38 MAPK-dependent cell cycle arrest with the JNK activation by BITC. We also found that BITC induced the cytotoxic effect more preferentially in the proliferating normal human colon epithelial cells than in the quiescent cells. Conversely, treatment with an excessive concentration of BITC resulted in necrotic cell death without DNA ladder formation. This review addresses the biological impact of cell death induction by BITC as well as other ITCs and the involved signal transduction pathways. [source] Expression of constructs of the neuronal isoform of myosin-Va interferes with the distribution of melanosomes and other vesicles in melanoma cellsCYTOSKELETON, Issue 2 2002João Carlos da Silva Bizario Abstract Myosin-Va has been implicated in melanosome translocation, but the exact molecular mechanisms underlying this function are not known. In the dilute, S91 melanoma cells, melanosomes move to the cell periphery but do not accumulate in the tips of dendrites as occurs in wild-type B16 melanocytes; rather, they return and accumulate primarily at the pericentrosomal region in a microtubule-dependent manner. Expression of the full-length neuronal isoform of myosin-Va in S91 cells causes melanosomes to disperse, occupying a cellular area approximately twice that observed in non-transfected cells, suggesting a partial rescue of the dilute phenotype. Overexpression of the full tail domain in S91 cells is not sufficient to induce melanosome dispersion, rather it causes melanosomal clumping. Overexpression of the head and head-neck domains of myosin-Va in B16 cells does not alter the melanosome distribution. However, overexpression of the full tail domain in these cells induces melanosome aggregation and the appearance of tail-associated, aggregated particles or vesicular structures that exhibit variable degrees of staining for melanosomal and Golgi ,-COP markers, as well as colocalization with the endogenous myosin-Va. Altogether, the present data suggest that myosin-Va plays a role in regulating the direction of microtubule-dependent melanosome translocation, in addition to promoting the capture of melanosomes at the cell periphery as suggested by previous studies. These studies also reinforce the notion that myosin-V has a broader function in melanocytes by acting on vesicular targeting or intracellular protein trafficking. Cell Motil. Cytoskeleton 51:57,75, 2002. © 2002 Wiley-Liss, Inc. [source] Activity of nAChRs containing ,9 subunits modulates synapse stabilization via bidirectional signaling programsDEVELOPMENTAL NEUROBIOLOGY, Issue 14 2009Vidya Murthy Abstract Although the synaptogenic program for cholinergic synapses of the neuromuscular junction is well known, little is known of the identity or dynamic expression patterns of proteins involved in non-neuromuscular nicotinic synapse development. We have previously demonstrated abnormal presynaptic terminal morphology following loss of nicotinic acetylcholine receptor (nAChR) ,9 subunit expression in adult cochleae. However, the molecular mechanisms underlying these changes have remained obscure. To better understand synapse formation and the role of cholinergic activity in the synaptogenesis of the inner ear, we exploit the nAChR ,9 subunit null mouse. In this mouse, functional acetylcholine (ACh) neurotransmission to the hair cells is completely silenced. Results demonstrate a premature, effusive innervation to the synaptic pole of the outer hair cells in ,9 null mice coinciding with delayed expression of cell adhesion proteins during the period of effusive contact. Collapse of the ectopic innervation coincides with an age-related hyperexpression pattern in the null mice. In addition, we document changes in expression of presynaptic vesicle recycling/trafficking machinery in the ,9 null mice that suggests a bidirectional information flow between the target of the neural innervation (the hair cells) and the presynaptic terminal that is modified by hair cell nAChR activity. Loss of nAChR activity may alter transcriptional activity, as CREB binding protein expression is decreased coincident with the increased expression of N-Cadherin in the adult ,9 null mice. Finally, by using mice expressing the nondesensitizing ,9 L9,T point mutant nAChR subunit, we show that increased nAChR activity drives synaptic hyperinnervation. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2009 [source] Loss of steroidogenic factor 1 alters cellular topography in the mouse ventromedial nucleus of the hypothalamusDEVELOPMENTAL NEUROBIOLOGY, Issue 4 2004Aline M. Davis Abstract Knockout (KO) mice lacking the orphan nuclear receptor steroidogenic factor 1 (SF-1) exhibit marked structural abnormalities of the ventromedial nucleus of the hypothalamus (VMH). In this study, we sought to determine the molecular mechanisms underlying the VMH abnormalities. To trace SF-1-expressing neurons, we used a SF-1/enhanced green fluorescent protein (eGFP) transgene. Although the total numbers of eGFP-positive cells in wild-type (WT) and SF-1 KO mice were indistinguishable, cells that normally localize precisely within the VMH were scattered more diffusely in adjacent regions in SF-1 KO mice. This abnormal distribution is likely due to the loss of SF-1 expression in VMH neurons rather than secondary effects of deficient steroidogenesis, as redistribution also was seen in mice with a CNS-specific KO of SF-1. Thus, the absence of SF-1 alters the distribution of cells that normally form the VMH within the mediobasal hypothalamus. Consistent with this model, the hypothalamic expression patterns of the transcription factors islet-1 and nkx2.1 also were displaced in SF-1 KO mice. Independent of gene expression, birthdate analyses further suggested that cells with earlier birthdates were affected more severely by the loss of SF-1 than were later born cells. We conclude that the absence of SF-1 causes major changes in cellular arrangement within and around the developing VMH that result from altered cell migration. © 2004 Wiley Periodicals, Inc. J Neurobiol 60: 424,436, 2004 [source] Progenitor cells in the adult pancreasDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 1 2004Andrew M. Holland Abstract The ,-cell mass in the adult pancreas possesses the ability to undergo limited regeneration following injury. Identifying the progenitor cells involved in this process and understanding the mechanisms leading to their maturation will open new avenues for the treatment of type 1 diabetes. However, despite steady advances in determining the molecular basis of early pancreatic development, the identification of pancreatic stem cells or ,-cell progenitors and the molecular mechanisms underlying ,-cell regeneration remain unclear. Recent advances in the directed differentiation of embryonic and adult stem cells has heightened interest in the possible application of stem cell therapy in the treatment of type 1 diabetes. Drawing on the expanding knowledge of pancreas development, ,-cell regeneration and stem cell research, this review focuses on progenitor cells in the adult pancreas as a potential source of ,-cells. Copyright © 2004 John Wiley & Sons, Ltd. [source] Molecular mechanisms of insulin resistanceDIABETIC MEDICINE, Issue 6 2005S. Schinner Abstract Currently, we observe an epidemic expansion of diabetes mellitus. In subjects with Type 2 diabetes the resistance of fat, muscle and liver to insulin is the central pathophysiological event in the development of this disease. Genetic and environmental factors play a major role in this process, although the precise pathogenesis of insulin resistance and Type 2 diabetes is still largely unknown. However, recent studies have contributed to a deeper understanding of the molecular mechanisms underlying this process. In this review we therefore summarize the current developments in understanding the pathophysiological process of insulin resistance and Type 2 diabetes. Among the many molecules involved in the intracellular processing of the signal provided by insulin, insulin receptor substrate (IRS)-2, the protein kinase B (PKB)-, isoform and the forkhead transcription factor Foxo1a (FKHR) are of particular interest in this context as recent data have provided strong evidence that dysfunction of these proteins results in insulin resistance in-vivo. Furthermore, we have now increasing evidence that the adipose tissue not only produces free fatty acids that contribute to insulin resistance, but also acts as a relevant endocrine organ producing mediators (adipokines) that can modulate insulin signalling. The identification of the molecular pathophysiological mechanisms of insulin resistance and Type 2 diabetes is essential for the development of novel and more effective therapies to better treat our patients with insulin resistance and Type 2 diabetes. [source] A possible role for dihydrodiol dehydrogenase in the formation of benzo[a]pyrene-DNA adducts in lung cancer cells and tumor tissuesENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 1 2007Ya-Wen Cheng Abstract Epidemiological studies indicate that there is a gender difference in the susceptibility to tobacco and environmental carcinogens, and this gender difference is suspected to result in a higher risk for lung cancer among women. However, the molecular mechanisms underlying this sexual dimorphism remain unclear. In the present study, we have evaluated the roles of CYP1A1 and dihydrodiol dehydrogenase (DDH) in the formation of benzo[a]pyrene (BaP) DNA adducts in various lung cancer cell lines. Among six lung cancer cell lines tested, higher adduct levels were observed in CL-3 and CL1-1 cells, which had relatively high expression of both CYP1A1 and DDH isoform 1 (DHH1). To determine whether a reduction in DDH expression changed the adduct levels, an siRNA was used to knock down DDH1 expression in CL-3 cells. The BaP adduct levels in siDDH-CL-3 cells increased 1.4,2.2-fold relative to that of the parental CL-3 cells. We also examined BaP-like DNA adducts, and CYP1A1 and DDH1 expression by immunohistochemistry in 120 lung tumors. Detection of DNA adducts correlated with CYP1A1-positive tumors (P = 0.023), but not with DDH1-positive tumors. In addition, 28 of 33 tumors (85%) that were CYP1A1-positive and DDH1-negative contained detectable levels of DNA adducts, a proportion that was higher than for tumors from the other three categories of CYP1A1 and DDH1 expression (P = 0.012). Finally, a greater proportion of adduct-positive tumors from females were CYP1A1-positive/DDH1-negative (45.3%) than were tumors from males (27.3%). These results suggest that the reduction of DDH expression in lung tumors may contribute to an increase in DNA adduct levels, which may be partly responsible for the higher susceptibility of female lung cancer patients to DNA damage. Environ. Mol. Mutagen., 2007. © 2006 Wiley-Liss, Inc. [source] Proteomic Identification of the Involvement of the Mitochondrial Rieske Protein in EpilepsyEPILEPSIA, Issue 3 2005Heike Junker Summary:,Purpose: Kindled seizures are widely used to model epileptogenesis, but the molecular mechanisms underlying the attainment of kindling status are largely unknown. Recently we showed that achievement of kindling status in the Sprague,Dawley rat is associated with a critical developmental interval of 25 ± 1 days; the identification of this long, well-defined developmental interval for inducing kindling status makes possible a dissection of the cellular and genetic events underlying this phenomenon and its relation to normal and pathologic brain function. Methods: By using proteomics on cerebral tissue from our new rat kindling model, we undertook a global analysis of protein expression in kindled animals. Some of the identified proteins were further investigated by using immunohistochemistry. Results: We report the identification of a modified variant of the Rieske iron-sulfur protein, a component of the mitochondrial cytochrome bc1 complex, whose isoelectric point is shifted toward more alkaline values in the hippocampus of kindled rats. By immunohistochemistry, the Rieske protein is well expressed in the hippocampus, except in the CA1 subfield, an area of selective vulnerability to seizures in humans and animal models. We also noted an asymmetric, selective expression of the Rieske protein in the subgranular neurons of the dorsal dentate gyrus, a region implicated in neurogenesis. Conclusions: These results indicate that the Rieske protein may play a role in the response of neurons to seizure activity and could give important new insights into the molecular pathogenesis of epilepsy. [source] AgC10, a mucin from Trypanosoma cruzi, destabilizes TNF and cyclooxygenase-2 mRNA by inhibiting mitogen-activated protein kinase p38EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 6 2004Pilar Alcaide Abstract Secretion of proinflammatory mediators by activated macrophages plays an important role in the immune response to Trypanosoma cruzi. We have previously reported that AgC10, a glycosylphosphatidylinositol-anchored mucin from T. cruzi, inhibits TNF secretion by activated macrophages (de Diego, J., Punzon, C., Duarte, M. and Fresno, M., Alteration of macrophage function bya Trypanosoma cruzi membrane mucin. J. Immunol. 1997. 159: 4983,4989). In this report we have further investigated the molecular mechanisms underlying this inhibition. AgC10 inhibited TNF, IL-10 and cyclooxygenase-2 (COX-2) synthesis by macrophages activated with LPS or LPS plus IFN-, in a dose-dependent manner. AgC10 did not affect other aspects of macrophage activation induced by LPS, such as inducible nitric oxide synthase (iNOS) expression. AgC10 also had no effect on TNF or COX-2 transcription or the induction of their promoters but inhibited the stability of TNF and COX-2 mRNA, which are regulated post-transcriptionally by the mitogen-activated protein kinase (MAPK) p38 pathway. AgC10 was found to inhibit both the activation and the activity of p38 MAPK, since MAPK activated protein kinase-2 (MAPKAP-K2 or MK-2) phosphorylation was also strongly inhibited. This led to TNF and COX-2 mRNA destabilization. In contrast, AgC10 did not affect p38 activation induced by TNF. Furthermore, AgC10 inhibition must lie upstream in the MAPK activation pathway by LPS, since this mucin also inhibited extracellularly regulated kinase (ERK) and Jun kinase (JNK)activation. [source] Aberrant trajectory of thalamocortical axons associated with abnormal localization of neurocan immunoreactivity in the cerebral neocortex of reeler mutant miceEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2005Hong-Peng Li Abstract We examined the molecular mechanisms underlying the formation of the thalamocortical pathway in the cerebral neocortex of normal and reeler mutant mice. During normal development of the mouse neocortex, thalamic axons immunoreactive for the neural cell adhesion molecule L1 rarely invaded the cortical plate and ran centered in the subplate which is immunoreactive for neurocan, a brain-specific chondroitin sulfate proteoglycan. On the other hand, in homozygous reeler mutant mice, thalamic axons took an aberrant course to run obliquely through the cortical plate. Injection of bromodeoxyuridine at embryonic day 11 specifically labeled subplate neurons in normal mice, whilst in the reeler neocortex it labeled cells scattered in the cortical plate as well as in the superficial layer (superplate). Neurocan immunoreactivity was associated with the bromodeoxyuridine-positive cells in the superplate, as well as being present in oblique bands within the cortical plate, along which L1-bearing thalamic axons preferentially ran. The present results support our previous hypothesis proposed for normal rats that a heterophilic molecular interaction between L1 and neurocan is involved in determining the thalamocortical pathway within the neocortical anlage [T. Fukuda et al. (1997)Journal of Comparative Neurology, 382, 141,152]. [source] Axonal morphogenesis controlled by antagonistic roles of two CRMP subtypes in microtubule organizationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2003Junichi Yuasa-Kawada Abstract During development, cells undergo dynamic morphological changes by rearrangements of the cytoskeleton including microtubules. However, molecular mechanisms underlying the microtubule remodeling between orientated and disoriented formations are almost unknown. Here we found that novel subtypes of collapsin response mediator proteins (CRMP-As) and the originals (CRMP-Bs), which occur from the alternative usage of different first coding exons, are involved in this conversion of microtubule patterns. Overexpression of CRMP2A and CRMP2B in chick embryonic fibroblasts induced orientated and disoriented patterns of microtubules, respectively. Moreover, sequential overexpression of another subtype overcame the effect of the former expression of the countersubtype. Overexpression experiments in cultured chick retinae showed that CRMP2B promoted axon branching and suppressed axon elongation of ganglion cells, while CRMP2A blocked these effects when co-overexpressed. Our findings suggest that the opposing activities of CRMP2A and CRMP2B contribute to the cellular morphogenesis including neuronal axonogenesis through remodeling of microtubule organization. [source] Enzymatic control of anhydrobiosis-related accumulation of trehalose in the sleeping chironomid, Polypedilum vanderplankiFEBS JOURNAL, Issue 20 2010Kanako Mitsumasu Larvae of an anhydrobiotic insect, Polypedilum vanderplanki, accumulate very large amounts of trehalose as a compatible solute on desiccation, but the molecular mechanisms underlying this accumulation are unclear. We therefore isolated the genes coding for trehalose metabolism enzymes, i.e. trehalose-6-phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP) for the synthesis step, and trehalase (TREH) for the degradation step. Although computational prediction indicated that the alternative splicing variants (PvTps,/,) obtained encoded probable functional motifs consisting of a typical consensus domain of TPS and a conserved sequence of TPP, PvTps, did not exert activity as TPP, but only as TPS. Instead, a distinct gene (PvTpp) obtained expressed TPP activity. Previous reports have suggested that insect TPS is, exceptionally, a bifunctional enzyme governing both TPS and TPP. In this article, we propose that TPS and TPP activities in insects can be attributed to discrete genes. The translated product of the TREH ortholog (PvTreh) certainly degraded trehalose to glucose. Trehalose was synthesized abundantly, consistent with increased activities of TPS and TPP and suppressed TREH activity. These results show that trehalose accumulation observed during anhydrobiosis induction in desiccating larvae can be attributed to the activation of the trehalose synthetic pathway and to the depression of trehalose hydrolysis. [source] Heme oxygenase-1/p21WAF1 mediates peroxisome proliferator-activated receptor-, signaling inhibition of proliferation of rat pulmonary artery smooth muscle cellsFEBS JOURNAL, Issue 6 2010Manxiang Li Activation of peroxisome proliferator-activated receptor (PPAR)-, suppresses proliferation of rat pulmonary artery smooth muscle cells (PASMCs), and therefore ameliorates the development of pulmonary hypertension in animal models. However, the molecular mechanisms underlying this effect remain largely unknown. This study addressed this issue. The PPAR, agonist rosiglitazone dose-dependently stimulated heme oxygenase (HO)-1 expression in PASMCs, 5 ,m rosiglitazone inducing a 12.1-fold increase in the HO-1 protein level. Cells pre-exposed to rosiglitazone showed a dose-dependent reduction in proliferation in response to serotonin; this was abolished by pretransfection of cells with sequence-specific small interfering RNA against HO-1. In addition, rosiglitazone stimulated p21WAF1 expression in PASMCs, a 2.34-fold increase in the p21WAF1 protein level being achieved with 5 ,m rosiglitazone; again, this effect was blocked by knockdown of HO-1. Like loss of HO-1, loss of p21WAF1 through siRNA transfection also reversed the inhibitory effect of rosiglitazone on PASMC proliferation triggered by serotonin. Taken together, our findings suggest that activation of PPAR, induces HO-1 expression, and that this in turn stimulates p21WAF1 expression to suppress PASMC proliferation. Our study also indicates that rosiglitazone, a medicine widely used in the treatment of type 2 diabetes mellitus, has potential benefits for patients with pulmonary hypertension. [source] Effect of monovalent cations and G-quadruplex structures on the outcome of intramolecular homologous recombinationFEBS JOURNAL, Issue 11 2009Paula Barros Homologous recombination is a very important cellular process, as it provides a major pathway for the repair of DNA double-strand breaks. This complex process is affected by many factors within cells. Here, we have studied the effect of monovalent cations (K+, Na+, and NH4+) on the outcome of recombination events, as their presence affects the biochemical activities of the proteins involved in recombination as well as the structure of DNA. For this purpose, we used an in vitro recombination system that includes a protein nuclear extract, as a source of recombination machinery, and two plasmids as substrates for intramolecular homologous recombination, each with two copies of different alleles of the human minisatellite MsH43. We found that the presence of monovalent cations induced a decrease in the recombination frequency, accompanied by an increase in the fidelity of the recombination. Moreover, there is an emerging consensus that secondary structures of DNA have the potential to induce genomic instability. Therefore, we analyzed the effect of the sequences capable of forming G-quadruplex on the production of recombinant molecules, taking advantage of the capacity of some MsH43 alleles to generate these kinds of structure in the presence of K+. We observed that the MsH43 recombinants containing duplications, generated in the presence of K+, did not include the repeats located towards the 5,-side of the G-quadruplex motif, suggesting that this structure may be involved in the recombination events leading to duplications. Our results provide new insights into the molecular mechanisms underlying the recombination of repetitive sequences. [source] Intracellular site of ,-secretase cleavage for A,42 generation in Neuro 2a cells harbouring a presenilin 1 mutationFEBS JOURNAL, Issue 7 2000Shinji Sudoh Previously, we reported that mutations in presenilin 1 (PS1) increased the intracellular levels of amyloid ,-protein (A,)42. However, it is still not known at which cellular site or how PS1 mutations exert their effect of enhancing A,42,,-secretase cleavage. In this study, to clarify the molecular mechanisms underlying this enhancement of A,42,,-secretase cleavage, we focused on determining the intracellular site of the cleavage. To address this issue, we used APP,C100 encoding the C-terminal ,-amyloid precursor protein (APP) fragment truncated at the N terminus of A, (C100); C100 requires only ,-secretase cleavage to yield A,. Mutated PS1 (M146L)-induced Neuro 2a cells showed enhanced A,1,42 generation from transiently expressed C100 as well as from full-length APP, whereas the generation of A,1,40 was not increased. The intracellular generation of A,1,42 from transiently expressed C100 in both mutated PS1 -induced and wild-type Neuro 2a cells was inhibited by brefeldin A. Moreover, the generation of A,1,42 and A,1,40 from a C100 mutant containing a di-lysine endoplasmic reticulum retention signal was greatly decreased, indicating that the major intracellular site of ,-secretase cleavage is not the endoplasmic reticulum. The intracellular generation of A,1,42/40 from C100 was not influenced by monensin treatment, and the level of A,1,42/40 generated from C100 carrying a sorting signal for the trans -Golgi network was higher than that generated from wild-type C100. These results using PS1 -mutation-harbouring and wild-type Neuro 2a cells suggest that A,42/40,,-secretase cleavages occur in the Golgi compartment and the trans -Golgi network, and that the PS1 mutation does not alter the intracelluar site of A,42,,-secretase cleavage in the normal APP proteolytic processing pathway. [source] Molecular mechanisms of pathogenicity: how do pathogenic microorganisms develop cross-kingdom host jumps?FEMS MICROBIOLOGY REVIEWS, Issue 3 2007Peter Van Baarlen Abstract It is common knowledge that pathogenic viruses can change hosts, with avian influenza, the HIV, and the causal agent of variant Creutzfeldt,Jacob encephalitis as well-known examples. Less well known, however, is that host jumps also occur with more complex pathogenic microorganisms such as bacteria and fungi. In extreme cases, these host jumps even cross kingdom of life barriers. A number of requirements need to be met to enable a microorganism to cross such kingdom barriers. Potential cross-kingdom pathogenic microorganisms must be able to come into close and frequent contact with potential hosts, and must be able to overcome or evade host defences. Reproduction on, in, or near the new host will ensure the transmission or release of successful genotypes. An unexpectedly high number of cross-kingdom host shifts of bacterial and fungal pathogens are described in the literature. Interestingly, the molecular mechanisms underlying these shifts show commonalities. The evolution of pathogenicity towards novel hosts may be based on traits that were originally developed to ensure survival in the microorganism's original habitat, including former hosts. [source] Clock-dependent and independent transcriptional control of the two isoforms from the mouse Ror,geneGENES TO CELLS, Issue 12 2008Valérie Mongrain Accumulating evidence indicate that molecular mechanisms generating circadian rhythms display some degree of tissue-specificity. More specifically, distinct patterns of expression for nuclear receptors of the ROR family indicate that the transcriptional control of the clock gene Bmal1 differs among tissues. This study aims to investigate the expression of Ror,isoforms (Ror, and Ror,t) and characterize the molecular mechanisms underlying their tissue-specific expression. The expression of Ror, isoforms was assessed in mouse liver, muscle, thymus and testis throughout 24 h using quantitative RT-PCR. Although the expression of Ror, was rhythmic in the liver and thymus, it was constitutively expressed in muscle and testis. In contrast, the expression of Ror,t was constitutive in all four tissues. Furthermore, rhythmic expression of Ror, was impaired in Clock mutant mice whereas the mutation had no effect on Ror,t expression. In line with these findings, luciferase assays revealed that transcription of the Ror, promoter is clock-controlled whereas that of Ror,t promoter is essentially clock-independent. Our results provide insights into the molecular mechanisms that lead to differential expression of Ror, and Ror,t and are suggestive of a framework that might account for tissue-specific circadian regulation. [source] Molecular mechanisms underlying inflammatory lung diseases in the elderly: Development of a novel therapeutic strategy for acute lung injury and pulmonary fibrosis,GERIATRICS & GERONTOLOGY INTERNATIONAL, Issue 3 2005Takahide Nagase In the elderly, inflammatory lung diseases, including acute lung injury and pulmonary fibrosis, are significant in terms of both mortality and difficulty in management. Acute respiratory distress syndrome (ARDS) is an acute lung injury and the mortality rate for ARDS ranges from 40 to 70% despite intensive care. Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal disorder of the lung parenchyma. No useful drugs are currently available to treat IPF. However, molecular mechanisms underlying these lung diseases are little understood and the development of a novel therapeutic strategy is urgently needed. Platelet-activating factor (PAF) and metabolites of arachidonic acid, i.e. eicosanoids, are lipid mediators that have various biological effects. A key enzyme for the production of these inflammatory mediators, including eicosanoids and PAF, is phospholipase A2. In particular, cytosolic PLA2 (cPLA2) is especially important. The purpose of this article is to report novel findings regarding the role of PAF and cPLA2 in lung inflammatory diseases, especially, acute lung injury and pulmonary fibrosis. To address this question, we used mutant mice, i.e. PAFR transgenic mice, PAFR gene-disrupted mice and cPLA2 gene-disrupted mice. We have shown that PAF and eicosanoids, downstream mediators of cPLA2, may be involved in the pathogenesis of ARDS and IPF, which are important diseases in the elderly. Although there exist extreme differences in clinical features between ARDS and IPF, both diseases are fatal disorders for which no useful drugs are currently available. On the basis of recent reports using mutant mice, cPLA2 might be a potential target to intervene in the development of pulmonary fibrosis and acute lung injury in the elderly. [source] Comparative gene expression profiling of olfactory ensheathing glia and Schwann cells indicates distinct tissue repair characteristics of olfactory ensheathing gliaGLIA, Issue 12 2008Elske H.P. Franssen Abstract Olfactory ensheathing glia (OEG) are a specialized type of glia that support the growth of primary olfactory axons from the neuroepithelium in the nasal cavity to the brain. Transplantation of OEG in the injured spinal cord promotes sprouting of injured axons and results in reduced cavity formation, enhanced axonal and tissue sparing, remyelination, and angiogenesis. Gene expression analysis may help to identify the molecular mechanisms underlying the ability of OEG to recreate an environment that supports regeneration in the central nervous system. Here, we compared the transcriptome of cultured OEG (cOEG) with the transcriptomes of cultured Schwann cells (cSCs) and of OEG directly obtained from their natural environment (nOEG), the olfactory nerve layer of adult rats. Functional data mining by Gene Ontology (GO)-analysis revealed a number of overrepresented GO-classes associated with tissue repair. These classes include "response to wounding," "blood vessel development," "cell adhesion," and GO-classes related to the extracellular matrix and were overrepresented in the set of differentially expressed genes between both comparisons. The current screening approach combined with GO-analysis has identified distinct molecular properties of OEG that may underlie their efficacy and interaction with host tissue after implantation in the injured spinal cord. These observations can form the basis for studies on the function of novel target molecules for therapeutic intervention after neurotrauma. © 2008 Wiley-Liss, Inc. [source] IFN-,-induced BACE1 expression is mediated by activation of JAK2 and ERK1/2 signaling pathways and direct binding of STAT1 to BACE1 promoter in astrocytesGLIA, Issue 3 2007Hyun Jin Cho Abstract ,-Site APP cleaving enzyme 1 (BACE1) is an essential enzyme for the production of , amyloid. Since we found that injection of interferon-, (IFN-,) into young mouse brains increased BACE1 expression in astrocytes, we investigated molecular mechanisms underlying this process by cloning a putative BACE1 promoter. BACE1 promoter activity was differentially regulated by IFN-, in a region specific manner and down-regulated by an inhibitor of Janus kinase 2 (JAK2). A dominant negative mutant of signal transducer and activator of transcription 1 (STAT1) expression suppressed BACE1 promoter activity, and this was rescued by transfecting wild type STAT1. Electrophoretic mobility shift assay and promoter activity assays indicated that STAT1 binds directly to the putative STAT1 binding sequence of BACE1 promoter. Because IFN-, treatment induced STAT1 phosphorylation, we examined whether the expression of a suppressor of cytokine signaling (SOCS), negative regulator of JAK2, suppresses BACE1 promoter activity. The results show that SOCS1 or SOCS3 expression suppressed BACE1 promoter by blocking phosphorylation of Tyr701 residue in STAT1. Also, because IFN-, treatment specifically potentiated extracellular signal regulated MAP kinase (ERK) 1/2 activation, pretreatment of mitogen-activated or extracellular signal-regulated protein kinase (MEK) inhibitor, PD98059, significantly attenuated IFN-,-induced BACE1 promoter activity and protein expression through blocking phosphorylation of Ser727 residue in STAT1, suggesting that ERK1/2 is associated with IFN-,-induced STAT1 signaling cascade. Taken together, our results suggest that IFN-, activates JAK2 and ERK1/2 and then phosphorylated STAT1 binds to the putative STAT1 binding sequences in BACE1 promoter region to modulate BACE1 protein expression in astrocytes. © 2006 Wiley-Liss, Inc. [source] Memory T-cell trafficking: new directions for busy commutersIMMUNOLOGY, Issue 2 2010Federica M. Marelli-Berg Summary The immune system is unique in representing a network of interacting cells of enormous complexity and yet being based on single cells travelling around the body. The development of effective and regulated immunity relies upon co-ordinated migration of each cellular component, which is regulated by diverse signals provided by the tissue. Co-ordinated migration is particularly relevant to the recirculation of primed T cells, which, while performing continuous immune surveillance, need to promptly localize to antigenic sites, reside for a time sufficient to carry out their effector function and then efficiently leave the tissue to avoid bystander damage. Recent advances that have helped to clarify a number of key molecular mechanisms underlying the complexity and efficiency of memory T-cell trafficking, including antigen-dependent T-cell trafficking, the regulation of T-cell motility by costimulatory molecules, T-cell migration out of target tissue and fugetaxis, are reviewed in this article. [source] Germ-line transformation and RNAi of the ladybird beetle, Harmonia axyridisINSECT MOLECULAR BIOLOGY, Issue 4 2006H. Kuwayama Abstract To elucidate the molecular mechanisms underlying the tremendous diversity of insect wing colour patterns, it is imperative to identify and functionally characterize the genes involved in this developmental process. Here we report the first successful germ-line transformation using the transposable element vector piggyBac in the ladybird beetle Harmonia axyridis, which demonstrates typical genetic polymorphism in its wing colour patterns. The transformation efficiency by piggyBac was 3.7% per fertile G0. We investigated the effectiveness of RNAi in Harmonia by injecting EGFP (enhanced green fluorescent protein) dsRNA into early transgenic EGFP-expressing embryos and observed substantial reduction of EGFP fluorescence in 87.2% of hatched larvae. Application of these new genetic tools to non-model insects such as Harmonia will facilitate the broad understanding of developmental mechanisms and evolutionary processes that are inaccessible using established model systems. [source] Cyclooxygenase-2 inhibition inhibits PI3K/AKT kinase activity in epithelial ovarian cancerINTERNATIONAL JOURNAL OF CANCER, Issue 2 2010Shahab Uddin Abstract Cyclooxygenase-2 (COX-2) expression contributes to tumor growth and invasion in epithelial ovarian cancer (EOC). COX-2 inhibitors exhibit important anticarcinogenic potential against EOC, but the molecular mechanisms underlying this effect and relation with PI3-kinase/AKT signaling remain the subject of intense investigations. Therefore, the role of COX-2 in EOC and its cross talk with PI3-kinase/AKT pathway were investigated using a large series of EOC tissues in a tissue micro array (TMA) format followed by in vitro and in vivo studies using EOC cell lines and NUDE mice. Clinically, COX-2 was overexpressed in 60.3% of EOC and was significantly associated with activated AKT (p < 0.0001). Cox-1 expression was seen in 59.9% but did not associate with AKT. Our in vitro data using EOC cell line showed that inhibition of COX-2 by aspirin, selective inhibitor NS398 and gene silencing by COX-2 specific siRNA impaired phosphorylation of AKT resulting decreased downstream signaling leading to cell growth inhibition and induction of apoptosis. Finally, treatment of MDAH2774 cell line xenografts with aspirin resulted in growth inhibition of tumors in NUDE mice via down-regulation of COX-2 and AKT activity. These data identify COX-2 as a potential biomarker and therapeutic target in distinct molecular subtypes of ovarian cancer. [source] | ||||||||||||||||||||||||||||||||||