Novel Role (novel + role)

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Selected Abstracts


Min H. Chew
Background: Tongue cancers are staged by the American Joint Committee on Cancer and the Union Internationale Contre le Cancer TNM staging systems. Cancer, however, evolves in a 3-D plane. Hence, using the largest tumour diameter will not reflect total cancer volume. We aim to evaluate the use of tongue cancer tumour volume (Tv) as a prognostic predictor of disease recurrence and survival. Methods: The study is a retrospective analysis of patients in Singapore General Hospital who underwent complete resection for histologically proven tongue carcinoma from 2000 to 2002. The Tv was measured on staging T2 -weighted magnetic resonance imaging datasets by semiautomated methods. Results: Seventeen patients with a median follow-up duration of 57.9 months were studied. A wide range of volumes was noted in each T stage. The median time to relapse was 8.6 months for those with Tv , 13 cc but was not achieved for those with Tv < 13 cc. The hazard ratio comparing Tv ,13 cc versus <13 cc is 9.02 (95% confidence interval (CI) 1.70,47.94, P = 0.014). Of the seven deaths reported, five patients had Tv , 13 cc. The median overall survival was 15.8 months for those with Tv , 13 cc but was not achieved for those with Tv < 13 cc. The hazards of death for Tv , 13 cc was 3.91 times that of Tv < 13 cc (95%CI 0.86,17.86, P = 0.078). Conclusion: Tongue cancer Tv measurement allows a more refined and accurate assessment of tumour status. This can be a possible prognostic indicator and be used in a novel staging method for the future. [source]

Novel role of peripheral guanylins as stimulators of duodenal mucosa-protective bicarbonate secretion

Hugo De JongeArticle first published online: 7 NOV 200
No abstract is available for this article. [source]

Novel role of nectin: implication in the co-localization of JAM-A and claudin-1 at the same cell,cell adhesion membrane domain

GENES TO CELLS, Issue 8 2008
Kaori Kuramitsu
Tight junctions (TJs) are formed at the apical side of adherens junctions (AJs) in epithelial cells. Major cell adhesion molecules (CAMs) at TJs are JAM and claudin, whereas major CAMs at AJs are nectin and cadherin. We previously showed that nectin initially forms cell,cell adhesion and then recruits cadherin to the nectin-based cell,cell adhesion sites to form AJs, followed by the recruitment of JAM and claudin to the apical side of AJs to form TJs. We investigated the roles of nectin in the formation of TJs by expressing various combinations of CAMs in L fibroblasts with no TJs or AJs. Co-expression of one of the AJ CAMs and one of the TJ CAMs formed two separate cell,cell adhesion membrane domains (CAMDs). Co-expression of nectin-3 and E-cadherin formed the same CAMD, but co-expression of JAM-A and claudin-1 did not form the same CAMD. Co-expression of JAM-A and claudin-1 with nectin-3, but not E-cadherin, made them form the same CAMD, which was separated from the nectin-based CAMD. Nectin-3 required afadin, a nectin- and F-actin-binding protein, for this ability. In conclusion, nectin plays a novel role in the co-localization of JAM and claudin at the same CAMD. [source]

Novel role of extracellular carbon dioxide in lymphocyte proliferation in culture

Ranjana Chakrabarti
Abstract CO2/HCO3, buffering system is indispensable to maintain the pH of culture media for long-term cell culture. Now-a-days, the zwiterionic hydrogen buffer HEPES is widely used as an additional buffer in the commonly used culture media. There are reports on the successful use of HEPES-buffered media, under CO2/HCO3, free conditions, for long-term cell cultures. However, still CO2/HCO3, buffering system is widely used. We aimed at investigating the reason for this. We found that lymphocytes proliferate in response to concanavalin A only in HCO3, -buffered medium in the presence of 5% CO2, but not in the HEPES-buffered medium in the absence of CO2. However, lymphocyte proliferation was observed in HEPES-buffered medium in the presence of 5% CO2 and in the absence of HCO3,. On the other hand, a low level proliferation was observed in HEPES-buffered medium supplemented with HCO3, in the absence of CO2. Supplementation of the culture medium with TCA cycle intermediates and the precursors for the salvage pathway of nucleotide synthesis did not support the lymphocyte proliferation at all. Based on these findings and other reports, we suggest that extracellular CO2 plays a novel role in cell proliferation. J. Cell. Biochem. 83: 200,203, 2001. © 2001 Wiley-Liss, Inc. [source]

Novel role for aspartoacylase in regulation of BDNF and timing of postnatal oligodendrogenesis

Jeremy S. Francis
Abstract Neuronal growth factors are thought to exert a significant degree of control over postnatal oligodendrogenesis, but mechanisms by which these factors coordinateoligodendrocyte development with the maturation of neural networks are poorly characterized. We present here a developmental analysis of aspartoacylase (Aspa)-null tremor rats and show a potential role for this hydrolytic enzyme in the regulation of a postnatal neurotrophic stimulus that impacts on early stages of oligodendrocyte differentiation. Abnormally high levels of brain-derived neurotrophic factor (BDNF) expression in the Aspa -null Tremor brain are associated with dysregulated oligodendrogenesis at a stage in development normally characterized by high levels of Aspa expression. BDNF promotes the survival of proliferating cells during the early stages of oligodendrocyte maturation in vitro, but seems to compromise the ability of these cells to populate the cortex in vivo. Aspartoacylase activity in oligodendrocytes is shown to provide for the negative regulation of BDNF in neurons, thereby determining the availability of a developmental stimulus via a mechanism that links oligodendroglial differentiation with neuronal maturation. © 2006 Wiley-Liss, Inc. [source]

Novel role of TGF-, in differential astrocyte-TIMP-1 regulation: Implications for HIV-1-dementia and neuroinflammation

Alok Dhar
Abstract Astrocyte production of tissue inhibitor of metalloproteinase (TIMP)-1 is important in central nervous system (CNS) homeostasis and inflammatory diseases such as HIV-1-associated dementia (HAD). TIMPs and matrix metalloproteinases (MMPs) regulate the remodeling of the extracellular matrix. An imbalance between TIMPs and MMPs is associated with many pathologic conditions. Our recently published studies uniquely demonstrate that HAD patients have reduced levels of TIMP-1 in the brain. Astrocyte-TIMP-1 expression is differentially regulated in acute and chronic inflammatory conditions. In this and the adjoining report (Gardner et al., 2006), we investigate the mechanisms that may be involved in differential TIMP-1 regulation. One mechanism for TIMP-1 downregulation is the production of anti-inflammatory molecules, which can activate signaling pathways during chronic inflammation. We investigated the contribution of transforming growth factor (TGF)-signaling in astrocyte-MMP/TIMP-1-astrocyte regulation. TGF-,1 and ,2 levels were upregulated in HAD brain tissues. Co-stimulation of astrocytes with IL-1, and TGF-, mimicked the TIMP-1 downregulation observed with IL-1, chronic activation. Measurement of astrocyte-MMP protein levels showed that TGF-, combined with IL-1, increased MMP-2 and decreased proMMP-1 expression compared to IL-1, alone. We propose that one of the mechanisms involved in TIMP-1 downregulation may be through TGF-signaling in chronic immune activation. These studies show a novel extracellular regulatory loop in astrocyte-TIMP-1 regulation. © 2006 Wiley-Liss, Inc. [source]

Novel role of plasmacytoid dendritic cells in humans: Induction of interleukin-10,producing treg cells by plasmacytoid dendritic cells in patients with rheumatoid arthritis responding to therapy

Melina Kavousanaki
Objective Reestablishing immune tolerance and long-term suppression of disease represent major therapeutic goals in rheumatoid arthritis (RA). Dendritic cells (DCs) likely play a central role in such regulation via the expansion and/or induction of Treg cells. The present study was undertaken to explore the contribution of DCs to the development of Treg cells in a human autoimmune disease setting. Methods DC subsets were characterized by flow cytometry in the peripheral blood and synovial fluid of patients with RA. Proliferation of and cytokine release by naive CD4+CD25, T cells were measured in cocultures of these cells with DCs from patients with RA and healthy controls. The suppressive capacity of DC-polarized T cells was explored in vitro by a standard suppression assay. Results Only very low numbers of both plasmacytoid DCs (CD303+) and myeloid DCs (CD1c+) were present in the peripheral blood of patients with active RA. In contrast, patients with therapy-induced remission of RA exhibited higher numbers of circulating plasmacytoid DCs. Mature plasmacytoid DCs from RA patients with low disease activity, but not those from healthy controls, expressed high levels of indoleamine 2,3-dioxygenase and promoted the differentiation of allogeneic naive CD4+CD25, T cells into interleukin-10,secreting Treg cells, or Tr1 cells, that showed poor proliferation in vitro. Importantly, these plasmacytoid DC,primed Treg cells potently suppressed the proliferation of autologous naive CD4+ T cells, in a dose-dependent manner. Conclusion These results demonstrate, for the first time, that human plasmacytoid DCs may be educated within the rheumatoid microenvironment to acquire a tolerogenic phenotype. Modulation of the immune response by plasmacytoid DCs might provide novel immune-based therapies in autoimmunity and transplantation. [source]

Novel role of curcumin in the prevention of cytokine-induced islet death in vitro and diabetogenesis in vivo

M Kanitkar
Background and purpose: Oxidative stress caused by cytokine exposure is a major cause of pancreatic islet death in vitro and of diabetogenesis. Antioxidant compounds may prevent cytokine-induced damage to islet cells. Hence, we studied the potential of curcumin, an antioxidant and anti-inflammatory compound, in vitro to protect islets against pro-inflammatory cytokines and in vivo to prevent the progression of diabetes induced by multiple low doses of streptozotocin (MLD-STZ). Experimental approach: Pancreatic islets from C57/BL6J mice were pretreated with curcumin (10 ,M) and then exposed to a combination of cytokines. Islet viability, reactive oxygen species (ROS), NO, inducible NO synthase and NF-,B translocation were studied. Curcumin pretreated (7.5 mg kg,1 day,1) C57/BL6J mice were given MLD-STZ (40 mg kg,1), and various parameters of diabetes induction and progression were monitored. Key results: Curcumin protected islets from cytokine-induced islet death in vitro by scavenging ROS and normalized cytokine-induced NF-,B translocation by inhibiting phosphorylation of inhibitor of kappa B alpha (I,B,). In vivo, curcumin also prevented MLD-STZ, as revealed by sustained normoglycaemia, normal glucose clearance and maintained pancreatic GLUT2 levels. Pro-inflammatory cytokine concentrations in the serum and pancreas were raised in STZ-treated animals, but not in animals pretreated with curcumin before STZ. Conclusions and implications: Here, we have demonstrated for the first time that curcumin in vitro protects pancreatic islets against cytokine-induced death and dysfunction and in vivo prevents STZ-induced diabetes. British Journal of Pharmacology (2008) 155, 702,713; doi:10.1038/bjp.2008.311; published online 11 August 2008 [source]

Novel role for polycystin-1 in modulating cell proliferation through calcium oscillations in kidney cells

G. Aguiari
Objectives: Polycystin-1 (PC1), a signalling receptor regulating Ca2+ -permeable cation channels, is mutated in autosomal dominant polycystic kidney disease, which is typically characterized by increased cell proliferation. However, the precise mechanisms by which PC1 functions on Ca2+ homeostasis, signalling and cell proliferation remain unclear. Here, we investigated the possible role of PC1 as a modulator of non-capacitative Ca2+ entry (NCCE) and Ca2+ oscillations, with downstream effects on cell proliferation. Results and discussion: By employing RNA interference, we show that depletion of endogenous PC1 in HEK293 cells leads to an increase in serum-induced Ca2+ oscillations, triggering nuclear factor of activated T cell activation and leading to cell cycle progression. Consistently, Ca2+ oscillations and cell proliferation are increased in PC1-mutated kidney cystic cell lines, but both abnormal features are reduced in cells that exogenously express PC1. Notably, blockers of the NCCE pathway, but not of the CCE, blunt abnormal oscillation and cell proliferation. Our study therefore provides the first demonstration that PC1 modulates Ca2+ oscillations and a molecular mechanism to explain the association between abnormal Ca2+ homeostasis and cell proliferation in autosomal dominant polycystic kidney disease. [source]

Novel role for ,-adrenergic signalling in skeletal muscle growth, development and regeneration

James G Ryall
Summary 1. In adult mammals, skeletal muscle mass is maintained through a precise balance of protein synthesis and protein degradation, whereas during development cellular (not protein) turnover predominates. When protein balance is shifted towards synthesis, skeletal muscle hypertrophy ensues. In contrast, increased protein degradation leads to skeletal muscle atrophy. Insulin-like growth factor (IGF)-I is among the best documented of the growth factors and regulates skeletal muscle mass by increasing protein synthesis and decreasing protein degradation. However, an IGF-I-independent growth pathway has been identified that involves the activation of ,-adrenoceptors and subsequent skeletal muscle growth, development and hypertrophy. 2. Although the importance of ,-adrenergic signalling in the heart has been well documented and continues to receive significant attention, it is only more recently that we have started to appreciate the importance of this signalling pathway in skeletal muscle structure and function. Studies have identified an important role for ,-adrenoceptors in myogenesis and work from our laboratory has identified a novel role for ,-adrenoceptors in regulating skeletal muscle regeneration after myotoxic injury. In addition, new data suggest that ,-adrenoceptors are markedly upregulated during differentiation of C2C12 cells. 3. It is now clear that ,-adrenoceptors play an important role in regulating skeletal muscle structure and function. Importantly, a clearer understanding of the pathways regulating skeletal muscle mass may lead to the identification of novel therapeutic targets for the treatment of muscle wasting disorders, including sarcopenia, cancer cachexia and the muscular dystrophies. [source]

The secreted and surface proteomes of the adult stage of the carcinogenic human liver fluke Opisthorchis viverrini

Jason Mulvenna
Abstract Infection with the human liver fluke, Opisthorchis viverrini, is a serious public health problem in Thailand, Laos and nearby locations in Southeast Asia. Both experimental and epidemiological evidence strongly implicate liver fluke infection in the etiology of one of the liver cancer subtypes, cholangiocarcinoma (CCA). To identify parasite proteins critical for liver fluke survival and the etiology of CCA, OFFGEL electrophoresis and multiple reaction monitoring were employed to characterize 300 parasite proteins from the O. viverrini excretory/secretory products and, utilizing selective labeling and sequential solubilization, from the host-exposed tegument. The excretory/secretory included a complex mixture of proteins that have been associated with cancers, including proteases of different mechanistic classes and orthologues of mammalian growth factors and anti-apoptotic proteins. Also identified was a cysteine protease inhibitor which, in other helminth pathogens, induces nitric oxide production by macrophages, and, hence may contribute to malignant transformation of inflamed cells. More than 160 tegumental proteins were identified using sequential solubilization of isolated teguments, and a subset of these was localized to the surface membrane of the tegument by labeling living flukes with biotin and confirming surface localization with fluorescence microscopy. These included annexins, which are potential immuno-modulators, and orthologues of the schistosomiasis vaccine antigens Sm29 and tetraspanin-2. Novel roles in pathogenesis were suggested for the tegument,host interface since more than ten surface proteins had no homologues in the public databases. The O. viverrini proteins identified here provide an extensive catalogue of novel leads for research on the pathogenesis of opisthorchiasis and the development of novel interventions for this disease and CCA, as well as providing a scaffold for sequencing the genome of this fluke. [source]

Local mechanisms for luteolysis in the cow: Novel roles of vasoactive substances in the luteolytic cascade within the corpus luteum

ABSTRACT The corpus luteum (CL) in the estrous cycle in the cow is a dynamic organ which has a lifespan of approximately 17,18 days. As the CL matures, the steroidogenic cells establish contact with many capillary vessels and the CL is composed of a large number of vascular endothelial cells that can account for up to 50% of the bovine CL. Furthermore, luteal cells and endothelial cells secrete several vasoactive substances such as prostaglandin F2, (PGF2,), endothelin-1 and angiotensin II. These vasoactive substances also function in regulating progesterone secretion in an autocrine/paracrine manner in the CL. The blood vessels and endothelial cells in the CL therefore have an essential role in the luteal function in the cow. Endometrial PGF2,, the primary luteolysin in the cow, stimulates luteal vasoactive substances during luteolysis. Moreover, luteal vasoactive substances may have key roles in the regulation of luteolysis to induce vasodilatation, vasoconstriction and angiolysis. This review describes the current concept for possible roles of vasoactive substances in the luteolytic cascade within the bovine CL. [source]

Role of interleukin-15 in the development of mouse olfactory nerve

Tsuyoshi Umehara
ABSTRACT Interleukin (IL)-15 interacts with components of the IL-2 receptor (R) and exhibits T cell-stimulating activity similar to that of IL-2. In addition, IL-15 is widely expressed in many cell types and tissues, including the central nervous system. We provide evidence of a novel role of IL-15 in olfactory neurogenesis. Both IL-15 and IL-15R, were expressed in neuronal precursor cells of the developing olfactory epithelium in mice. Adult IL-15R, knockout mice had fewer mature olfactory neurons and proliferating cells than wild-type. Our results suggest that IL-15 plays an important role in regulating cell proliferation in olfactory neurogenesis. [source]

Kinesin-5 is not essential for mitotic spindle elongation in Dictyostelium

CYTOSKELETON, Issue 11 2008
Irina Tikhonenko
Abstract The proper assembly and operation of the mitotic spindle is essential to ensure the accurate segregation of chromosomes and to position the cytokinetic furrow during cell division in eukaryotes. Not only are dynamic microtubules required but also the concerted actions of multiple motor proteins are necessary to effect spindle pole separation, chromosome alignment, chromatid segregation, and spindle elongation. Although a number of motor proteins are known to play a role in mitosis, there remains a limited understanding of their full range of functions and the details by which they interact with other spindle components. The kinesin-5 (BimC/Eg5) family of motors is largely considered essential to drive spindle pole separation during the initial and latter stages of mitosis. We have deleted the gene encoding the kinesin-5 member in Dictyostelium, (kif13), and find that, in sharp contrast with results found in vertebrate, fly, and yeast organisms, kif13, cells continue to grow at rates indistinguishable from wild type. Phenotype analysis reveals a slight increase in spindle elongation rates in the absence of Kif13. More importantly, there is a dramatic, premature separation of spindle halves in kif13, cells, suggesting a novel role of this motor in maintaining spindle integrity at the terminal stages of division. Cell Motil. Cytoskeleton 2008. © 2008 Wiley-Liss, Inc. [source]

Myosin Va phosphorylated on Ser1650 is found in nuclear speckles and redistributes to nucleoli upon inhibition of transcription

CYTOSKELETON, Issue 6 2008
Maria Cristina S. Pranchevicius
Abstract Nuclear actin and nuclear myosins have been implicated in the regulation of gene expression in vertebrate cells. Myosin V is a class of actin-based motor proteins involved in cytoplasmic vesicle transport and anchorage, spindle-pole alignment and mRNA translocation. In this study, myosin-Va, phosphorylated on a conserved serine in the tail domain (phospho-ser1650 MVa), was localized to subnuclear compartments. A monoclonal antibody, 9E6, raised against a peptide corresponding to phosphoserine1650 and flanking regions of the murine myosin Va sequence, was immunoreactive to myosin Va heavy chain in cellular and nuclear extracts of HeLa cells, PC12 cells and B16-F10 melanocytes. Immunofluorescence microscopy with this antibody revealed discrete irregular spots within the nucleoplasm that colocalized with SC35, a splicing factor that earmarks nuclear speckles. Phospho-ser1650 MVa was not detected in other nuclear compartments, such as condensed chromatin, Cajal bodies, gems and perinucleolar caps. Although nucleoli also were not labeled by 9E6 under normal conditions, inhibition of transcription in HeLa cells by actinomycin D caused the redistribution of phospho-ser1650 MVa to nucleoli, as well as separating a fraction of phospho-ser1650 MVa from SC35 into near-neighboring particles. These observations indicate a novel role for myosin Va in nuclear compartmentalization and offer a new lead towards the understanding of actomyosin-based gene regulation. Cell Motil. Cytoskeleton 2008. © 2008 Wiley-Liss, Inc. [source]

A novel role of differentiation-inducing factor-1 in Dictyostelium development, assessed by the restoration of a developmental defect in a mutant lacking mitogen-activated protein kinase ERK2

Hidekazu Kuwayama
It has been previously reported that the differentiating wild-type cells of Dictyostelium discoideum secrete a diffusible factor or factors that are able to rescue the developmental defect in the mutant lacking extracellular signal-regulated kinase 2 (ERK2), encoded by the gene erkB. In the present study, it is demonstrated that differentiation-inducing factor-1 (DIF-1) for stalk cells can mimic the role of the factor(s) and the mechanism of the action of DIF-1 in the erkB null mutant is also discussed. The mutant usually never forms multicellular aggregates, because of its defect in cyclic adenosine monophosphate (cAMP) signaling. In the presence of 100 n M DIF-1, however, the mutant cells formed tiny slugs, which eventually developed into small fruiting bodies. In contrast, DIF-1 never rescued the developmental arrest of other Dictyostelium mutants lacking adenylyl cyclase A (ACA), cAMP receptors cAR1 and cAR3, heterotrimeric G-protein, the cytosolic regulator of ACA, or the catalytic subunit of cAMP-dependent protein kinase (PKA-C). Most importantly, it was found that DIF-1 did not affect the cellular cAMP level, but rather elevated the transcriptional level of pka during the development of erkB null cells. These results suggest that DIF-1 may rescue the developmental defect in erkB null cells via the increase in PKA activity, thus giving the first conclusive evidence that DIF-1 plays a crucial role in the early events of Dictyostelium development as well as in prestalk and stalk cell induction. [source]

A novel role of CXCR4 and SDF-1 during migration of cloacal muscle precursors

Rizwan Rehimi
Abstract The cloaca acts as a common chamber into which gastrointestinal and urogenital tracts converge in lower vertebrates. The distal end of the cloaca is guarded by a ring of cloacal muscles or sphincters, the equivalent of perineal muscles in mammals. It has recently been shown that the development of the cloacal musculature depends on hindlimb muscle formation. The signaling molecules responsible for the outward migration of hindlimb myogenic precursors are not known. Based on the expression studies for CXCR4 and SDF-1, we hypothesized a role of this signaling pair during cloacal muscle precursor migration. The aim of our study was to investigate the role of SDF-1/CXCR4 during cloacal muscle precursor migration in the chicken embryos. We show that SDF-1 is expressed in the cloacal region, and by experimentally manipulating the SDF-1/CXCR4 signaling, we can show that SDF-1 guides the migration of CXCR4-expressing cloacal muscle precursors. Developmental Dynamics 239:1622,1631, 2010. © 2010 Wiley-Liss, Inc. [source]

Churchill and Sip1a repress fibroblast growth factor signaling during zebrafish somitogenesis

Fatma O. Kok
Abstract Cell-type specific regulation of a small number of growth factor signal transduction pathways generates diverse developmental outcomes. The zinc finger protein Churchill (ChCh) is a key effector of fibroblast growth factor (FGF) signaling during gastrulation. ChCh is largely thought to act by inducing expression of the multifunctional Sip1 (Smad Interacting Protein 1). We investigated the function of ChCh and Sip1a during zebrafish somitogenesis. Knockdown of ChCh or Sip1a results in misshapen somites that are short and narrow. As in wild-type embryos, cycling gene expression occurs in the developing somites in ChCh and Sip1a compromised embryos, but expression of her1 and her7 is maintained in formed somites. In addition, tail bud fgf8 expression is expanded anteriorly in these embryos. Finally, we found that blocking FGF8 restores somite morphology in ChCh and Sip1a compromised embryos. These results demonstrate a novel role for ChCh and Sip1a in repression of FGF activity. Developmental Dynamics 239:548,558, 2010. © 2009 Wiley-Liss, Inc. [source]

Tulp3 is a critical repressor of mouse hedgehog signaling

Don A. Cameron
Abstract Precise regulation of the morphogen sonic hedgehog (Shh) and modulation of the Shh signaling pathway is required for proper specification of cell fate within the developing limbs and neural tube, and resultant tissue morphogenesis. Tulp3 (tubby-like protein 3) is a protein of unknown function which has been implicated in nervous system development through gene knockout studies. We demonstrate here that mice lacking the Tulp3 gene develop abnormalities of both the neural tube and limbs consistent with improper regulation of Shh signaling. Tulp3,/, embryos show expansion of Shh target gene expression and display a ventralization of neural progenitor cells in the caudal neural tube. We further show that Tulp3,/,/Shh,/, compound mutant embryos resemble Tulp3 mutants, and express Shh target genes in the neural tube and limbs which are not expressed in Shh,/, embryos. This work uncovers a novel role for Tulp3 as a negative regulatory factor in the Hh pathway. Developmental Dynamics 238:1140,1149, 2009. © 2009 Wiley-Liss, Inc. [source]

Nuclear receptor NR5A2 is required for proper primitive streak morphogenesis

Cassandre Labelle-Dumais
Abstract NR5A2, also known as liver receptor homologue 1 (LRH-1) and fetoprotein transcription factor (FTF), is an orphan nuclear receptor involved in the regulation of cholesterol metabolism and steroidogenesis in the adult. NR5A2 was also shown to be expressed during early mouse embryogenesis. Consistent with its early expression pattern, a targeted disruption of this gene leads to embryonic lethality around the gastrulation period. To characterize the embryonic phenotype resulting from NR5A2 loss of function, we undertook morphological and marker gene analyses and showed that NR5A2,/, embryos display growth retardation, epiblast disorganization, a mild embryonic,extraembryonic constriction, as well as abnormal thickening of the proximo-posterior epiblast. We demonstrated that, although initial specification of the anterior,posterior axis occurred in the absence of NR5A2, primitive streak formation was impaired and neither embryonic nor extraembryonic mesoderm was generated. Moreover, although the visceral endoderm does not show major morphological abnormalities in NR5A2,/, embryos, a decrease in the expression level of HNF4 and GATA4 was observed. Aggregation experiments demonstrated that, in the presence of wild-type tetraploid cells, NR5A2 mutant cells in the epiblast are capable of undergoing normal gastrulation. Therefore, our results suggest a requirement for NR5A2 in extraembryonic tissues and identify a novel role of this gene in proper primitive streak morphogenesis. Developmental Dynamics 235:3359,3369, 2006. © 2006 Wiley-Liss, Inc. [source]

Mice with mutations in Mahogunin ring finger-1 (Mgrn1) exhibit abnormal patterning of the left,right axis

Christina D. Cota
Abstract Mahogunin Ring Finger 1 (Mgrn1) encodes a RING-containing protein with ubiquitin ligase activity that has been implicated in pigment-type switching. In addition to having dark fur, mice lacking MGRN1 develop adult-onset spongy degeneration of the central nervous system and have reduced embryonic viability. Observation of complete situs inversus in a small proportion of adult Mgrn1 mutant mice suggested that embryonic lethality resulted from congenital heart defects due to defective establishment and/or maintenance of the left,right (LR) axis. Here we report that Mgrn1 is expressed in a pattern consistent with a role in LR patterning during early development and that many Mgrn1 mutant embryos show abnormal expression of asymmetrically expressed genes involved in LR patterning. A range of complex heart defects was observed in 20,25% of mid-to-late gestation Mgrn1 mutant embryos and another 20% were dead. This finding was consistent with 46,60% mortality of mutants by weaning age. Our results indicate that Mgrn1 acts early in the LR signaling cascade and is likely to provide new insight into this developmental process as Nodal expression was uncoupled from expression of other Nodal-responsive genes in Mgrn1 mutant embryos. Our work identifies a novel role for MGRN1 in embryonic patterning and suggests that the ubiquitination of MGRN1 target genes is essential for the proper establishment and/or maintenance of the LR axis. Developmental Dynamics 235:3438,3447, 2006. © 2006 Wiley-Liss, Inc. [source]

Gli3 null mice display glandular overgrowth of the developing stomach

Jae H. Kim
Abstract The role of the Hedgehog signaling pathway in various aspects of gut development is still poorly understood. In the developing stomach, Sonic (Shh) and Indian (Ihh) hedgehog are expressed in both distinct and overlapping regions. Loss of Sonic hedgehog function in the stomach results in a glandular phenotype of intestinal transformation and overgrowth. These changes are reminiscent of the pre-malignant lesion, intestinal metaplasia. To determine the role of Hedgehog-related transcription factors, Gli2 and Gli3, in Shh signaling during stomach development, we conducted a mutant analysis of glandular stomach from Shh, Gli2, and Gli3 mutant mice. Although Gli2 principally mediates the activator function of Shh, surprisingly we observed minimal changes in glandular development in the Gli2 mutant stomach. Furthermore, Gli3, which typically functions as a repressor of Hedgehog signal, showed a striking phenocopy of the glandular expansion and intestinal transformation found in Shh mutant stomach. A reduction in apoptotic events was seen in all mutant stomachs with no appreciable changes in proliferation. Both Shh and Gli3 mutant stomachs displayed early changes of intestinal transformation but these did not impact on the overall differentiation of the gastric epithelium. Interestingly, the observation that Gli3 shares a similar glandular phenotype to Shh mutant stomach reveals a possible novel role of Gli3 activator in the developing stomach. The embryonic stomach is a unique model of the Hedgehog pathway function and one that may help to uncover some of the mechanisms underlying the development of intestinal metaplasia. Developmental Dynamics 234:984,991, 2005. © 2005 Wiley-Liss, Inc. [source]

Transcriptional profiling of brain-derived-neurotrophic factor-induced neuronal plasticity: A novel role for nociceptin in hippocampal neurite outgrowth

Robert H. Ring
Abstract Brain derived neurotrophic factor (BDNF) exhibits a sequence of actions on neurons ranging from acute enhancement of transmission to long-term promotion of neurite outgrowth and synaptogenesis associated with learning and memory. The manifold effects of BDNF on neuronal modifications may be mediated by genomic alterations. We previously found that BDNF treatment acutely increases transcription of the synaptic vesicle protein Rab3A, required for trophin-induced synaptic plasticity, as well as the peptide VGF, which increases during learning. To elucidate comprehensive transcriptional programs associated with short- and long-term BDNF exposure, we now examine mRNA abundance and complexity using Affymetrix GeneChips in cultured hippocampal neurons. Consistent with the modulation of synaptic plasticity, BDNF treatment (3,6 h) induced mRNAs encoding the synapse-associated proteins synaptojanin 2, neuronal pentraxin 1, septin 9, and ryanodine receptor 2. BDNF also induced expression of mRNAs encoding neuropeptides (6,12 h), including prepronociceptin, neuropeptide Y, and secretogranin. To determine whether these neuropeptides induced by BDNF mediate neuronal development, we examined their effects on hippocampal neurons. The four mature peptides derived from post-translational processing of the ppNociceptin propeptide induced the expression of several immediate early genes in hippocampal cultures, indicating neuronal activation. To examine the significance of activation, the effects of nociceptin (orphanin FQ) and nocistatin on neurite outgrowth were examined. Quantitative morphometric analysis revealed that nociceptin significantly increased both average neurite length and average number of neurites per neuron, while nocistatin had no effect on these parameters. These results reveal a novel role for nociceptin and suggest that these neuropeptide systems may contribute to the regulation of neuronal function by BDNF. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006 [source]

IL-27 controls the development of inducible regulatory T cells and Th17 cells via differential effects on STAT1

Clemens Neufert
Abstract IL-27 is an IL-12-related cytokine frequently present at sites of inflammation that can promote both anti- and pro-inflammatory immune responses. Here, we have analyzed the mechanisms how IL-27 may drive such divergent immune responses. While IL-27 suppressed the development of proinflammatory Th17 cells, a novel role for this cytokine in inhibiting the development of anti-inflammatory, inducible regulatory T cells (iTreg) was identified. In fact, IL-27 suppressed the development of adaptive, TGF-,-induced Forkhead box transcription factor p3-positive (Foxp3+) Treg. Whereas the blockade of Th17 development was dependent on the transcription factor STAT1, the suppression of iTreg development was STAT1 independent, suggesting that IL-27 utilizes different signaling pathways to shape T cell-driven immune responses. Our data thus demonstrate that IL-27 controls the development of Th17 and iTreg cells via differential effects on STAT1. [source]

Lung CD11c+ cells from mice deficient in Epstein-Barr virus-induced gene,3 (EBI-3) prevent airway hyper-responsiveness in experimental asthma

Michael Hausding
Abstract Epstein-Barr virus-induced gene (EBI)-3 codes for a soluble type,1 cytokine receptor homologous to the p40 subunit of IL-12 that is expressed by antigen-presenting cells following activation. Here, we analyzed the functional role of EBI-3 in a murine model of asthma associated with airway hyper-responsiveness (AHR) in ovalbumin-sensitized mice. Upon allergen challenge, EBI-3,/, mice showed less severe AHR, decreased numbers and degranulation of eosinophils and a significantly reduced number of VCAM-1+ cells in the lungs as compared to wild-type littermates. We thus analyzed lung CD11c+ cells before and after allergen challenge in these mice and found that before allergen challenge, lung CD11c+ cells isolated from EBI-3,/, mice express markers of a more plasmacytoid phenotype without releasing IFN-, as compared to those from wild-type littermates. Moreover, allergen challenge induced the development of myeloid CD11c+ cells in the lungs of EBI-3,/, mice, which released increased amounts of IL-10 and IL-12 while not expressing IFN-,. Finally, inhibition of EBI-3 expression in lung DC could prevent AHR in adoptive transfer studies by suppressing mediator release of effector cells into the airways. These results indicate a novel role for EBI-3 in controlling local immune responses in the lungs in experimental asthma. [source]

A novel role for MNTB neuron dendrites in regulating action potential amplitude and cell excitability during repetitive firing

Richardson N. Lećo
Abstract Principal cells of the medial nucleus of the trapezoid body (MNTB) are simple round neurons that receive a large excitatory synapse (the calyx of Held) and many small inhibitory synapses on the soma. Strangely, these neurons also possess one or two short tufted dendrites, whose function is unknown. Here we assess the role of these MNTB cell dendrites using patch-clamp recordings, imaging and immunohistochemistry techniques. Using outside-out patches and immunohistochemistry, we demonstrate the presence of dendritic Na+ channels. Current-clamp recordings show that tetrodotoxin applied onto dendrites impairs action potential (AP) firing. Using Na+ imaging, we show that the dendrite may serve to maintain AP amplitudes during high-frequency firing, as Na+ clearance in dendritic compartments is faster than axonal compartments. Prolonged high-frequency firing can diminish Na+ gradients in the axon while the dendritic gradient remains closer to resting conditions; therefore, the dendrite can provide additional inward current during prolonged firing. Using electron microscopy, we demonstrate that there are small excitatory synaptic boutons on dendrites. Multi-compartment MNTB cell simulations show that, with an active dendrite, dendritic excitatory postsynaptic currents (EPSCs) elicit delayed APs compared with calyceal EPSCs. Together with high- and low-threshold voltage-gated K+ currents, we suggest that the function of the MNTB dendrite is to improve high-fidelity firing, and our modelling results indicate that an active dendrite could contribute to a ,dual' firing mode for MNTB cells (an instantaneous response to calyceal inputs and a delayed response to non-calyceal dendritic excitatory postsynaptic potentials). [source]

A novel role for polyamines in adult neurogenesis in rodent brain

Jordane Malaterre
Abstract Although neurogenesis in the adult is known to be regulated by various internal cues such as hormones, growth factors and cell-adherence molecules, downstream elements underlying their action at the cellular level still remain unclear. We previously showed in an insect model that polyamines (putrescine, spermidine and spermine) play specific roles in adult brain neurogenesis. Here, we demonstrate their involvement in the regulation of secondary neurogenesis in the rodent brain. Using neurosphere assays, we show that putrescine addition stimulates neural progenitor proliferation. Furthermore, in vivo depletion of putrescine by specific and irreversible inhibition of ornithine decarboxylase, the first key enzyme of the polyamine synthesis pathway, induces a consistent decrease in neural progenitor cell proliferation in the two neurogenic areas, the dentate gyrus and the subventricular zone. The present study reveals common mechanisms underlying birth of new neurons in vertebrate and invertebrate species. [source]

Postsynaptic M1 and M3 receptors are responsible for the muscarinic enhancement of retrograde endocannabinoid signalling in the hippocampus

Takako Ohno-Shosaku
Abstract The cholinergic system is crucial for higher brain functions including learning and memory. These functions are mediated primarily by muscarinic acetylcholine receptors (mAChRs) that consist of five subtypes (M1,M5). A recent study suggested a novel role of acetylcholine as a potent enhancer of endocannabinoid signalling that acts retrogradely from postsynaptic to presynaptic neurons. In the present study, we further investigated the mechanisms of this cholinergic effect on endocannabinoid signalling. We made paired whole-cell recordings from cultured hippocampal neurons, and monitored inhibitory postsynaptic currents (IPSCs). The postsynaptic depolarization induced a transient suppression of IPSCs (DSI), a phenomenon known to involve retrograde signalling by endocannabinoids. The cholinergic agonist carbachol (CCh) markedly enhanced DSI at 0.01,0.3 µm without changing the presynaptic cannabinoid sensitivity. The facilitating effect of CCh on DSI was mimicked by the muscarinic agonist oxotremorine-M, whereas it was eliminated by the muscarinic antagonist atropine. It was also blocked by a non-hydrolizable analogue of GDP (GDP-,-S) that was applied intracellularly to postsynaptic neurons. The muscarinic enhancement of DSI persisted to a substantial degree in the neurons prepared from M1 -knockout and M3 -knockout mice, but was virtually eliminated in the neurons from M1/M3 -compound-knockout mice. CCh still enhanced DSI significantly under the blockade of postsynatpic K+ conductance, and did not significantly influence the depolarization-induced Ca2+ transients. These results indicate that the activation of postsynaptic M1 and M3 receptors facilitates the depolarization-induced release of endocannabinoids. [source]

The mouse VPAC2 receptor confers suprachiasmatic nuclei cellular rhythmicity and responsiveness to vasoactive intestinal polypeptide in vitro

David J. Cutler
Abstract Expression of coherent and rhythmic circadian (, 24 h) variation of behaviour, metabolism and other physiological processes in mammals is governed by a dominant biological clock located in the hypothalamic suprachiasmatic nuclei (SCN). Photic entrainment of the SCN circadian clock is mediated, in part, by vasoactive intestinal polypeptide (VIP) acting through the VPAC2 receptor. Here we used mice lacking the VPAC2 receptor (Vipr2,/,) to examine the contribution of this receptor to the electrophysiological actions of VIP on SCN neurons, and to the generation of SCN electrical firing rate rhythms SCN in vitro. Compared with wild-type controls, fewer SCN cells from Vipr2,/, mice responded to VIP and the VPAC2 receptor-selective agonist Ro 25-1553. By contrast, similar proportions of Vipr2,/, and wild-type SCN cells responded to gastrin-releasing peptide, arginine vasopressin or N -methyl- d -aspartate. Moreover, VIP-evoked responses from control SCN neurons were attenuated by the selective VPAC2 receptor antagonist PG 99-465. In firing rate rhythm experiments, the midday peak in activity observed in control SCN cells was lost in Vipr2,/, mice. The loss of electrical activity rhythm in Vipr2,/, mice was mimicked in control SCN slices by chronic treatment with PG 99-465. These results demonstrate that the VPAC2 receptor is necessary for the major part of the electrophysiological actions of VIP on SCN cells in vitro, and is of fundamental importance for the rhythmic and coherent expression of circadian rhythms governed by the SCN clock. These findings suggest a novel role of VPAC2 receptor signalling, and of cell-to-cell communication in general, in the maintenance of core clock function in mammals, impacting on the cellular physiology of SCN neurons. [source]

Interaction between Lim15/Dmc1 and the homologue of the large subunit of CAF-1 , a molecular link between recombination and chromatin assembly during meiosis

FEBS JOURNAL, Issue 9 2008
Satomi Ishii
In eukaryotes, meiosis leads to genetically variable gametes through recombination between homologous chromosomes of maternal and paternal origin. Chromatin organization following meiotic recombination is critical to ensure the correct segregation of homologous chromosomes into gametes. However, the mechanism of chromatin organization after meiotic recombination is unknown. In this study we report that the meiosis-specific recombinase Lim15/Dmc1 interacts with the homologue of the largest subunit of chromatin assembly factor 1 (CAF-1) in the basidiomycete Coprinopsis cinerea (Coprinus cinereus). Using C. cinerea LIM15/DMC1 (CcLIM15) as the bait in a yeast two-hybrid screen, we have isolated the C. cinerea homologue of Cac1, the largest subunit of CAF-1 in Saccharomyces cerevisiae, and named it C. cinerea Cac1-like (CcCac1L). Two-hybrid assays confirmed that CcCac1L binds CcLim15 in vivo. ,-Galactosidase assays revealed that the N-terminus of CcCac1L preferentially interacts with CcLim15. Co-immunoprecipitation experiments showed that these proteins also interact in the crude extract of meiotic cells. Furthermore, we demonstrate that, during meiosis, CcCac1L interacts with proliferating cell nuclear antigen (PCNA), a component of the DNA synthesis machinery recently reported as an interacting partner of Lim15/Dmc1. Taken together, these results suggest a novel role of the CAF-1,PCNA complex in meiotic events. We propose that the CAF-1,PCNA complex modulates chromatin assembly following meiotic recombination. [source]