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Tissue-specific Manner (tissue-specific + manner)
Selected AbstractsCaenorhabditis elegans expresses three functional profilins in a tissue-specific mannerCYTOSKELETON, Issue 1 2006D. Polet Abstract Profilins are actin binding proteins, which also interact with polyphosphoinositides and proline-rich ligands. On the basis of the genome sequence, three diverse profilin homologues (PFN) are predicted to exist in Caenorhabditis elegans. We show that all three isoforms PFN-1, PFN-2, and PFN-3 are expressed in vivo and biochemical studies indicate they bind actin and influence actin dynamics in a similar manner. In addition, they bind poly(L -proline) and phosphatidylinositol 4,5-bisphosphate micelles. PFN-1 is essential whereas PFN-2 and PFN-3 are nonessential. Immunostainings revealed different expression patterns for the profilin isoforms. In embryos, PFN-1 localizes in the cytoplasm and to the cell,cell contacts at the early stages, and in the nerve ring during later stages. During late embryogenesis, expression of PFN-3 was specifically detected in body wall muscle cells. In adult worms, PFN-1 is expressed in the neurons, the vulva, and the somatic gonad, PFN-2 in the intestinal wall, the spermatheca, and the pharynx, and PFN-3 localizes in a striking dot-like fashion in body wall muscle. Thus the model organism Caenorhabditis elegans expresses three profilin isoforms and is the first invertebrate animal with tissue-specific profilin expression. Cell Motil. Cytoskeleton, 2006.© 2005 Wiley-Liss, Inc. [source] Gene expression in the efferent ducts, epididymis, and vas deferens during embryonic development of the mouseDEVELOPMENTAL DYNAMICS, Issue 9 2010Elizabeth M. Snyder Abstract The tissues of the male reproductive tract are characterized by distinct morphologies, from highly coiled to un-coiled. Global gene expression profiles of efferent ducts, epididymis, and vas deferens were generated from embryonic day 14.5 to postnatal day 1 as tissue-specific morphologies emerge. Expression of homeobox genes, potential mediators of tissue-specific morphological development, was assessed. Twenty homeobox genes were identified as either tissue-enriched, developmentally regulated, or both. Additionally, ontology analysis demonstrated cell adhesion to be highly regulated along the length of the reproductive tract. Regulators of cell adhesion with variable expression between the three tissues were identified including Alcam, various cadherins, and multiple integrins. Immunofluorescence localization of the cell adhesion regulators POSTN and CDH2 demonstrated cell adhesion in the epithelium and mesenchyme of the epididymis may change throughout development. These results suggest cell adhesion may be modulated in a tissue-specific manner, playing an important role in establishing each tissue's final morphology. Developmental Dynamics 239:2479,2491, 2010. © 2010 Wiley-Liss, Inc. [source] Effect of trefoil factors on the viscoelastic properties of mucus gelsEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 7 2002L. Thim Abstract Background Trefoil peptides (TFFs) are expressed and secreted in a tissue-specific manner in the gastrointestinal tract. Evidence of coexpression of trefoil peptides and mucins has been demonstrated in most mucus-producing cells in the gastrointestinal tract. The expression of trefoil peptides is up-regulated in gastric ulceration and colitis. It is believed that TFF peptides interact with mucin to increase viscosity but this has never been confirmed. The aims of the present study were to elucidate the direct effect of trefoil peptides on mucus gel formation. Materials and methods The viscosity of mucin solutions was measured by means of a rotational rheometer after adding three mammalian trefoil peptides: TFF1, TFF2, and TFF3. Results Adding TFF2 (0·3%) to the mucin solutions (8%) resulted in more than a factor 10 increase in viscosity and elasticity, and the mucin solution was transformed into a gel-like structure with serpentine-like complexes between the mucin and TFF2. The dimer form of TFF3 also increased viscosity but resulted in a spider's web-like structure. The monomer forms of TFF1 and TFF3 had very little effect on the viscosity and elasticity of the mucin solutions. Conclusions The addition of TFF2 to mucin solutions results in significantly increased viscosity and elasticity, under which the mucin solutions are transformed into a gel-like state. The ability of some trefoil peptides to catalyse the formation of stable mucin complexes may be one of the ways by which these peptides exert their protective and healing functions. [source] Identification of ERR, as a specific partner of PGC-1, for the activation of PDK4 gene expression in muscleFEBS JOURNAL, Issue 8 2006Makoto Araki Pyruvate dehydrogenase kinase 4 (PDK4) is a key regulatory enzyme involved in switching the energy source from glucose to fatty acids in response to physiological conditions. Transcription of the PDK4 gene is activated by fasting or by the administration of a PPAR, ligand in a tissue-specific manner. Here, we show that the two mechanisms are independent, and that ERR, is directly involved in PPAR,-independent transcriptional activation of the PDK4 gene with PGC-1, as a specific partner. This conclusion is based on the following evidence. First, detailed mutation analyses of the cloned PDK4 gene promoter sequence identified a possible ERR,-binding motif as the PGC-1, responsive element. Second, overexpression of ERR, by cotransfection enhanced, and the knockout of it by shRNAs diminished, PGC-1,-dependent activation. Third, specific binding of ERR, to the identified PGC-1, responsive sequence was confirmed by the electrophoresis mobility shift assay. Finally, cell-type-specific responsiveness to PGC-1, was observed and this could be explained by differences in the expression levels of ERR,, however, ectopic expression of ERR, in poorly responsive cells did not restore PGC-1, responsiveness, indicating that ERR, is necessary, but not sufficient for the response. [source] Identification of rat cyclic nucleotide phosphodiesterase 11A (PDE11A)FEBS JOURNAL, Issue 16 2001Comparison of rat, human PDE11A splicing variants ,We have isolated and characterized rat cyclic nucleotide phosphodiesterase (PDE)11A, which exhibits properties of a dual-substrate PDE, and its splice variants (RNPDE11A2, RNPDE11A3, and RNPDE11A4). The deduced amino-acid sequence of the longest form of rat PDE11A splice variant, RNPDE11A4, was 94% identical with that of the human variant (HSPDE11A4). Rat PDE11A splice variants were expressed in a tissue-specific manner. RNPDE11A4 showed unique tissue distribution distinct from HSPDE11A4, which is specifically expressed in the prostate. Rat PDE11A splice variants were expressed in COS-7 cells, and their enzymatic characteristics were compared. Although the Km values for cAMP and cGMP were similar for all of them (1.3,1.6 and 2.1,3.9 µm, respectively), the Vmax values differed significantly (RNPDE11A4 >> RNPDE11A2 > RNPDE11A3). Human PDE11A variants also displayed very similar Km values and significantly different Vmax values (HSPDE11A4 >> HSPDE11A2 > HSPDE11A3 >> HSPDE11A1). The Vmax values of HSPDE11A4 for cAMP and cGMP were at least 100 times higher than those of HSPDE11A1. These observations indicate unique characteristics of PDE11A splicing variants. [source] Hormonal regulation of multiple promoters of the rat mitochondrial glycerol-3-phosphate dehydrogenase geneFEBS JOURNAL, Issue 14 2001Identification of a complex hormone-response element in the ubiquitous promoter B Rat mitochondrial glycerol-3-phosphate dehydrogenase (mGPDH) is regulated by multiple promoters in a tissue-specific manner. Here, we demonstrate that thyroid hormone (3,5,3,-tri-iodo- l -thyronine) and steroid hormone but not the peroxisome proliferator clofibrate and retinoic acid stimulate the activation of the ubiquitous promoter B in a receptor-dependent manner, whereas the more tissue-restricted promoters A and C are not inducible by these hormones. Thyroid hormone action is mediated by a direct repeat +4 (DR+4) hormone-response element as identified by deletion and mutation analyses of promoter B in transient transfection analyses. The DR+4 element was able to bind to an in vitro translated thyroid hormone receptor in band-shift and supershift experiments. The hormone-response element comaps with a recognition site for the transcription factor Sp1, suggesting complex regulation of this sequence element. Mutation of this Sp1-recognition site reduces the basal promoter B activity dramatically in HepG2 and HEK293 cells in transient transfection and abolishes the binding of Sp1 in band-shift experiments. As demonstrated by Western-blot experiments, administration of tri-iodothyronine to euthyroid rats increases hepatic mGPDH protein concentrations in vivo. As it has recently been reported that human mGPDH promoter B is not regulated by tri-iodothyronine, this is the first example of a differentially tri-iodothyronine-regulated orthologous gene promoter in man and rat. [source] Complement and its implications in cardiac ischemia/reperfusion: strategies to inhibit complementFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 5 2001Tiphaine Monsinjon Although reperfusion of the ischemic myocardium is an absolute necessity to salvage tissue from eventual death, it is also associated with pathologic changes that represent either an acceleration of processes initiated during ischemia or new pathophysiological changes that were initiated after reperfusion. This so-called ,reperfusion injury' is accompanied by a marked inflammatory reaction, which contributes to tissue injury. In addition to the well known role of oxygen free radicals and white blood cells, activation of the complement system probably represents one of the major contributors of the inflammatory reaction upon reperfusion. The complement may be activated through three different pathways: the classical, the alternative, and the lectin pathway. During reperfusion, complement may be activated by exposure to intracellular components such as mitochondrial membranes or intermediate filaments. Two elements of the activated complement contribute directly or indirectly to damages: anaphylatoxins (C3a and C5a) and the membrane attack complex (MAC). C5a, the most potent chemotactic anaphylatoxin, may attract neutrophils to the site of inflammation, leading to superoxide production, while MAC is deposited over endothelial cells and smooth vessel cells, leading to cell injury. Experimental evidence suggests that tissue salvage may be achieved by inhibition of the complement pathway. As the complement is composed of a cascade of proteins, it provides numerous sites for pharmacological interventions during acute myocardial infarction. Although various strategies aimed at modulating the complement system have been tested, the ideal approach probably consists of maintaining the activity of C3 (a central protein of the complement cascade) and inhibiting the later events implicated in ischemia/reperfusion and also in targeting inhibition in a tissue-specific manner. [source] Generation of a mouse with conditionally activated signaling through the BMP receptor, ALK2,GENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 4 2006Tomokazu Fukuda Abstract BMP signaling plays pleiotropic roles in various tissues. Transgenic mouse lines that overexpress BMP signaling in a tissue-specific manner would be beneficial; however, production of each tissue-specific transgenic mouse line is labor-intensive. Here, using a Cre-loxP system, we generated a conditionally overexpressing mouse line for BMP signaling through the type I receptor ALK2 (alternatively known as AVCRI, ActRI, or ActRIA). By mating this line with Cre-expression mouse lines, Cre-mediated recombination removes an intervening floxed lacZ expression cassette and thereby permits the expression of a constitutively active form of Alk2 (caAlk2) driven by a ubiquitous promoter, CAG. Tissue specificity of Cre recombination was monitored by a bicistronically expressed EGFP following Alk2 cDNA. Increased BMP signaling was confirmed by ectopic phosphorylation of SMAD1/5/8 in the areas where Cre recombination had occurred. The conditional overexpression system described here provides versatility in investigating gene functions in a tissue-specific manner without having to generate independent tissue-specific transgenic lines. genesis 44:159,167, 2006. Published 2006 Wiley-Liss, Inc. [source] A T3 allele in the CFTR gene exacerbates exon 9 skipping in vas deferens and epididymal cell lines and is associated with Congenital Bilateral Absence of Vas Deferens (CBAVD),HUMAN MUTATION, Issue 1 2005Antoine Disset Abstract The different alleles at the (TG)m(T)n polymorphic loci at the 3, end of the human CFTR intron 8 determine the efficiency by which exon 9 is spliced. We identified a novel TG12T3 allele in a congenital bilateral absence of vas deferens (CBAVD) patient who carries a [TG11T7; p.Phe508Cys; p.Met470Val] haplotype on the other chromosome. To better understand the complex regulation of exon 9 splicing, we analyzed the levels of correctly spliced CFTR transcripts in six CFTR-expressing epithelial cell lines derived from lung, colon, testis, vas deferens, and epididymis transiently transfected with four CFTR minigenes (pTG11T7, pTG12T7, pTG12T5, and pTG12T3). In this work, we show that a decrease in the Ts at the polymorphic locus in a TG12 background determines a cell-type dependent reduction in exon 9+ transcripts that is not related to the basal splicing efficiency in the cell line. These data emphasize the role of the T5 allele in CBAVD and identify the T3 allele as a severe cystic fibrosis (CF) disease-causing mutation. Finally, UV cross-linking experiments demonstrated that tissue-specific trans -acting splicing factors do not contribute to the different patterns of exon 9 splicing found between the cell lines. However, we observed that lower numbers of Ts can alter the binding of TDP-43 (TDP43 or TARDBP) to its specific target ug12 in a tissue-specific manner. Our results support the idea that the ratio of general splicing factors plays a role in the tissue variability of exon 9 alternative splicing. Hum Mutat 25:72,81, 2005. © 2004 Wiley-Liss, Inc. [source] Expression of GLUT8 in mouse intestine: Identification of alternative spliced variantsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2009Amparo Romero Abstract GLUT8 is a facilitative glucose transporter composed of 10 exons coding for a 477 amino acids protein. It is mainly expressed in the testis, but it has also been studied in a number of tissues such as brain, adipose tissue, and liver. In this work, we have characterized the expression of GLUT8 in the small and large intestine under normal physiological conditions. Protein assay revealed low GLUT8 protein levels in the intestine compared to the testis, with higher levels in the colon than in the small intestine. Immunohistochemistry studies showed an intracellular localization of GLUT8 in enterocytes and colonocytes with a supranuclear distribution next to the apical membrane. GLUT8 immunoreactivity was also detected in the crypt cells. Interestingly, we have identified three additional transcriptional variants in mouse intestine (mGLUT-SP1, mGLUT8-SP2, and mGLUT8-SP3) produced by the deletion of one, two, and four exons, respectively, whereas only the entire mRNA was detected in the testis. Expression of these alternative variants did not have an effect on glucose consumption in 3T3-L1 cells. Although the specific function of GLUT8 in intestine remains unclear, the alternative splicing of GLUT8 could reflect a mechanism for the regulation of the gene expression in a tissue-specific manner by targeting GLUT8 mRNA for nonsense-mediated decay. J. Cell. Biochem. 106: 1068,1078, 2009. © 2009 Wiley-Liss, Inc. [source] THE CONNEXIN 32 NERVE-SPECIFIC PROMOTER IS DIRECTLY ACTIVATED BY Egr2/Krox20 IN HeLa CELLSJOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2002M. Musso Connexin 32 (Cx32) belongs to a protein family that forms intercellular channels mediating the exchange of ions and chemical messengers. In the peripheral nervous system (PNS) Cx32 is expressed in Schwann cells and contributes to the homeostasis and structural integrity of myelin. Mutations of this gene determine X-linked form of Charcot Marie-Tooth (CMTX) disease. Cx 32 is transcriptionally regulated in a tissue-specific manner by two different promoters termed P1 and P2. P2, active in Schwann cells, is located 5 kb downstream from the P1 promoter and at 500 bp from the exon 2 that contains the entire coding region. Previously, by Electrophoretical Mobility Shift Assay (EMSA) we have identified a sequence (-101/-93), within P2, specifically recognized by recombinant Egr2. In order to prove the direct involvement of Egr2 in the transcriptional control of the Cx32 gene, we have performed transfection experiments in HeLa cells with a luciferase driven by the P2 promoter in presence or not of a vector expressing Krox20, the mouse homologue of human Egr2. We have found that the construct in which the sequence -103/-93 is mutated is not activated as well as the wild type sequence. Moreover we have detected another upstream sequence (-236/-213) recognized by recombinant Egr2 and other transcription factors present in HeLa nuclear extract like SP1. The construct, lacking this sequence and carrying the mutated downstream Egr2 recognition sequence, is not activated at all by Krox20. Taken together these findings strongly suggest the role of Egr2 in the transcriptional control of Connexin 32 through both sequences. The laboratory is a member of the European CMT Consortium; partially granted by Ministero della Sanit, to PM, MURST and Ateneo to FA. [source] Regulation of Endothelial Cell Adhesion Molecule Expression in an Experimental Model of Cerebral MalariaMICROCIRCULATION, Issue 6 2002PHILLIPE R. BAUER ABSTRACT Objective: Plasmodium falciparum malaria in humans and animal models of this disease have revealed changes in the infected host that are consistent with a systemic inflammatory response. Although it has been proposed that endothelial cell adhesion molecules (CAM) contribute to the adhesive interactions of Plasmodium -infected erythrocytes and immune cells with vascular endothelial cells, ECAM expression has not been systematically studied in Plasmodium -infected animals. Methods: In this study, the dual radiolabeled monoclonal antibody method was used to quantify the expression of different ECAMs (ICAM-1, VCAM-1, P-selectin, E-selectin) in different regional vascular beds of Plasmodium berghei ANKA-inffected mice (PbA), a well-recognized model of human cerebral malaria. The roles of T lymphocytes and certain cytokines (TNF-,, IL-12, IFN-,) in mediating the infection-induced expression of ICAM-1 and P-selectin were assessed by using relevant mutant mice. Results: Wild-type (WT) mice exhibited highly significant increases in the expression of ICAM-1, VCAM-1, and P-selectin (but not E-selectin) in all vascular beds on the 6th day of PbA infection. The PbA -induced upregulation of ICAM-1 was significantly blunted in mice that were either deficient in IFN-,, IL-12 (but not TNF1b) or T lymphocytes (Rag-1 deficiency); however, these responses were tissue specific. Conclusions: These findings indicate that vascular endothelial cells in most regional circulations assume an inflammatory phenotype and that cytokines and immune cells mediate this response in a tissue-specific manner. [source] Over-expression of SOB5 suggests the involvement of a novel plant protein in cytokinin-mediated developmentTHE PLANT JOURNAL, Issue 5 2006Jingyu Zhang Summary Cytokinins are a class of phytohormones that play a critical role in plant growth and development. sob5-D, an activation-tagging mutant, shows phenotypes typical of transgenic plants expressing the Agrobacterium tumefaciens isopentenyltransferase (ipt) gene that encodes the enzyme catalyzing the first step of cytokinin biosynthesis. The sob5-D mutant phenotypes are caused by over-expression of a novel gene, SOB5. Sequence analysis places SOB5 in a previously uncharacterized family of plant-specific proteins. A translational fusion between SOB5 and the green fluorescent protein reporter was localized in the cytoplasm as well as associated with the plasma membrane when transiently expressed in onion epidermal cells. Analysis of transgenic plants harboring an SOB5:SOB5,, -glucuronidase (GUS) translational fusion under the control of the SOB5 promoter region showed GUS activity in vegetative tissues (hydathodes and trichomes of leaves, shoot meristems and roots) as well as in floral tissues (pistil tips, developing anthers and sepal vasculature). Cytokinin quantification analysis revealed that adult sob5-D plants accumulated higher levels of trans -zeatin riboside, trans -zeatin riboside monophosphate and isopentenyladenine 9-glucoside when compared to the wild-type. Consistent with this result, AtIPT3 and AtIPT7 were found to be up-regulated in a tissue-specific manner in sob5-D mutants. Physiological analysis of the sob5-D mutant demonstrated reduced responsiveness to exogenous cytokinin in both root-elongation and callus-formation assays. Taken together, our data suggest a role for the novel gene SOB5 in cytokinin-mediated plant development. [source] Aberrantly differentiated cells in benign pilomatrixoma reflect the normal hair follicle: immunohistochemical analysis of Ca2+ -binding S100A2, S100A3 and S100A6 proteinsBRITISH JOURNAL OF DERMATOLOGY, Issue 2 2005K. Kizawa Summary Background, Pilomatrixoma is a common benign cutaneous tumour containing differentiated hair matrix cells. This tumour is mainly composed of basophilic, transitional, shadow and squamoid cells. Although some S100 proteins are expressed in a tissue-specific manner in the hair follicle (e.g. S100A2 in the outer root sheath, S100A3 in the cortex and cuticle, and S100A6 in the inner root sheath), little information is available concerning their distribution in the aberrantly differentiated tissues of pilomatrixoma. Objectives, To characterize the disordered epithelial elements of pilomatrixoma by localizing S100A2, S100A3 and S100A6 proteins. Methods, Immunohistochemistry and dual-immunofluorescence microscopy were performed on 22 pilomatrixoma specimens using antibodies specific to the three proteins. Results, Tissue-specific distribution of the S100 proteins investigated was preserved in the morphologically disordered tumour tissues. Anti-S100A2 antibody stained squamoid cells and putative outer root sheath cells; basophilic and potential hair matrix cells were occasionally stained. S100A3 staining was found in transitional cells and putative cortical cells, and was strong in both dispersed cells and hair-like structures surrounding cells which were presumably cuticular cells. Anti-S100A6 antibody labelled some S100A3-negative transitional cell strands, potentially inner root sheath cells. Conclusions, The epithelial elements of pilomatrixoma can be characterized using S100 proteins as biochemical markers. Our results show that pilomatrixomas retain a certain degree of differentiation indicative of distinct hair-forming cells. [source] Therapeutic manipulation of glucocorticoid metabolism in cardiovascular diseaseBRITISH JOURNAL OF PHARMACOLOGY, Issue 5 2009Patrick W.F. Hadoke The therapeutic potential for manipulation of glucocorticoid metabolism in cardiovascular disease was revolutionized by the recognition that access of glucocorticoids to their receptors is regulated in a tissue-specific manner by the isozymes of 11,-hydroxysteroid dehydrogenase. Selective inhibitors of 11,-hydroxysteroid dehydrogenase type 1 have been shown recently to ameliorate cardiovascular risk factors and inhibit the development of atherosclerosis. This article addresses the possibility that inhibition of 11,-hydroxsteroid dehydrogenase type 1 activity in cells of the cardiovascular system contributes to this beneficial action. The link between glucocorticoids and cardiovascular disease is complex as glucocorticoid excess is linked with increased cardiovascular events but glucocorticoid administration can reduce atherogenesis and restenosis in animal models. There is considerable evidence that glucocorticoids can interact directly with cells of the cardiovascular system to alter their function and structure and the inflammatory response to injury. These actions may be regulated by glucocorticoid and/or mineralocorticoid receptors but are also dependent on the 11,-hydroxysteroid dehydrogenases which may be expressed in cardiac, vascular (endothelial, smooth muscle) and inflammatory (macrophages, neutrophils) cells. The activity of 11,-hydroxysteroid dehydrogenases in these cells is dependent upon differentiation state, the action of pro-inflammaotory cytokines and the influence of endogenous inhibitors (oxysterols, bile acids). Further investigations are required to clarify the link between glucocorticoid excess and cardiovascular events and to determine the mechanism through which glucocorticoid treatment inhibits atherosclerosis/restenosis. This will provide greater insights into the potential benefit of selective 11,-hydroxysteroid dehydrogenase inhibitors in treatment of cardiovascular disease. [source] Cardiovascular and renal phenotyping of genetically modified mice: A challenge for traditional physiologyCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 4 2003Sharyn M Fitzgerald Summary 1.,The advent of techniques to genetically modify experimental animals and produce directed mutations in both a conditional and tissue-specific manner has dramatically opened up new fields for physiologists in cardiovascular and renal research. 2.,A consequence of altering the genetic background of mice is the difficulty in predicting the phenotypic outcome of the genetic mutation. We therefore suggest that physiologists may need to change their current experimental paradigms to face this new era. Hence, our aim is to propose a complementary research philosophy for physiologists working in the post-genomic era. That is, instead of using strictly hypothesis-driven research philosophies, one will have to perform screening studies of mutant mice, within a field of interest, to find valuable phenotypes. Once a relevant phenotype is found, in-depth studies of the underlying mechanisms should be performed. These follow-up studies should be performed using a traditional hypothesis-driven research philosophy. 3.,The rapidly increasing availability of mutated mouse models of human disease also necessitates the development of techniques to characterize these various mouse phenotypes. In particular, the miniaturization and refinement of techniques currently used to study the renal and cardiovascular system in larger animals will be discussed in the present review. Hence, we aim to outline what techniques are currently available and should be present in a laboratory to screen and study renal and cardiovascular phenotypes in genetically modified mice, with particular emphasis on methodologies used in the intact, conscious animal. [source] Molecular Diversity Of Vascular Potassium Channel IsoformsCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 4 2002Victoria P Korovkina SUMMARY 1. One essential role for potassium channels in vascular smooth muscle is to buffer cell excitation and counteract vasoconstrictive influences. Several molecular mechanisms regulate potassium channel function. The interaction of these mechanisms may be one method for fine-tuning potassium channel activity in response to various physiological and pathological challenges. 2. The most prevalent K+ channels in vascular smooth muscle are large-conductance calcium- and voltage-sensitive channels (maxi-K channels) and voltage-gated channels (Kv channels). Both channel types are complex molecular structures consisting of a pore-forming , -subunit and an ancillary , -subunit. The maxi-K and Kv channel , -subunits assemble as tetramers and have S4 transmembrane domains that represent the putative voltage sensor. While most vascular smooth muscle cells identified to date contain both maxi-K and Kv channels, the expression of individual , -subunit isoforms and , -subunit association occurs in a tissue-specific manner, thereby providing functional specificity. 3. The maxi-K channel , -subunit derives its molecular diversity by alternative splicing of a single-gene transcript to yield multiple isoforms that differ in their sensitivity to intracellular Ca2+ and voltage, cell surface expression and post- translational modification. The ability of this channel to assemble as a homo- or heterotetramer allows for fine-tuning control to intracellular regulators. Another level of diversity for this channel is in its association with accessory , -subunits. Multiple , -subunits have been identified that can arise either from separate genes or alternative splicing of a , -subunit gene. The maxi-K channel , -subunits modulate the channel's Ca2+ and voltage sensitivity and kinetic and pharmacological properties. 4. The Kv channel , -subunit derives its diverse nature by the expression of several genes. Similar to the maxi-K channel, this channel has been shown to assemble as a homo- and heterotetramer, which can significantly change the Kv current phenotype in a given cell type. Association with a number of the ancillary , -subunits affects Kv channel function in several ways. Beta-subunits can induce inactivating properties and act as chaperones, thereby regulating channel cell-surface expression and current kinetics. [source] Sp1-like transcription factors are regulators of embryonic development in vertebratesDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 4 2005Chengtian Zhao Sp1-like family is an expanding transcription factor family. Members of this family bind to the GC-box or GT-box elements in the promoter/enhancers and regulate the expression of the target genes. Currently, this family consists of at least nine members, which may act as a transactivator or a repressor on target promoters. Sp1-like transcription factors are expressed during development of vertebrate embryos in ubiquitous or tissue-specific manners and play various roles in embryonic development. This review mainly summarises their expression patterns and functions during vertebrate embryogenesis. [source] Tissue-specific variation of heat shock protein gene expression in relation to diapause in the bumblebee Bombus terrestrisENTOMOLOGICAL RESEARCH, Issue 1 2008Back-Guen KIM Abstract Diapause-associated expression patterns of heat shock protein genes (hsp) were determined in the queen of the bumblebee Bombus terrestris, a pollination insect. Partial cDNA sequences of three hsp genes ,shsp, hsc70 and hsp90, were obtained, and the deduced amino acid sequences were found to be highly homologous with corresponding hsp of hymenopteran insects. Using northern hybridization, the transcript level of each gene was compared in six stages relating to diapause: pre-mating, post-mating, chilling for 1, 2 and 3 months, and post-chilling. The transcript level was also compared in four tissues of adult queens: brain, thoracic muscle, gut and ovary. The transcript levels of the three hsp genes changed at various rates in relation to diapause, and each pattern was highly tissue-specific. Overall patterns of hsc70 and hsp90 expression were similar in each tissue. The shsp level in the brain was downregulated after 1 month chilling, but its level in the ovary was upregulated during a long chilling period; levels in muscle and gut did not change in relation to diapause. The levels of both hsc70 and hsp90 in muscle were gradually upregulated in late diapause and postdiapause stages, but levels in the ovary were downregulated during the chilling period, while levels in the brain and gut did not change in relation to diapause. Our results show that the three hsp genes were differentially regulated in stage- and tissue-specific manners throughout diapause, and suggest unique physiological roles for these genes in relation to diapause in each tissue of queen bumblebees. [source] Group IID heparin-binding secretory phospholipase A2 is expressed in human colon carcinoma cells and human mast cells and up-regulated in mouse inflammatory tissuesFEBS JOURNAL, Issue 11 2002Makoto Murakami Group IID secretory phospholipase A2 (sPLA2 -IID), a heparin-binding sPLA2 that is closely related to sPLA2 -IIA, augments stimulus-induced cellular arachidonate release in a manner similar to sPLA2 -IIA. Here we identified the residues of sPLA2 -IID that are responsible for heparanoid binding, are and therefore essential for cellular function. Mutating four cationic residues in the C-terminal portion of sPLA2 -IID resulted in abolition of its ability to associate with cell surface heparan sulfate and to enhance stimulus-induced delayed arachidonate release, cyclooxygenase-2 induction, and prostaglandin generation in 293 cell transfectants. As compared with several other group II subfamily sPLA2s, which were equally active on A23187- and IL-1-primed cellular membranes, sPLA2 -IID showed apparent preference for A23187-primed membranes. Several human colon carcinoma cell lines expressed sPLA2 -IID and sPLA2 -X constitutively, the former of which was negatively regulated by IL-1. sPLA2 -IID, but not other sPLA2 isozymes, was expressed in human cord blood-derived mast cells. The expression of sPLA2 -IID was significantly altered in several tissues of mice with experimental inflammation. These results indicate that sPLA2 -IID may be involved in inflammation in cell- and tissue-specific manners under particular conditions. [source] Distinct localizations and repression activities of MM-1 isoforms toward c-Myc,JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2006Yuko Hagio Abstract MM-1 was identified as a c-Myc-binding protein and has been reported to repress the E-box-dependent transcription activity of c-Myc by recruiting HDAC1 complex via TIF1 ,/KAP1. In this study, originally isolated MM-1 was found to be a fusion protein comprised of the N-terminal 13 amino acids from the sequence of chromosome 14 and of the rest of the amino acids from that of chromosome 12 and was found to be expressed ubiquitously in all human tissues. Four splicing isoforms of MM-1, MM-1,, MM-1,, MM-1,, and MM-1,, which are derived from the sequence of chromosome 12, were then identified. Of these isoforms, MM-1,, MM-1,, and MM-1, were found to be expressed in tissue-specific manners and MM-1, was found to be expressed ubiquitously. Although all of the isoforms potentially possessed c-Myc- and TIF1,-binding activities, MM-1, and MM-1, were found to be mainly localized in the cytoplasm and MM-1, and MM-1, were found to be localized in the nucleus together with both c-Myc and TIF1,. Furthermore, when repression activities of MM-1 isoforms toward c-Myc transcription activity were examined by reporter gene assays in HeLa cells, MM-1,, MM-1,, and MM-1,, but not MM-1,, were found to repress transcription activity of c-Myc, and the degrees of repression by MM-1, and MM-1, were smaller than those by MM-1 and MM-1,. These results suggest that each MM-1 isoform distinctly regulates c-Myc transcription activity in respective tissues. J. Cell. Biochem. © 2005 Wiley-Liss, Inc. [source] | |||||||||||||