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Predominant Isoform (predominant + isoform)
Selected AbstractsCloning and characterization of SDF-1,, a novel SDF-1 chemokine transcript with developmentally regulated expression in the nervous systemEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2000Marc Gleichmann Abstract The cytokines SDF-1, and -1, are two alternatively spliced variants of the CXC (,) chemokines that are highly conserved among species. SDF-1, was shown to function as a B-cell maturation factor, a ligand for the CXCR4 (LESTR/fusin) chemokine receptor, thereby inhibiting replication of T cell-tropic HIV-1 strains and inducing cell death in human neuronal cell lines. In this report the cloning of the rat SDF-1, cDNA and a new SDF-1 isoform, SDF-1,, are presented. Using Northern blot analysis, the expression pattern of both isoforms was studied in different tissues and it is shown that during postnatal development of the central and peripheral nervous system SDF-1,- and SDF-1,-mRNA expression is inversely regulated. Whilst SDF-1,-mRNA is the predominant isoform in embryonic and early postnatal nerve tissue, SDF-1,-mRNA is expressed at higher levels in adulthood. After peripheral nerve lesion a transient increase in SDF-1,-mRNA expression is observed. As revealed by in situ hybridization, neurons and Schwann cells are the main cellular sources of both SDF-1, and SDF-1, mRNAs in the nervous system. Computer-assisted analysis revealed that both transcripts encode secreted peptides with putative proteolytic cleavage sites which might generate novel neuropeptides. [source] AKT2 is a downstream target of metabotropic glutamate receptor 1 (Grm1)PIGMENT CELL & MELANOMA RESEARCH, Issue 1 2010Seung-Shick Shin Summary We reported earlier on the oncogenic properties of Grm1 by demonstrating that stable Grm1 -mouse-melanocytic clones proliferate in the absence of growth supplement and anchorage in vitro. In addition, these clones also exhibit aggressive tumorigenic phenotypes in vivo with short latency in tumor formation in both immunodeficient and syngeneic mice. We also detected strong activation of AKT in allograft tumors specifically AKT2 as the predominant isoform involved. In parallel, we assessed several human melanoma biopsy samples and found again that AKT2 was the predominantly activated AKT in these human melanoma biopsies. In cultured stable Grm1 -mouse-melanocytic clones, as well as an metabotropic glutamate receptor 1 (Grm1) expressing human melanoma cell line, C8161, stimulation of Grm1 by its agonist led to the activation of AKT, while preincubation with Grm1-antagonist abolished Grm1-agonist-induced AKT activation. In addition, a reduction in tumor volume of Grm1 -mouse-melanocytic-allografts was detected in the presence of small interfering AKT2 RNA (siAKT2). Taken together, these results showed that, in addition to the MAPK pathway previously reported being a downstream target of stimulated Grm1, AKT2 is another downstream target in Grm1 mediated melanocyte transformation. [source] Selective over-expression of fibroblast growth factor receptors 1 and 4 in clinical prostate cancer,THE JOURNAL OF PATHOLOGY, Issue 1 2007K Sahadevan Abstract Fibroblast growth factor receptors (FGFRs) mediate the tumourigenic effects of FGFs in prostate cancer. These receptors are therefore potential therapeutic targets in the development of inhibitors to this pathway. To identify the most relevant targets, we simultaneously investigated FGFR1,4 expression using a prostate cancer tissue microarray (TMA) and in laser capture microdissected (LCM) prostate epithelial cells. In malignant prostates (n = 138) we observed significant FGFR1 and FGFR4 protein over-expression in comparison with benign prostates (n = 58; p < 0.0001). FGFR1 was expressed at high levels in the majority of tumours (69% of grade 3 or less, 74% of grade 4 and 70% of grade 5), while FGFR4 was strongly expressed in 83% of grade 5 cancers but in only 25% of grade 1,3 cancers (p < 0.0001). At the transcript level we observed a similar pattern, with FGFR1 and FGFR4 mRNA over-expressed in malignant epithelial cells compared to benign cells (p < 0.0005 and p < 0.05, respectively). While total FGFR2 was increased in some cancers, there was no association between expression and tumour grade or stage. Transcript analysis, however, revealed a switch in the predominant isoform expressed from FGFR2IIIb to FGFR2IIIc among malignant epithelial cells. In contrast, protein and transcript expression of FGFR3 was very similar between benign and cancer biopsies. The functional effect of targeting FGFR4 in prostate cancer cells has not previously been investigated. In in vitro experiments, suppression of FGFR4 by RNA interference effectively blocked prostate cancer cell proliferation (p < 0.0001) and invasion (p < 0.001) in response to exogenous stimulation. This effect was evident regardless of whether the cells expressed the FGFR4 Arg388 or Gly388 allele. In parallel experiments, FGFR3 suppression had no discernible effect on cancer cell behaviour. These results suggest evidence of selective over-expression of FGFR1 and FGFR4 in clinical prostate cancer and support the notion of targeted inhibition of these receptors to disrupt FGF signalling. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Dominant Negative p63 Isoform Expression in Head and Neck Squamous Cell Carcinoma,THE LARYNGOSCOPE, Issue 12 2004Joseph C. Sniezek MD Abstract Objectives/Hypothesis: p63, a member of the p53 family of genes, is vital for normal epithelial development and may play a critical role in epithelial tumor formation. Although p63 has been identified in various head and neck malignancies, a detailed analysis of which of the six isoforms of the p63 gene is present in normal mucosa and head and neck malignancies has not yet been performed. The study analyzed p63 isoform expression on the RNA and protein level in normal, diseased, and malignant mucosa of the head and neck to examine the differential expression of p63 isoforms in head and neck tumors versus adjacent nonmalignant tissue and to identify the predominant p63 isoform expressed in head and neck squamous cell carcinoma (HNSCC). Study Design: Three experiments were performed. In experiment 1, p63 expression was analyzed by immunohistochemical analysis in 36 HNSCC specimens and matched normal tissue control specimens harvested from the same patient. Western blot analysis was also performed on matched specimens to confirm the identity of the p63 isoforms that were found. In experiment 2, reverse transcriptase polymerase chain reaction (RT-PCR) analysis was performed on matched normal and tumor specimens to analyze and quantitatively compare p63 isoform expression at the RNA level. In experiment 3, p63 expression was evaluated by immunohistochemical analysis in oral lichen planus, a benign mucosal lesion marked by hyperdifferentiation and apoptosis. Methods: Immunohistochemical analysis, RT-PCR, and Western blot analysis of p63 were performed on HNSCC specimens and matched normal tissue control specimens. p63 expression in oral lichen planus specimens was also examined by immunohistochemical analysis. Results: In experiment 1, analysis of 36 HNSCC specimens from various head and neck subsites showed p63 expression in all tumors and matched normal tissue specimens (36 of 36). Western blot analyses indicated that dominant negative (,N) isoform p63, (,Np63,) is the major isoform expressed at the protein level in tumors and adjacent normal tissue. In experiment 2, RT-PCR analyses of 10 matched specimens confirmed that, although all three ,Np63 isoforms (,Np63,, ,Np63,, and ,Np63,) are expressed in normal and malignant mucosa of the head and neck, ,Np63, is the predominant transcript expressed. In experiment 3, immunohistochemical analysis of p63 in the pro-apoptotic condition of lichen planus indicated that p63 is underexpressed as compared with normal mucosal specimens. Conclusion: Although all three ,Np63 isoforms are present in HNSCC, ,Np63, protein is the predominant isoform expressed in these malignancies. ,Np63, is also overexpressed in tumors compared with matched normal tissue specimens and is underexpressed in the pro-apoptotic condition of lichen planus. These findings suggest that ,Np63, plays an anti-differentiation and anti-apoptotic role in the mucosal epithelium of the head and neck, possibly playing a pivotal role in the formation of HNSCC. Currently, ,Np63, is an attractive target for mechanistic study aimed at therapeutic intervention. [source] Regulation and Role of the Presynaptic and Myocardial Na+/H+ Exchanger NHE1: Effects on the Sympathetic Nervous System in Heart FailureCARDIOVASCULAR THERAPEUTICS, Issue 2 2007Kirsten Leineweber ABSTRACT In acute myocardial ischemia and in chronic heart failure, sympathetic activation with excessive norepinephrine (NE) release from and reduced NE reuptake into sympathetic nerve endings is a prominent cause of arrhythmias and cardiac dysfunction. The Na+/H+ exchanger NHE1 is the predominant isoform in the heart. It contributes to cellular acid,base balance, and electrolyte, and volume homeostasis, and is activated in response to intracellular acidosis and/or activation of guanine nucleotide binding (G) protein-coupled receptors. NHE1 mediates its signaling via protein kinases A (PKA) or C (PKC). In cardiomyocytes, NHE1 is restricted to specialized membrane domains, where it regulates the activity of pH-sensitive proteins and modulates the driving force of the Na+/Ca2+ exchanger. During acute ischemia/reperfusion and in heart failure the activity/amount of NHE1 is increased, leading to intracellular Ca2+ overload and promoting structural (apoptosis, hypertrophy) and functional (arrhythmias, hypercontraction) myocardial damage. In sympathetic nerve endings, increased NHE1 activity results in the accumulation of axoplasmic Na+ that diminishes the inward and/or favors the outward transport of NE via the neuronal norepinephrine transporter (NET). The increased NE levels within the nerve,muscle junction facilitate the sustained stimulation of myocardial ,- and ,-adrenoceptors (ARs), which in turn aggravate the increases in myocardial NHE1 activity and the associated deleterious effects. Furthermore, the responsiveness of the ,-AR declines overtime, which results in further release of NE, initiating a vicious cycle. Accordingly, NHE1 is a potential candidate for targeted intervention to suppress this feedback loop. [source] Expression and alternative splicing of N-RAP during mouse skeletal muscle development,CYTOSKELETON, Issue 12 2008Shajia Lu Abstract N-RAP alternative splicing and protein localization were studied in developing skeletal muscle tissue from pre- and postnatal mice and in fusing primary myotubes in culture. Messages encoding N-RAP-s and N-RAP-c, the predominant isoforms of N-RAP detected in adult skeletal muscle and heart, respectively, were present in a 5:1 ratio in skeletal muscle isolated from E16.5 embryos. N-RAP-s mRNA levels increased three-fold over the first 3 weeks of postnatal development, while N-RAP-c mRNA levels remained low. N-RAP alternative splicing during myotube differentiation in culture was similar to the pattern observed in embryonic and neonatal muscle, with N-RAP-s expression increasing and N-RAP-c mRNA levels remaining low. In both developing skeletal muscle and cultured myotubes, N-RAP protein was primarily associated with developing myofibrillar structures containing ,-actinin, but was not present in mature myofibrils. The results establish that N-RAP-s is the predominant spliced form of N-RAP present throughout skeletal muscle development. Cell Motil. Cytoskeleton 2008. Published 2008 Wiley-Liss, Inc. [source] Structural Features of the NAD-Dependent In Situ Retinoic Acid Supply System in Esophageal MucosaALCOHOLISM, Issue 2010Hirokazu Yokoyama Background:, We previously reported that an NAD-dependent in situ retinoic acid supply system, which comprises some isoforms of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) and provides retinoic acid from retinol via a 2-step oxidation process, exists in the rat esophagus. Herein, their isoforms responsible for the pathway and its localization in the rat esophagus was examined. Methods:, The expressions of mRNAs of various isoforms of ADH and ALDH were examined in the fraction mainly comprising mucosal layer of the rat esophagus by RT-PCR. Expression levels of Class IV ADH and ALDH 1A1 were compared between the fractions and that mainly comprising muscle layer of the rat esophagus by quantitative PCR. The catalytic activities producing retinoic acid from retinal were compared between the 2 fractions and its optimum pH was also determined. Results:, Classes I, III, and IV ADHs and ALDHs 1A1 and 3A1 were predominant isoforms in the rat esophageal mucosa. The expression levels of mRNA of Class IV ADH and ALDH 3A1 were significantly higher in the mucosal than in the muscle layer. Consistently, the catalytic activities producing retinoic acid from retinal were significantly higher in the former than the latter. The optimum pH of the process was 9.0. Conclusions:, Considering the affinities for retinol and retinal of ADHs and ALDHs expressed in the rat esophagus, the NAD-dependent in situ retinoic acid supply system in the rat esophagus is thought to comprise Class IV ADH and ALDH 1A1. In the rat esophagus, the system exists predominantly in the mucosal layer. [source] | |||||||||||||