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II Isoform (ii + isoform)
Selected AbstractsDifferential expression of PKC beta II in the rat organ of CortiEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2007S. Ladrech Abstract To investigate a possible involvement of protein kinase C (PKC) in cochlear efferent neurotransmission, we studied the expression of the calcium-dependent PKC beta II isoform in the rat organ of Corti at different postnatal ages using immunofluorescence and immunoelectron microscopy. We found evidence of PKC beta II as early as postnatal day (PND) 5 in efferent axons running in the inner spiral bundle and in Hensen cells. At PND 8, we also found PKC beta II in efferents targeting outer hair cells (OHCs), and a slight detection at the synaptic pole in the first row of the basal and middle cochlear turns. At PND 12, PKC beta II expression declined in the efferent fibres contacting OHCs, whereas expression was concentrated at the postsynaptic membrane, from the basal and middle turns. The adult-like pattern of PKC beta II distribution was observed at PND 20. Throughout the cochlea, we found PKC beta II expression in the Hensen cells, non-sensory cells involved in potassium re-cycling, and lateral efferent terminals of the inner spiral bundle. In addition, we observed expression in OHCs at the postsynaptic membrane facing the endings of the medial efferent system, with the exception of some OHCs located in the most apical region of the cochlea. These data therefore suggest an involvement of PKC beta II in both cochlear efferent neurotransmission and ion homeostasis. Among other functions, PKC beta II could play a role in the efferent control of OHC activity. [source] Interferon-, priming is involved in the activation of arginase by oligodeoxinucleotides containing CpG motifs in murine macrophagesIMMUNOLOGY, Issue 1pt2 2009Miriam V. Liscovsky Summary Recognition of microbial products by macrophages (M,) stimulates an inflammatory response and plays a critical role in directing the host immune response against infection. In the present work, we showed for the first time that synthetic oligodeoxynucleotides containing unmethylated cytosine guanine motifs (CpG) are able to stimulate, in the presence of interferon-, (IFN-,), both arginase and inducible nitric oxide synthase (iNOS) in murine M,. Unexpectedly, IFN-,, a cytokine believed to be an inhibitor of arginase activity, intervened in the activation of this enzyme. A significant increase in arginase activity was observed upon a short pre-incubation (1 hr) with IFN-, and subsequent CpG stimulation. Therefore, a very interesting observation of this study was that the CpG-mediated arginase activity is dependent on IFN-, priming. The increase in arginase activity as a result of stimulation with CpG plus IFN-,was correlated with augmented expression of the arginase II isoform. The use of pharmacological specific inhibitors revealed that arginase activity was dependent on p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated protein kinase (ERK), but independent of c-Jun N-terminal kinase (JNK) activation. This report reveals a singular effect of the combination of CpG and IFN-,, one of the mayor cytokines produced in response to CpG administration in vivo. [source] Pituitary adenylate cyclase-activating polypeptide-induced differentiation of embryonic neural stem cells into astrocytes is mediated via the , isoform of protein kinase CJOURNAL OF NEUROSCIENCE RESEARCH, Issue 8 2006Jun Watanabe Abstract We have found previously that pituitary adenylate cyclase-activating polypeptide (PACAP) increases the number of astrocytes generated from cultured mouse neural stem cells (NSCs) via a mechanism that is independent of the cyclic AMP/protein kinase A pathway (Ohno et al., 2005). In the present study, the signaling pathway involved in the differentiation process was further investigated. PACAP-induced differentiation was inhibited by the phospholipase C inhibitor, U73122, the protein kinase C (PKC) inhibitor, chelerythrine, and the intracellular calcium chelator, BAPTA-AM, and was mimicked by phorbol 12-myristate 13-acetate (PMA), but not by 4,-PMA. These results suggest that the PACAP-generated signal was mediated via the PACAP receptor, PAC1 stimulated heterotrimeric G-protein, resulting in activation of phospholipase C, followed by calcium- and phospholipid-dependent protein kinase C (cPKC). To elucidate the involvement of the different isoforms of cPKC, their gene and protein expression were examined. Embryonic NSCs expressed , and ,II PKC, but lacked PKC,. When NSCs were exposed to 2 nM PACAP, protein expression levels of the ,II isoform transiently increased two-fold before differentiation, returning to basal levels by Day 4, whereas the level of PKC, increased linearly up to Day 6. Overexpression of PKC,II with adenovirus vector synergistically enhanced differentiation in the presence of 1 nM PACAP, whereas expression of the dominant-negative mutant of PKC,II proved inhibitory. These results indicate that the , isoform of PKC plays a crucial role in the PACAP-induced differentiation of mouse embryonic NSCs into astrocytes. © 2006 Wiley-Liss, Inc. [source] Calcium sensing and cell signaling processes in the local regulation of osteoclastic bone resorptionBIOLOGICAL REVIEWS, Issue 1 2004Mone Zaidi ABSTRACT The skeletal matrix in terrestrial vertebrates undergoes continual cycles of removal and replacement in the processes of bone growth, repair and remodeling. The osteoclast is uniquely important in bone resorption and thus is implicated in the pathogenesis of clinically important bone and joint diseases. Activated osteoclasts form a resorptive hemivacuole with the bone surface into which they release both acid and osteoclastic lysosomal hydrolases. This article reviews cell physiological studies of the local mechanisms that regulate the resorptive process. These used in vitro methods for the isolation, culture and direct study of the properties of neonatal rat osteoclasts. They demonstrated that both local microvascular agents and products of the bone resorptive process such as ambient Ca2+ could complement longer-range systemic regulatory mechanisms such as those that might be exerted through calcitonin (CT). Thus elevated extracellular [Ca2+], or applications of surrogate divalent cation agonists for Ca2+, inhibited bone resorptive activity and produced parallel increases in cytosolic [Ca2+], cell retraction and longer-term inhibition of enzyme release in isolated rat osteoclasts. These changes showed specificity, inactivation, and voltage-dependent properties that implicated a cell surface Ca2+ receptor (CaR) sensitive to millimolar extracellular [Ca2+]. Pharmacological, biophysical and immunochemical evidence implicated a ryanodine-receptor (RyR) type II isoform in this process and localized it to a unique, surface membrane site, with an outward-facing channel-forming domain. Such a surface RyR might function either directly or indirectly in the process of extracellular [Ca2+] sensing and in turn be modulated by cyclic adenosine diphosphate ribose (cADPr) produced by the ADP-ribosyl cyclase, CD38. The review finishes by speculating about possible detailed models for these transduction events and their possible interactions with other systemic mechanisms involved in Ca2+ homeostasis as well as the possible role of the RyR-based signaling mechanisms in longer-term cell regulatory processes. [source] Mycophenolate mofetil in uveitisACTA OPHTHALMOLOGICA, Issue 2009P NERI Purpose To review the current Literature and to describe the experience of a tertiary referral centre on the use of mycophenolate mofetil (MMF) treatment in uveitis. Methods The current literature is reviewed and the experience of a tertiary referral centre is reported. Results The long-lasting remission in several systemic diseases, such as Crohn's disease, severe atopic dermatitis, Wegener's granulomatosis and microscopic polyangioitis, rheumatoid arthritis, pemphigus vugaris, and psoriasis, have been proven. Recent publications have have recently confirmed the satisfactory control of uveitis with MMF in a large cohort of patients. Moreover, the long-term control of cystoid macular oedema (CMO) unresponsive to the traditional therapy has been described, as well as for the choroidal neovascularization (CNV). Conclusion Non-infectious uveitis is one of the leading causes of visual impairment in ophthalmology. Steroids can control such disease, even though a long-term treatment is not recommended: several complications, such as high blood sugar level, osteoporosis, blood cell abnormalities, cataract and glaucoma, can occur. MMF is a reversible, non competitive, selective inhibitor of the de-novo pathway of purine synthesis; mycophenolic acid has a strong effect to Type II isoform of inosine monophosphate dehydrogenase enzyme, providing a stronger cytostatic effect on lymphocytes than on other cells types, with minor action to Type I expressed in most other cells. The specific action of MMF on selected targets makes it a promising drug for the control of non-infectious intraocular inflammations. [source] Non-muscle myosin IIB helps mediate TNF cell death signaling independent of actomyosin contractility (AMC)JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2010Patrick G. Flynn Abstract Non-muscle myosin II (NM II) helps mediate survival and apoptosis in response to TNF-alpha (TNF), however, NM II's mechanism of action in these processes is not fully understood. NM II isoforms are involved in a variety of cellular processes and differences in their enzyme kinetics, localization, and activation allow NM II isoforms to have distinct functions within the same cell. The present study focused on isoform specific functions of NM IIA and IIB in mediating TNF induced apoptosis. Results show that siRNA knockdown of NM IIB, but not NM IIA, impaired caspase cleavage and nuclear condensation in response to TNF. NM II's function in promoting cell death signaling appears to be independent of actomyosin contractility (AMC) since treatment of cells with blebbistatin or cytochalasin D failed to inhibit TNF induced caspase cleavage. Immunoprecipitation studies revealed associations of NM IIB with clathrin, FADD, and caspase 8 in response to TNF suggesting a role for NM IIB in TNFR1 endocytosis and the formation of the death inducing signaling complex (DISC). These findings suggest that NM IIB promotes TNF cell death signaling in a manner independent of its force generating property. J. Cell. Biochem. 9999: 1365,1375, 2010. © 2010 Wiley-Liss, Inc. [source] Myosin IIA is required for neurite outgrowth inhibition produced by repulsive guidance moleculeJOURNAL OF NEUROCHEMISTRY, Issue 1 2008Takekazu Kubo Abstract Although myelin-associated neurite outgrowth inhibitors express their effects through RhoA/Rho-kinase, the downstream targets of Rho-kinase remain unknown. We examined the involvement of myosin II, which is one of the downstream targets of Rho-kinase, by using blebbistatin , a specific myosin II inhibitor , and small interfering RNA targeting two myosin II isoforms, namely, MIIA and MIIB. We found that neurite outgrowth inhibition by repulsive guidance molecule (RGMa) was mediated via myosin II, particularly MIIA, in cerebellar granule neurons. RGMa induced myosin light chain (MLC) phosphorylation by a Rho-kinase-dependent mechanism. After spinal cord injury in rats, phosphorylated MLC in axons around the lesion site was up-regulated, and this effect depends on Rho-kinase activity. Further, RGMa-induced F-actin reduction in growth cones and growth cone collapse were mediated by MIIA. We conclude that Rho-kinase-dependent activation of MIIA via MLC phosphorylation induces F-actin reduction and growth cone collapse and the subsequent neurite retraction/outgrowth inhibition triggered by RGMa. [source] In Vitro and In Vivo Relaxation of Corpus Cavernosum Smooth Muscle by the Selective Myosin II Inhibitor, BlebbistatinTHE JOURNAL OF SEXUAL MEDICINE, Issue 10 2009Xin-hua Zhang MD ABSTRACT Introduction., Blebbistatin (BLEB) is a small cell permeable molecule originally reported as a selective inhibitor of myosin II isoforms expressed by striated muscle and non-muscle cells (IC50 = 0.5,5 µM) with poor inhibition of turkey gizzard smooth muscle (SM) myosin II (IC50,80 µM). However, recently it was found that BLEB can potently inhibit mammalian arterial SM (IC50,5 µM). Aim., To investigate the effect of BLEB on corpus cavernosum SM (CCSM) tone and erectile function (EF). Methods., CC tissue obtained from penile implant patients along with CC, aorta and bladder from adult male rats were used for BLEB organ bath studies. Intracavernosal BLEB was administered to rats and EF was assessed via intracavernous pressure (ICP). Main Outcome Measures., Effects of BLEB on agonist-induced CCSM, aorta and bladder contraction in vitro and ICP in vivo. Results., BLEB completely relaxed human CCSM pre-contracted with phenylephrine (PE) in a dose-dependent manner decreasing tension by 76.5% at 10 µM. BLEB pre-incubation attenuated PE-induced contraction of human CC by ,85%. Human CC strips pre-contracted with endothelin-1 or KCl were almost completely relaxed by BLEB. Rat CCSM pre-contracted with PE showed BLEB relaxation comparable to human CCSM. BLEB inhibition was similar for rat aorta but slower for bladder. Both maximal ICP and ICP/mean arterial pressure were dose-dependently increased by BLEB intracavernous injections with full erection at 1 micromole. Conclusion., Our novel data reveals that BLEB nearly completely relaxes rat and human CCSM pre-contracted with a variety of potent agonists and exhibits tissue selectivity. Coupled with our in vivo data in which nanomole doses of BLEB significantly increase ICP, our data substantiates an important role for the SM contractile apparatus in the molecular mechanism for EF and suggests the possibility of BLEB binding at myosin II as a therapeutic treatment for ED by targeting SM contractile pathways. Zhang X, Aydin M, Kuppam D, Melman A, and DiSanto ME. In vitro and in vivo relaxation of corpus cavernosum smooth muscle by the selective myosin II inhibitor, blebbistatin. J Sex Med 2009;6:2661,2671. [source] | |||||||||||||