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Translation Inhibitor Cycloheximide (translation + inhibitor_cycloheximide)
Selected AbstractsProteasome inhibitor-induced apoptosis in human monocyte-derived dendritic cellsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 3 2006Alessio Nencioni Dr. Abstract Proteasome inhibitors possess potent antitumor activity against a broad spectrum of human malignancies. However, the effects of these compounds on the immune system still have to be clearly determined. In the present study, we have investigated the effects of proteasome inhibitors on dendritic cells (DC), antigen-presenting cells playing a key role in the initiation of immune responses. Exposure to the proteasome inhibitors bortezomib, MG132 or epoxomicin was found to promote apoptosis of human monocyte-derived DC and to reduce the yield of viable DC when given to monocytes early during differentiation to DC. DC apoptosis via proteasome inhibition was accompanied by mitochondria disruption and subsequent activation of the caspase cascade. Up-regulation and intracellular redistribution of Bcl-2-associated X,protein (Bax), a pro-apoptotic Bcl-2 family protein, were observed in DC treated with these compounds and represent a suitable mechanism leading to activation of the intrinsic apoptotic pathway. Finally, active protein synthesis was found to represent an upstream prerequisite for DC apoptosis induced by proteasome inhibitors, since the translation inhibitor cycloheximide blocked all of the steps of the observed apoptotic response. In conclusion, induction of apoptosis in DC may represent a novel mechanism by which proteasome inhibitors affect the immune response at the antigen-presenting cell level. [source] The MHC class,II transactivator (CIITA) mRNA stability is critical for the HLA class,II gene expression in myelomonocytic cellsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2005Andrea De Lerma Barbaro Abstract The human promyelocytic U937 cells express detectable levels of MHC class,II (MHC-II) molecules. Treatment with 12-o- - tetradecanoyl phorbol 13-acetate (TPA), inducing macrophage-like differentiation, produces a dramatic decrease of MHC-II expression as result of down-modulation of the activation of immune response gene,1 (AIR-1)-encoded MHC-II transactivator (CIITA). This event is specific, as MHC class,I remains unaffected. Similar results are observed with U937 cells expressing an exogenous full-length CIITA. Molecular studies demonstrate that TPA treatment affects the stability of CIITA mRNA rather than CIITA transcription. Importantly, cis -acting elements within the distal 650,bp of the 1035-bp 3,,untranslated region (3,UTR, nucleotides 3509,4543) are associated to transcript instability. Transcription inhibitors actinomycin,D and 5,6-dichlororibofuranosyl benzimidazole, and the translation inhibitor cycloheximide significantly rescue the accumulation of CIITA mRNA in TPA-treated cells. A similar effect is also observed after treatment with staurosporine and the PKC-specific inhibitor GF109203X. The instability of CIITA mRNA produced by TPA in U937 cells is not seen in B,cells. These results demonstrate the presence of an additional level of control of MHC-II expression in the macrophage cell lineage depending upon the control of CIITA mRNA stability, most likely mediated by differentiation-induced, 3,UTR-interacting factors which require kinase activity for their destabilizing function. [source] Mechanosensitive hyaluronan secretion: stimulus,response curves and role of transcription,translation,translocation in rabbit jointsEXPERIMENTAL PHYSIOLOGY, Issue 3 2009A. K. T. Wann Joint movement was recently shown to stimulate the secretion of the lubricant hyaluronan (HA); also, exercise therapy and intra-articular hyaluronan injections are used to treat moderate osteoarthritis. The present study quantifies the stimulus,response curves for HA secretion in vivo and reports a role of transcription,translation,translocation in the secretory response. After washing out endogenous HA from anaesthetized, cannulated rabbit knees, the joints were cycled passively at various frequencies and durations, with or without intra-articular inhibitors of protein synthesis and Golgi processing. Newly secreted HA was harvested for analysis after 5 h. Joints displayed graded, non-linear stimulus,response curves to both duration and frequency of movement; 1 min duration per 15 min or a frequency of 0.17 Hz raised HA secretion by 42,54%, while rapid (1.5 Hz) or prolonged cycling (9 min per 15 min) raised it by 110,130%. Movement-stimulated secretion and phorbol ester-stimulated secretion were partly inhibited by the translation inhibitor cycloheximide, by the transcription,translation inhibitors actinomycin D and puromycin and by the Golgi translocation inhibitor brefeldin A. There is thus a graded coupling between HA secretion and cyclic joint movement that depends partly on new protein synthesis. This is likely to be important for joint homeostasis, providing protection during repetitive cycling and potentially contributing to exercise therapy for osteoarthritis. [source] The activation of matrix metalloproteinase-2 induced by protein kinase C alpha in decidualization,JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2009Jen-Hsiang Tsai Abstract This study investigated the protein kinase C (PKC) and matrix metalloproteinase-2 (MMP-2) in the development of deciduomata in pseudo-pregnant and pregnant rats. The results showed that the expression of MMP-2 was significantly increased from day 2 to day 5 in pseudo-pregnancy and from day 7 to day 9 in pregnancy. To further investigate the correlation between MMP-2 and protein kinase C, (PKC,), the expression of MMP-2 in the 12- O -tetradecanoylphorbol 13-acetate (TPA)-treated organotypic culture of decidual tissue was determined. The results showed that the active form of MMP-2 was significantly increased in the TPA-treated cultures. Moreover, this response was inhibited by the PKC inhibitor H7, the PKC, specific inhibitor Gö-6976 and the translation inhibitor cycloheximide, but not by the transcription inhibitor actinomycin D or the replication inhibitor mitomycin C. In addition, TPA also reversed the MMP-2 expression after by progesterone pretreatment in the primary decidual cells. These findings indicate that PKC, may play an important role in the regulation of the MMP-2 expression during decidualization. J. Cell. Biochem. 108: 547,554, 2009. © 2009 Wiley-Liss, Inc. [source] Induction and maintenance of late-phase long-term potentiation in isolated dendrites of rat hippocampal CA1 pyramidal neuronesTHE JOURNAL OF PHYSIOLOGY, Issue 3 2005Catherine A. Vickers Expression of N -methyl- d -aspartate (NMDA) receptor-dependent long-term potentiation (LTP) in the CA1 region of the hippocampus can be divided into an early (1,2 h), protein synthesis-independent phase and a late (>4 h), protein synthesis-dependent phase. In this study we have addressed whether the de novo protein synthesis required for the expression of late-LTP can be sustained solely from the translation of mRNAs located in the dendrites of CA1 pyramidal neurones. Our results show that late-LTP, lasting at least 5 h, can be maintained in hippocampal slices where the dendrites located in stratum radiatum have been isolated from their cell bodies by a microsurgical cut. The magnitude of the potentiation of the slope of field EPSPs in these ,isolated' slices was similar to that recorded in ,intact' slices. Incubation of the slices with the mRNA translation inhibitor cycloheximide or the mammalian target of rapamycin (mTOR) inhibitor rapamycin blocked late-LTP in both ,intact' and ,isolated' slice preparations. In contrast, incubation of slices with the transcription inhibitor, actinomycin D, resulted in a reduction of sustained potentiation, at 4 h, in ,intact' slices while in ,isolated' slices the magnitude of potentiation was similar to that seen in untreated slices. These results indicate that late-LTP can be induced and maintained in ,isolated' dendritic preparations via translation of pre-existing mRNAs. [source] | ||||||||||