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The Drosophila splicing regulator sex-lethal directly inhibits translation of male-specific-lethal 2 mRNA. 总被引:3,自引:1,他引:2
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Male-specific expression of the protein male-specific-lethal 2 (MSL-2) controls dosage compensation in Drosophila. msl-2 gene expression is inhibited in females by Sex-lethal (SXL), an RNA binding protein known to regulate pre-mRNA splicing. An intron present at the 5' untranslated region (UTR) of msl-2 mRNA contains putative SXL binding sites and is retained in female flies. Here we show that SXL plays a dual role in the inhibition of msl-2 expression. Cotransfection of Drosophila Schneider cells with an SXL expression vector and a reporter containing the 5' UTR of msl-2 mRNA resulted in retention of the 5' UTR intron and efficient accumulation of the unspliced mRNA in the cytoplasm, where its translation was blocked by SXL, but not by the intron per se. Both splicing and translation inhibition by SXL were recapitulated in vitro and found to be dependent upon SXL binding to high-affinity sites within the intron, showing that SXL directly regulates these events. Our data reveal a coordinated mechanism for the regulation of msl-2 expression by the same regulatory factor: SXL enforces intron retention in the nucleus and subsequent translation inhibition in the cytoplasm. 相似文献
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Herring BP Lyons GE Hoggatt AM Gallagher PJ 《American journal of physiology. Cell physiology》2001,280(1):C12-C21
Telokin is a 17-kDa protein with an amino acid sequence that is identical to the COOH terminus of the 130-kDa myosin light chain kinase (MLCK). Telokin mRNA is transcribed from a second promoter, located within an intron, in the 3' region of the MLCK gene. In the current study, we show by in situ mRNA hybridization that telokin mRNA is restricted to the smooth muscle cell layers within adult smooth muscle tissues. In situ mRNA analysis of mouse embryos also revealed that telokin expression is restricted to smooth muscle tissues during embryonic development. Telokin mRNA expression was first detected in mouse gut at embryonic day 11.5; no telokin expression was detected in embryonic cardiac or skeletal muscle. Expression of telokin was also found to be regulated during postnatal development of the male and female reproductive tracts. In both uterus and vas deferens, telokin protein expression greatly increased between days 7 and 14 of postnatal development. The increase in telokin expression correlated with an increase in the expression of several other smooth muscle-restricted proteins, including smooth muscle myosin and alpha-actin. 相似文献
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Wicksteed B Alarcon C Briaud I Lingohr MK Rhodes CJ 《The Journal of biological chemistry》2003,278(43):42080-42090
Proinsulin biosynthesis is regulated in response to nutrients, most notably glucose. In the short term (=2h) this is due to increases in the translation of pre-existing mRNA. However, prolonging glucose stimulation (24 h) also increases preproinsulin mRNA levels. It has been proposed that secreted insulin from the pancreatic beta-cell regulates its own synthesis through a positive autocrine feedback mechanism. Here the comparative contributions of translation and mRNA levels on the levels of proinsulin biosynthesis were examined in isolated pancreatic islets. Also, the autocrine role of insulin upon four beta-cell functions (insulin secretion, proinsulin translation, preproinsulin mRNA levels, and total protein synthesis) was investigated in parallel. The results showed that proinsulin biosynthesis is regulated, in the short term (1 h), solely at the level of translation, through an approximately 6-fold increase in response to glucose (2.8 mm versus 16.7 mm glucose). In the longer term, when preproinsulin mRNA levels have increased approximately 2-fold, a corresponding increase was observed in the fold response of proinsulin translation to a stimulatory glucose concentration (>/=10-fold). Importantly, neither exogenously added nor secreted insulin were found to play any role in regulating insulin secretion, proinsulin translation, preproinsulin mRNA levels, or total protein synthesis. The results presented here indicate that long term nutritional state sets the preproinsulin mRNA level in the beta-cell at which translation control regulates short term changes in rates of proinsulin biosynthesis in response to glucose, but this is not mediated by any autocrine effect of insulin. 相似文献
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c-Jun (AP-1) activates BMP-4 transcription in Xenopus embryos 总被引:2,自引:0,他引:2
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We identified cDNAs encoding the Xenopus Smad proteins most closely related to mammalian Smad8, and we present a functional analysis of this activity (also referred to recently as xSmad11). Misexpression experiments indicate that xSmad8(11) regulates pathways distinct from those regulated by the closely related xSmad1. Embryos that develop from eggs depleted of xSmad8(11) mRNA fail to gastrulate; instead, at the time of gastrulation, they initiate a widespread program of apoptosis, via a CPP32/caspase 3 pathway. Embryos that avoid this fate display gastrulation defects. Activation of apoptosis is rescued by expression of xSmad8(11) but not xSmad1. Our results demonstrate an embryonic requirement for Smad8(11) activity and show that a maternally derived Smad signaling pathway is required for gastrulation and for mediating a cell survival program during early embryogenesis. We suggest that xSmad8(11) functions as part of a maternally derived mechanism shown previously by others to monitor Xenopus early embryonic cell cycles. 相似文献
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Insulin production in pancreatic beta cells is predominantly regulated through glucose control of proinsulin translation. Previously, this was shown to require sequences within the untranslated regions (UTRs) of the preproinsulin (ppI) mRNA. Here, those sequences were found to be sufficient for specific glucose-regulated proinsulin translation. Furthermore, an element 40-48 bp from the 5' end of the ppI mRNA specifically bound a factor present in islets of Langerhans. Glucose-responsive factor binding to this cis-element exhibited temporal and glucose-concentration-dependent patterns that paralleled proinsulin biosynthesis. Mutating this cis-element abolished the ability of ppI mRNA UTRs to confer glucose regulation upon translation. Like the rat 5'UTR, the human ppI 5'UTR conferred glucose regulation of translation. However alternative splicing of the human 5'UTR that disrupts the cis-element abolished glucose-regulated translation. These data indicate that glucose regulation of cis-element/trans-acting factor interaction is a key component of the mechanism by which glucose regulates insulin production. 相似文献
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The regulation of gene expression in transformed maize aleurone and endosperm protoplasts. Analysis of promoter activity, intron enhancement, and mRNA untranslated regions on expression. 总被引:4,自引:1,他引:3
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Gene expression in the aleurone and endosperm is highly regulated during both seed development and germination. Studies of alpha-amylase expression in the aleurone of barley (Hordeum vulgare) have generated the current paradigm for hormonal control of gene expression in germinating cereal grain. Gene expression studies in both the aleurone and endosperm tissues of maize (Zea mays) seed have been hampered because of a lack of an efficient transformation system. We report here the rapid isolation of protoplasts from maize aleurone and endosperm tissue, their transformation using polyethylene glycol or electroporation, and the regulation of gene expression in these cells. Adh1 promoter activity was reduced relative to the 35S promoter in aleurone and endosperm protoplasts compared to Black Mexican Sweet suspension cells in which it was nearly as strong as the 35S promoter. Intron-mediated stimulation of expression was substantially higher in transformed aleurone or endosperm protoplasts than in cell-suspension culture protoplasts, and the data suggest that the effect of an intron may be affected by cell type. To examine cytoplasmic regulation, the 5' and 3' untranslated regions from a barley alpha-amylase were fused to the firefly luciferase-coding region, and their effect on translation and mRNA stability was examined following the delivery of in vitro synthesized mRNA to aleurone and endosperm protoplasts. The alpha-amylase untranslated regions regulated translational efficiency in a tissue-specific manner, increasing translation in aleurone or endosperm protoplasts but not in maize or carrot cell-suspension protoplasts, in animal cells, or in in vitro translation lysates. 相似文献
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Essential role of NAT1/p97/DAP5 in embryonic differentiation and the retinoic acid pathway 总被引:1,自引:0,他引:1
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Yamanaka S Zhang XY Maeda M Miura K Wang S Farese RV Iwao H Innerarity TL 《The EMBO journal》2000,19(20):5533-5541