Granneman J G, Lahners K N
Department of Psychiatry and Behavioral Neuroscience, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
Am J Physiol. 1995 Apr;268(4 Pt 1):C1040-4. doi: 10.1152/ajpcell.1995.268.4.C1040.
This study examined the regulation of murine beta 3-receptor mRNA and determined whether the recently described mRNA splice variants are differentially regulated by agents that alter total beta 3-receptor mRNA levels. In vivo treatment of mice with the beta 3-receptor agonist BRL-26830 reduced total beta 3-transcripts by 64% in white adipose tissue but did not alter the mRNA splicing pattern. Further analysis in cultured 3T3-F442A adipocytes showed that isoproterenol, dexamethasone, or phorbol 12-myristate 13-acetate also greatly reduced beta 3-receptor mRNA levels without selectively altering poly-U-containing transcripts. Blockade of transcription with actinomycin D produced a rapid loss of beta 3-receptor mRNA, which was prevented by blockade of mRNA translation with cycloheximide. However, neither actinomycin D nor cycloheximide altered the splicing pattern of beta 3-receptor mRNA. Analysis of transcription rate by nuclear run-off assay indicated that 8-bromoadenosine 3',5'-cyclic monophosphate and phorbol 12-myristate 13-acetate reduce beta 3-receptor gene transcription and that suppression of transcription is sufficient to account for the reduction in beta 3-receptor mRNA levels by these agents.
本研究检测了小鼠β3-受体mRNA的调控情况，并确定最近描述的mRNA剪接变体是否受改变总β3-受体mRNA水平的药物的差异调控。用β3-受体激动剂BRL-26830对小鼠进行体内治疗，可使白色脂肪组织中的总β3-转录本减少64%，但不会改变mRNA剪接模式。在培养的3T3-F442A脂肪细胞中进行的进一步分析表明，异丙肾上腺素、地塞米松或佛波酯12-肉豆蔻酸酯13-乙酸酯也能大幅降低β3-受体mRNA水平，而不会选择性地改变含聚U的转录本。用放线菌素D阻断转录会导致β3-受体mRNA迅速丢失，而用环己酰亚胺阻断mRNA翻译可防止这种情况发生。然而，放线菌素D和环己酰亚胺均未改变β3-受体mRNA的剪接模式。通过核转录分析对转录速率进行分析表明，8-溴腺苷3',5'-环磷酸和佛波酯12-肉豆蔻酸酯13-乙酸酯可降低β3-受体基因转录，且转录抑制足以解释这些药物导致的β3-受体mRNA水平降低。
