Zou L, Menon R K, Sperling M A
Department of Pediatrics, University of Pittsburgh School of Medicine, PA 15213, USA.
Metabolism. 1997 Jan;46(1):114-8. doi: 10.1016/s0026-0495(97)90177-3.
Adipose tissue is a growth hormone (GH)-responsive tissue in which GH regulates energy metabolism. GH exerts its effect by interacting with its specific GH receptor (GHR). In rodents, alternative splicing of the nascent transcript from the GHR gene produces two major transcripts: GHR mRNA and GHR binding protein (GHBP) mRNA. These two transcripts share the common extracellular ligand-binding domain, but differ in the C-terminal sequence. Since GHR plays an important role in mediating the actions of GH in adipose metabolism, we initiated these studies to examine GHR gene expression in the course of mouse 3T3-L1 preadipocyte-adipocyte conversion. GHR and GHBP transcripts were detected by RNase protection assay (RPA) using the antisense riboprobes complementary either to the specific sequence of the GHR or to the sequence shared by both GHR and GHBP mRNAs. After stimulation of differentiation, mRNA abundance increased 28-fold and reached a maximal level by day 7 of adipogenesis. The GHR mRNA:GHBP mRNA ratio was 1.1 +/- 0.12 and remained unchanged during differentiation. The decay rate for both mRNAs, estimated by treating the cells with actinomycin D, was approximately 24 hours and showed no significant difference between preadipocytes and adipocytes. Thus, GHR gene expression is dramatically upregulated during preadipocyte-adipocyte differentiations.
脂肪组织是一种对生长激素（GH）有反应的组织，在该组织中GH调节能量代谢。GH通过与其特异性生长激素受体（GHR）相互作用发挥作用。在啮齿动物中，GHR基因新生转录本的可变剪接产生两种主要转录本：GHR mRNA和GHR结合蛋白（GHBP）mRNA。这两种转录本共享共同的细胞外配体结合域，但C端序列不同。由于GHR在介导GH在脂肪代谢中的作用方面发挥重要作用，我们开展了这些研究，以检测小鼠3T3-L1前脂肪细胞向脂肪细胞转化过程中GHR基因的表达。使用与GHR的特定序列或GHR和GHBP mRNA共有的序列互补的反义核糖探针，通过核糖核酸酶保护分析（RPA）检测GHR和GHBP转录本。在诱导分化后，mRNA丰度增加了28倍，并在脂肪生成的第7天达到最高水平。GHR mRNA与GHBP mRNA的比率为1.1±0.12，在分化过程中保持不变。用放线菌素D处理细胞估计的两种mRNA的衰减率约为24小时，在前脂肪细胞和脂肪细胞之间没有显著差异。因此，在前脂肪细胞向脂肪细胞分化过程中，GHR基因表达显著上调。
