Ehrman Melissa M, Melroe Gregory T, Kittilson Jeffrey D, Sheridan Mark A
Department of Zoology and Regulatory Biosciences Center, North Dakota State University, Fargo 58105, USA.
Zoolog Sci. 2004 Jan;21(1):87-91. doi: 10.2108/0289-0003(2004)21[87:GSGEIT]2.0.CO;2.
Previously, we showed that glucose increases the steady-state levels of the mRNAs encoding two distinct preprosomatostatins (each containing [Tyr7, Gly10]-somatostatin-14 at their C-termini; denoted PPSS II' and PPSS II") in the endocrine pancreas (Brockmann body) of rainbow trout (Oncorhynchus mykiss). In the present study, isolated islet cells were used to determine whether glucose-stimulated expression resulted from altered rates of transcription and/or from changes in RNA stability. Nuclear run-on assays indicated that the number of PPSS II nascent transcripts were significantly higher in nuclei isolated from islet cells cultured in 10 mM glucose compared to those isolated from cells incubated in 4 mM glucose. High glucose (10 mM) did not, however, affect the stability of PPSS II mRNAs. These results indicate that glucose-stimulated somatostatin expression in the Brockmann bodies of rainbow trout results from increased endogenous mRNA transcription and not from altered mRNA stability.
此前，我们发现葡萄糖可提高虹鳟（Oncorhynchus mykiss）内分泌胰腺（布罗克曼体）中编码两种不同前体生长抑素（每种在其C末端均含有[Tyr7, Gly10]-生长抑素-14；分别表示为PPSS II'和PPSS II"）的mRNA的稳态水平。在本研究中，使用分离的胰岛细胞来确定葡萄糖刺激的表达是由转录速率改变和/或RNA稳定性变化引起的。核转录分析表明，与在4 mM葡萄糖中孵育的细胞分离的细胞核相比，从在10 mM葡萄糖中培养的胰岛细胞分离的细胞核中PPSS II新生转录本的数量显著更高。然而，高葡萄糖（10 mM）并未影响PPSS II mRNA的稳定性。这些结果表明，虹鳟布罗克曼体中葡萄糖刺激的生长抑素表达是由内源性mRNA转录增加引起的，而非mRNA稳定性改变所致。
