| First Author | Kim C | Year | 2016 |
| Journal | Biochim Biophys Acta | Volume | 1859 |
| Issue | 4 | Pages | 675-85 |
| PubMed ID | 26945853 | Mgi Jnum | J:250986 |
| Mgi Id | MGI:6106274 | Doi | 10.1016/j.bbagrm.2016.02.017 |
| Citation | Kim C, et al. (2016) RNA-binding protein HuD reduces triglyceride production in pancreatic beta cells by enhancing the expression of insulin-induced gene 1. Biochim Biophys Acta 1859(4):675-85 |
| abstractText | Although triglyceride (TG) accumulation in the pancreas leads to beta-cell dysfunction and raises the chance to develop metabolic disorders such as type 2 diabetes (T2DM), the molecular mechanisms whereby intracellular TG levels are regulated in pancreatic beta cells have not been fully elucidated. Here, we present evidence that the RNA-binding protein HuD regulates TG production in pancreatic beta cells. Mouse insulinoma betaTC6 cells stably expressing a small hairpin RNA targeting HuD (shHuD) (betaTC6-shHuD) contained higher TG levels compared to control cells. Moreover, downregulation of HuD resulted in a decrease in insulin-induced gene 1 (INSIG1) levels but not in the levels of sterol regulatory element-binding protein 1c (SREBP1c), a key transcription factor for lipid production. We identified Insig1 mRNA as a direct target of HuD by using ribonucleoprotein immunoprecipitation (RIP) and biotin pulldown analyses. By associating with the 3''-untranslated region (3''UTR) of Insig1 mRNA, HuD promoted INSIG1 translation; accordingly, HuD downregulation reduced while ectopic HuD expression increased INSIG1 levels. We further observed that HuD downregulation facilitated the nuclear localization of SREBP1c, thereby increasing the transcriptional activity of SREBP1c and the expression of target genes involved in lipogenesis; likewise, we observed lower INSIG1 levels in the pancreatic islets of HuD-null mice. Taken together, our results indicate that HuD functions as a novel repressor of lipid synthesis in pancreatic beta cells. |
