Division of Digestive Diseases, Emory University, 615 Michael St., Atlanta, GA 30307, USA..
Am J Physiol Gastrointest Liver Physiol. 2010 Jul;299(1):G283-92. doi: 10.1152/ajpgi.00096.2010. Epub 2010 May 6.
Glial cell line-derived neurotrophic factor (GDNF) is a factor produced by glial cells that is required for the development of the enteric nervous system. In transgenic mice that overexpress GDNF in the pancreas, GDNF has been shown to enhance beta-cell mass and improve glucose control, but the transcriptional and cellular processes involved are not known. In this study we examined the influence of GDNF on the expression of neurogenin3 (Ngn3) and other transcription factors implicated in early beta-cell development, as well as on beta-cell proliferation during embryonic and early postnatal mouse pancreas development. Embryonic day 15.5 (E15.5) mouse pancreatic tissue when exposed to GDNF for 24 h showed higher Ngn3, pancreatic and duodenal homeobox gene 1 (Pdx1), neuroD1/beta(2), paired homeobox gene 4 (Pax4), and insulin mRNA expression than tissue exposed to vehicle only. Transgenic expression of GDNF in mouse pancreata was associated with increased numbers of Ngn3-expressing pancreatic cells and higher beta-cell mass at embryonic day 18 (E18), as well as higher beta-cell proliferation and Pdx1 expression in beta-cells at E18 and postnatal day 1. In the HIT-T15 beta-cell line, GDNF enhanced the expression of Pax6. This response was, however, blocked in the presence of Pdx1 small interfering RNA (siRNA). Chromatin immunoprecipitation studies using the HIT-T15 beta-cell line demonstrated that GDNF can influence Pdx1 gene expression by enhancing the binding of Sox9 and neuroD1/beta(2) to the Pdx1 promoter. Our data provide evidence of a mechanism by which GDNF influences beta-cell development. GDNF could be a potential therapeutic target for the treatment and prevention of diabetes.
胶质细胞源性神经营养因子（GDNF）是一种由神经胶质细胞产生的因子，对于肠神经系统的发育是必需的。在胰腺中过表达 GDNF 的转基因小鼠中，已经表明 GDNF 可以增强β细胞的质量并改善葡萄糖控制，但涉及的转录和细胞过程尚不清楚。在这项研究中，我们研究了 GDNF 对神经基因 3（Ngn3）和其他涉及早期β细胞发育的转录因子表达的影响，以及对胚胎和出生后早期小鼠胰腺发育过程中β细胞增殖的影响。当将胚胎 15.5 天（E15.5）的小鼠胰腺组织暴露于 GDNF 24 小时时，与仅暴露于载体的组织相比，Ngn3、胰腺十二指肠同源框基因 1（Pdx1）、神经 D1/β（2）、配对同源框基因 4（Pax4）和胰岛素 mRNA 的表达更高。在小鼠胰腺中过表达 GDNF 与 E18 时表达 Ngn3 的胰腺细胞数量增加和β细胞质量增加有关，以及 E18 和出生后第 1 天β细胞中更高的β细胞增殖和 Pdx1 表达有关。在 HIT-T15β细胞系中，GDNF 增强了 Pax6 的表达。然而，当存在 Pdx1 小干扰 RNA（siRNA）时，这种反应被阻断。使用 HIT-T15β细胞系进行的染色质免疫沉淀研究表明，GDNF 可以通过增强 Sox9 和神经 D1/β（2）与 Pdx1 启动子的结合来影响 Pdx1 基因的表达。我们的数据提供了 GDNF 影响β细胞发育的机制的证据。GDNF 可能是治疗和预防糖尿病的潜在治疗靶标。
