Cell Biology Section, Division of Intramural Research, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
J Biol Chem. 2011 Jun 24;286(25):22077-89. doi: 10.1074/jbc.M111.224964. Epub 2011 May 4.
Glis3 is a member of the Glis subfamily of Krüppel-like zinc finger transcription factors. Recently, Glis3 has been linked to both type I and type II diabetes and shown to positively regulate insulin gene expression. In this study, we have identified a region within the N terminus of Glis3 that shares high levels of homology with the Cubitus interruptus (Ci)/Gli family of proteins. We demonstrated that Glis3 interacts with Suppressor of Fused (SUFU), which involves a VYGHF motif located within this conserved region. We further showed that SUFU is able to inhibit the activation of the insulin promoter by Glis3 but not the activation by a Glis3 mutant deficient in its ability to bind SUFU, suggesting that the inhibitory effect is dependent on the interaction between the two proteins. Exogenous SUFU did not affect the nuclear localization of Glis3; however, Glis3 promoted the nuclear accumulation of SUFU. Additionally, we demonstrated that SUFU stabilizes Glis3 in part by antagonizing the Glis3 association with a Cullin 3-based E3 ubiquitin ligase that promotes the ubiquitination and degradation of Glis3. This is the first reported instance of Glis3 interacting with SUFU and suggests a novel role for SUFU in the modulation of Glis3 signaling. Given the critical role of Glis3 in pancreatic β-cell generation and maintenance, the elevated Glis3 expression in several cancers, and the established role of SUFU as a tumor suppressor, these data provide further insight into Glis3 regulation and its function in development and disease.
Glis3 是 Krüppel 样锌指转录因子 Glis 亚家族的成员。最近，Glis3 与 1 型和 2 型糖尿病有关，并被证明可正向调节胰岛素基因表达。在这项研究中，我们在 Glis3 的 N 端鉴定出一个与 Cubitus interruptus (Ci)/Gli 蛋白家族具有高度同源性的区域。我们证明 Glis3 与 Suppressor of Fused (SUFU) 相互作用，涉及位于该保守区域内的 VYGHF 基序。我们进一步表明，SUFU 能够抑制 Glis3 对胰岛素启动子的激活，但不能抑制 Glis3 突变体对 SUFU 结合能力缺失的激活，这表明抑制作用依赖于两种蛋白质之间的相互作用。外源性 SUFU 不影响 Glis3 的核定位；然而，Glis3 促进了 SUFU 的核积累。此外，我们证明 SUFU 通过拮抗 Glis3 与基于 Cullin 3 的 E3 泛素连接酶的关联，在部分稳定 Glis3，该酶促进 Glis3 的泛素化和降解。这是首次报道 Glis3 与 SUFU 相互作用，并表明 SUFU 在调节 Glis3 信号中的新作用。鉴于 Glis3 在胰腺 β 细胞生成和维持中的关键作用、几种癌症中升高的 Glis3 表达以及 SUFU 作为肿瘤抑制因子的既定作用，这些数据提供了对 Glis3 调节及其在发育和疾病中的功能的进一步了解。
