在小鼠KK1颗粒细胞系中，HIF1α介导的STAR表达的转录调控涉及cJUN、CREB和CBP依赖性途径。

Transcriptional regulation of HIF1α-mediated STAR expression in murine KK1 granulosa cell line involves cJUN, CREB and CBP-dependent pathways.

作者信息

Lanfranchi Bettina, Rubia Ricardo Fernandez, Gassmann Max, Schuler Gerhard, Kowalewski Mariusz P

机构信息

Institute of Veterinary Anatomy, Vetsuisse Faculty, University of Zurich (UZH), Zurich, Switzerland.

出版信息

Gen Comp Endocrinol. 2022 Jan 1;315:113923. doi: 10.1016/j.ygcen.2021.113923. Epub 2021 Oct 2.

DOI:10.1016/j.ygcen.2021.113923

PMID:34606743

Abstract

Gonadal function is connected to hypoxia, with hypoxia-inducible factor (HIF) 1α, as a component of HIF1-complexes, regulating cellular adaptation to hypoxic conditions. In the ovary, it regulates follicular maturation, ovulation and luteal development. At the cellular level, HIF1-complexes coordinate the expression of steroidogenic acute regulatory protein (STAR), and thereby ovarian steroidogenesis. The functionality of STAR is associated with the cAMP/PKA-dependent pathways. In vitro, HIF1α is required for basal and cAMP-induced STAR expression, under ambient and reduced oxygen (O) tension. Lowering O increases the responsiveness of the Star promoter towards cAMP and PKA mediates activation/phosphorylation (P) of several transcriptional factors, including cJUN and cAMP response element-binding protein (CREB), whose functionality is linked to HIF1 through utilization of CREB-binding protein (CBP). Since the mechanisms underlying HIF1α-dependent expression of STAR remain unknown, we investigated the involvement of HIF1α in CREB-, cJUN- and CBP-mediated expression of STAR using a well-characterized steroidogenic model, murine KK1 granulosa cells; ambient and lowered (10%) O were applied. Our main findings were that while functional suppression of the α-subunit of HIF1 lowered STAR/P-STAR and steroidogenic output from granulosa cells, surprisingly the levels of P-CREB and its transcriptional activity were strongly induced. However, its association with the Star promoter was decreased, indicating dissociation of P-CREB from the promoter. Further, suppression of HIF1 activity ultimately diminished the expression of cJUN/P-cJUN and CBP. Finally, the study suggests that HIF1-complex: (1) regulates cJUN expression in granulosa cells, (2) is involved in regulating the recruitment of P-CREB to the Star promoter in (3) a mechanism which possibly involves the HIF1-dependent regulation of CBP expression.

摘要

性腺功能与缺氧相关，缺氧诱导因子（HIF）1α作为HIF1复合物的一个组成部分，调节细胞对缺氧条件的适应。在卵巢中，它调节卵泡成熟、排卵和黄体发育。在细胞水平上，HIF1复合物协调类固醇生成急性调节蛋白（STAR）的表达，从而调节卵巢类固醇生成。STAR的功能与cAMP/PKA依赖性途径相关。在体外，在环境氧和低氧（O）张力下，基础和cAMP诱导的STAR表达都需要HIF1α。降低氧会增加Star启动子对cAMP的反应性，PKA介导几种转录因子的激活/磷酸化（P），包括cJUN和cAMP反应元件结合蛋白（CREB），其功能通过利用CREB结合蛋白（CBP）与HIF1相关联。由于HIF1α依赖性STAR表达的潜在机制尚不清楚，我们使用特征明确的类固醇生成模型——小鼠KK1颗粒细胞，研究了HIF1α在CREB、cJUN和CBP介导的STAR表达中的作用；应用了环境氧和低氧（10%）条件。我们的主要发现是，虽然HIF1α亚基的功能抑制降低了颗粒细胞中STAR/P-STAR和类固醇生成输出，但令人惊讶的是，P-CREB水平及其转录活性却被强烈诱导。然而，它与Star启动子的结合减少，表明P-CREB从启动子上解离。此外，HIF1活性的抑制最终降低了cJUN/P-cJUN和CBP的表达。最后，该研究表明HIF1复合物：（1）调节颗粒细胞中cJUN的表达，（2）参与调节P-CREB向Star启动子的募集，（3）其机制可能涉及HIF1依赖性CBP表达的调节。