Comparative analysis of the Progesterone Receptor interactome in the human ovarian granulosa cell line KGN and other female reproductive cells

The nuclear steroid hormone receptor Progesterone Receptor (PGR) is expressed in granulosa cells in the ovarian follicle in a tightly regulated pattern in response to the surge of Luteinizing Hormone (LH) that stimulates ovulation. PGR plays a critical role in mediating ovulation in response to LH, however the mechanism for this is still unknown. Using the KGN human granulosa cell line expressing the primary PGR isoforms PGR-A or PGR-B, we performed immunoprecipitation-mass spectrometry to identify novel interacting proteins that regulate PGR function in these ovary-specific target cells. Proteomic analysis revealed protein interactions with both PGR isoforms that were gained (e.g. transcriptional coactivators) or lost (e.g. chaperone proteins) in response to the PGR agonist R5020. Additionally, isoform-specific interactions, including different families of transcriptional regulators, were identified. Comparison with published datasets of PGR interacting proteins in human breast cancer cell lines and decidualised endometrial stromal cells demonstrated a remarkable number of tissue-specific interactions, shedding light on how PGR can maintain diverse functions in different tissues. In conclusion, our dataset provides new insights into ovary-specific PGR transcriptional mechanisms.

核类固醇激素受体孕激素受体（Progesterone Receptor, PGR）会以严格调控的模式在卵巢卵泡的颗粒细胞中表达，其表达响应于触发排卵的促黄体生成素（Luteinizing Hormone, LH）峰。PGR在介导LH诱导的排卵过程中发挥关键作用，但其具体分子机制至今仍未阐明。本研究使用表达主要PGR亚型PGR-A或PGR-B的人颗粒细胞系KGN，通过免疫沉淀-质谱联用技术（immunoprecipitation-mass spectrometry），在这些卵巢特异性靶细胞中鉴定出调控PGR功能的新型相互作用蛋白。蛋白质组学分析显示，在响应孕激素受体激动剂R5020时，两种PGR亚型均出现了部分蛋白相互作用的获得（如转录共激活因子（transcriptional coactivators））或丢失（如分子伴侣蛋白（chaperone proteins））；此外，研究还鉴定出了亚型特异性的蛋白相互作用，涵盖不同家族的转录调控因子。将本研究数据集与已发表的乳腺癌细胞系及蜕膜化子宫内膜基质细胞（decidualised endometrial stromal cells）中PGR相互作用蛋白的数据集进行比对，发现了大量组织特异性的相互作用，为解析PGR在不同组织中维持多样功能的机制提供了新的线索。综上，本数据集为卵巢特异性PGR的转录调控机制提供了全新的研究视角。