Progesterone receptor membrane component 1 and 2 regulate granulosa cell mitosis and survival through a NFΚB-dependent mechanism†

Abstract

Progesterone receptor membrane component 1 (PGRMC1) interacts with PGRMC2, and disrupting this interaction in spontaneously immortalized granulosa cells (SIGCS) leads to an inappropriate entry into the cell cycle, mitotic arrest, and ultimately cell death. The present study revealed that PGRMC1 and PGRMC2 localize to the cytoplasm of murine granulosa cells of nonatretric follicles with their staining intensity being somewhat diminished in granulosa cells of atretic follicles. Compared to controls (Pgrmc1 fl/fl), the rate at which granulosa cells entered the cell cycle increased in nonatretic and atretic follicles of mice in which Pgrmc1 was conditionally deleted (Pgrmc1 d/d) from granulosa cells. This increased rate of entry into the cell cycle was associated with a ≥ 2-fold increase in follicular atresia and the nuclear localization of nuclear factor-kappa-B transcription factor P65; (NF K B/p65, or RELA). GTPase activating protein binding protein 2 (G3BP2) binds NF K B/p65 through an interaction with NF K B inhibitor alpha (IκBα), thereby maintaining NF K B/p65's cytoplasmic localization and restricting its transcriptional activity. Since PGRMC1 and PGRMC2 bind G3BP2, studies were designed to assess the functional relationship between PGRMC1, PGRMC2, and NF K B/p65 in SIGCs. In these studies, disrupting the interaction between PGRMC1 and PGRMC2 increased the nuclear localization of NF K B/p65, and depleting PGRMC1, PGRMC2, or G3BP2 increased NF K B transcriptional activity and the progression into the cell cycle. Taken together, these studies suggest that PGRMC1 and 2 regulate granulosa cell cycle entry in follicles by precisely controlling the localization and thereby the transcriptional activity of NF K B/p65.

The Interface of Nuclear and Membrane Steroid Signaling

“…Similar results were obtained in a follow-up study, where double knockout of pgrmc1/2 resulted in reduced fertility, presumably due to reduced oocyte ovulation ( 84 ). A role for PGRMC1 in granulosa cell mitosis and survival was also demonstrated via conditional knockout in murine granulosa cells ( 85 ). Global knockout of PGRMC1 impaired mammary gland development in mice ( 86 ).…”

PGRMC Proteins Are Coming of Age: A Special Issue on the Role of PGRMC1 and PGRMC2 in Metabolism and Cancer Biology

“…The field has been substantially advanced by the development of a cre/lox tissue-targetable mouse knockout system for PGRMC1 and PGRMC2, which have demonstrated roles in reproductive tissues [ 15 , 16 , 17 , 18 ], and in heme trafficking by PGRMC2 from mitochondria to nucleus [ 19 ]. Zebrafish knockouts produce analogous results [ 20 ].…”

lncRNA XIST knockdown suppresses hypoxia/reoxygenation (H/R)‐induced apoptosis of H9C2 cells by regulating miR‐545‐3p/G3BP2

“…They are both RNA‐binding proteins and regulate stress granule formation 19 . G3BP2 maintains NFKB/p65 cytoplasmic localization and, therefore, restricts NFKB/p65 transcriptional activity 20 . The NFKB pathway is involved in multiple cellular functions, including proliferation and apoptosis.…”