Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA.
Biol Reprod. 2013 Jan 25;88(1):20. doi: 10.1095/biolreprod.112.103036. Print 2013 Jan.
Progesterone receptor membrane component 1 (PGRMC1) mediates the antiapoptotic action of progesterone (P4). PGRMC1 interacts with plasminogen activator inhibitor 1 RNA-binding protein (PAIRBP1), but the functional significance of this interaction is unknown. To examine the function of PGRMC1-PAIRBP1 interaction, PAIRBP1 was depleted from spontaneously immortalized granulosa cells (SIGCs) and the effects on the expression and localization of PGRMC1 as well as P4's ability to bind to SIGCs and prevent apoptosis was assessed. Depleting PAIRBP1 enhanced cellular (3)H-P4 binding and did not alter the expression or cellular localization of PGRMC1 but attenuated P4's antiapoptotic action. Transfection of a PGRMC1-green fluorescent protein (GFP) peptide mimic, which binds PAIRBP1 as demonstrated by in situ proximity assay, doubled the rate at which SIGCs undergo apoptosis compared to cells transfected with either the empty GFP expression vector or Pairbp1 small interfering RNA. Moreover, P4 did not prevent these cells from undergoing apoptosis. Similar studies conducted with granulosa cells isolated from immature rats also showed that PGRMC1 interacts with PAIRBP1 and that transfection of PGRMC1-GFP peptide mimic accelerates the rate of granulosa cell apoptosis by 4-fold even in the presence of serum and P4. These studies support the concept that the interaction between PAIRBP1-PGRMC1 is an essential component of the mechanism through which P4 inhibits apoptosis. Surprisingly, PGRMC1-PAIRBP1 interaction is not required for P4 binding or the cellular localization of PGRMC1 but rather appears to couple PGRMC1 to downstream components of the P4-PGRMC1 signal transduction pathway.
孕激素受体膜成分 1（PGRMC1）介导孕激素（P4）的抗凋亡作用。PGRMC1 与纤溶酶原激活物抑制剂 1 RNA 结合蛋白（PAIRBP1）相互作用，但这种相互作用的功能意义尚不清楚。为了研究 PGRMC1-PAIRBP1 相互作用的功能，从自发永生化颗粒细胞（SIGCs）中耗尽 PAIRBP1，并评估其对 PGRMC1 的表达和定位以及 P4 结合 SIGCs 和防止细胞凋亡能力的影响。耗尽 PAIRBP1 增强了细胞（3）H-P4 结合，而不改变 PGRMC1 的表达或细胞定位，但减弱了 P4 的抗凋亡作用。转染 PGRMC1-绿色荧光蛋白（GFP）肽模拟物，如原位接近测定所示，与转染空 GFP 表达载体或 Pairbp1 小干扰 RNA 的细胞相比，将 SIGCs 凋亡的速度提高了一倍。此外，P4 并不能阻止这些细胞发生凋亡。在从未成熟大鼠分离的颗粒细胞中进行的类似研究也表明，PGRMC1 与 PAIRBP1 相互作用，并且即使在存在血清和 P4 的情况下，转染 PGRMC1-GFP 肽模拟物也可将颗粒细胞凋亡的速度提高 4 倍。这些研究支持这样一种观点，即 PAIRBP1-PGRMC1 相互作用是 P4 抑制细胞凋亡的机制的重要组成部分。令人惊讶的是，PGRMC1-PAIRBP1 相互作用对于 P4 结合或 PGRMC1 的细胞定位不是必需的，而是似乎将 PGRMC1 与 P4-PGRMC1 信号转导途径的下游成分偶联。
