Jin Jing,Kou Xinhui,Wang Xinzhe,Yun Xue,Ding Yinyin,Cai Keshu,Zhai Yongning,Zhou Huifang
PurposeTo investigate how steroid receptor RNA activator (SRA) regulates follicular development in mice.MethodsSystemic SRA knockout mice were introduced. SRA expression was reinstated in the anteroventral periventricular nucleus (AVPV) of the hypothalamus using lentiviral vectors. Subsequently, the estrous cycle, serum hormone levels, follicle development, and hypothalamic kisspeptin expression in mice were assessed. Kiss1 promoter activity was tested with a fluorescent reporter system in Neuro-2a cells.ResultsSRA deficiency caused a shift to shorter metestrus and longer diestrus phases, reduced numbers of large antral and preovulatory follicles, increased formation of atretic cyst-like follicles, lowered serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and estradiol (E2), and decreased expression of hypothalamic AVPV-kisspeptin in mice. The reinstatement of SRA expression in the AVPV nucleus normalized kisspeptin expression, hormone levels, and follicle development. In Neuro-2a cells, SRA increased Kiss1 transcription upon E2 treatment, a response that was nullified by the estrogen receptor alpha (ERα) inhibitor.ConclusionSRA enhances ERα-mediated Kiss1 transcription in the AVPV nucleus to control the kisspeptin-GPR54 system in hypothalamus, essential for regulating ovulation through the hypothalamus-pituitary-ovary axis.
Gemcitabine is a widely employed first-line chemotherapeutic drug for pancreatic cancer (PCa). However, the rapid emergence of gemcitabine resistance poses a major clinical hurdle. Here, we identified REG3A as a crucial determinant of poor prognosis in PCa. Notably, REG3A was upregulated in tumor tissues from clinical gemcitabine-resistant PCa patients. Through comprehensive in vitro cellular assays and in vivo studies using Reg3g (the murine homolog of REG3A) knockout mice, we demonstrated that REG3A deficiency sensitized PCa to gemcitabine treatment. Mechanistically, RNA sequencing (RNA-Seq) combined with Protein-Protein Interaction (PPI) analysis revealed that REG3A functioned as an exocytosis protein binds to the novel membrane receptor GPR54. The interaction increased membrane localization of GPR54, which subsequently engaged ARRB2 as a scaffolding molecule, leading to activation of the ERK1/2 pathway and suppression of gemcitabine-induced apoptosis. Moreover, the GPR54 agonist KP10 synergistically enhanced gemcitabine resistance in conjunction with REG3A, while interference with GPR54 or its antagonist KP234 attenuated REG3A-induced gemcitabine resistance. Targeting REG3A or pharmacologically inhibiting its downstream signaling molecules may represent a promising strategy to overcome gemcitabine resistance. Overall, REG3A could serve as a potential biomarker for gemcitabine resistance in PCa, offering a new avenue for therapeutic intervention and patient stratification.
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