Endocrine Abstracts

Context: The regulation of heterogeneous nuclear ribonucleoproteins (hnRNPs) and their interactions with steroid hormone signaling in Fallopian tubes and endometrium are not clearly understood.

Objective: We determined whether hnRNP expression is regulated during the menstrual cycle and correlates with estrogen receptor (ER) and progesterone receptor (PR) levels in human Fallopian tubes in vivo. We also explored the mechanisms of hnRNP regulation in human endometrium in vitro.

Design and methodology: Fallopian tissue was obtained from patients in early, late, and postovulatory phases and mid-secretory phase, and endometrial tissue from premenopausal and postmenopausal women undergoing hysterectomy. We measured expression of hnRNPs and assessed their intracellular localization and interactions with ERs and PRs. We also determined the effects of human chorionic gonadotropin (hCG), 17β-estradiol (E₂), and progesterone (P₄) on hnRNP expression.

Results: In Fallopian tubes, mRNA and protein levels of hnRNP A1, AB, D, G, H, and U changed dynamically during ovulation and in the mid-secretory phase. In coimmunolocation and coimmunoprecipitation experiments, hnRNPs interacted with each other and with ERs and PRs in Fallopian tubes. After treatment with E₂ and/or P₄ to activate ERs and PRs, hnRNP A1, AB, D, G, and U proteins displayed overlapping but distinct patterns of regulation in the endometrium in vitro.

Conclusion: Our findings expand the physiological repertoire of hnRNPs in human Fallopian tubes and endometrium and suggest that steroid hormones regulate different hnRNPs directly by interacting with ERs and/or PRs or indirectly by binding other hnRNPs. Both actions may contribute to regulation of gene transcription.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: