Shao Ruijin, Egecioglu Emil, Weijdegård Birgitta, Ljungström Karin, Ling Charlotte, Fernandez-Rodriguez Julia, Billig Håkan
Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at Göteborg University, SE-40530 Göteborg, Sweden.
J Endocrinol. 2006 Sep;190(3):857-70. doi: 10.1677/joe.1.06896.
Progesterone (P(4)) regulates many aspects of physiological functions via two nuclear P(4) receptors (PR), PRA and PRB, which are members of a structurally related nuclear hormone receptor superfamily that includes glucocorticoid receptors (GR). The regulation and cellular distribution of PR protein isoforms have been extensively studied in reproductive tissues, but this is not the case in the lung. In the present study, reverse transcriptase (RT)-PCR, Western blotting, and immunolocalization supported the presence of PRA in the lung of female mice, with PRA protein levels significantly increased between postnatal day 7 and 12, declined at postnatal day 26, and minimal in adults when compared to postnatal day 2. The peak was temporally related to postnatal lung maturation in rodents. Immunoreactivity for PR was detected in the alveolar and bronchial epithelia. We then extended this study to examine, for the first time, the regulation of PRA protein expression in female mouse lung in vivo. Neither the increase in endogenous P(4) nor treatment with exogenous P(4) regulated PRA protein expression in female mouse lung. However, treatment of mice with the GR/PR antagonist RU 486, but not Org 31710 (a specific PR antagonist), significantly increased PRA protein expression in parallel to a decrease in GR protein expression. In addition, treatment with the synthetic glucocorticoid dexamethasone led to a decrease in PRA protein expression independent of endogenous P(4) levels. Furthermore, immunoprecipitation followed by Western blot analysis revealed that, under in vivo conditions, PRA physically interacted with GR in mouse lung. Confocal laser microscopy revealed that PRA and GR co-localized in the nuclei of alveolar epithelia cells, whereas nuclear PR and cytoplasmic GR were detected in bronchial epithelium. Taken together, our observations suggest that PRA may be an important physiological factor involved in postnatal lung development and that the regulation of PRA protein expression is not dependent on P(4), but rather on functional glucocorticoid/GR signaling mediated by protein-protein interaction in the mouse lung.
孕酮（P(4)）通过两种核孕酮受体（PR），即PR-A和PR-B，调节生理功能的许多方面，这两种受体是结构相关的核激素受体超家族的成员，该家族包括糖皮质激素受体（GR）。PR蛋白异构体的调节和细胞分布在生殖组织中已得到广泛研究，但在肺中并非如此。在本研究中，逆转录酶（RT）-PCR、蛋白质印迹法和免疫定位法证实雌性小鼠肺中存在PR-A，PR-A蛋白水平在出生后第7天至12天显著升高，在出生后第26天下降，与出生后第2天相比，成年时降至最低。该峰值在时间上与啮齿动物出生后肺的成熟相关。在肺泡和支气管上皮中检测到PR的免疫反应性。然后，我们首次将这项研究扩展到体内雌性小鼠肺中PR-A蛋白表达的调节。内源性P(4)的增加或外源性P(4)的处理均未调节雌性小鼠肺中PR-A蛋白的表达。然而，用GR/PR拮抗剂RU 486处理小鼠，但不是用Org 31710（一种特异性PR拮抗剂）处理，显著增加了PR-A蛋白的表达，同时GR蛋白表达下降。此外，用合成糖皮质激素地塞米松处理导致PR-A蛋白表达下降，且与内源性P(4)水平无关。此外，免疫沉淀后进行蛋白质印迹分析表明，在体内条件下，PR-A在小鼠肺中与GR发生物理相互作用。共聚焦激光显微镜显示，PR-A和GR共定位于肺泡上皮细胞的细胞核中，而在支气管上皮中检测到核PR和细胞质GR。综上所述，我们的观察结果表明，PR-A可能是参与出生后肺发育的重要生理因子，PR-A蛋白表达的调节不依赖于P(4)，而是依赖于小鼠肺中蛋白质-蛋白质相互作用介导的功能性糖皮质激素/GR信号传导。
