Anatomical location and redistribution of G protein-coupled estrogen receptor-1 during the estrus cycle in mouse kidney and specific binding to estrogens but not aldosterone

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• 作者：Shi-Bin Cheng ; Jing Dong ; Yefei Pang ; Jessica LaRocca ; Mary Hixon ; Peter Thomas ; Edward J. Filardo
• 关键词：GPER-1 ; Aldosterone binding ; Estradiol binding ; Distal convoluted tubules ; Estrus cycle ; Mineralocorticoid receptor
• 刊名：Molecular and Cellular Endocrinology
• 出版年：15 February, 2014
• 年：2014
• 卷：382
• 期：2
• 页码：950-959
• 全文大小：3243 K

文摘

Prior studies have linked renoprotective effects of estrogens to G-protein-coupled estrogen receptor-1 (GPER-1) and suggest that aldosterone may also activate GPER-1. Here, the role of GPER-1 in murine renal tissue was further evaluated by examining its anatomical distribution, subcellular distribution and steroid binding specificity. Dual immunofluorescent staining using position-specific markers showed that GPER-1 immunoreactivity primarily resides in distal convoluted tubules and the Loop of Henle (stained with Tamm-Horsfall Protein-1). Lower GPER-1 expression was observed in proximal convoluted tubules marked with megalin, and GPER-1 was not detected in collecting ducts. Plasma membrane fractions prepared from whole kidney tissue or HEK293 cells expressing recombinant human GPER-1 (HEK-GPER-1) displayed high-affinity, specific [³H]-17尾-estradiol ([³H]-E2) binding, but no specific [³H]-aldosterone binding. In contrast, cytosolic preparations exhibited specific binding to [³H]-aldosterone but not to [³H]-E2, consistent with the subcellular distribution of GPER-1 and mineralocorticoid receptor (MR) in these preparations. Aldosterone and MR antagonists, spironolactone and eplerenone, failed to compete for specific [³H]-E2 binding to membranes of HEK-GPER-1 cells. Furthermore, aldosterone did not increase [³⁵S]-GTP-纬S binding to membranes of HEK-GPER-1 cells, indicating that it is not involved in G protein signaling mediated through GPER-1. During the secretory phases of the estrus cycle, GPER-1 is upregulated on cortical epithelia and localized to the basolateral surface during proestrus and redistributed intracellularly during estrus. GPER-1 is down-modulated during luteal phases of the estrus cycle with significantly less receptor on the surface of renal epithelia. Our results demonstrate that GPER-1 is associated with specific estrogen binding and not aldosterone binding and that GPER-1 expression is modulated during the estrus cycle which may suggest a physiological role for GPER-1 in the kidney during reproduction.