Activity of retinoic acid receptor-alpha is directly regulated at its protein kinase A sites in response to follicle-stimulating hormone signaling.
Activity of retinoic acid receptor-alpha is directly regulated at its protein kinase A sites in response to follicle-stimulating hormone signaling.
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DOI：
10.1210/en.2009-1338
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发表时间：
2010-05
期刊：
影响因子：
4.8
通讯作者：
N. C. Santos;K. Kim
中科院分区：
文献类型：
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作者：
N. C. Santos;K. Kim
视黄酸受体-α（RARA）对睾丸中的生殖细胞发育至关重要，如Rara基因敲除小鼠中的睾丸退化所示，其是不育的。类似地，已知FSH调节支持细胞增殖和分化，间接控制生精输出的量。有趣的是，FSH通过激活FSH受体、cAMP和蛋白激酶A（PKA）抑制RARA的核定位和转录活性。鉴于视黄酸，RARA的配体，已知调节细胞增殖和分化，我们研究了FSH是否通过直接的翻译后磷酸化机制调节RARA。RARA上PKA位点的丝氨酸219（S219）和S369突变为双丙氨酸或双谷氨酸，表明两个PKA位点对RARA活性都很重要。PKA位点的负电荷，无论是来自谷氨酸还是丝氨酸的磷酸化，都降低了RARA的核定位，与类维生素A X受体α的异二聚化以及受体的转录活性。另一方面，不能在219和369氨基酸位置磷酸化的双丙氨酸突变体不响应cAMP和PKA活化。野生型和双突变型RARA与PKA相互作用，但仅在cAMP或FSH存在下。这些结果共同表明，FSH可以调节细胞增殖和Sertoli细胞的分化，至少部分地，通过直接影响PKA位点的RARA和控制受体的转录功能。
Retinoic acid receptor-alpha (RARA) is crucial for germ cell development in the testis, as shown by the degenerated testis in Rara gene knockout mice, which are sterile. Similarly, FSH is known to regulate Sertoli cell proliferation and differentiation, indirectly controlling the quantity of the spermatogenic output. Interestingly, FSH inhibited, via activation of FSH receptor, cAMP, and protein kinase A (PKA), the nuclear localization and transcriptional activity of RARA. Given that retinoic acid, the ligand for RARA, is known to regulate cell proliferation and differentiation, we investigated whether FSH regulates RARA by a direct posttranslational phosphorylation mechanism. Mutagenesis of serine 219 (S219) and S369 at the PKA sites on RARA to either double alanines or double glutamic acids showed that both PKA sites are important for RARA activity. The negative charges at the PKA sites, whether they are from glutamic acids or phosphorylation of serines, decreased the nuclear localization of RARA, heterodimerization with retinoid X receptor-alpha, and the transcriptional activity of the receptor. On the other hand, the double-alanine mutant that cannot be phosphorylated at the 219 and 369 amino acid positions did not respond to cAMP and PKA activation. Wild-type and double-mutant RARA interacted with PKA, but only in the presence of cAMP or FSH. These results together suggest that FSH may regulate cell proliferation and differentiation of Sertoli cells, at least partially, by directly affecting the PKA sites of RARA and controlling the transcriptional function of the receptor.