An Beum-Soo, Choi Kyung-Chul, Hong Eui-Ju, Jung Yong-Woo, Manabe Noboru, Jeung Eui-Bae
Laboratory of Veterinary Biochemistry and Molecular Biology, College of Veterinary Medicine and Research Institute of Veterinary Medicine, Chungbuk National University, Korea.
J Reprod Dev. 2004 Aug;50(4):445-53. doi: 10.1262/jrd.50.445.
Calbindin-D(9k) (CaBP-9k) is a cytosolic calcium binding protein mainly expressed in the duodenum, placenta and uterus, and intestinal CaBP-9k is regulated by 1, 25-dyhydroxyvitamin D3. However, despite the presence of vitamin D receptors, uterine CaBP-9k is not under the control of vitamin D, but seems to be regulated by sex steroids. This steroids-dependent regulation of CaBP-9k is not only limited to a tissue-specific manner but also extends to a species-specific manner. In this study, we examined the regulation of CaBP-9k gene at the transcriptional and translational levels, and also localized CaBP-9k protein in the uterus of immature mice. Treatment with progesterone (P4) resulted in the induction of CaBP-9k mRNA, and a co-treatment with estrogen (E2) plus P4 evoked a synergic effect on its mRNA level in this tissue. Interestingly, the translation of CaBP-9k protein was enhanced by E2, while no difference was observed at the transcriptional level. Not only P4 but also E2 itself induced an increase of CaBP-9k protein, and co-treatment with E2 and P4 showed a similar effect on its protein level in the uterus of immature mice. The CaBP-9k protein was localized in the glandular epithelium of stroma in the uterus of immature mice at diestrus, indicating that the expression of CaBP-9k protein is differentially regulated by sex steroids. A potential mechanism of synergic effect of P4 and E2 may be E2 action in the increase of progesterone receptor (PR), with up-regulated PR increasing P4-induced CaBP-9k expression. This complicated relationship between CaBP-9k and steroid receptors suggests that P4 regulates CaBP-9k gene in the uterus of immature mice, in addition, E2 also can affect the expression of CaBP-9k through the regulation of PR. The expression levels of ERalpha and PR were further examined in this tissue. E2 stimulated the expression levels of ERalpha and PR mRNAs and P4 inhibited the expression of these transcripts at an early time point (12 h) and increased them at 24 and 48 h, while co-treatments with both steroids increased transcripts of ERalpha and PR at 24 h. In conclusion, P4 and PR may be dominant factors in the regulation of CaBP-9k. Also, E2 and ERalpha can influence the expression of the CaBP-9k gene via an indirect pathway in the uterus of immature mice.
钙结合蛋白-D(9k)(CaBP-9k)是一种胞质钙结合蛋白，主要在十二指肠、胎盘和子宫中表达，肠道CaBP-9k受1,25-二羟维生素D3调节。然而，尽管存在维生素D受体，但子宫CaBP-9k不受维生素D的控制，似乎受性类固醇调节。CaBP-9k的这种类固醇依赖性调节不仅限于组织特异性方式，还扩展到物种特异性方式。在本研究中，我们在转录和翻译水平上研究了CaBP-9k基因的调节，并在未成熟小鼠子宫中定位了CaBP-9k蛋白。孕酮(P4)处理导致CaBP-9k mRNA的诱导，雌激素(E2)加P4的联合处理对该组织中其mRNA水平产生协同作用。有趣的是，E2增强了CaBP-9k蛋白的翻译，而在转录水平上未观察到差异。不仅P4，E2本身也诱导CaBP-9k蛋白增加，E2和P4联合处理对未成熟小鼠子宫中其蛋白水平显示出类似的作用。CaBP-9k蛋白在动情间期未成熟小鼠子宫的基质腺上皮中定位，表明CaBP-9k蛋白的表达受性类固醇的差异调节。P4和E2协同作用的潜在机制可能是E2在增加孕酮受体(PR)方面的作用，上调的PR增加P4诱导的CaBP-9k表达。CaBP-9k与类固醇受体之间的这种复杂关系表明，P4调节未成熟小鼠子宫中的CaBP-9k基因，此外，E2也可通过调节PR影响CaBP-9k的表达。在该组织中进一步检测了雌激素受体α(ERα)和PR的表达水平。E2刺激ERα和PR mRNA的表达水平，P4在早期时间点(12小时)抑制这些转录本的表达，并在24和48小时增加它们的表达，而两种类固醇联合处理在24小时增加ERα和PR的转录本。总之，P4和PR可能是调节CaBP-9k的主要因素。此外，E2和ERα可通过间接途径影响未成熟小鼠子宫中CaBP-9k基因的表达。
