Laboratory of Veterinary Biochemistry and Molecular Biology, College of Veterinary Medicine, Chungbuk National University, Chungbuk, Korea.
J Pineal Res. 2009 Nov;47(4):301-7. doi: 10.1111/j.1600-079X.2009.00714.x. Epub 2009 Oct 1.
Calbindin-D9k (CaBP-9k) is a 9-kDa polypeptide possessing two calcium-binding sites that is expressed in the mammalian intestine, uterus, and pituitary gland. The factors regulating the expression of the estrogen receptor (ER) and CaBP-9k in the pituitary gland are currently unknown. In this study, we investigated whether the ER and CaBP-9k expression are regulated by melatonin during H(2)O(2)-induced cell death in rat pituitary GH3 cells. Cell survival increased by approximately 27-36% in H(2)O(2) plus melatonin compared to H(2)O(2) alone, and CaBP-9k expression was augmented by treatment with H(2)O(2) plus melatonin. These results suggest that the increase in cell survival and the melatonin-induced CaBP-9k expression may play a role in protecting cells against H(2)O(2)-mediated cell death. This result is also consistent with the increase in CaBP-9k expression leading to rises in p-ERK and p-Bad (S112). Over-expression of CaBP-9k caused an increase in p-ERK. ERalpha expression was higher in H(2)O(2) plus melatonin-treated cells compared to those treated with H(2)O(2) alone, while ERbeta expression was not. Also, ERalpha in the nuclear fraction increased in the presence of melatonin and decreased in the presence of ICI 182 780 or ICI 182 780 plus melatonin. The relative binding affinity of ERalpha for melatonin was higher than that of ERbeta, suggesting that melatonin has the potential to preferentially bind ERalpha. In conclusion, these results indicate that melatonin may increase CaBP-9k expression through ERalpha.
钙结合蛋白 9k（CaBP-9k）是一种具有两个钙结合位点的 9kDa 多肽，在哺乳动物的肠道、子宫和垂体中表达。目前尚不清楚调节垂体中雌激素受体（ER）和 CaBP-9k 表达的因素。在这项研究中，我们研究了 ER 和 CaBP-9k 的表达是否受褪黑素调节在 H2O2 诱导的大鼠垂体 GH3 细胞死亡过程中。与单独使用 H2O2 相比，H2O2 加褪黑素使细胞存活率增加了约 27-36%，并且 CaBP-9k 的表达也增强了。这些结果表明，细胞存活的增加和褪黑素诱导的 CaBP-9k 表达可能在保护细胞免受 H2O2 介导的细胞死亡中起作用。这一结果也与 CaBP-9k 表达增加导致 p-ERK 和 p-Bad（S112）升高一致。过表达 CaBP-9k 导致 p-ERK 增加。与单独使用 H2O2 相比，H2O2 加褪黑素处理的细胞中 ERalpha 的表达更高，而 ERbeta 的表达没有增加。此外，在存在褪黑素的情况下，核部分的 ERalpha 增加，而在存在 ICI 182 780 或 ICI 182 780 加褪黑素的情况下则减少。ERalpha 对褪黑素的相对结合亲和力高于 ERbeta，表明褪黑素有可能优先结合 ERalpha。总之，这些结果表明，褪黑素可能通过 ERalpha 增加 CaBP-9k 的表达。
