Long-term cold exposure (5-7 days) is known to induce concomitant increases in the levels of adrenomedullary tyrosine hydroxylase (TH) RNA, protein, and enzyme activity. In this report, we compare the time courses of these changes and investigate the effects of cold exposure on the levels of biopterin, the cofactor required for tyrosine hydroxylation. After only 1 h of cold exposure, TH mRNA abundance increased 71% compared with nonstressed controls. Increases in total cellular TH RNA levels were maximal (threefold over control values) within 3-6 h of cold exposure and remained elevated throughout the duration of the experiment (72 h). TH protein levels increased rapidly after 24 h of cold exposure and reached a maximal value threefold above that of controls at 48-72 h. Despite the relatively rapid and large elevations in TH RNA and protein content, only modest increases in TH activity were detected during the initial 48 h of cold exposure. Adrenomedullary biopterin increased rapidly after the onset of cold exposure, rising to a level approximately twofold that of the nonstressed controls at 24 h, and remained at this level throughout the duration of the stress period. Taken together, the results of this time course study indicate that cold-induced alterations in adrenal TH activity are mediated by multiple cellular control mechanisms, which may include pre- and posttranslational regulation. Our findings also suggest that cold stress-induced increases in the levels of the TH cofactor may represent another key event in the sympathoadrenal system's response to cold stress.

译文

:已知长期冷暴露(5-7天)会引起肾上腺髓质酪氨酸羟化酶(TH)RNA,蛋白质和酶活性的同时升高。在本报告中,我们比较了这些变化的时程,并研究了冷暴露对生物蝶呤水平的影响,生物蝶呤是酪氨酸羟化所需的辅助因子。低温暴露仅1小时后,与未受压力的对照组相比,TH mRNA的丰度增加了71%。在冷暴露的3-6小时内,总细胞TH RNA水平的增加最大(比对照值高三倍),并且在整个实验过程中(72小时)保持升高。在冷暴露24小时后,TH蛋白水平迅速升高,在48-72 h时达到最大值,是对照的三倍。尽管TH RNA和蛋白质含量的升高相对较快且幅度较大,但在冷暴露的最初48小时内仅检测到TH活性的适度增加。冷暴露开始后,肾上腺髓质生物蝶呤迅速增加,在24 h时升高至非应激对照组的两倍,并在整个应激期一直保持在该水平。两者合计,此时间过程研究的结果表明,冷诱导的肾上腺TH活性的改变是由多种细胞控制机制介导的,其中可能包括翻译前和翻译后调控。我们的发现还表明,冷应激诱导的TH辅助因子水平升高可能代表交感肾上腺系统对冷应激反应的另一个关键事件。

+1
+2
100研值 100研值 ¥99课程
检索文献一次
下载文献一次

去下载>

成功解锁2个技能,为你点赞

《SCI写作十大必备语法》
解决你的SCI语法难题!

技能熟练度+1

视频课《玩转文献检索》
让你成为检索达人!

恭喜完成新手挑战

手机微信扫一扫,添加好友领取

免费领《Endnote文献管理工具+教程》

微信扫码, 免费领取

手机登录

获取验证码
登录