Endocrinology Unit, BHF/University Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, Scotland, UK.
Int J Obes (Lond). 2012 Jul;36(7):982-5. doi: 10.1038/ijo.2011.172. Epub 2011 Aug 30.
In the adipose tissue, activation of AMP-activated protein kinase (AMPK) by phosphorylation favours local fatty acid oxidation and inhibition of lipogenesis. We have previously shown that the potent androgen dihydrotestosterone (DHT) can inhibit phosphorylation of AMPK in adipose tissue and 3T3-L1 adipocytes in a dose-dependent manner. This negative effect of DHT was reversed by oestrogen treatment. The purpose of this current study was to determine the underlying mechanisms whereby androgens and oestrogens can regulate AMPK phosphorylation in adipocytes, and whether this mechanism is receptor dependent.
Phosphorylation of AMPK was assessed by western blot in cells treated for 24 h with testosterone or DHT (1-1000 nM). Testosterone and DHT significantly inhibited basal phosphorylation of AMPK. Addition of the androgen receptor antagonist Flutamide (1 μM) to the media reversed the negative effect of testosterone and DHT by returning AMPK phosphorylation levels to those of basal. To further dissect the mechanism underlying AMPK inhibition by testosterone or DHT, we examined the mRNA expression of the upstream activator of AMPK, namely LKB1. Testosterone and DHT treatment of murine 3T3-L1 or human SGBS adipocytes for 24 h significantly decreased the mRNA expression of LKB1. In contrast, 17β-estradiol treatment increased LKB1 mRNA, an effect mediated by oestrogen receptor alpha.
We conclude that regulation of AMPK phosphorylation by androgens and oestrogens is receptor-dependent, and demonstrate for the first time that LKB1 is regulated by sex hormones in adipocytes.
在脂肪组织中，AMP 激活蛋白激酶（AMPK）的磷酸化激活有利于局部脂肪酸氧化和抑制脂肪生成。我们之前已经表明，强效雄激素二氢睾酮（DHT）可以以剂量依赖的方式抑制脂肪组织和 3T3-L1 脂肪细胞中 AMPK 的磷酸化。DHT 的这种负效应可以通过雌激素处理来逆转。本研究的目的是确定雄激素和雌激素调节脂肪细胞中 AMPK 磷酸化的潜在机制，以及这种机制是否依赖于受体。
用睾酮或 DHT（1-1000 nM）处理细胞 24 h 后，通过 Western blot 评估 AMPK 的磷酸化。睾酮和 DHT 显著抑制 AMPK 的基础磷酸化。向培养基中添加雄激素受体拮抗剂氟他胺（1 μM）可逆转睾酮和 DHT 的负效应，使 AMPK 磷酸化水平恢复到基础水平。为了进一步剖析睾酮或 DHT 抑制 AMPK 的机制，我们检查了 AMPK 的上游激活剂 LKB1 的 mRNA 表达。用睾酮或 DHT 处理 24 h 后，小鼠 3T3-L1 或人 SGBS 脂肪细胞的 LKB1 mRNA 表达显著降低。相比之下，17β-雌二醇处理增加了 LKB1 mRNA，这是由雌激素受体 α 介导的效应。
我们得出结论，雄激素和雌激素对 AMPK 磷酸化的调节是受体依赖性的，并首次证明 LKB1 受激素在脂肪细胞中的调节。
