cAMP-Specific Phosphodiesterases 8A and 8B, Essential Regulators of Leydig Cell Steroidogenesis
cAMP-Specific Phosphodiesterases 8A and 8B, Essential Regulators of Leydig Cell Steroidogenesis
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DOI：
10.1124/mol.111.076125
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发表时间：
2012-04-01
影响因子：
3.6
通讯作者：
Beavo, Joseph A.
中科院分区：
文献类型：
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作者：
Shimizu-Albergine, Masami;Tsai, Li-Chun Lisa;Beavo, Joseph A.
磷酸二酯酶 (PDE) 8A 和 PDE8B 是高亲和力、cAMP 特异性磷酸二酯酶，在 Leydig 细胞中高度表达。 PDE8A 主要与线粒体相关，而 PDE8B 广泛分布在细胞质中。我们使用新型 PDE8 选择性抑制剂 PF-04957325 和基因消除的 PDE8A(-/-)、PDE8B(-/-) 和 PDE8A(-/-)/B(-/-) 小鼠来确定这些 PDE 在调节睾酮产生中的作用。 PF-04957325 处理 WT Leydig 细胞或 MA10 细胞会增加类固醇的产生，但对 PDE8A (-/-)/B(-/-) 双敲除细胞没有影响，证实了该药物的选择性。此外，在基础条件下，与 PF-04957325 和咯利普兰（一种 PDE4 选择性抑制剂）共同治疗，可协同增强类固醇的产生。这些结果表明，调节雄激素产生的 cAMP 库是由与 PDE4 协同工作的 PDE8 控制的。同样，PDE8A (-/-)/B(-/-) 细胞比来自 PDE8A(-/-) 或 PDE8B(-/-) 小鼠的细胞具有更高的睾酮产量，表明两种 PDE8 协同调节类固醇的产生。我们进一步证明，PDE8s 和 PDE4 的联合抑制大大增加了 PKA 活性，包括胆固醇酯水解酶 (CEH)/激素敏感脂肪酶 (HSL) 的磷酸化。与WT细胞相比，PDE8A(-/-)/B(-/-)细胞中CEH/HSL磷酸化也增加。最后，PDE8s 和 PDE4 的联合抑制增加了类固醇生成急性调节 (StAR) 蛋白的表达。这些发现共同表明，PDE8A 和 PDE8B 在维持低 cAMP 水平方面发挥着重要作用，从而通过保持 CEH/HSL 不活跃和 StAR 蛋白表达低来抑制静息类固醇生成。他们还建议，为了使 PDE 抑制剂疗法成为类固醇生成的有效刺激剂，需要同时靶向 PDE8 同工酶和 PDE4。
Phosphodiesterase (PDE) 8A and PDE8B are high-affinity, cAMP-specific phosphodiesterases that are highly expressed in Leydig cells. PDE8A is largely associated with mitochondria, whereas PDE8B is broadly distributed in the cytosol. We used a new, PDE8-selective inhibitor, PF-04957325, and genetically ablated PDE8A(-/-), PDE8B(-/-) and PDE8A(-/-)/B(-/-) mice to determine roles for these PDEs in the regulation of testosterone production. PF-04957325 treatment of WT Leydig cells or MA10 cells increased steroid production but had no effect in PDE8A (-/-)/B(-/-) double-knockout cells, confirming the selectivity of the drug. Moreover, under basal conditions, cotreatment with PF-04957325 plus rolipram, a PDE4-selective inhibitor, synergistically potentiated steroid production. These results suggest that the pool(s) of cAMP regulating androgen production are controlled by PDE8s working in conjunction with PDE4. Likewise, PDE8A (-/-)/B(-/-) cells had higher testosterone production than cells from either PDE8A(-/-) or PDE8B(-/-) mice, suggesting that both PDE8s work in concert to regulate steroid production. We further demonstrate that combined inhibition of PDE8s and PDE4 greatly increased PKA activity including phosphorylation of cholesterol-ester hydrolase (CEH)/hormone-sensitive lipase (HSL). CEH/HSL phosphorylation also was increased in PDE8A(-/-)/B(-/-) cells compared with WT cells. Finally, combined inhibition of PDE8s and PDE4 increased the expression of steroidogenic acute regulatory (StAR) protein. Together these findings suggest that both PDE8A and PDE8B play essential roles to maintain low cAMP levels, thereby suppressing resting steroidogenesis by keeping CEH/HSL inactive and StAR protein expression low. They also suggest that in order for PDE inhibitor therapy to be an effective stimulator of steroidogenesis, both PDE8 isozymes and PDE4 need to be simultaneously targeted.