Sussman Caroline R, Ward Christopher J, Leightner Amanda C, Smith Jordan L, Agarwal Reema, Harris Peter C, Torres Vicente E
Nephrology and Hypertension, Mayo Clinic College of Medicine, Rochester, Minnesota
Nephrology and Hypertension, Mayo Clinic College of Medicine, Rochester, Minnesota.
J Am Soc Nephrol. 2014 Oct;25(10):2222-30. doi: 10.1681/ASN.2013040421. Epub 2014 Apr 3.
Substantial evidence indicates the importance of elevated cAMP in polycystic kidney disease (PKD). Accumulation of cAMP in cystic tissues may be, in part, caused by enhanced adenylyl cyclase activity, but inhibition of cAMP degradation by phosphodiesterases (PDE) likely has an important role, because cAMP is inactivated much faster than it is synthesized. PDE1 is the only PDE family activated by Ca(2+), which is reduced in PKD cells. To assess the contribution of the PDE1A subfamily to renal cyst formation, we examined the expression and function of PDE1A in zebrafish. We identified two splice isoforms with alternative starts corresponding to human PDE1A1 and PDE1A4. Expression of the two isoforms varied in embryos and adult tissues, and both isoforms hydrolyzed cAMP with Ca(2+)/calmodulin dependence. Depletion of PDE1A in zebrafish embryos using splice- and translation-blocking morpholinos (MOs) caused pronephric cysts, hydrocephalus, and body curvature. Human PDE1A RNA and the PKA inhibitors, H89 and Rp-cAMPS, partially rescued phenotypes of pde1a morphants. Additionally, MO depletion of PDE1A aggravated phenotypes in pkd2 morphants, causing more severe body curvature, and human PDE1A RNA partially rescued pkd2 morphant phenotypes, pronephric cysts, hydrocephalus, and body curvature. Together, these data indicate the integral role of PDE1A and cAMP signaling in renal development and cystogenesis, imply that PDE1A activity is altered downstream of polycystin-2, and suggest that PDE1A is a viable drug target for PKD.
大量证据表明，环磷酸腺苷（cAMP）升高在多囊肾病（PKD）中具有重要作用。cAMP在囊性组织中的积累可能部分是由于腺苷酸环化酶活性增强所致，但磷酸二酯酶（PDE）对cAMP降解的抑制可能起重要作用，因为cAMP的失活速度比其合成速度快得多。PDE1是唯一由Ca(2+)激活的PDE家族，而PKD细胞中的Ca(2+)含量降低。为了评估PDE1A亚家族对肾囊肿形成的作用，我们研究了斑马鱼中PDE1A的表达和功能。我们鉴定出两种具有不同起始位点的剪接异构体，分别对应于人类的PDE1A1和PDE1A4。这两种异构体在胚胎和成年组织中的表达各不相同，并且都以Ca(2+)/钙调蛋白依赖性方式水解cAMP。使用剪接和翻译阻断吗啉代寡核苷酸（MOs）使斑马鱼胚胎中的PDE1A缺失会导致前肾囊肿、脑积水和身体弯曲。人类PDE1A RNA以及蛋白激酶A（PKA）抑制剂H89和Rp-cAMPS部分挽救了pde1a morphants（基因敲降胚胎）的表型。此外，MO介导的PDE1A缺失加重了pkd2 morphants的表型，导致更严重的身体弯曲，而人类PDE1A RNA部分挽救了pkd2 morphants的表型、前肾囊肿、脑积水和身体弯曲。总之，这些数据表明PDE1A和cAMP信号在肾脏发育和囊肿形成中起不可或缺的作用，意味着PDE1A活性在多囊蛋白-2的下游发生改变，并提示PDE1A是PKD的一个可行药物靶点。
