Phosphodiesterase 1A Modulates Cystogenesis in Zebrafish

Abstract

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.

Modulation of Polycystic Kidney Disease Severity by Phosphodiesterase 1 and 3 Subfamilies

“…9 Correspondingly, the knockdown of the calcium/calmodulin-dependent pde1a using morpholinos induces or aggravates the cystic phenotype of wild-type or pkd2 morphant zebrafish embryos, respectively, whereas PDE1a RNA partially rescues the phenotype of pkd2 morphants. 10 Because the hydrolytic capacity of PDEs far exceeds the maximum rate of synthesis by adenylyl cyclases, 11 cellular levels of cAMP are likely more sensitive to inhibition of PDEs than to activation of adenylyl cyclases.…”

The Future of Polycystic Kidney Disease Research—As Seen By the 12 Kaplan Awardees

“…Disrupted calcium may enhance cAMP and protein kinase A signaling through activation of calcium-inhibitable adenylyl cyclases and inhibition of calcium-dependent phosphodiesterases (PDE1 and indirectly cGMP-inhibited PDE3). 78 Enhanced protein kinase A activity may in turn disrupt intracellular calcium homeostasis through hyperphosphorylation of calcium cycling proteins in the endoplasmic reticulum. Preclinical studies have targeted calcium signaling with some success.…”

Generation and phenotypic characterization of Pde1a mutant mice

“…It has been proposed that the increase in cAMP signaling is, in part, a direct consequence of a reduction in intracellular calcium homeostasis through the inhibition of phosphodiesterase (PDE)-1, the only PDE activated by calcium [ 6 ]. The PDE1 family consists of three isoforms encoded by three distinct genes, PDE1A , PDE1B and PDE1 C. We have shown that pde1a interference using splice- and translation-blocking morpholinos causes pronephric cysts, hydrocephalus, and body curvature in wild-type zebrafish embryos and aggravates the cystic phenotype in pkd2 morphants, while human PDE1A RNA partially rescues the pde1a and pkd2 morphant phenotypes [ 12 ]. To study the role of PDE1A in a mammalian system we created Pde1a null mouse lines using TALENs.…”