Chemical modifier screen identifies HDAC inhibitors as suppressors of PKD models

Abstract

Polycystic kidney disease (PKD) is a common human genetic disease with severe medical consequences. Although it is appreciated that the cilium plays a central role in PKD, the underlying mechanism for PKD remains poorly understood and no effective treatment is available. In zebrafish, kidney cyst formation is closely associated with laterality defects and body curvature. To discover potential drug candidates and dissect signaling pathways that interact with ciliary signals, we performed a chemical modifier screen for the two phenotypes using zebrafish pkd2 hi4166 and ift172 hi2211 models. pkd2 is a causal gene for autosomal dominant PKD and ift172 is essential for building and maintaining the cilium. We identified trichostatin A (TSA), a pan-HDAC (histone deacetylase) inhibitor, as a compound that affected both body curvature and laterality. Further analysis verified that TSA inhibited cyst formation in pkd2 knockdown animals. Moreover, we demonstrated that inhibiting class I HDACs, either by valproic acid (VPA), a class I specific HDAC inhibitor structurally unrelated to TSA, or by knocking down hdac1, suppressed kidney cyst formation and body curvature caused by pkd2 deficiency. Finally, we show that VPA was able to reduce the progression of cyst formation and slow the decline of kidney function in a mouse ADPKD model. Together, these data suggest body curvature may be used as a surrogate marker for kidney cyst formation in large-scale high-throughput screens in zebrafish. More importantly, our results also reveal a critical role for HDACs in PKD pathogenesis and point to HDAC inhibitors as drug candidates for PKD treatment.

Biological Screening of Novel Derivatives of Valproic Acid for Anticancer and Antiangiogenic Properties

“…Besides interfering with angiogenic blood vessels formation, the compounds from valproylglycine hydrazide series also induced severe cardiac edema (Figure 1 black arrow in D). The cardiac edema has also been shown in previous studies which are HDAC mutant (Pillai et al, 2004;Yamaguchi et al, 2005) or embryos were treated with VPA or any other HDAC inhibitor (Farooq et al, 2008;Cao et al, 2009;Johnson et al, 2013). We have not analyzed the HDAC enzymatic activity with these compounds but most likely that the cardiac edema which is result of newly synthesized VPA derivatives could be due to their HDAC inhibition activity.…”

Analysis of the retina in the zebrafish model

“…In this type of experiment, hundreds or even thousands of small batches of embryos are each exposed to a different chemical compound, and analyzed for developmental or behavioral changes. Such an approach has been applied either to wild-type embryos or to carriers of genetic defects (Cao et al, 2009;North et al, 2007North et al, , 2009Peterson et al, 2004). In the latter case, compounds that rescue a mutant phenotype can be screened for.…”

Polycystic kidney disease and therapeutic approaches

“…It has been demonstrated that p53 functions as a negative regulator of Pkd1 gene transcription by binding to the Pkd1 gene promoter in vivo. Importantly, trichostatin A (TSA), a general inhibitor of class I and II HDACs, has been shown to abolish the p53-mediated repression of Pkd1 gene expression in Pkd1 mutant mice (67,68). This indicates that p53 negatively controls Pkd1 gene expression in cooperation with HDACs and may contribute to deregulated Pkd1 expression and cyst formation (67).…”

“…The results of recent studies have demonstrated that the acetylation of histone lysine residues might be correlated with PKD and CKD pathogenesis (27,28,(67)(68)(69). The PKD1 gene is the most critical factor in ADPKD pathogenesis (1).…”

“…Moreover, HDAC1 is responsible for p53 deacetylation, and may result in the p53-induced repression of PKD1 gene transcription (27,69). Either treatment with HDAC1 inhibitors such as TSA and valproic acid (VPA) or hdac1 knockdown results in a reduction in kidney cyst formation in Pkd2 knockdown fish, as well as Pkd1 mutant mice (68). Another important point is that HDAC5 is associated with fluid flow-induced calcium signaling in kidney epithelial cells (27).…”