Histone deacetylase 1 is required to repress Notch target gene expression during zebrafish neurogenesis and to maintain the production of motoneurones in response to hedgehog signalling

174

156

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.

“…S4 B-D). Notably, these phenotypes are reminiscent of those observed in hdac1/hi1618, an insertional mutant of hdac1 (25) (Fig. 4 A and B and Fig.…”

Section: Knockdown Of a Class I Hdac Gene Hdac1 Can Suppress Pkd2supporting

confidence: 52%

Chemical modifier screen identifies HDAC inhibitors as suppressors of PKD models

Cao¹,

Semanchik²,

Lee

et al. 2009

174

156

“…It is likely the transient and incomplete nature of pharmacological inhibition allows for the survival of neuronal precursors; and the derepression of proneurogenic genes allows for the specific induction of neurogenesis, whereas the genetic loss of HDAC1 and HDAC2 is so robust, differentiation is blocked and cellular death ensues. A similar phenotype is seen in lower organisms such as zebrafish, where loss-offunction mutants for hdac1 show a blockade of neuronal differentiation in vivo through the activation of the neurogenic repressor, Hes, and show significant apoptosis in hindbrain neural progenitor cells (22)(23)(24). Additionally, neuronal precursors transduced with a mutant HDAC1 that lacks catalytic activity show a fifty percent reduction in neuronal specification (25).…”

Section: Contrasting Phenotypes Between Inhibitors and Genetic Deletionmentioning

confidence: 63%

Histone deacetylases 1 and 2 control the progression of neural precursors to neurons during brain development

Montgomery¹,

Hsieh²,

Barbosa³

et al. 2009

277

254

The molecular mechanism by which neural progenitor cells commit to a specified lineage of the central nervous system remains unknown. We show that HDAC1 and HDAC2 redundantly control neuronal development and are required for neuronal specification. Mice lacking HDAC1 or HDAC2 in neuronal precursors show no overt histoarchitectural phenotypes, whereas deletion of both HDAC1 and HDAC2 in developing neurons results in severe hippocampal abnormalities, absence of cerebellar foliation, disorganization of cortical neurons, and lethality by postnatal day 7. These abnormalities in brain formation can be attributed to a failure of neuronal precursors to differentiate into mature neurons and to excessive cell death. These results reveal redundant and essential roles for HDAC1 and HDAC2 in the progression of neuronal precursors to mature neurons in vivo.cerebellum ͉ hippocampus ͉ neurogenesis ͉ neuronal precursors H istone acetyltransferases (HATs) and histone deacetylases (HDACs) provide the enzymatic basis for transcriptional activation and repression, respectively, through alterations of the chromatin landscape (1). Transcription factors recruit HDACs, either individually, or in repressive complexes to deacetylate lysine residues on histone tails, resulting in chromatin condensation and repression of gene expression (2). There are 4 classes of HDACs that coordinate proper gene regulation for numerous cellular processes: class I (HDAC1, -2, -3, and -8), class II (HDAC4, -5, -6, -7, -9, and -10), sirtuin class III, and class IV (HDAC11) (3). Although much has been learned through in vitro and inhibitor studies, little is known about the biological function of these individual enzymes in vivo (4). We have shown that the class I HDACs, HDAC1 and HDAC2, redundantly regulate cardiac growth and morphogenesis (5), however, the functions of HDAC1 and HDAC2 in other tissues remain unknown.HDAC inhibitors have shown significant potential for therapeutic use in a variety of disorders, including those of the central nervous system (CNS), such as neurodegenerative disease, motor neuron disease, and a number of other neurological disease states (6). Furthermore, it has been shown that HDAC inhibitors induce differentiation of both embryonic and adult cortical neuronal progenitor cells to neurons specifically (7-9). The wide expression pattern of a number of HDACs in the developing brain suggests specific roles for individual HDACs in neuronal development (10), however, the broad inhibition of classical HDAC inhibitors has precluded the analysis of individual HDACs pharmacologically. Additionally, the early lethality associated with global deletion of class I HDACs in knockout mice has compounded the difficulties in analyzing the functions of these enzymes during specific stages of neurogenesis in vivo (5, 11).To further investigate the specific roles of HDAC1 and HDAC2 in neuronal development, we generated conditional deletions of HDAC1 and HDAC2 in the central nervous system. Here, we show both HDAC1 and HDAC2 are required for multip...

“…Valproic acid, an inhibitor of class I and class II HDACs, inhibits the differentiation of preadipocyte cells (26), whereas it promotes the neuronal differentiation of adult hippocampal neural progenitors (27). HDAC1 represses MyoD and thereby inhibits myogenesis (28), but it induces differentiation of NPCs during zebrafish neurogenesis (29).…”

Section: Discussionmentioning

confidence: 99%

Histone deacetylase SIRT1 modulates neuronal differentiation by its nuclear translocation

Hisahara

Chiba

Matsumoto

et al. 2008

254

228

Neural precursor cells (NPCs) differentiate into neurons, astrocytes, and oligodendrocytes in response to intrinsic and extrinsic changes. Notch signals maintain undifferentiated NPCs, but the mechanisms underlying the neuronal differentiation are largely unknown. We show that SIRT1, an NAD ؉ -dependent histone deacetylase, modulates neuronal differentiation. SIRT1 was found in the cytoplasm of embryonic and adult NPCs and was transiently localized in the nucleus in response to differentiation stimulus. SIRT1 started to translocate into the nucleus within 10 min after the transfer of NPCs into differentiation conditions, stayed in the nucleus, and then gradually retranslocated to the cytoplasm after several hours. The number of neurospheres that generated Tuj1 ؉ neurons was significantly decreased by pharmacological inhibitors of SIRT1, dominant-negative SIRT1 and SIRT1-siRNA, whereas overexpression of SIRT1, but not that of cytoplasm-localized mutant SIRT1, enhanced neuronal differentiation and decreased Hes1 expression. Expression of SIRT1-siRNA impaired neuronal differentiation and migration of NPCs into the cortical plate in the embryonic brain. Nuclear receptor corepressor (N-CoR), which has been reported to bind SIRT1, promoted neuronal differentiation and synergistically increased the number of Tuj1 ؉ neurons with SIRT1, and both bound the Hes1 promoter region in differentiating NPCs. Hes1 transactivation by Notch1 was inhibited by SIRT1 and/or N-CoR. Our study indicated that SIRT1 is a player of repressing Notch1-Hes1 signaling pathway, and its transient translocation into the nucleus may have a role in the differentiation of NPCs.