Hcfc1a regulates neural precursor proliferation and asxl1 expression in the developing brain

Background: Precise regulation of neural precursor cell (NPC) proliferation and differentiation is essential to ensure proper brain development and function. The HCFC1 gene encodes a transcriptional co-factor that regulates cell proliferation, and previous studies suggest that HCFC1 regulates NPC function. However, the molecular mechanism underlying these cellular deficits has not been completely characterized. Methods: Here we created a zebrafish harboring mutations in the hcfc1a gene (the hcfc1aco60/+ allele), one ortholog of HCFC1, and utilized immunohistochemistry and RNA-sequencing technology to understand the function of hcfc1a during neural development. Results: The hcfc1aco60/+ allele results in an increased number of NPCs, neurons, and radial glial cells. These deficits are associated with the abnormal expression of asxl1, a polycomb transcription factor, which we identified as a downstream effector of hcfc1a using high throughput RNA sequencing technology. Inhibition of asxl1 activity and/or expression in larvae harboring the hcfc1aco60/+ allele completely restored the number of NPCs to normal levels. Conclusion: Collectively, our data demonstrate a novel pathway in which hcfc1a regulates NPCs and neurogenesis.