Abstract

Neuronal differentiation requires precise coordination of progenitor proliferation, lineage commitment, and chromatin regulation to establish functional brain architecture. Host Cell Factor-1 (HCF-1), an X-linked transcriptional co-regulator linked to human intellectual disability, is essential for early development, yet its lineage-specific roles during mammalian neurogenesis remain incompletely defined. Here, we investigate the function of the HCF-1-OGT axis during neuronal differentiation and forebrain development. Early embryonic loss of HCF-1 resulted in developmental arrest due to gastrulation defects, while conditional deletion in Nkx2.1-derived neuronal lineages caused pronounced cortical disorganization, reduced GABAergic interneuron survival, and severe defects in forebrain commissures, including the corpus callosum and anterior commissure. These abnormalities were not observed following glial-restricted deletion, indicating a neuron-specific requirement for HCF-1. Neuronal ablation alone did not phenocopy these defects; however, combined neuronal ablation and HCF-1 loss exacerbated cortical and commissural abnormalities, revealing increased neuronal vulnerability. Transcriptomic profiling following HCF-1 depletion identified widespread dysregulation of gene networks associated with neuronal differentiation, synaptic organization, chromatin regulation, and axon guidance. Consistently, HCF-1 directly occupied promoters of key neuronal genes, including Elavl3 and NeuroD1, and its loss reduced activating chromatin marks at these loci. In vitro, depletion of HCF-1 or inhibition of OGT impaired neuronal proliferation, differentiation, and neurite outgrowth. Glycoproteomic analysis further revealed disruption of OGT-dependent protein networks involved in neuronal structure and maturation. Together, these findings identify HCF-1 as a central regulator of neuronal differentiation and forebrain organization and provide mechanistic insight into how disruption of the HCF-1-OGT axis contributes to neurodevelopmental disorders.

Abstract 

Regeneration of the central nervous system (CNS) is a complex and tightly regulated process, yet the precise molecular players and transcriptional regulators involved remain incompletely understood. Here, we identify Host Cell Factor-1 (Hcfc1), a transcriptional co-regulator, and O-GlcNAc transferase (Ogt), which cleaves and O-GlcNAcylates HCF-1, as crucial regulators of zebrafish brain and retinal regeneration. We uncover their interplay with the Hippo/Yap signalling pathway, a well-known regulator of tissue growth and repair. Knockdown of hcfc1a/b or Ogt activity inhibition disrupts regeneration and reduces Yap levels, while Yap inhibition alone also impairs regeneration. Strikingly, overexpression of constitutively active Yap5SA rescues proliferation defects caused by Hcfc1 depletion and Ogt inhibition in retinal regeneration. Further, yap1 knockdown reduces hcfc1a/b levels, suggesting potential feedback regulation. These findings reveal a previously unrecognised regulatory axis involving Hcfc1, Ogt, and the Hippo/Yap pathway, which governs CNS regeneration. Targeting this pathway could offer a strategy for enhancing CNS regeneration. 

Abstract 

The vacuolar protein sorting-associated protein 13B (VPS13B) is a large and highly conserved protein. Disruption of VPS13B causes the autosomal recessive Cohen syndrome, a rare disorder characterized by microcephaly and intellectual disability among other features, including developmental delay, hypotonia, and friendly-personality. However, the underlying mechanisms by which VPS13B disruption leads to brain dysfunction still remain unexplained. To gain insights into the neuropathogenesis of Cohen syndrome, we systematically characterized brain changes in Vps13b-mutant mice and compared murine findings to 235 previously published and 17 new patients diagnosed with VPS13B-related Cohen syndrome. We showed that Vps13b is differentially expressed across brain regions with the highest expression in the cerebellum, the hippocampus and the cortex with postnatal peak. Half of the Vps13b− /− mice die during the first week of life. The remaining mice have a normal lifespan and display the core phenotypes of the human disease, including microcephaly, growth delay, hypotonia, altered memory, and enhanced sociability. Systematic 2D and 3D brain histo-morphological analyses reveal specific structural changes in the brain starting after birth. The dentate gyrus is the brain region with the most prominent reduction in size, while the motor cortex is specifically thinner in layer VI. The fornix, the fasciculus retroflexus, and the cingulate cortex remain unaffected. Interestingly, these neuroanatomical changes implicate an increase of neuronal death during infantile stages with no progression in adulthood, suggesting that VPS13B promotes neuronal survival early in life. Importantly, whilst both sexes were affected, some neuroanatomical and behavioral phenotypes were less pronounced or even absent in females. We evaluate sex differences in Cohen patients and conclude that females are less affected both in mice and patients.