Alu-mediated SPAST deletion impairs golgi zinc transport and reveals a druggable vulnerability

HUWE1 targets mitochondria via RMC1 to promote neurodevelopment.

The HECT-type E3 ubiquitin ligase HUWE1 is a critical regulator of protein homeostasis, genome stability, and neurodevelopment. Variants in HUWE1 are linked to X-linked intellectual disability (XLID), yet a significant number of HUWE1 variants are noncatalytic, leaving their disease mechanisms unresolved. Here, we identify an AMBRA1-RMC1-HUWE1 signaling axis that directs HUWE1-mediated ubiquitination to mitochondria to regulate neural development. In zebrafish, noncatalytic HUWE1 variants found in XLID patients (M375I, G660R, and H669Q) recapitulate key neurodevelopmental deficits, including impaired brain growth and motor neuron defects. Global ubiquitin profiling reveals that these variants selectively disrupt the ubiquitination of mitochondrial proteins without affecting nuclear substrates. Mechanistically, AMBRA1 acts as a mitochondrial scaffold that recruits RMC1, enabling HUWE1 localization to mitochondria through direct interaction with RMC1. Disruption of this recruitment by disease-associated HUWE1 variants prevents mitochondrial targeting and impairs mitochondrial substrate ubiquitination. Notably, Urolithin A treatment ameliorates neurodevelopmental phenotypes in HUWE1-deficient zebrafish. Together, our findings define an AMBRA1-organized mitochondrial recruitment pathway in which RMC1 links HUWE1 to mitochondria, explain noncatalytic HUWE1-associated XLID, and suggest mitochondrial quality-control enhancement as a potential therapeutic strategy.

Modeling Cohen Syndrome in Phoenix Cells: VPS13B Loss Causes Organelle Stress, G1/S Delay, and Fibrillary Inclusion Bodies Formation

Cohen syndrome, caused by pathogenic variants in VPS13B, is characterized by microcephaly, developmental delay, and progressive retinal degeneration, yet the cellular mechanisms linking VPS13B dysfunction to disease pathology remain incompletely understood. Here, we used CRISPR-Cas9 to delete VPS13B exons 2–4 in Phoenix HEK293 cells, generating five independent knockout clones. In all mutant lines, VPS13B disruption caused a marked slowing of cell proliferation due to prolongation of the G1 phase. Immunocytochemistry and transmission electron microscopy revealed that VPS13B mutations causes Golgi apparatus fragmentation, loss of VPS13B Golgi localization, ER lumen dilation with rigid membrane morphology, mitochondrial damage, impaired autophagic maturation, and the appearance of cytoplasmic fibrillary inclusions located close to ER and absent from control cells. RNA-seq analysis identified 27 differentially expressed genes common to all four mutant clones, including downregulation of genes involved in transcriptional regulation, lipid metabolism, and neuronal signaling, alongside upregulation of the stress-response genes CLU and CDKN1A (p21). While our results do not support classical unfolded protein response activation, they are consistent with a model in which lipid bilayer stress and disrupted ER–Golgi trafficking may play a role in the pathophysiology of Cohen syndrome. Together, these findings demonstrate that VPS13B deficiency results in coordinated defects in organelle homeostasis, proteostasis, and cell-cycle progression, providing new dates for understanding Cohen syndrome pathogenesis.

ASXL3 truncating patient variants mediate transcriptional gain-of-function and are antisense oligonucleotide-responsive

ASXL3 patient truncations in neurodevelopmental condition Bainbridge-Ropers syndrome are shown to mediates gain-of-function (GOF) by escaping nonsense-mediated decay and Cullin 4-dependent degradation, resulting in aberrant protein accumulation, widespread transcriptional dysregulation, and altered chromatin accessibility.

The ZBTB16/CUL3/ROC1 ubiquitin ligase drives the degradation of pathogenic pendrin (SLC26A4) protein variants

A primary mechanism of SLC26A4 regulation in the inner ear and kidney and of SLC26A4 loss of function in Pendred syndrome and deafness DFNB4 is described and a atomistic model of the complete SLC26A4/ZBTB16/Cullin 3/RocI complex is provided in agreement with experimental results.

Cross-species functional analysis of a de novo DCLK1 variant associated with a neurodevelopmental disorder

The findings implicate DCLK1 in a previously unrecognized progressive neurodevelopmental disorder and demonstrate the power of integrative cross-species functional genomics in resolving ultra-rare disease variants.

Disease-linked mutations in hnRNPA2B1 accelerate condensate maturation and promote amyloid aggregation