Biology subjects

Almad, A.

Publications and source records attributed to Almad, A..

2 recordsLinked to original sources

bioRxiv2026

Deletion of TUBB4A mitigates the oligodendrocyte and neuronal deficits in human iPSCs derived from individuals affected by H-ABC

TUBB4A-related leukodystrophy (TUBB4A-LD) is a rare neurologic disorder with a broad spectrum of phenotypes, including severe early infantile encephalopathy, late infantile Hypomyelination with Atrophy of the Basal ganglia and Cerebellum (H-ABC), and milder late infantile forms. H-ABC is closely associated with a recurrent pathogenic variant, p.Asp249Asn, in the gene encoding tubulin beta class IVA (TUBB4A), a microtubule component. H-ABC presents with progressive dystonia, mobility loss, aphasia, and swallowing dysfunction in childhood. H-ABC results in cell-autonomous deficits in oligodendrocytes (OLs), cerebellar granule neurons, and medium spiny neurons (MSNs). Antisense oligonucleotides targeting Tubb4a can alleviate symptoms in H-ABC mouse models. However, the efficacy and safety of TUBB4A knockout in human cells remain poorly understood. We studied patient-derived TUBB4AD249N, TUBB4A KO, and control individual pluripotent stem cells (iPSCs). TUBB4AD249N iPSC-derived OLs failed to mature, showing less complexity and myelination, reduced microtubule acetylation and detyrosination. TUBB4AD249N iPSC-derived MSNs also showed impaired maturation and neurite extension. TUBB4A KO in mutant iPSCs reduced cellular deficits and was well tolerated. These findings support that suppression of TUBB4A could be a safe, effective therapy for TUBB4A-LD.

neuroscience↗

bioRxiv2024

Therapeutic suppression of Tubb4a rescues H-ABC leukodystrophy

Hypomyelination and atrophy of basal ganglia and cerebellum (H-ABC) is a rare leukodystrophy associated with causal variants in {beta}-tubulin 4A (TUBB4A). The recurring variant p.Asp249Asn (D249N) presents in infancy with dystonia, communication deficits, and loss of ambulation during the first decade of life. In this study, we characterized a genetic murine series (Tubb4aKO/KO, Tubb4aD249N/+, Tubb4aD249N/KO, and Tubb4aD249N/D249N) to demonstrate that disease severity correlates with the expression of mutant Tubb4a and relative preservation of WT tubulin. To further evaluate the translational potential of Tubb4a suppression as a therapy in H-ABC, we identified a well-tolerated Tubb4a-targeted antisense oligonucleotide (ASO) candidate that selectively reduces Tubb4a. Notably, single intracerebroventricular (i.c.v.) administration of ASO in postnatal Tubb4aD249N/KO mice drastically extends its lifespan, improves motor phenotypes, and reduces seizures. Neuropathologically, treating ASO Tubb4aD249N/KO mice prevents myelin and oligodendrocyte loss and recovers visual evoked potential latencies in vivo. Furthermore, the microtubule function of Mbp mRNA transport from oligodendrocyte (OL) soma to myelin sheath is retained. A major limitation we noted is that ASOs fail to target cerebellar granule neurons even with multiple routes of administration in the brain. This is the first preclinical proof-of-concept for Tubb4a suppression via ASO as a disease-modifying therapy for H-ABC.

neuroscience↗