Biology subjects

Zuberi, A.

Publications and source records attributed to Zuberi, A..

4 recordsLinked to original sources

bioRxiv2026

BxbI-mediated insertion of a 77kb human RET sensitive haplotype into the mouse genome to generate a humanized model of Hirschsprung disease

Hirschsprung disease (HSCR) is a complex developmental disorder of the enteric nervous system, primarily driven by regulatory variants within enhancer elements of the RET gene. To investigate how these variants lead to aganglionosis, we developed a humanized mouse model by inserting an intact 77kb human RET genomic locus into the Rosa26 safe-harbor locus. Utilizing "big DNA" synthetic biology and Bxb1-mediated recombination, we integrated the complete human locus including all exons, introns, and upstream regulatory elements which we validated via nanopore and short-read sequencing. Functional analysis confirmed in vivo human RET expression; however, our initial HSCR-associated "sensitive" haplotype expressed at only 21% of wild-type levels. This significant reduction proved insufficient to rescue the viability when endogenous mouse Ret was deleted. We identified that this deficiency is partially driven by five risk SNPs within established enhancers. Specifically, using CRISPR/Cas9 to restore a conserved Sox10 binding site (converting a sensitive SNP to a protective one) increased RET expression by 1.9-fold and restored transcription factor binding. This study provides a robust framework for modeling human-specific regulatory disorders and demonstrates the critical impact of non-coding variation on disease pathogenesis.

synthetic biology↗

bioRxiv2024

Alternating hemiplegia of childhood associated mutations in Atp1a3 reveal diverse neurological alterations in mice.

Pathogenic variants in the neuronal Na+/K+ ATPase transmembrane ion transporter (ATP1A3) cause a spectrum of neurological disorders including alternating hemiplegia of childhood (AHC). The most common de novo pathogenic variants in AHC are p.D801N ([~]40% of patients) and p.E815K ([~]25% of patients), which lead to early mortality by spontaneous death in mice. Nevertheless, knowledge of the development of clinically relevant neurological phenotypes without the obstacle of premature death, is critical for the identification of pathophysiological mechanisms and ultimately, for the testing of therapeutic strategies in disease models. Here, we used hybrid vigor attempting to mitigate the fragility of AHC mice and then, performed behavioral, electrophysiological, biochemical, and molecular testing to comparatively analyze mice that carry either of two most common AHC patient observed variants in the Atp1a3 gene. Collectively, our data reveal the presence but also the differential impact of the p.D801N and p.E815K variants on disease relevant alterations such as spontaneous and stress-induced paroxysmal episodes, motor function, behavioral and neurophysiological activity, and neuroinflammation. Our alternate AHC mouse models with their phenotypic deficits open novel avenues for the investigation of disease biology and therapeutic testing for ATP1A3 research.

neuroscience↗

bioRxiv2023

Loss of Endothelial TDP-43 Leads to Blood Brain Barrier Defects in Mouse Models of Amyotrophic Lateral Sclerosis and Frontotemporal Dementia.

Loss of nuclear TDP-43 occurs in a wide range of neurodegenerative diseases, and specific mutations in the TARDBP gene that encodes the protein are linked to familial Frontal Temporal Lobar Dementia (FTD), and Amyotrophic Lateral Sclerosis (ALS). Although the focus has been on neuronal cell dysfunction caused by TDP-43 variants, TARDBP mRNA transcripts are expressed at similar levels in brain endothelial cells (ECs). Since increased permeability across the blood brain barrier (BBB) precedes cognitive decline, we postulated that altered functions of TDP-43 in ECs contributes to BBB dysfunction in neurodegenerative disease. To test this hypothesis, we examined EC function and BBB properties in mice with either knock-in mutations found in ALS/FTLD patients (TARDBPG348C and GRNR493X) or EC-specific deletion of TDP-43 throughout the endothelium (Cdh5(PAC)CreERT2; Tardbpff) or restricted to brain endothelium (Slco1c1(BAC)CreERT2; Tardbpff). We found that TARDBPG348Cmice exhibited increased permeability to 3kDa Texas Red dextran and NHS-biotin, relative to their littermate controls, which could be recapitulated in cultured brain ECs from these mice. Nuclear levels of TDP-43 were reducedin vitro and in vivo in ECs from TARDBPG348Cmice. This coincided with a reduction in junctional proteins VE-cadherin, claudin-5 and ZO-1 in isolated ECs, supporting a cell autonomous effect on barrier function through a loss of nuclear TDP-43. We further examined two models of Tardbp deletion in ECs, and found that the loss of TDP-43 throughout the endothelium led to systemic endothelial activation and permeability. Deletion specifically within the brain endothelium acutely increased BBB permeability, and eventually led to hallmarks of FTD, including fibrin deposition, microglial and astrocyte activation, and behavioral defects. Together, these data show that TDP-43 dysfunction specifically within brain ECs would contribute to the BBB defects observed early in the progression of ALS/FTLD.

neuroscience↗

bioRxiv2022

Stathmin-2 loss leads to neurofilament-dependent axonal collapse driving motor and sensory denervation

The human mRNA most affected by TDP-43 loss-of-function is transcribed from the STMN2 gene and encodes stathmin-2 (also known as SCG10), whose loss is a neurodegenerative disease hallmark. Here using multiple in vivo approaches, including transient antisense oligonucleotide (ASO)-mediated suppression, chronic shRNA-mediated depletion in aging mice, and germline deletion, we establish stathmin-2 to be essential for acquisition and maintenance of neurofilament-dependent structuring of axoplasm critical for maintaining diameter and conduction velocity of large-myelinated axons. Sustained stathmin-2 loss from an otherwise mature adult nervous system is demonstrated over a time course of eight months to initiate and drive motor neuron disease that includes 1) shrinkage in inter-neurofilament spacing that is required to produce a three-dimensional space filling array that defines axonal caliber, 2) collapse of mature axonal caliber with tearing of outer myelin layers, 3) reduced conduction velocity, 4) progressive motor and sensory deficits (including reduction of the pain transducing neuropeptide CGRP), and 5) muscle denervation. Demonstration that chronic stathmin-2 reduction is itself sufficient to trigger motor neuron disease reinforces restoration of stathmin-2 as an attractive therapeutic approach for TDP-43-dependent neurodegeneration, including the fatal adult motor neuron disease ALS.

cell biology↗