Biology subjects

Cutrupi, A. N.

Publications and source records attributed to Cutrupi, A. N..

4 recordsLinked to original sources

bioRxiv2026

Quantification of X-chromosome inactivation in fibroblast and iPSC models of UBQLN2 ALS/FTD using allele-selective qPCR

Pathogenic missense variants in the X chromosome gene UBQLN2 cause amyotrophic lateral sclerosis (ALS), often accompanied by frontotemporal dementia (FTD). As an X-linked gene, UBQLN2 is subject to X chromosome inactivation (XCI), a process wherein one X chromosome in each cell is randomly inactivated to a Barr body throughout the body in females, creating a mosaic of allelic expression in the tissues of heterozygotes. Despite heterozygous females constituting a majority of reported cases of UBQLN2-linked ALS/FTD, and the known influence of XCI on neurological disorders at large, no current disease models account for XCI. Here we report the characterisation of 12 iPSC clones carrying the ALS/FTD-causing p.T487I (c.1460C>T) UBQLN2 variant. These clones, originally derived from 3 heterozygous carrier fibroblast lines, underwent validation of homeostatic Barr body retention. Erosion of XCI in a subset of the lines was correlated with biallelic expression (of both wildtype and mutant UBQLN2), as measured through a novel allele-selective qPCR (AS-qPCR) assay and verified by amplicon-based Illumina sequencing and Sanger chromatogram quantification, enabling selection of iPSC clones best retaining XCI. Together, this UBQLN2 AS-qPCR assay and selected iPSC clones will enable studies of the role of XCI and its skew in female resilience to UBQLN2 p.T487I-linked ALS/FTD and enable development of allele-selective therapies.

molecular biology↗

bioRxiv2026

The Charcot-Marie-Tooth Neuropathy (CMTX3) Complex Structural Variation Causes Differential SOX3 Spatiotemporal Expression

Charcot-Marie-Tooth (CMT) neuropathy is a clinically and genetically heterogeneous group of diseases characterised by the length dependent axonal degeneration of peripheral nerves. We previously mapped a rare form of X-linked CMT, CMTX3, to a 5.7-Mb interval on chromosome Xq26.3-q27.1 and excluded the coding region of all known genes in the linkage interval for mutations. Whole genome sequencing subsequently identified a 78-kb region of chromosome 8q24.3, that had been duplicated and inserted into the CMTX3 locus between the genes HAPSTR2 and SOX3. The 78-kb insertion, which contains a partial transcript of ARHGAP39, fully segregated in families with CMTX3 and was absent in neurologically normal controls. To retain the CMTX3 insertion and investigate its consequences in appropriate neuronal tissue, we generated induced pluripotent stem cells (iPSC) from CMTX3 fibroblasts. Using bulk RNA sequencing of patient-derived spinal motor neurons, ARHGAP39 was deemed non-pathogenic by excluding both the formation of novel fusion transcripts and dosage effects from the partial duplication. Subsequent NanoString expression analyses of candidate genes within the CMTX3 locus, across different stages of neuronal differentiation, identified spatiotemporal dysregulation of SOX3. NanoString showed reduced SOX3 expression in patient iPSC. RNA sequencing detected SOX3 downregulation in CMTX3 neuroepithelial progenitor cells, which was further confirmed by quantitative proteomics. Given the early onset and relatively rapid progression of CMTX3, these data prioritise SOX3 as a leading candidate gene, consistent with its role as one of the earliest transcription factors expressed in the developing nervous system and a key regulator of neuronal fate.

neuroscience↗

bioRxiv2022

Transgenic mice overexpressing mutant TDP-43 show aberrant splicing of autism associated gene Zmynd11 prior to onset of motor symptoms

Mutations in TDP-43 are known to cause Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD). TDP-43 binds to and regulates splicing of several RNA including Zmynd11. Zmynd11 is a transcriptional repressor and a potential E3 ubiquitin ligase family member, known for its role in neuron and muscle differentiation. Mutations in Zmynd11 have been associated with autism with significant developmental motor delays, intellectual disability, and ataxia. Here, we show that Zmynd11 is aberrantly spliced in the brain and spinal cord of transgenic mice overexpressing a mutant human TDP-43 (A315T), and that these changes occur before the onset of motor symptoms.

neuroscience↗

bioRxiv2022

Novel gene-intergenic fusion involving ubiquitin E3 ligase UBE3C causes distal hereditary motor neuropathy: A new mechanism for motor neuron degeneration.

Distal hereditary motor neuropathies (dHMNs) are a group of inherited diseases involving the progressive, length-dependent axonal degeneration of the lower motor neurons. There are currently 29 reported causative genes and 4 disease loci implicated in dHMN. Despite the high genetic heterogeneity, mutations in the known genes account for less than 20% of dHMN cases with the mutations identified predominantly being point mutations or indels. We have expanded the spectrum of dHMN mutations with the identification of a 1.35 Mb complex structural variation (SV) causing a form of autosomal dominant dHMN (DHMN1 OMIM %182906). Given the complex nature of SV mutations and the importance of studying pathogenic mechanisms in a neuronal setting, we generated a patient-derived DHMN1 motor neuron model harbouring the 1.35 Mb complex insertion. The DHMN1 complex insertion creates a duplicated copy of the first 10 exons of the ubiquitin-protein E3 ligase gene (UBE3C) and forms a novel gene-intergenic fusion sense transcript by incorporating a terminal pseudo-exon from intergenic sequence within the DHMN1 locus. The UBE3C intergenic fusion (UBE3C-IF) transcript does not undergo nonsense-mediated decay and results in a significant reduction of wild type full length UBE3C (UBE3C-WT) protein levels in DHMN1 iPSC-derived motor neurons. An engineered transgenic C. elegans model expressing the UBE3C-IF transcript in GABA-ergic motor neurons shows neuronal synaptic transmission deficits. Furthermore, the transgenic animals are susceptible to heat stress which may implicate defective protein homeostasis underlying DHMN1 pathogenesis. Identification of the novel UBE3C-IF gene-intergenic fusion transcript in motor neurons highlights a potential new disease mechanism underlying axonal and motor neuron degeneration. These complementary models serve as a powerful paradigm for studying the DHMN1 complex SV and an invaluable tool for defining therapeutic targets for DHMN1.

neuroscience↗