Endogenous TDP-43 mislocalization in a novel knock-in mouse model reveals DNA repair impairment, inflammation, and neuronal senescence

• DOI: 10.1186/s40478-025-01962-9
• Publication Date: 2025-03-08T10:48:56Z
• Authors: Joy Mitra; Manohar Kodavati; Prakash Dharmalingam; Erika N. Guerrero; K. S. Rao; Ralph M. Garruto; Muralidhar L. Hegde
• Keywords: Gene knockin

Abstract TDP-43 mislocalization and aggregation are key pathological features of amyotrophic lateral sclerosis (ALS)- frontotemporal dementia (FTD). However, existing transgenic hTDP-43 WT or ∆NLS-overexpression animal models primarily focus on late-stage proteinopathy. To complement these to study the early-stage motor neuron-specific pathology during pre-symptomatic phases disease progression, we generated a new endogenous knock-in (KI) mouse model using combination CRISPR/Cas9 FLEX Cre-switch strategy for conditional expression mislocalized Tdp-43∆NLS variant Tdp-43. This is expressed either in whole body (WB) specifically neurons (MNs) two distinct models. These mice exhibit loss nuclear Tdp-43, with concomitant cytosolic accumulation targeted cells, leading increased DNA double-strand breaks (DSBs), signs inflammation, associated cellular senescence. Notably, unlike which functionally interacts Xrcc4 Ligase 4, DSB repair proteins non-homologous end-joining (NHEJ) pathway, mutant sequesters them into aggregates, exacerbating neuronal damage brain. The also myogenic degeneration hindlimb soleus muscles deficits, consistent characteristics neuron (MND). Our findings reveal progressive degenerative mechanisms expressing mutant, independent Tdp-43 overexpression other confounding factors. Thus, this unique KI model, displays molecular phenotypic proteinopathy, offers significant opportunity characterize progression MND further opens avenues developing repair-targeted approaches treating pathology-linked neurodegenerative diseases.