CELLULAR STRESS PATHWAYS AND VESICULAR TRAFFICKING DEFECTS IN HUMAN CELLULAR MODELS OF CNTNAP1-ASSOCIATED CONGENITAL HYPOMYELINATING NEUROPATHY TYPE 3

CNTNAP1-associated congenital hypomyelinating neuropathy type 3 (CHN3) is a rare autosomal recessive neurodevelopmental disorder caused by pathogenic variants in CNTNAP1, which encodes the axonal adhesion protein Caspr1. Affected individuals present with severe neonatal hypotonia, profound neurodevelopmental impairment, hypomyelination, and progressive brain and cerebellar atrophy. Despite the essential role of CNTNAP1 in myelinated axons, the cellular mechanisms underlying disease pathogenesis remain poorly understood. In this project, we use patient-derived dermal fibroblasts and induced neurons generated by direct reprogramming as human cellular models of CNTNAP1-mediated CHN3. Preliminary data show that Caspr1 is retained within the Golgi apparatus and exhibits reduced expression compared to control fibroblasts. Notably, Golgi cisternae display marked structural disorganization, suggesting impaired vesicular trafficking. In parallel, we observe alterations in the autophagic pathway, including increased LC3B and p62 accumulation, reduced lysosomal acidification, and defective autophagic flux. Based on these findings, we investigate the unfolded protein response (UPR) as a potential upstream mechanism linking ER stress, Golgi dysfunction, and autophagy impairment. Immunofluorescence analysis reveals degeneration of the endoplasmic reticulum network, evidenced by altered calnexin staining. Ongoing studies using Western blot and immunofluorescence aim to characterize UPR activation and chaperone dysregulation, alongside pharmacological screening to rescue disease-associated cellular phenotypes. Together, this work identifies convergent ER–Golgi–autophagy stress pathways in CNTNAP1-related neuropathy, providing mechanistic insight and establishing a platform for therapeutic screening in patient-specific neuronal models. In addition, this project contributes to the understanding of Caspr1-mediated mechanisms affecting to the development of the congenital hypomyelinating neuropathy type 3.