Investigation on the relationship between the Leu224Val mutation in the gene encoding the subunit 5 of the chaperonin CCT with a rare genetic neuromyopathy, and study of the potential oxidative stress alterations associated with the CCT5 subunit

Abstract This PhD thesis investigates the association between the mutation in the CCT5 subunit of the chaperonin-containing TCP-1 (CCT) complex and a rare genetic distal neuromyopathy. The CCT complex, composed of two stacked rings each constituted by eight subunits including the submit number 5 (CCT5), plays a crucial role in protein folding and cellular proteostasis. Distal neuromyopathies are a group of disorders characterized by degeneration of peripheral nerves, resulting in sensory disturbances, motor deficits, muscular atrophy and progressive weakness in the distal extremities. Through a comprehensive literature review, this thesis explores the current understanding of the chaperone system in the context of motor neuromyopathy, focusing on the molecular basis and underlying pathogenic mechanisms. Additionally, it delves into the role of the CCT complex and its subunits in protein folding, emphasizing the importance of proper chaperone function in maintaining cellular homeostasis.The thesis outlines the research methodology employed to investigate rare genetic motor neuromyopathy. This includes patient biopsy acquisition, histological and molecular analysis, and characterization of the associated alterations with identified mutation and patient phenotype. The study assessed the effects of the CCT5 mutation on protein expression and distribution pattern, sarcomere structure and cellular morphology in skeletal muscle tissue. Further, it also delved into cellular model featuring mutated CCT5 to further elucidate the role of CCT5 in cellular pathophysiology. Specifically, we employed a cellular model harboring induced oxidative stress to explore the cellular responses and uncover potential alterations in cellular pathways and functions associated with CCT5. The results obtained from this study provide novel insights into the possible role of the mutated CCT5 subunit in the pathogenesis of rare genetic neuromyopathy. Through histological and molecular analysis we show that the specific mutation in the CCT5 gene has affected the protein expression and localization within skeletal muscle tissue resulting in the accumulation of misfolded proteins. Furthermore, the morphology of the myofibrils has been affected. It may result in the alteration of the sarcomere function and other chaperones' activity. These molecular and cellular changes may contribute to the development and progression of genetic neuromyopathy.Moreover, our employed cellular model of induced oxidative stress uncovered potential alterations in cellular pathways associated with CCT5. These findings offer valuable insights into the functional consequences of CCT5 mutations and their involvement in cellular responses to oxidative stress, contributing to a deeper understanding of CCT5's role in cellular pathophysiology.Overall, this PhD thesis may suggest the potential contribution of the mutated CCT5 subunit of the CCT complex in a rare genetic neuromyopathy. The research methodology employed allows for a comprehensive understanding of the pathogenic mechanisms underlying this disorder, which may pave the way for the development of targeted therapeutic approaches aimed at alleviating the symptoms and slowing the progression of this devasting disorder. By elucidating the role of the mutated CCT5 subunit in protein folding defects and cellular dysfunction, potential targets for interventions and therapeutic strategies can be identified.The study's findings not only contribute to the understanding of this specific rare genetic distal neuromyopathy but also shed light on the broader role of chaperonin CCT complex in cells.