Investigation of mechanoregulatory role of desmin protein

Desmin, a muscle-specific protein, shapes the network of intermediate filaments (IFs) in different types of muscles, such as cardiac, skeletal, and smooth muscles. Recent studies have elucidated cytoskeletal proteins' well-defined structural and cytoplasmic functions, including Desmin. Contrary to the traditional understanding of these proteins primarily residing in the cytoplasm, emerging evidence suggests their subcellular translocation into the nucleus, where they can carry out crucial functions. In the C-terminal tail domain of Desmin, there exists a binding domain for Lamin B, which is localized in the nucleus. The dysfunction of this domain has been associated with myofibrillar myopathy-1. However, despite its impact on mechanotransduction pathways and the nuclear localization of Desmin in affected individuals, there is no identified pathophysiology for this condition. This thesis aims to contribute to understanding the nuclear localization of Desmin under mechanical stress conditions and investigate the role of Desmin in regulatory pathways. Immunofluorescence co-staining analyses demonstrated the concurrent colocalization of Desmin with the nuclear markers DAPI and Lamin B. This colocalization was notably higher under mechanical strain and showed a strain-dependent manner. Immunoblotting confirmed Desmin's presence in the nuclear fraction, providing additional validation. Proteomic integration with an extended transcriptomic dataset from wild-type and Desmin KO mice revealed Desmin's role in the post-transcriptional process, affecting RNA binding proteins. Actinomycin-D (Act-D) chase assay for MyoD and Myogenin, two myogenic differentiation markers, in Desmin knockdown cells, confirmed this role. The investigation into the myogenic potency and morphological characteristics of myotubes in Desmin knockdown cells revealed defects in morphological parameters associated with myotube maturation and commitment in myogenesis.