Introduction:
Desmin, a specialized protein found in muscle tissue, plays a crucial role in the formation of the intermediate filament (IF) network and is present in cardiac, skeletal, and smooth muscles. The C-terminal tail domain of Desmin, identified as the nuclear Lamin B binding domain, is essential for its function. Disruption of this interaction has been linked to myofibrillar myopathy-1, a condition characterized by unclear pathophysiology. In cases lacking definitive Desminopathy pathology, the inability of mutant Desmin to interact with lamin B, coupled with defects in nuclear mechanotransduction, may contribute to the development of this condition in affected individuals. This study aims to investigate the nuclear localization of Desmin in skeletal muscle cells, assess the impact of mechanical strain on Desmin's nuclear import, and uncover potential new functions beyond its structural role.

Methods:

• Immunofluorescence Co-staining (IF): Immunofluorescence was used to demonstrate the colocalization of Desmin with nuclear markers DAPI and Lamin B. The effect of mechanical strain on this colocalization was also examined.


• Immunoblotting: Western blot analysis was conducted to confirm the presence of Desmin in the nuclear fraction, further validating its localization.


• Proteomic and Transcriptomic Analysis: Proteomic data were integrated with an extended transcriptomic dataset derived from wild-type and Desmin knockout (KO) mice to investigate Desmin's potential role in mRNA stability and its interaction with RNA-binding proteins.


• Actinomycin-D Chase Assay: The stability of mRNA for MyoD and Myogenin (markers of myogenic differentiation) was assessed using the Actinomycin-D chase assay in Desmin knockdown cells.

Results:

• Desmin Colocalization: Immunofluorescence results showed that Desmin colocalized with nuclear markers DAPI and Lamin B. This colocalization was notably increased under conditions of mechanical strain.


• Nuclear Fraction Validation: Immunoblotting confirmed the presence of Desmin in the nuclear fraction, supporting the immunofluorescence findings.


• mRNA Stability Role: The proteomic and transcriptomic analyses revealed that Desmin plays a role in mRNA stability by interacting with RNA-binding proteins.


• MyoD and Myogenin mRNA Stability: The Actinomycin-D chase assay confirmed that Desmin knockdown affects the stability of MyoD and Myogenin mRNA, further supporting its role in myogenic differentiation.

Conclusion:
These findings highlight Desmin's impact on the transcript fate of myogenic factors regulatory and gene expression through post-transcriptional processes.

 

This comprehensive approach contributes valuable insights to the ongoing scientific discussions about nucleocytoplasmic communication pathways within cells. This work was supported by The Scientific and Technological Research Council of Turkey (123Z114).