Trans-cellular desmin-lamin B intermediate filament network in cardiac myocytes

Area of Science:

• Cardiovascular Biology
• Cell Biology
• Biophysics

Background:

• Myocardial hypertrophy is linked to excessive cardiac muscle stretch.
• Cardiac myocyte and nuclear shape are coupled, suggesting mechanical forces influence nuclear structure.
• Cytoskeletal elements likely mediate the connection between cell and nuclear shape.

Purpose of the Study:

• To investigate the role of cytoskeletal and nucleoskeletal intermediate filaments in mammalian cardiac myocytes.
• To examine the topological associations of desmin and lamin B filaments with intracellular structures.
• To test the hypothesis that nuclear deformation due to stretch contributes to hypertrophy.

Main Methods:

• Immunogold labeling was used to visualize desmin and lamin B filaments.
• The study focused on topological associations within mammalian cardiac myocytes.
• Intermediate filament networks were examined in relation to cellular and nuclear structures.

Main Results:

• Desmin filaments form a sarcoplasmic network from the sarcolemma to the nuclear surface.
• Desmin filaments associate with Z-discs, mitochondria, and the sarcolemma.
• Desmin filaments extend towards nuclear pores, where lamin B filaments are located, suggesting a physical link.

Conclusions:

• Desmin and lamin B filaments form a network connecting the cell surface to the nucleus.
• This network may physically link cytoskeletal deformation to nuclear shape changes.
• The desmin-lamin B interaction at the nuclear pore could be a key mechanism in stretch-induced nuclear remodeling and hypertrophy.