Amino-terminally truncated desmin rescues fusion of des(-/-) myoblasts but negatively affects cardiomyogenesis and smooth muscle development.

Desmin fulfils important functions in maintenance of muscle cells and mutations in the desmin gene have been linked to a variety of myopathies. To ascertain the role of desmin's amino-terminal domain in muscle cells we generated embryonic stem cells constitutively expressing desmin(Delta1-48) in a null background and investigated muscle cell development in vitro. Desmin(Delta1-48) lacking the first 48 amino acid residues promotes fusion of myoblasts, rescues myogenesis and down-regulates vimentin expression in embryoid bodies, but hampers cardiomyogenesis and blocks smooth muscle development. These results demonstrate that desmin's amino-terminus has different roles in skeletal, cardiac, and smooth muscle cell development and function.