General information on Desmin protein
Desmin is a muscle-specific protein encoded by DES gene in humans. It is a type III intermediate filament whose main role is to integrate the nuclear membrane and the Z disk in skeletal muscle cells also known as sarcomere. In skeletal muscle cells, desmin protein is essential in regulating the architecture of sarcomere. This protein is also located in cardiac and smooth muscle cells. In cardiac muscle cells, desmin is located in the Z-discs and intercalated discs. Desmin protein also is involved in in maintaining an optimal conformation of the nebulette. The latter, also located in the Z-discs of cardiac muscle cells, is essential in regulating the length of actin thin filaments.
Desmin protein consists of a conserved alpha helix rod, a non-alpha helix head which is variable and a carboxy-terminal tail. Similar to other intermediate filaments, desmin protein has no polarity when assembled. The rod region contains parallel alpha coiled coil dimers and three non-heliacal linkers. The head domain which is rich in arginine, serine and aromatic residues is important for dimer-dimer interactions. The carboxy-terminal tail, on the other hand, is responsible for desmin interactions with proteins and organelles within the cell.
Desmin protein is present early in muscle cell development and is often considered as an early marker of muscle tissue. Initially it is presented at low levels but its concentration in the cell increases as the cell is near its terminal development. In cardiac progenitor cells, desmin protein is believed to contribute as a transcriptional regulator of the NKX2-5 gene which is essential for heart formation and development. Desmin protein links mitochondria to sarcomere and is believed to be involved in regulating respiration rate in muscle cells. Desmin protein expression level is upregulated in human heart failure. It has been suggested that this a defense mechanism in attempt to maintain normal sarcomere organization amid the disease.