Myosin-9

Myosin-9 (MYH9) is a cellular myosin heavy chain involved in cytokinesis, cell shape maintenance, and specialized cellular functions including secretion and membrane capping. It plays important roles in cell motility, cytoskeleton reorganization, focal contact formation, and lamellipodial retraction during cell spreading (UniProt: P35579). The protein is also known to act as a receptor for herpes simplex virus 1 envelope glycoprotein.

MYH9 mutations are associated with macrothrombocytopenia and granulocyte inclusions (MATINS) and autosomal dominant deafness (DFNA17), both involving disrupted cellular dynamics and structural integrity (UniProt: P35579). The protein's roles in actin dynamics and cell motility implicate it in processes relevant to neuronal function and organization.

In Alzheimer's disease, Myosin-9 is significantly upregulated in post-mortem human AD brain tissue compared to age-matched controls, with a mean log2 fold-change of +0.28 (Chaparral AD proteomics). This increase was measured across subcellular fractions in TMT-labeled quantitative proteomics analysis, suggesting potential dysregulation of cytoskeletal dynamics in AD pathophysiology.