Leiomodin-1

Leiomodin-1 (LMOD1) is an actin nucleation factor essential for proper contractility of visceral smooth muscle cells (UniProt: P29536). It mediates the initiation of actin filament polymerization, a critical process for muscle contraction dynamics. The protein is 600 amino acids in length with a molecular mass of approximately 67 kDa.

LMOD1 is primarily characterized in the context of smooth muscle physiology and developmental biology. Mutations in LMOD1 cause megacystis-microcolon-intestinal hypoperistalsis syndrome 3 (MMIHS3; MIM 619362), an autosomal recessive congenital visceral myopathy affecting smooth muscle contractility in the bladder and intestine, with typically fatal outcomes in affected infants (UniProt: P29536).

In Alzheimer's Disease, LMOD1 is significantly upregulated in post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics), with a mean log2 fold-change of 0.72 across subcellular fractions. This upregulation was detected via TMT-labeled tandem mass spectrometry analysis across four subcellular compartments, suggesting a potential role in AD-associated pathology, though the mechanistic basis remains to be elucidated.