TMOD1 is an actin-capping protein that blocks elongation and depolymerization of actin filaments at the pointed end by binding to tropomyosin 1. This regulation of actin filament length is essential for sarcomere organization and muscle function, with TMOD1 working in complex with other regulatory proteins like FLII to maintain proper thin filament geometry 2. Pathogenic TMOD1 mutations cause childhood-onset cardiomyopathy through compromised filament length regulation. The R189W variant demonstrates weakened pointed-end capping activity, resulting in abnormally elongated thin filaments and impaired contractile dynamics 3. Beyond cardiac muscle, TMOD1 participates in neuronal actin dynamics, contributing to neurite outgrowth and synaptic plasticity 4, and regulates kidney water homeostasis through tubule-specific actin organization 5. In immune responses, TMOD1 negatively regulates TLR4 endocytosis in macrophages by modulating actin cytoskeleton reorganization and membrane tension, thereby exacerbating inflammatory responses 6. Clinically, elevated TMOD1 expression correlates with enhanced cancer progression, including regional lymph node metastasis in oral squamous cell carcinoma 7 and acute myeloid leukemia cell proliferation 8, establishing TMOD1 as both a disease biomarker and potential therapeutic target.