Calcium-regulated mitochondria remodeling by Myo19 is required for filopodia tip-extension and supports collective cell migration

Mitochondria dynamically remodel their morphology and positioning to meet cellular demands. We previously demonstrated that Myo19-dependent mitochondrial motility is coupled to filopodia formation under stress. Here, we investigate how epidermal growth factor (EGF) remodels mitochondrial behavior in A431 carcinoma cells, suppressing proliferation while promoting calcium signaling and cytoskeletal remodeling. EGF stimulation promotes mitochondrial fission, generating smaller, highly mobile mitochondria that are actively trafficked to the cellular leading edge and filopodia. Mitochondrial motility to filopodia requires cooperation between two motor proteins: Kif5B (microtubule-based) and Myo19 (actin-based). EGF stimulation elevates cytosolic calcium, impairing Kif5B-mediated motility while enhancing Myo19 activity, shifting mitochondrial trafficking predominantly toward the actin network. Disrupting mitochondrial fission or lowering intracellular calcium severely impairs mitochondrial motility and significantly reduces filopodia formation. Live-cell imaging reveals coordinated mitochondrial motility, involving sequential fission events, motor protein switching, and localized calcium signaling at protrusion sites. To examine Myo19 function within a broader cellular context, we performed a 2D wound-healing assay in Myo19-KD cell lines to measure Myo19’s impact on collective cell migration. We found that Myo19 depletion severely impairs wound-healing closure in several cell lines, suggesting that Myo19-driven mitochondrial network remodeling at the leading edge and filopodia is important for cell migration. Our findings illuminate a mechanism linking mitochondrial dynamics and motility to actin cytoskeletal remodeling and cellular protrusions formation. Collectively, Myo19’s strong link to cell migration opens the door to developing new therapeutic strategies that target mitochondrial-cytoskeletal interactions during metastasis.