INTRODUCTION: Skeletal muscle regeneration following damage relies on proliferation and differentiation of muscle precursor cells (MPCs). We recently observed increased NF-kB activity in vascular-associated muscle resident pericytes following muscle damage in humans. We determined how altered NF-kB activity in human primary pericytes (HPPs) affects their myogenic differentiation (cell-autonomous effects), as well as proliferation and differentiation of co-cultured MPCs (non-cell-autonomous effects). METHODS: HPPs were transfected with vectors that increased or decreased NF-kB activity. Transfected HPPs were co-cultured with C2 C12 myoblasts under differentiation conditions, and HPP fusion to myotubes was measured. We also co-cultured HPPs with C2 C12 myoblasts and measured proliferation and myotube formation. RESULTS: Inhibition of NF-kB activity increased HPP fusion to C2 C12 myotubes. Moreover, enhanced NF-kB activity in HPPs suppressed differentiation and enhanced proliferation of co-cultured myoblasts. CONCLUSIONS: NF-kB activity acts cell-autonomously to inhibit HPP myogenic differentiation and non-cell-autonomously to promote MPC proliferation and suppress MPC differentiation in vitro.
INTRODUCTION: Skeletal muscle regeneration following damage relies on proliferation and differentiation of muscle precursor cells (MPCs). We recently observed increased NF-kB activity in vascular-associated muscle resident pericytes following muscle damage in humans. We determined how altered NF-kB activity in human primary pericytes (HPPs) affects their myogenic differentiation (cell-autonomous effects), as well as proliferation and differentiation of co-cultured MPCs (non-cell-autonomous effects). METHODS: HPPs were transfected with vectors that increased or decreased NF-kB activity. Transfected HPPs were co-cultured with C2 C12 myoblasts under differentiation conditions, and HPP fusion to myotubes was measured. We also co-cultured HPPs with C2 C12 myoblasts and measured proliferation and myotube formation. RESULTS: Inhibition of NF-kB activity increased HPP fusion to C2 C12 myotubes. Moreover, enhanced NF-kB activity in HPPs suppressed differentiation and enhanced proliferation of co-cultured myoblasts. CONCLUSIONS: NF-kB activity acts cell-autonomously to inhibit HPP myogenic differentiation and non-cell-autonomously to promote MPC proliferation and suppress MPC differentiation in vitro.