title: Dual roles of palladin protein in in vitro myogenesis: inhibition of early induction but promotion of myotube maturation.
abstract: Palladin is a microfilament-associated phosphoprotein whose function in skeletal muscle has rarely been studied. Therefore, we investigate whether myogenesis is influenced by the depletion of palladin expression known to interfere with the actin cytoskeleton dynamic required for skeletal muscle differentiation. The inhibition of palladin in C2C12 myoblasts leads to precocious myogenic differentiation with a concomitant reduction in cell apoptosis. This premature myogenesis is caused, in part, by an accelerated induction of p21, myogenin, and myosin heavy chain, suggesting that palladin acts as a negative regulator in early differentiation phases. Paradoxically, palladin-knockdown myoblasts are unable to differentiate terminally, despite their ability to perform some initial steps of differentiation. Cells with attenuated palladin expression form thinner myotubes with fewer myonuclei compared to those of the control. It is noteworthy that a negative regulator of myogenesis, myostatin, is activated in palladin-deficient myotubes, suggesting the palladin-mediated impairment of late-stage myogenesis. Additionally, overexpression of 140-kDa palladin inhibits myoblast differentiation while 200-kDa and 90-kDa palladin-overexpressed cells display an enhanced differentiation rate. Together, our data suggest that palladin might have both positive and negative roles in maintaining the proper skeletal myogenic differentiation in vitro.
authors: Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan; Center for Cell Dynamics, National Cheng Kung University, Tainan, Taiwan.
authors: Ngoc-Uyen-Nhi
authors: NU
authors: Nguyen
authors: Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan; University Center for Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan; Center for Cell Dynamics, National Cheng Kung University, Tainan, Taiwan.
authors: Hao-Ven
authors: HV
authors: Wang
mesh_terms: D000818:Animals; D017209:Apoptosis; D053179:Caspase 7 / Q000378:metabolism; D002454:Cell Differentiation; D002460:Cell Line; D002465:Cell Movement; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D024510:Muscle Development; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D032446:Myoblasts / Q000166:cytology / Q000378:metabolism; D018008:Myogenin / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000378:metabolism; D055435:Myostatin / Q000378:metabolism; D010750:Phosphoproteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; D003598:Cytoskeletal Proteins; D018008:Myogenin; D055435:Myostatin; D010750:Phosphoproteins; D020033:Protein Isoforms; D034741:RNA, Small Interfering; C485873:palladin protein, mouse; D053179:Caspase 7; D018995:Myosin Heavy Chains