P21 deficiency delays regeneration of skeletal muscular tissue

• Published in: PloS one 2015-05, Vol.10 (5), p.e0125765-e0125765
• Main Authors: Chinzei, Nobuaki, Hayashi, Shinya, Ueha, Takeshi, Fujishiro, Takaaki, Kanzaki, Noriyuki, Hashimoto, Shingo, Sakata, Shuhei, Kihara, Shinsuke, Haneda, Masahiko, Sakai, Yoshitada, Kuroda, Ryosuke, Kurosaka, Masahiro
• Format: Article
• Language: English
• Subjects: Animals; Antigens, Differentiation - metabolism; Arthritis; Bone surgery; Bupivacaine; Care and treatment; Cell cycle; Cell Membrane - metabolism; Cell proliferation; Cyclin D1; Cyclin D1 - genetics; Cyclin-dependent kinase inhibitor p21; Cyclin-Dependent Kinase Inhibitor p21 - deficiency; Cyclin-Dependent Kinase Inhibitor p21 - genetics; Cyclin-Dependent Kinase Inhibitor p21 - metabolism; Cyclin-dependent kinases; Deoxyribonucleic acid; Development and progression; Differentiation; DNA; Gene expression; Immune response; Immune system; Immunofluorescence; Immunohistochemistry; Injuries; Ki-67 Antigen - metabolism; Laboratory animals; Medicine; Mice; Mice, Knockout; Muscle Development - genetics; Muscle recovery; Muscle, Skeletal - anatomy & histology; Muscle, Skeletal - cytology; Muscle, Skeletal - injuries; Muscle, Skeletal - physiology; Muscles; Musculoskeletal system; MyoD protein; Myogenesis; Myogenin; Orthopedics; Proliferating cell nuclear antigen; Proliferating Cell Nuclear Antigen - metabolism; Regeneration; Regeneration - genetics; RNA, Messenger - genetics; Rodents; Skeletal muscle; Sports injuries; Tissue engineering; University graduates; Wound Healing - genetics
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0125765

The potential relationship between cell cycle checkpoint control and tissue regeneration has been indicated. Despite considerable research being focused on the relationship between p21 and myogenesis, p21 function in skeletal muscle regeneration remains unclear. To clarify this, muscle injury model was recreated by intramuscular injection of bupivacaine hydrochloride in the soleus of p21 knockout (KO) mice and wild type (WT) mice. The mice were sacrificed at 3, 14, and 28 days post-operation. The results of hematoxylin-eosin staining and immunofluorescence of muscle membrane indicated that muscle regeneration was delayed in p21 KO mice. Cyclin D1 mRNA expression and both Ki-67 and PCNA immunohistochemistry suggested that p21 deficiency increased cell cycle and muscle cell proliferation. F4/80 immunohistochemistry also suggested the increase of immune response in p21 KO mice. On the other hand, both the mRNA expression and western blot analysis of MyoD, myogenin, and Pax7 indicated that muscular differentiation was delayed in p21KO mice. Considering these results, we confirmed that muscle injury causes an increase in cell proliferation. However, muscle differentiation in p21 KO mice was inhibited due to the low expression of muscular synthesis genes, leading to a delay in the muscular regeneration. Thus, we conclude that p21 plays an important role in the in vivo healing process in muscular injury.