Table 1.
Comparison of muscle weight/body weight.
Fig 1.
Histological analysis of muscle tissues control, 3, 14, and 28 days post-operation hematoxylin-eosin (HE) staining.
WT: wild type, KO: knockout. (A) Muscle tissues at control and 3 days post-operation, (B) Muscle tissues at 14 and 28 days post-operation. (Scale bar = 50μm). (A and B) The injured muscle was almost recovered 14 days after injury in WT group, but not in the p21 KO group.
Fig 2.
Immunofluorescence analysis of muscle basement membrane and plasma membrane.
The expression of DAPI, laminin, and dystrophin was examined in wild-type (WT; upper panel) and p21 knockout (KO; lower panel) mice. (A) Expression in control, (B) Expression in 3 days, (C) Expression in 14 days, and (D) Expression in 28 days post-operation. (Scale bar = 50μm). (E) Quantification of laminin expression, (F) Quantification of dystrophin expression. (A-F) The injured membrane structure was almost repaired 14 days after injury in WT group, but not in the p21 KO group (p < 0.05).
Fig 3.
Relative expression of Cyclin D1 mRNA (expressed in the logarithmic scale).
WT: wild type, KO: knockout. Cyclin D1 expression levels were significantly higher in p21 KO group than in WT group, through the 28 days post-injury.
Fig 4.
Ki-67 expression after muscular injury.
(A) Immunohistochemistry of Ki-67, (B) Quantitative analysis of Ki-67. (A and B) Ki-67 expression levels in WT and p21KO mice were significantly different at control and 3 days after injury (p < 0.05). Ki-67 expression in p21KO mice at 3 days after injury was the highest (p < 0.05).
Fig 5.
PCNA and F4/80 immunohistochemical expression after muscular injury.
WT: wild type, KO: knockout. (A) Immunohistochemistry of PCNA. (Scale bar = 50μm), (B) Quantitative analysis of PCNA-positive cells, (C) Immunohistochemistry of F4/80. (Scale bar = 50μm), (D) Quantitative analysis of F4/80-positive cells. (B and D) Both PCNA and F4/80 expression in p21KO mice at 3 days after injury were the highest (p < 0.05).
Fig 6.
mRNA expression profiles of myogenic markers.
The relative mRNA expression of (A) MyoD, (B) myogenin, and (C) Pax7 was determined in wild-type (WT) and p21 knockout (KO) mice using the relative gene expression level at 0 day post-operation as control. (A-C) The mRNA expression of MyoD, myogenin, and Pax7 peaked on day 3 in WT mice and on day 14 for MyoD and myogenin in KO mice. The peaks for WT were observed to be stronger than those for KO mice.
Fig 7.
Western blot analysis of myogenic differentiation-related proteins.
WT: wild type, KO: knockout. The expression levels of MyoD, myogenin, and Pax7 was increased 3 days after injury in WT mice, but not in p21KO mice.