Fig. 2

Loss of Wwp2 during aging, injury or inflammation. a Human samples were classified using a modified Outer bridge scale (grade 0-IV). RNA-seq analyses of articular cartilage to compare normal cartilage (grade ≤ I) and OA cartilage (grade ≥ III). After the data were normalized, the counts of the NEDD4 family were sorted. (n = 8-10, Welch’s t test). The ages of subjects are following: normal cartilage, 37.8 ± 13.0 years-old; OA cartilage, 62.7 ± 7.5 years-old, respectively. b RT-qPCR analyses of articular cartilage to compare normal and OA cartilage (n = 8-10, Welch’s t test, normalized with GAPDH). The ages of subjects are follows: normal cartilage, 50.5 ± 11.5 years-old; OA cartilage, 62.9 ± 8.2 years-old. c–e IHC staining of WWP2 in human articular cartilage. c, d Classification of zones and representative images. Wwp2 was stained with AEC (red). e WWP2 positive cell rate (n = 7–8, Dunn test compared with Grade III). The ages of subjects are as follows: grade 0, 18.7 ± 1.7 years-old; Grade I, 44.8 ± 18.8 years-old; Grade III, 70.9 ± 20.0 years-old, respectively. f Representative images of IHC staining of Wwp2 in wild-type (WT) mouse articular cartilage, detected as green (Wwp2) and blue (DAPI, nuclei), to compare between 6-month-old and 24-month-old (aging OA). Right images are IHC staining for surgically (DMM) induced OA specimens. g Wwp2 positive cell rate (n = 5, Welch’s t test). h RT-qPCR for human and mouse articular chondrocytes stimulated with IL-1β (10 ng/ml) (n = 5 and 4, Student’s t test, normalized with GAPDH and Gapdh, respectively). Black scale bar = 1 mm. Source data are provided as a Source Data file. Data are presented as the mean ± SD