Fig. 8: HNRNPD-mediated chondrocyte senescence occurs in a FOXM1-dependent manner.

A, B Elevated FOXM1 levels closely associated with the progression of OA. Immunofluorescence analysis of FOXM1 in the cartilage surface from sham or control and OA model rat (scale bars; up: 1200 µm, down: 30 µm) or OA patient (scale bars; up: 240 µm, down: 40 µm). C The ratios of immunoreactive cells of FOXM1 were analyzed (n = 5). D The representative TEM images of rat synovium. Red arrowheads indicate mitochondrial structure (scale bars; up: 1 µm, down: 500 nm). E Immunofluorescence with antibodies to FOXM1 in articular cartilage from the DMM-induced OA rats with rAAV-HNRNPD treatment at 10 weeks post-surgery (n = 5, scale bars; up: 1200 µm, down: 30 µm). F The ratios of FOXM1 immunoreactive cells were quantified in articular cartilage according to immunofluorescence. G The protein expression of FOXM1 and HNRNPD was assessed via western blotting with tubulin as a loading control. H The ratios of FOXM1 and HNRNPD to tubulin were analyzed (n = 3). I Co-IP assay between HNRNPD and FOXM1 was performed. J The protein expressions of P16INK4A, P21, P53, Bcl-2, and Tom 20 were assessed via western blotting with tubulin as a loading control. K The ratios of P16INK4A, P21, P53, Bcl-2, and Tom 20 to tubulin were analyzed (n = 3). L, M The RIP analysis was performed to verify the correlation of HNRNPD and FOXM1 (n = 3). N The unique hydrophobic cavity of FOXM1 was large enough to bind the hydrophobic surface of HNRNPD. The hydrophobic surface of HNRNPD binds the FOXM1 with a binding energy of −53.88 kcal/mol. Data were expressed as mean ± SD. ^*P < 0.05 and ^***P < 0.001 vs. control, sham-operated group or input group; ^#P < 0.05 and ^##P < 0.01 vs. IL-1β or DMM induction group; ^&P < 0.05 and ^&&&P < 0.001 vs. IL-1β + HNRNPD group.