Fig. 2.

Decreased mitochondrial biogenesis with knockdown of mitochondrial transcriptional factor A (TFAM). (a) Expression of mitochondrial respiratory complexes I–IV and ATP synthase (complex V) in normal and OA chondrocytes transfected with TFAM siRNA or control siRNA, as determined by Western blotting. Results are representative of 5 independent experiments using five different pairs of normal donors and donors with OA. (b) and (c) Mitochondrial DNA (mtDNA) content (b) and mitochondrial mass (c) in human knee chondrocytes (passage 1) from both normal donors and donors with osteoarthritis (OA) (grade IV) transfected with TFAM siRNA and control (Ctrl) siRNA, as determined by the mtDNA-encoded cytochrome c oxidase subunit I or II (COX1 or COX2): nucleus-encoded 18S ribosomal DNA (18S rDNA) ratio. Values are the mean ± SD and are representative of three independent experiments performed using chondrocytes from three different donors. (This figure is reproduced from ref. 6 with permission from John Wiley & Sons)