Figure 9.

CBS contributes to the suppression of mitochondrial function in Down syndrome fibroblasts. Dermal fibroblasts from a female individual with DS (Detroit 539: DSC) exhibit markedly higher CBS expression, which is, in part, localized to the mitochondria, than cells from an age-matched healthy female subject (control cells, Detroit 551: CC), shown by (A) Western blotting and (B) confocal microscopy. (C) SiRNA-mediated silencing of CBS in DSCs reduces CBS protein expression to a level comparable to the expression seen in CCs, (D) reduces the H₂S overproduction observed in DSCs as opposed to CCs (measured by the fluorescent H₂S probe AzMC) and (E) restores the proliferation of DSCs to values comparable to CCs. In addition, CBS silencing in DSCs (F) improves mitochondrial oxygen consumption rate (OCR) and (G) restores mitochondrial Complex IV activity. Western blotting for the mitochondrial protein Tom 20 served as a mitochondrial isolation quality control in (A). *, ** shows a difference between CC and DSC (* p < 0.05; ** p < 0.01); ^{#, ##} shows the effect of CBS silencing in DSCs (^# p < 0.05; ^## p < 0.01). Reproduced by permission from [90].