Figure 4
From: Sirtuin 5 depletion impairs mitochondrial function in human proximal tubular epithelial cells
SIRT5-knockdown affects OPA1 processing by OMA1 and YME1L. hPTECs were transfected with siRNA against SIRT5 or non-targeting siRNA control. Seventy-two hours post-transfection cells were exposed to 6 h OND (1%O2 + HBSS) or normoxia and complete medium (21%O2 + CM). (A) WBs showing protein levels of OPA1 (five isoforms: L1, L2, S1–3) and the OPA1 processing proteases, OMA1 (ATP-independent) and YME1L (ATP-dependent). Whole WBs shown in supplementary file (Supplementary Fig. S8f) (B) Scatter plots showing densitometric quantitation of long (l)-OPA1, short (s)-OPA1, OMA1 and YME1L. Data are from three to four independent experiments with n = 3 replicates/group. Tubulin was used as loading controls. ImageJ was used for densitometric analysis. To determine statistical significance a two-way ANOVA was carried out followed by Tukey’s post hoc test to normalize for multiple comparisons. Data are mean ± SD. *p < 0.05, **p < 0.01, and ***p < 0.001. (C) Schematic of the proposed model of SIRT5 RNAi-induced l-OPA1 processing by OMA1 and YME1L. In control RNAi-transfected cells, l-OPA1 processing is limited due to the inhibitory effect of YME1L on OMA1. SIRT5 RNAi induced OMA1-mediated degradation of YME1L resulting in increased l-OPA1 processing.
