Fig. 2
From: Parkin targets HIF-1α for ubiquitination and degradation to inhibit breast tumor progression
Parkin negatively regulates HIF-1α protein levels in cells. a Myc-Parkin expression reduced levels of exogenous HA-HIF-1α protein in MCF7 and MDA-MB231 cells. Cells were transfected with the HA-HIF-1α vector together with varying amounts of Myc-Parkin or empty control (Con) vectors. b Ectopic Myc-Parkin expression reduced levels of endogenous HIF-1α protein in different human breast cells. c Knockdown of endogenous Parkin by 2 different shRNA vectors increased levels of endogenous HIF-1α protein in different human breast cells. d HIF-1α protein levels were higher in Parkin−/− MEFs compared with Parkin + / + MEFs. e Myc-Parkin expression downregulated HIF-1α protein levels in MCF7 cells under both normoxic (20% O2) and hypoxic (1% O2) conditions. f Knockdown of Parkin increased HIF-1α protein levels in MCF7 cells under both normoxic and hypoxic conditions. g Higher HIF-1α protein levels in Parkin−/− MEFs than Parkin + / + MEFs under both normoxic and hypoxic conditions. h Myc-Parkin expression reduced the levels of endogenous HIF-1α protein in both VHL-deficient RCC4 cells and VHL-proficient RCC4/VHL cells. i Knockdown of Parkin increased HIF-1α protein levels in both RCC4 and RCC4/VHL cells. j Knockdown of Parkin in MCF7 cells with VHL knockdown further increased HIF-1α protein levels
