Hypoxia Associated Proteolytic Processing of OS-9 by the Metalloproteinase Meprin β

Figure 6

Immunoblots for OS-9 and HIF-1α in MDCK cells exposed to CoCl₂. Meprin β transfected MDCK cells and mock transfected control MDCK cells were cultured in DMEM media supplemented with 10% FBS to 90% confluence, serum-starved overnight, and exposed to 125 μM CoCl₂ for 0–3 h. Western blot analysis and optic densitometry were used to quantify the levels of HIF-1α and OS-9 in the nuclear-enriched protein fractions. Tubulin was used as a loading control. The fold-change in protein levels was calculated relative to the 0 h levels. A time-dependent decrease in OS-9 levels was observed in meprin β transfected cells, but not in mock transfected controls cells. CoCl₂ exposure induced an increase in nuclear levels of HIF-1α in both genotypes of MDCK cells. The relative OD was determined by the intensity of the protein relative to the intensity of the tubulin loading control as measured by spectrophotometry. The fold-change represents a comparison of the relative OD at each time point to the relative OD at 0 h. ; ; .