Translocation of endogenous Bax during UV-induced apoptosis is not inhibited by PECAM-1. HEK 293 T cells (107 cells) were transfected with 10 μg pcDNA3-control vector (control and UV) or pcDNA3 encoding wild-type PECAM-1 (UV+PECAM-1). One day following transfection, cells were treated with 200 J/m2 UV-C irradiation. Cells were collected 24 hours later, and subcellular fractionation was performed as described in “Materials and methods” to yield soluble cytosol, nuclei, and heavy membranes (HM) containing mitochondria. Lactate dehydrogenase (LDH), proliferating cell nuclear antigen (PCNA), and FoF1 ATP synthase subunit α (F1α) were used as markers for cytosolic, nuclear, and mitochondrial fractions, respectively. Bax is found predominantly in the cytosol in untreated, vector-transfected control 293 cells but translocates to the heavy membrane fraction following treatment with UV irradiation. PECAM-1 transfection does not inhibit Bax translocation (uppermost right lane) but still suppresses apoptosis by more than 50% (Table 1).
