Figure 1

OxLDL-mediated activation of CD36 repressed Hsp70 expression. (A) U937 cells were incubated in SFM in the absence or presence of varying concentrations (10-80 µg/ml) of OxLDL for 8 h. Expression levels of Hsp70 and Hsp27 protein were evaluated by Western blot analysis. Results were replicated in three independent experiments. Relative expression levels of Hsp70 are shown as relative intensity of bands measured with a densitometer. Results shown in the lower panel are values relative to the Hsp70 expression level of untreated controls, designated as 100%. (B) CD36ΔN, ΔC, or ΔN/C construct plasmids, having deletions in the N-terminal, C-terminal cytoplasmic domain, or both cytoplasmic domains of CD36, respectively, were transiently transfected into HEK293T cells. Cell surface expression was then verified by flow cytometry using anti-CD36 mAb. (C) U937 mock-transfectants or dominant negative CD36-transfectants were incubated in 1 ml of SFM in the presence of 80 µg of normal LDL, OxLDL or heat-shocked for 20 min at 42℃. After 8 h, expression levels of Hsp70 protein were evaluated by Western blot (WB) analysis. (D) U937 mock transfectants or CD36 ΔN/C transfectants were treated with 1 µM 15d-PGJ₂, 5 µM ciglitazone (Cig), and 5 µM troglitazone (Trog) for 8 h. Expression levels of Hsp70 protein were evaluated by Western blot analysis.