Induction of TGF-β1 Synthesis by Macrophages in Response to Apoptotic Cells Requires Activation of the Scavenger Receptor CD36
Figure 4
Both Lyn kinase and ERK1/2 MAPK are required for TGF-β1 synthesis induced by activating anti-CD36 mIgA.
A, RAWTβRII cells were stimulated with activating anti-CD36 mIgA (2 µg/ml) for the times indicated. Total cell lysates were immunoblotted for phospho-Lyn kinase and the band density was normalized to total Lyn kinase. B, RAWTβRII cells were pretreated with the src-family kinase inhibitor PP2 (0.001 to 100 µM) for 2 h and then stimulated with anti-CD36 mIgA (2 µg/ml). After 6 h, TGF-β1 mRNA expression was analyzed by real-time PCR and normalized to GAPDH. Total TGF-β1 in the conditioned medium was analyzed by ELISA after 18 h. C, A time course of ERK1/2 phosphorylation was assessed by Western blotting in RAWTβRII cells treated with anti-CD36 mIgA (2 µg/ml). Phospho-ERK1/2 band density was normalized to total ERK1/2. D, RAWTβRII cells were preincubated with MEK kinase inhibitor U0126 or inactive analogue U0124 for 2 h and then stimulated with anti-CD36 mIgA for 6 h to detect TGF-β1 mRNA expression or for 18 h to detect secreted TGF-β1 protein as in Figure 1. Values represent means ± SD of six separate experiments.