Fig. 5.

Agonist stimulation of GPR120 in Caco-2 cells increases β-arrestin-2-TAB1 (TAK1 binding protein 1) interaction and attenuates TAB1 binding to TAK1 (transforming growth factor-β-activated kinase 1). A, left: lysates of control or agonist (50 μM GW9508 or 10 μM TUG-891)-treated (30 min) Caco-2 cells, containing equal amounts of proteins, were used to IP TAB1 with anti-β-arrestin-2 antibody. IPs were subjected to SDS-PAGE and probed with anti-TAB1 antibody in immunoblotting. After being stripped with 0.2 N NaOH, blots were reprobed with anti-β-arrestin-2 antibody. Left: densitometric analysis of band intensities of TAB1/β-arrestin-2 in different groups is shown. Values are means ± SE; n = 3. *Different from control, P ≤ 0.05. B, right: Caco-2 cells with or without pretreatments with TNF-α (10 ng/ml) for 6 h were treated with the agonists [GW9508 (50 μM) or TUG-891 (10 μM)] in presence or absence of TNF-α (10 ng/ml) for 30 min. Cell lysates containing equal amounts of proteins were used to IP TAB1 with anti-TAK1 antibody. IPs were subjected to SDS-PAGE and probed with anti-TAB1 antibody in immunoblotting. After being stripped with 0.2 N NaOH, blots were reprobed with anti-TAK1 antibody. Left: densitometric analysis of band intensities of TAB1/TAK1 in different groups is shown. Values are means ± SE; n = 3. *Difference between groups: control vs. TNF-α or agonists, TNF-α vs. agonists, P ≤ 0.05.