Activation of SMAD2 by recombinant GDF15 was caused by TGF-β.

Abstract

<p><i>In vitro</i> differentiated macrophages (A) or THP-1 cells (B) were treated with increasing doses of recombinant GDF15 (R&D Systems, Lot# EHF0914051) or TGF-β for four hours. C. INA-6 cells were treated with increasing doses of TGF-β for 1 hour. D. INA-6 cells were treated for 1 hour with the indicated doses of TGF-β, GDF15 (Abcam) or GDF15 (Peprotech). E. INA-6 cells were treated for 1 hour with GDF15 (Peprotech) or TGF-β pre-treated with neutralizing antibodies targeting GDF15 or TGF-β. For C-E, the experiments were performed in RPMI with 0.1% bovine serum albumin (BSA). Phosphorylation of SMAD2 was determined using immunoblotting and GAPDH, ERK1/2 or SMAD2/3 antibodies were used as loading controls. All experiments were performed at least three times, except for D and E, which were performed twice.</p