Fig. 6

The ERK1/2-STAT3 pathway is the intracellular signal of histamine/H₁R involved in enhancing cardiac differentiation. hiPSC were treated with histamine or pyrilamine on day 3 to 5 of cardiac differentiation. a–c Representative images of the protein levels of MEF2C, NKX2.5, phosphorylated β-catenin, β-catenin phosphorylated ERK, and total ERK along with the quantitative results. d hiPSC-CPCs were treated with or without the p-ERK inhibitor AS703026 on days 3–5 of differentiation. Representative immunoblots of NKX2.5, MEF2C, p-ERK, and t-ERK protein levels along with the quantitative results. e The percentages of NKX2.5⁺ cells under histamine and AS703026 treatment were analyzed by FACS. f The protein levels of MEF2C, NKX2.5, p-ERK, ERK, p-STAT3, and STAT3 along with the quantitative results. g Human iPSC-CPCs were treated with or without p-ERK inhibitor AS703026 on days 3–5 of differentiation. Representative immunoblots of p-ERK, t-ERK, p-STAT3, and STAT3 protein levels are shown along with the quantitative results. h The protein levels of cardiac genes (NKX2.5, GATA4) on day 5 post-treatment with histamine, pyrilamine, and p-STAT3 inhibitor C188-9 along with the quantitative results. i The percentages of NKX2.5-positive cells were identified by FACS. Representative univariate histograms and quantitative data are shown. Data are expressed as the mean ± SEM. *p < 0.05, **p < 0.01 vs control, ^#p < 0.05 vs His (n = 3 for each group)