Fig. 6: Activation of GPR81 induces WAT browning via Gβγ–RhoA–p38 cascade.
From: Activation of GPR81 by lactate drives tumour-induced cachexia
a, Representative western blots and statistical results showing the levels of phospho-PKA substrates, phosphorylated p38 (p-p38) and UCP1 in the SVF-derived adipocytes treated with PKA inhibitor H89 (n = 4 biologically independent samples in each group). b, Body weights of mice implanted with osmotic minipumps loaded with PBS or sodium l-lactate and treated with H89 or vehicle (n = 6 for each group). c,d, Representative western blots and statistical results showing that the lactate-induced activation of p38-ATF2 and upregulation of UCP1 were blocked by inhibitor for Gαi (PTX) or Gβγ (gallein) (c) or silencing the expression of Gβ1 or Gβ2 by siRNA (d) (n = 5 biologically independent samples in each group). e, Representative images and statistical results of immunofluorescence staining of the SVF-derived adipocytes with antibodies against RhoA and rhotekin (n = 6 biologically independent samples in each group). Scale bars, 20 μm. f,g, Representative western blots and statistical results showing that knocking down the expression of RhoA or ROCK1 by siRNA (f) or treating the cells with inhibitor for p38 (SB203580) or ROCK1 (Y-27632) (g) abolished the lactate-induced activation of p38-ATF2 and upregulation of UCP1 (n = 5 biologically independent samples in each group). h,i, Injection of inhibitor for p38 (SB203580), ROCK1 (Y-27632) or Gβγ (gallein) into the inguinal fat pads in the tumour-bearing mice alleviated tumour-induced losses of body weight (h) and tissue weights (i) (n = 6 for each group). All data are presented as the mean ± s.e.m. P values were determined by one-way ANOVA with Tukey’s multiple-comparisons test (a–g and i), or two-tailed unpaired Student’s t-test comparing body weights 24 days after injection of LLC cells (h).
