Figure 8. PZR tyrosyl phosphorylation induces autocrine/paracrine-mediated IL-6 secretion to activate STAT3 phosphorylation and Col1a expression.

(A) WT (Mpzl1^+/+) and PZR^Y242F (Mpzl1^Y242F/Y242F+) MEFs were serum-starved and stimulated with 5 μg/mL of ConA for 4 hours, and medium was collected (conditioned medium, CM). CM from WT MEFs (CM-WT) or PZR^Y242F MEFs (CM-PZR^Y242F) was applied to PZR^Y242F MEFs for 2 hours. Whole-cell lysates were immunoblotted with anti–p-STAT3 (Y702) and -STAT3 antibodies. Total RNA was isolated and the relative expression of Col1a was measured by qRT-PCR (n = 3). (B) CM-WT was incubated with either mock IgG or anti–IL-6 neutralizing antibody and then incubated onto PZR^Y242F MEFs for 2 hours. Whole-cell lysates were immunoblotted with anti–p-STAT3 (Y702) and -STAT3 antibodies. Total RNA was isolated and the relative expression of Col1a was measured by qRT-PCR (n = 3). (C) Schematic representation of PZR/SHP2 signaling in NSML. All data represent mean ± SEM. Statistical significance was analyzed with 1-way ANOVA with 2-stage linear step-up procedure of Benjamini, Krieger, and Yekutieli correction for multiple comparisons.