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. Author manuscript; available in PMC: 2025 Aug 22.
Published in final edited form as: J Mol Cell Cardiol. 2025 Jul 29;207:13–23. doi: 10.1016/j.yjmcc.2025.07.017

Fig. 2.

Fig. 2.

Defective STAT3 signaling in Jak1-deleted cardiomyocytes. (A) Experimental assessment of JAK-STAT signaling in Jak1-deleted cardiomyocytes. Adult ventricular cardiomyocytes (ACMs) were isolated from male and female control (Jak1fl/fl) or Jak1-deleted (Jak1cKO) hearts at 2 months of age and treated with vehicle or oncostatin-M (OSM, 10 ng/mL) for 30 min before harvesting for Western blotting or fixing for immunocytochemistry to assess STAT3 phosphorylation and nuclear translocation, respectively, or for 16 h to assess gene expression. (B) Western blotting and quantification of (C) STAT3 phosphorylation at Tyr-705 normalized to total STAT3 and (D) total STAT3 protein normalized to Gapdh in control Jak1fl/fl or Jak1cKO ACMs with or without OSM treatment. n = 3. (E) Stat3 mRNA levels were quantified by qPCR in ACMs isolated from Jak1fl/fl or Jak1cKO hearts. n = 4. (F) Representative images of immunostaining for endogenous STAT3 (red) in control (Jak1fl/fl) or Jak1-deleted (Jak1cKO) ACMs with or without OSM treatment. Nuclei were stained blue with DAPI. Scale bar = 20 μm. (G) Relative Manders coefficients for colocalization of STAT3 with nuclear DAPI signal in ACMs of the indicated genotype and treatment. n = 3 independent experiments with 35–60 ACMs analyzed per biological replicate. Data are presented as the mean value ± the standard error of the mean. **P < 0.01, ***P < 0.001, ****P < 0.0001, ns, not significant, two-way ANOVA with post-hoc Tukey’s multiple comparisons test. Also see Supplemental Fig. S1.