The canonical Wnt/β-catenin signaling pathway upregulates carbonic anhydrase 2 via transcription factor 7-like 2 to promote cardiomyopathy in type 2 diabetic mice

Diabetic cardiomyopathy (DCM) is a major complication of diabetes mellitus. Excessive activation of the canonical Wnt/β-catenin pathway contributes to the development of cardiomyopathy in type 1 diabetes mellitus (T1DM). Transcription factor 7-like 2 (TCF7L2) is the main β-catenin partner of the TCF family in adult human hearts. In this study, we investigated the role of Wnt/β-catenin in the development of cardiomyopathy in type 2 diabetes mellitus (T2DM) by using streptozotocin (STZ)/high-fat diet (HFD)-induced diabetic mice and high glucose-stimulated neonatal rat cardiomyocytes (NRCMs) as in-vivo and in-vitro models of T2DM, respectively. Compared with the control mice, the T2DM mice exhibited increased myocardial β-catenin and TCF7L2 expression that was concentrated in the nucleus. Treatment of diabetic mice with the β-catenin/TCF7L2 bipartite inhibitor iCRT14 prevented myocardial remodeling and improved cardiac dysfunction. iCRT14 also prevented high glucose-induced hypertrophy in NRCMs, while the β-catenin stabilizer SKL2001 worsened hypertrophy. Immunoprecipitation experiments confirmed the formation of the β-catenin/TCF7L2 bipartite in the control and T2DM mouse cardiomyocytes. Moreover, carbonic anhydrase 2 (CA2) was upregulated in T2DM cardiomyocytes in vitro and in vivo. TCF7L2 overexpression upregulated CA2, while iCRT14 treatment or TCF7L2 knockdown downregulated CA2. Chromatin immunoprecipitation (ChIP) experiments revealed an increased interaction between β-catenin/TCF7L2 and the transcription initiation region of CA2 in the heart tissue of T2DM mice. CA2 knockdown ameliorated NRCM hypertrophy induced by high glucose and SKL2001. A luciferase reporter assay confirmed that CA2 is directly regulated by the β-catenin/TCF7L2 bipartite. Collectively, these results indicate that the canonical Wnt/β-catenin pathway upregulates CA2 via TCF7L2 to promote cardiomyopathy in T2DM. This research sheds new light on the pathogenesis of DCM and presents new potential therapeutic targets for this disease. Primary neonatal rat cardiomyocytes (NRCMs) were isolated from 1–2-day-old neonatal SD rats. In brief, hearts collected from anesthetized neonatal rats were digested with pancreatic enzymes and type II collagenase. For TCF7L2 overexpression or knockdown, the NRCMs were infected with Lenti-TCF7L2, Lenti-shTCF7L2 , or Lenti-NC (Lentiviral vector control) for 16 h, followed by incubation in culture medium containing 10% fetal bovine serum and 1% penicillin-streptomycin for 48 h. Total RNA was extracted from lenti-TCF7L2-, lenti-shTCF7L2 -or lenti-NC-infected NRCMs using a Trizol reagent kit. We then performed gene expression profiling analysis using data obtained fromRNA-seq of lentiviral infected cardiomyocytes. Comparative gene expression profilling analysis of RNA-Seq data for infected cells.