Insulin resistance contributed to the development of type 2 diabetes (T2D) and is a major risk factor for diabetic cardiomyopathy (DCM). We have previously reported that insulin resistance led to impaired Akt1 translocation into myocardial mitochondria in DCM. To study the role of mitochondrial Akt1 in DCM, we have generated two cardiac-specific inducible Cre-lox transgenic mice models that expresses (1) a mitochondria-targeting dominant negative Akt (CAMDAKT) or (2) a mitochondria-targeting constitutively active Akt (CAMCAKT) upon Tamoxifen induction (T). T-CAMDAKT mice showed LV dysfunction with increased heart failure markers, while T-CAMCAKT mice restored LV dysfunction to normal in the T2D model. In a T2D model induced by high fat/high fructose diet with relative insulin deficiency, T-CAMCAKT mice showed lower body fat mass (16.6% vs. 26.5%, p<0.001) and higher body lean mass (77.1% vs. 68.1%, p<0.001). To study the mechanism underlying the changes of body composition, we performed transcriptomic profiling and analysis in gonadal white adipose tissues (WAT) by bulk RNA sequencing. When compared to the control T2D mice, 544 genes were upregulated and 1077 genes were downregulated in the WAT of T-CAMCAKT T2D mice. The result indicated enhanced lipid catabolism, triglyceride catabolism, HDL assembly, and downregulated critical nuclear transcription. Pathway analysis revealed the Liver X receptor/Retinoid X receptor signaling was activated in WAT of T-CAMCAKT mice as compared to the controls. This was accompanied by increased fatty acid oxidation and apolipoproteins expression. These findings suggest that impaired mitochondrial Akt signaling in DCM could remotely increase adiposity by reducing lipid catabolism in WAT through modulating LXR/RXR signaling.
Y. Chen: None. A. Ta: None. E. Tom: None. Y. Chen: None. P.H. Wang: Board Member; Self; Dianavi.
National Institutes of Health (R01HL096987)