We have previously shown that a zinc finger transcription factor, Krüppel-like factor 5 (KLF5), plays an important role in pathogenesis of cardiovascular diseases, such as atherosclerosis. KLF5 heterozygous knockout (
KLF5
+/
−
) mice exhibited much less neointima formation, cardiac hypertrophy and fibrosis. We also found that expression of KLF5 correlated with a higher incidence of restenosis following PCI and the SNP located within the
KLF5
promoter was associated with an increased risk of hypertension in man. Interestingly, KLF5 is also expressed in metabolic tissues such as adipose tissue, skeletal muscle, and pancreatic β-cells. Thus, we hypothesized that KLF5 might play a role in metabolic diseases. To test this,
KLF5
+/
−
mice were fed with high-fat diet. Although
KLF5
+/
−
mice ate more food than wild-type littermates, they were resistant to high-fat diet-induced obesity and protected from dyslipidemia, glucose intolerance and hepatic steatosis, indicating that
KLF5
+
/−
mice were less susceptible to metabolic syndrome. The systemic O
2
consumption and expression of genes involved in energy expenditure in skeletal muscle were increased in
KLF5
+
/−
mice, demonstrating enhanced energy expenditure, which partly explains the phenotype. Knocking down KLF5 by siRNA increased expression levels of UCP2/3 and CPT-1b in C2C12 myotubes, suggesting that KLF5 may inhibit energy expenditure-related genes. Chromatin immunoprecipitation and coimmunoprecipitation assays showed that KLF5 interacted with corepressors, such as SMRT and NCoR, and strongly inhibited the
UCP
and
CPT-1b
promoters. We found that this inhibitory activity of KLF5 depended on its SUMOylation. When KLF5 was deSUMOylated, it activated the promoters. These data demonstrate that KLF5 acts as a molecular switch for energy expenditure and the posttranslational modifications of KLF5 including SUMOylation turns on/off the switch function of KLF5. Given that KLF5 also controls tissue remodeling in response to external stress, KLF5 may mediate metabolic dysfunction and atherosclerosis in metabolic syndrome. Our findings also suggest that the posttranscriptional modification of KLF5 is an attractive novel therapeutic target.
Maternal exercise programs skeletal muscle metabolic dysfunction in offspring mice challenged with high fat diet.