Functional Analysis of KLF13 in the Heart

Congenital heart defects (CHD) are the largest class of birth defects in humans and are a major cause of infant mortality and morbidity. Deciphering the molecular and genetic etiologies central for heart development and the pathogenesis of congenital heart diseases (CHD) is a challenging puzzle. We have previously demonstrated that the zinc-finger kruppel-like transcription factor KLF13, expressed predominantly in the atria, binds evolutionarily conserved regulatory elements known as CACC-boxes and transcriptionally activates several cardiac promoters. KLF13 loss of function in Xenopus embryos was associated with cardiac developmental defects underscoring its critical role in the heart. In the current study, using in vivo and in vitro approaches, we examined KLF13’s mechanisms of action and its interaction with other cardiac regulators. To test the evolutionary conserved role in the mammalian heart, we deleted the Klf13 gene in transgenic mice using homologous recombination. Mice with homozygote deletion of Klf13 were born at reduced frequency owing to severe heart defects. We also report the existence of a novel isoform of KLF13, referred to here as KLF13b. Furthermore, we report that KLF13 interacts biochemically and genetically with the T-box transcription factor TBX5 which is a key regulator of heart development. Our data provide novel insight into the role of KLF13 in cardiac transcription and suggest that KLF13 maybe a genetic modifier of congenital heart disease. Furthering our knowledge of protein-protein interactions and gene transcription will enhance genotype-phenotype correlation and contribute to better understanding of the etiology of CHD