title: Krüppel-like factor 2 is required for normal mouse cardiac development.
abstract: Krüppel-like factor 2 (KLF2) is expressed in endothelial cells in the developing heart, particularly in areas of high shear stress, such as the atrioventricular (AV) canal. KLF2 ablation leads to myocardial thinning, high output cardiac failure and death by mouse embryonic day 14.5 (E14.5) in a mixed genetic background. This work identifies an earlier and more fundamental role for KLF2 in mouse cardiac development in FVB/N mice. FVB/N KLF2-/- embryos die earlier, by E11.5. E9.5 FVB/N KLF2-/- hearts have multiple, disorganized cell layers lining the AV cushions, the primordia of the AV valves, rather than the normal single layer. By E10.5, traditional and endothelial-specific FVB/N KLF2-/- AV cushions are hypocellular, suggesting that the cells accumulating at the AV canal have a defect in endothelial to mesenchymal transformation (EMT). E10.5 FVB/N KLF2-/- hearts have reduced glycosaminoglycans in the cardiac jelly, correlating with the reduced EMT. However, the number of mesenchymal cells migrating from FVB/N KLF2-/- AV explants into a collagen matrix is reduced considerably compared to wild-type, suggesting that the EMT defect is not due solely to abnormal cardiac jelly. Echocardiography of E10.5 FVB/N KLF2-/- embryos indicates that they have abnormal heart function compared to wild-type. E10.5 C57BL/6 KLF2-/- hearts have largely normal AV cushions. However, E10.5 FVB/N and C57BL/6 KLF2-/- embryos have a delay in the formation of the atrial septum that is not observed in a defined mixed background. KLF2 ablation results in reduced Sox9, UDP-glucose dehydrogenase (Ugdh), Gata4 and Tbx5 mRNA in FVB/N AV canals. KLF2 binds to the Gata4, Tbx5 and Ugdh promoters in chromatin immunoprecipitation assays, indicating that KLF2 could directly regulate these genes. In conclusion, KLF2-/- heart phenotypes are genetic background-dependent. KLF2 plays a role in EMT through its regulation of important cardiovascular genes.
authors: Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia, United States of America.
authors: Aditi R
authors: AR
authors: Chiplunkar
authors: Tina K
authors: TK
authors: Lung
authors: Yousef
authors: Y
authors: Alhashem
authors: Benjamin A
authors: BA
authors: Koppenhaver
authors: Fadi N
authors: FN
authors: Salloum
authors: Rakesh C
authors: RC
authors: Kukreja
authors: Jack L
authors: JL
authors: Haar
authors: Joyce A
authors: JA
authors: Lloyd
mesh_terms: D000818:Animals; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D005260:Female; D050991:GATA4 Transcription Factor / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006025:Glycosaminoglycans / Q000032:analysis; D006321:Heart / Q000196:embryology* / Q000503:physiopathology; D006330:Heart Defects, Congenital / Q000235:genetics* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D051741:Kruppel-Like Transcription Factors / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice / Q000002:abnormalities / Q000196:embryology*; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009206:Myocardium / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D020825:T-Box Domain Proteins / Q000378:metabolism
chemical_list: D050991:GATA4 Transcription Factor; C484171:Gata4 protein, mouse; D006025:Glycosaminoglycans; C498314:Klf2 protein, mouse; D051741:Kruppel-Like Transcription Factors; D020825:T-Box Domain Proteins; C103172:T-box transcription factor 5