Targeted disruption of the Basic Krüppel-like Factor (Klf3) gene reveals a role in adipogenesis

School of Molecular and Microbial Biosciences, University of Sydney, NSW, 2006, Australia; School of Medical Sciences, University of Sydney, NSW, 2006, Australia; Diabetes and Obesity Program, Garvan Institute of Medical Research, NSW, 2010, Australia; Institute for Molecular Bioscience, Queensland Bioscience Precinct, University of Queensland, QLD, 4072, Australia; Dana Farber Cancer Institute, Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, Mass., USA, 02115

^* To whom correspondence should be addressed. Email: m.crossley{at}mmb.usyd.edu.au.

	Abstract

Krüppel-like Factors (Klfs) recognize CACCC and GC-rich sequences in gene regulatory elements. Here we describe the disruption of the murine Basic Krüppel-like Factor (Bklf) or Klf3 gene. Klf3 knockout mice have less white adipose tissue, their fat pads contain smaller and fewer cells. Adipocyte differentiation is altered in murine embryonic fibroblasts from Klf3 knockouts. Klf3 expression was studied in the 3T3-L1 cellular system. Adipocyte differentiation is accompanied by a decline in Klf3 expression and forced over-expression of Klf3 blocks 3T3-L1 differentiation. Klf3 represses transcription by recruiting C-terminal Binding Protein (CtBP) co-repressors. CtBPs bind NADH and may function as metabolic sensors. A Klf3 mutant that does not bind CtBP cannot block adipogenesis. Other Klfs, Klf2, Klf5, and Klf15, also regulate adipogenesis and functional CACCC elements occur in key adipogenic genes, including in the C/ebp promoter. We find that C/ebp is de-repressed in Klf3 and Ctbp knockout fibroblasts and adipocytes from Klf3 knockout mice. Chromatin immunoprecipitations confirm that Klf3 binds the C/ebp promoter in vivo. These results implicate Klf3 and CtBP in controlling adipogenesis.