The intestinal fatty acid binding protein is not essential for dietary fat absorption in mice

Abstract

The intestinal fatty acid binding protein (I-FABP) belongs to a family of 15 kDa clamshell-like proteins that are found in many different tissues. So far, nine types have been identified. Their primary structures are highly conserved between species but somewhat less so among the different types. The function of these proteins, many of which are highly expressed, is not well understood. Their ability to bind lipid ligands suggests a role in lipid metabolism, but direct evidence for this idea is still lacking. We tested the hypothesis that I-FABP serves an essential role in the assimilation of dietary fatty acids by disrupting its gene (Fabpi) in the mouse. We discovered that Fabpi-/- mice are viable, but they display alterations in body weight and are hyperinsulinemic. Male Fabpi-/- mice had elevated plasma triacylglycerols and weighed more regardless of the dietary fat content. In contrast, female Fabpi-/- mice gained less weight in response to a high-fat diet. The results clearly demonstrate that I-FABP is not essential for dietary fat absorption. We propose that I-FABP functions as a lipid-sensing component of energy homeostasis that alters body weight gain in a gender-specific fashion.

Effects of dietary lipids and Clostridium butyricum on serum lipids and lipid-related gene expression in broiler chickens

“…There are two main FABPs in the small intestine, the intestinal type (I-FABP) and the liver-type (L-FABP). Previous reports indicated that I-FABP was not essential for fatty acid absorption (Vassileva et al, 2000) and that L-FABP exhibited a higher affinity for unsaturated LCFA than I-FABP (Richieri et al, 1994). In addition, L-FABP had the ability to increase fatty acid uptake (Prows et al, 1995), so we examined the changes in L-FABP mRNA expression in jejunum under changing dietary conditions.…”

The fatty acid transport function of fatty acid-binding proteins

“…The crystal structure of human heart FABP (HFABP) containing an oleic acid ligand (1HMS.pdb). The protein structure is similar for all the FABPs and shows the β-barrel domain and the N-terminal helixturn-helix motif (37).…”

Tissue-specific Functions in the Fatty Acid-binding Protein Family

“…Differentiated enterocytes of the proximal small intestine express high levels of two FABPs, LFABP and the intestine-specific form, intestinal FABP (IFABP; FABP2). The distal small intestine expresses a third member of the FABP family, ileal bile acid-binding protein (ILBP; FABP6) (47,48). There appears to be no compensatory up-regulation of LFABP upon ablation of IFABP or vice versa, again indicating unique functional roles.…”