Identification and Characterization of a Small Molecule Inhibitor of Fatty Acid Binding Proteins

Abstract

Molecular disruption of the lipid carrier AFABP/aP2 in mice results in improved insulin sensitivity and protection from atherosclerosis. Since small molecule inhibitors may be efficacious in defining the mechanism(s) of AFABP/aP2 action, a chemical library was screened and identified 1 (HTS01037) as a pharmacologic ligand capable of displacing the fluorophore 1-anilinonaphthalene 8-sulfonic acid from the lipid binding cavity. The X-ray crystal structure of 1 bound to AFABP/aP2 revealed that the ligand binds at a structurally similar position to a long-chain fatty acid. Similar to AFABP/aP2 knockout mice, 1 inhibits lipolysis in 3T3-L1 adipocytes and reduces LPS-stimulated inflammation in cultured macrophages. 1 acts as an antagonist of the protein-protein interaction between AFABP/aP2 and hormone sensitive lipase but does not activate PPARγ in macrophage or CV-1 cells. These results identify 1 as an inhibitor of fatty acid binding and a competitive antagonist of protein-protein interactions mediated by AFABP/aP2.

Adipocyte fatty acid binding protein: a novel adipokine involved in the pathogenesis of metabolic and vascular disease?

“…Work using mutational analysis coupled with fluorescence resonance energy transfer suggests that interaction between AFABP and HSL depends on AFABP-bound NEFA and HSL phosphorylation [20]. In accordance with these findings, a small molecular inhibitor blocking NEFA binding to AFABP also antagonises physical interaction with HSL [21]. Furthermore, four amino acids on the helical domain of AFABP (D17, D18, K21 and R30), termed the charge quartet, are responsible for HSL interaction (Fig.…”

Adipocyte Fatty Acid-binding Protein Modulates Inflammatory Responses in Macrophages through a Positive Feedback Loop Involving c-Jun NH2-terminal Kinases and Activator Protein-1

“…At the molecular level, A-FABP deficiency in macrophages results in decreased production of a cluster of pro-inflammatory cytokines, such as tumor necrosis factor-␣, interleukin-6, monocyte chemoattractant protein (MCP)-1, and interleukin-1␤. These findings are corroborated by the observation that pharmacological inhibition of A-FABP by its selective inhibitors protects mice against atherosclerosis and compromises inflammatory responses in macrophage cells (10,11). In addition, the pivotal role of A-FABP in inflammation is highlighted by the findings that A-FABP-deficient mice are resistant to develop several other inflammatory disorders, including allergic airway inflammation (12) and experimental autoimmune encephalomyelitis/ multiple sclerosis (13).…”

Small-molecule inhibitors of FABP4/5 ameliorate dyslipidemia but not insulin resistance in mice with diet-induced obesity

“…However, no biological characterization in cell-based or in vivo assays has been reported. Another FABP4 inhibitor, HTS01037, has recently been reported ( 17 ). In ligand displacement assays using 1,8-ANS, this compound displayed K i values of 670 nM, 3.4 µM, and 9.1 µM for FABP4, FABP5, and FABP3, respectively.…”