Cocoa flavanol metabolites activate HNF ‐3β, S p1, and NFY ‐mediated transcription of apolipoprotein AI in human cells

Scope To identify the mechanisms by which cocoa induces HDL levels and since apolipoprotein AI ( A po AI ) is the major protein in HDL s, we analyzed, upon incubation with cocoa metabolites, A po AI m RNA levels, its transcriptional regulation, and the levels of the transcription factors involved in this process. Methods and results Epicatechin and cocoa metabolites caused an increase in A po AI expression in H ep G 2 cells. Electrophoretic mobility shift assays revealed the involvement of Sites A and B of the A po AI promoter in the induction of A po AI m RNA upon incubation with cocoa metabolites. Using supershift assays, we demonstrated the binding of HNF ‐3β, HNF ‐4, ER ‐α, and RXR ‐α to S ite A and the binding of HNF ‐3β, NFY , and S p1 to S ite B. Luciferase assays performed with a construct containing S ite B confirmed its role in the upregulation of A po AI by cocoa metabolites. Incubation with 3‐methyl‐epicatechin led to an increase in HNF ‐3β m RNA , HNF ‐3β, ER ‐α, S p1, and NFY protein levels and the activation of A po AI transcription mediated by NFY , S p1, and ER ‐α. Conclusion The activation of A po AI transcription through S ite B by cocoa flavanol metabolites is mainly mediated by an increase in HNF ‐3β, with a significant contribution of S p1 and NFY , as a mechanism for the protective role of these compounds in cardiovascular diseases.