Aim: Bitter melon (Momordica charantia L.) is a common vegetable grown in Okinawa that has also been used recently in medicine for the treatment of diseases such as diabetes, hypertension, and dyslipidemia. Among Bitter melon extracts compounds, we focused on an extract known as momordin in the present study, to examine its effect on peroxisome-proliferator activated-receptor (PPAR) δ (also called PPARδ in rodents) expression and promoter activity of the human PPARδ gene.
Methods: A human PPARδ promoter-reporter plasmid was made as a template from a BAC CLONE (RPCI-11C) containing a -3076 bp (BglI site) +74 bp (EcoRI site) sequence. Luciferase assay of PPARδ promoter activity was performed using HepG2 cells.
Results: 10 and 25 nM Momordin significantly increased the expression of PPARδ mRNA 1.5-fold (relative to the control). Moreover, 10 and 25 nM Momordin significantly increased PPARδ promoter activity in a dose-dependent manner, reaching more than 1.5-fold relative to the control.
Conclusion: Our present data obtained through successful cloning of the PPARδ promoter demonstrate that PPARδ production and activation are upregulated through PPARδ promoter activity following momordin treatment.