[Cloning and functional analysis of melanocortin 4 receptor mutation gene F261S].

Objective: To evaluate the function change of the melanocortin 4 receptor (MC4R) protein with mutation of F261S.

Methods: Human embryonic cells of the HEK293 line were cultured. Wild-type genomic DNA and F261S mutation human melanocortin 4 receptor genes from the genomic DNA of aproband of homozygotic F612 mutation were amplified and cloned into a topo-TA eukaryotic expression plasmid vector. After the wild-type and F261S mutated proteins were expressed in HEK293 cells, alpha-MSH (10(-11) approximately 10(-5) mmol/L) was added, then the intracellular cAMP was detected with dual luciferase reporter assay system.

Results: When the concentration of alpha-MSH added was 10(-9) approximately 10(-8) mmol/L, the intracellular alpha-MSH concentration of the cells transfected with wild-type MC4R gene was significantly higher than that of the cells transfected with F261S mutation gene (P < 0.05). When the concentration of alpha-MSH added went to 10(-7) approximately 10(-5) mmol/L, the differences became even more significant (all P < 0.01).

Conclusion: The novel MC4R mutation F261S undermines the signal transduction. It may be the possible reason leading to monogenic mutation obesity in Chinese.