The predictive power of mRNA mapping for Cannabinoid 1 receptor protein in the human brain

Abstract

Type 1 cannabinoid (CB1) receptor is expressed in cortex, hippocampus, amygdala, basal ganglia, and cerebellum. With the help of the Allen Human Brain Atlas, genomic maps visualize not only the gene expression across whole brain regions, but also the functional profile of brain structures. Therefore, it is more timely than ever to integrate genomic mapping from brain mRNA atlas with the protein expression from positron emission tomography (PET) scans for better understanding of CB1 receptor of the human brain. F18-FMPEP-d2 PET scans were retrieved from the AIVO neuroinformatics project. Autoradiography data were based on the study with H3-CP55940. mRNA expressions of CNR1 gene (Cannabinoid receptor 1) were downloaded from the Allen Human Brain Atlas. Volume of distribution (VT) from F18-FMPEP-d2 PET scans, CNR1 gene expression, and H3-CP55940 binding were calculated and Spearman correlation analysis was performed. Also, a meta-analysis was done to investigate the association between protein expression from PET and mRNA expression from the Allen Human Brain Atlas. Between VT of F18-FMPEP-d2 PET scans and CNR1 mRNA expression, moderate strength of correlation was observed (rho = 0.5026, p = 0.0354). Strong positive correlation was also found between CNR1 mRNA expression and H3-CP55940 binding (rho = 0.6727, p = 0.0281), validating the finding between F18-FMPEP-d2 PET scans and CNR1 mRNA. From the meta-analysis, the correlation coefficient ranged from −0.46 to 0.99, with a pooled effect of 0.58. In conclusion, the moderate to strong associations between gene and protein expression for CB1 receptor in the human brain were observed that CNR1 mRNA mapping might have the predictive power for in vivo CB1 receptor protein expression. From the meta-analysis, the moderate to strong correlation was observed between mRNA expression and protein expressions across multiple genes, showing the predictive power of genes to estimate protein levels of human brains.HIGHLIGHTSWe investigated the association between CNR1 gene expression from the Allen Human Brain Atlas and type 1 cannabinoid (CB1) receptor expression from F18-FMPEP-d2 PET scans.The moderate to strong associations between gene and protein expression for CB1 receptor in the human brain were observed that CNR1 mRNA mapping might have the predictive power for in vivo CB1 receptor protein expression.From the meta-analysis, the moderate to strong correlation was observed between mRNA expression and protein expressions across multiple genes, showing the predictive power of genes to estimate protein levels of human brains.