A Comparison of Collection Techniques for Gene Expression Analysis of Human Oral Taste Tissue

Abstract

Variability in human taste perception is associated with both genetic and environmental factors. The influence of taste receptor expression on this variability is unknown, in part, due to the difficulty in obtaining human oral tissue that enables quantitative expression measures of taste genes. In a comparison of six current techniques (Oragene RNeasy Kit, Isohelix swab, Livibrush cytobrush, tongue saliva, cheek saliva collection, and fungiform papillae biopsy), we identify the fungiform papillae biopsy is the optimal sampling technique to analyse human taste gene expression. The fungiform papillae biopsy resulted in the highest RNA integrity, enabling amplification of all the assessed taste receptor genes (TAS1R1, TAS1R2, TAS1R3, SCNN1A and CD36) and taste tissue marker genes (NCAM1, GNAT3 and PLCβ2). Furthermore, quantitative expression was observed in a subset of taste genes assessed from the saliva collection techniques (cheek saliva, tongue saliva and Oragene RNA kit). These saliva collection techniques may be useful as a non-invasive alternative sampling technique to the fungiform papillae biopsy. Identification of the fungiform papillae biopsy as the optimal collection method will facilitate further research into understanding the effect of gene expression on variability in human taste perception.

Fig 1. Flowchart of study design to identify collection techniques that enable quantitative measures of taste gene expression.

Samples were collected from 8 volunteers using the six different methods, the RNA was extracted and analysed with the NanoDrop ND-1000 Spectrophotometer (for quantity and purity) and Bio-analyser (analysis of RNA integrity). Real-time quantitative PCR was completed on taste tissue markers and taste genes, allowing for the identification of methods enabling quantitative measures of taste gene expression.

Fig 2. Representative Lightcycler 480 amplification profiles of taste genes using the different collection techniques.

Pap—Papillae biopsy (red), Che—Cheek saliva (Green), Ton—Tongue saliva (orange), Ora—Oragene kit (blue), Iso—Isohelix brush (black), Cyto—Livibrush cytobrush (purple), NTC—no template control (grey).