A new gene related to human obesity identified by suppression subtractive hybridization

The aim of the research was to identify genes specially expressed in the obese state and potentially involved in the pathogenesis of obesity.

We used the technique of suppression subtractive hybridization (SSH), which combines subtractive hybridization with PCR, to generate a population of PCR fragments enriched for transcripts of high or low abundance from differentially expressed genes. PolyA+ mRNA was isolated from subcutaneous abdominal adipose tissue of five massively obese (>35 kg/m(2)) and five normal-weight (<25 kg/m(2)) women. cDNA generated from RNA pooled from the obese subjects was contrasted by SSH with an excess of pooled cDNA from the normal-weight women.

Seventy-nine clones were obtained among which one showed by RT-PCR a higher expression in obese than in normal-weight subjects. This gene was shown to be predominantly expressed in adipose tissue in contrast to brain, liver, kidney, heart and skeletal muscle, and was called "Adipogene". No expression was detected in lung, pancreas and placenta. The cDNA was 1.5 kb long with an open reading frame of 1004 nucleotides encoding a protein of 334 amino acids (37 kDa). No significant sequence similarity was found in databanks, except for weak amino acid homologies with prokaryotic AraC/XylS transcriptional regulator family. Adipogene is encoded on chromosome 8, less than 1 centiMorgan (cM) from the beta3 adrenergic receptor (ADRB3) locus. Weak linkages were observed with body mass index (BMI) and three microsatellite markers located within 10 cM of Adipogene, whereas no linkage was observed with Trp64Arg ADRB3 polymorphism using the Québec Family Study database.

Using the SSH technique, we have identified a new gene, called Adipogene, which is overexpressed in the adipose tissue of the obese individuals and could be involved in obesity.