Molecular cloning, sequencing and expression of obese gene in the Chinese

Objective To construct the human obese(ob) cDNA clone in the Chinese, and a nalyze the expression of the ob gene in adipose tissue of obese, non-obese subjects and nooinsulin-dependent diabetes mellitus (NIDDM) Chinese patient s. Methods A ob cDNA clone was isolated by reverse transcription polymerase ch ain reaction (RT-PCR). Four groups of Chinese subjects participated in the study: 1) 12 obese subjects [body mass index (BMI): 28.5 +/- 2.3 kg/m(2)]; 2) 11 non-obese subjects (BMI: 21.0 +/- 1.5 kg/m(2)); 3) 8 obese NIDDM pati ents (BMI: 27.0 +/- 1.4 kg/m(2)); 4) 11 non-obese NIDDM patients (BMI: 21.2 +/- 1.4 kg/m(2)). The expression of ob gene mRNA in abdominal subcutaneous adipose tissue was examined using RNA dot blot hybridization with a digoxi genin-labeled human ob cDNA probe. The hybridized signals were quantitated by densitometry. Results A full human ob cDNA fragment which included a glutamine codon at 49 was obtained. A base substitution (A to G) in the coding region at posi tion 287 was found, resulting in a glutamine being replaced by an arginine. Expression of the ob gene was significantly higher in Chinese obese subjec ts compared to non-obese ones (P < 0.05) and positively correlated with the BMI. No significant difference in the amount of ob mRNA was detected betwe en non-diabetic and diabetic groups at the same BMI level. Conclusions We constructed a full length human ob cDNA clone. The expressio n of the ob gene was significantly higher in Chinese obese subjects than in non-obese ones. The metabolic and hormonal changes associated with NIDDM a re not the main factors regulating the expression of the ob gene.