Objective: To construct the human obese (ob) cDNA clone in the Chinese, and analyze the expression of the ob gene in adipose tissue of obese, non-obese subjects and nooinsulin-dependent diabetes mellitus (NIDDM) Chinese patients.
Methods: A ob cDNA clone was isolated by reverse transcription polymerase chain 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/m2]; 2) 11 non-obese subjects (BMI: 21.0 +/- 1.5 kg/m2); 3) 8 obese NIDDM patients (BMI: 27.0 +/- 1.4 kg/m2); 4) 11 non-obese NIDDM patients (BMI: 21.2 +/- 1.4 kg/m2). The expression of ob gene mRNA in abdominal subcutaneous adipose tissue was examined using RNA dot blot hybridization with a digoxigenin-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 position 287 was found, resulting in a glutamine being replaced by an arginine. Expression of the ob gene was significantly higher in Chinese obese subjects 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 between non-diabetic and diabetic groups at the same BMI level.
Conclusions: We constructed a full length human ob cDNA clone. The expression of the ob gene was significantly higher in Chinese obese subjects than in non-obese ones. The metabolic and hormonal changes associated with NIDDM are not the main factors regulating the expression of the ob gene.