OP-2：The identification of a transcriptional factor induced by leptin and analysis of its polymorphism

Masahiro Nishi, Shohei Matsuno, Takeshi Shono, Hiroto Furuta, Tadasuke Komori*, Yoshihiro Morikawa*, Emiko Senba*, Hideyuki Sasaki, Kishio Nanjo

The First Department of Medicine, and *The Department of Anatomy and Neurobiology, Wakayama Medical University

Aim of the study: To clarify the pathogenesis of obese type 2 diabetes and leptin resistance, we have identified leptin-induced genes, analyzed their function and correlation of their polymorphism and diseases.  

Methods: ob/ob mice were injected leptin or PBS intravenously, sacrificed and extracted RNA from brain or pancreas. Genes induced by leptin was identified by PCR-select cDNA  method. Obtained clones were further analyzed by Northern analysis and in situ hybridization. A gene thought to be a transcriptional factor was further analyzed.   The effect on insulin promoter activity was assessed by cotransfection of this clone and luciferase vector under control of insulin promoter into beta TC3 cells. The polymorphism of this gene was also analyzed.

Results: Using PCR-select cDNA subtraction method, we have identified 20 clones, and in 9 of these, induction by leptin were confirmed by Northern analysis. Two clones showed letin-induced expression in hypothalamus by in situ hybridization. A clone, a transcriptional factor, also expressed in beta cells and inhibited the insulin promoter activity. A polymorphism of this clone associated with obesity but not diabetes.

Conclusion: A transcriptional factor identified by PCR-select cDNA subtraction method is thought to be a candidate gene for obesity or diabetes. However, further analysis should be needed.    

Address correspondence to:

Masahiro Nishi, MD, PhD.

The First Department of Medicine, Wakayama Medical University       

811-1 Kimiidera, Wakayama 641-8509 JAPAN

Phone: +81-73-441-0625, FAX: +81-73-445-9436

E-mail: mnishi@wakayama-med.ac.jp