Analysis of a 762-bp proximal leptin promoter to drive and control regulation of transgene expression of growth hormone receptor in mice

Transgenic (TG) mice expressing porcine GH receptor (pGHR) directed by a 762-bp proximal leptin promoter were used to analyze the capability of the promoter to drive and regulate pGHR expression in vivo. Transgene expression occurred in inguinal, retroperitoneal, and epididymal/parametrial fat depots in both male and female TG mice, but not in wild type (WT) mice. pGHR transgene was also expressed in liver, heart, kidney, muscle, lung, and brain. Levels of pGHR transgene mRNA were higher in tissues other than adipose tissue. Fasting reduced leptin mRNA levels in adipose; however, pGHR transgene expression was not affected in either adipose or muscle. These results suggest (1) the region between +3 and -759 bp of the leptin promoter is able to drive gene expression in vivo, (2) this region may not be responsible for adipose tissue specificity of leptin expression, and (3) this region may not be responsible for negative regulation of leptin gene expression during fasting.