LEPTIN RECEPTOR ISOFORMS EXPRESSED IN HUMAN ADIPOSE-TISSUE

Leptin and its structural gene, Ob, are exclusively expressed in adipo se tissue. Leptin is secreted into the blood and is responsible for fa t mass regulation via leptin receptors in the hypothalamus. This has b een considered the major role of leptin, but leptin receptor isoforms are expressed not only in the brain but also in most other tissues in humans and rodents: heart, placenta, lung, liver, muscle, kidney, panc reas, spleen, thymus, prostate, testes, ovary, small intestine, and co lon. This implicates leptin regulation in other systems apart from Cat mass regulation, and leptin action has been demonstrated in human fet al development and reproductive development, liver metabolism, hematop oiesis, and insulin secretion. Four splice variants of the leptin rece ptor have been identified in humans: the long isoform huOb-R and the s horter isoforms B219.1 to B219.3. It is known that the long isoform ha s full intracellular signaling capacity, and is responsible for anorec tic action in the hypothalamus. The roles of the other isoforms are ye t to be elucidated. Here, we report the identification by reverse tran scriptase-polymerase chain reaction (RT-PCR) of three leptin receptor isoforms coexpressed in human visceral adipose tissue: the long isofor m huOb-R and the short isoforms huB219.1 and huB219.3. The possible ro les of these isoforms are discussed. Copyright (C) 1998 by W.B. Saunde rs Company.