Anorexigenic Hormones Leptin Insulin and α-Melanocyte-Stimulating Hormone Directly Induce Neurotensin (NT) Gene Expression in Novel NT-Expressing Cell Models

摘要

Neurotensin (NT) is implicated in the regulation of energy homeostasis, in addition to its many described physiological functions. NT is postulated to mediate, in part, the effects of leptin in the hypothalamus. We generated clonal, immortalized hypothalamic cell lines, N-39 and N-36/1, which are the first representative NT-expressing cell models available for the investigation of NT gene regulation and control mechanisms. The cell lines express the Ob-Rb leptin receptor neuropeptide Y (NPY)-Y1, Y2, Y4, Y5 receptors, melanocortin 4 receptor, insulin receptor, and the NT receptor. NT mRNA levels are induced by ∼1.5-fold to twofold with leptin, insulin, and α-melanocyte stimulating hormone treatments but not by NPY. Leptin-mediated induction of NT gene expression was biphasic at 10^-11 and 10^-7 M. The leptin responsive region was localized to within -381 to -250 bp of the 5′ regulatory region of the NT gene. Furthermore, we demonstrated direct leptin-mediated signal transducers and activators of transcription (STAT) binding to this region at 10^-11 m, but not 10^-7 m leptin, in chromatin precipitation assays. Leptin-induced NT regulation was attenuated by dominant-negative STAT3 protein expression. These data support the hypothesis that NT may have a direct role in the neuroendocrine control of feeding and energy homeostasis.