Prolactin receptor signaling is essential for perinatal brown adipocyte function: a role for insulin-like growth factor-2.
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BACKGROUND: The lactogenic hormones prolactin (PRL) and placental lactogens (PL) play central roles in reproduction and mammary development. Their actions are mediated via binding to PRL receptor (PRLR), highly expressed in brown adipose tissue (BAT), yet their impact on adipocyte function and metabolism remains unclear. METHODOLOGY/PRINCIPAL FINDINGS: PRLR knockout (KO) newborn mice were phenotypically characterized in terms of thermoregulation and their BAT differentiation assayed for gene expression studies. Derived brown preadipocyte cell lines were established to evaluate the molecular mechanisms involved in PRL signaling on BAT function. Here, we report that newborn mice lacking PRLR have hypotrophic BAT depots that express low levels of adipocyte nuclear receptor PPARgamma2, its coactivator PGC-1alpha, uncoupling protein 1 (UCP1) and the beta3 adrenoceptor, reducing mouse viability during cold challenge. Immortalized PRLR KO preadipocytes fail to undergo differentiation into mature adipocytes, a defect reversed by reintroduction of PRLR. That the effects of the lactogens in BAT are at least partly mediated by Insulin-like Growth Factor-2 (IGF-2) is supported by: i) a striking reduction in BAT IGF-2 expression in PRLR KO mice and in PRLR-deficient preadipocytes; ii) induction of cellular IGF-2 expression by PRL through JAK2/STAT5 pathway activation; and iii) reversal of defective differentiation in PRLR KO cells by exogenous IGF-2. CONCLUSIONS: Our findings demonstrate that the lactogens act in concert with IGF-2 to control brown adipocyte differentiation and growth. Given the prominent role of brown adipose tissue during the perinatal period, our results identified prolactin receptor signaling as a major player and a potential therapeutic target in protecting newborn mammals against hypothermia.
Gene Expression Regulation
Insulin-Like Growth Factor II
Published Version (Please cite this version)10.1371/journal.pone.0001535
Publication InfoBinart, N; Fève, B; Freemark, Michael Scott; Lombès, M; Servel, N; & Viengchareun, S (2008). Prolactin receptor signaling is essential for perinatal brown adipocyte function: a role for insulin-like growth factor-2. PLoS One, 3(2). pp. e1535. 10.1371/journal.pone.0001535. Retrieved from http://hdl.handle.net/10161/4483.
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Robert C. Atkins, M.D. and Veronica Atkins Professor of Pediatrics, in the School of Medicine
The primary objective of my basic research has been to elucidate the roles of placental and fetal hormones in the regulation of maternal metabolism and fetal growth. My work has focused on the lactogenic hormones produced by the pituitary gland and placenta. In recent studies we have used targeted knockout mice to explore the molecular mechanisms by which prolactin and placental lactogen regulate pancreatic beta cell mass and insulin production during pregnancy and postnatal life. I also