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PDK1-Foxo1 in agouti-related peptide neurons regulates energy homeostasis by modulating food intake and energy expenditure.

ABSTRACT: Insulin and leptin intracellular signaling pathways converge and act synergistically on the hypothalamic phosphatidylinositol-3-OH kinase/3-phosphoinositide-dependent protein kinase 1 (PDK1). However, little is known about whether PDK1 in agouti-related peptide (AGRP) neurons contributes to energy homeostasis. We generated AGRP neuron-specific PDK1 knockout (AGRPPdk1(-/-)) mice and mice with selective expression of transactivation-defective Foxo1 (?256Foxo1(AGRP)Pdk1(-/-)). The AGRPPdk1(-/-) mice showed reductions in food intake, body length, and body weight. The ?256Foxo1(AGRP)Pdk1(-/-) mice showed increased body weight, food intake, and reduced locomotor activity. After four weeks of calorie-restricted feeding, oxygen consumption and locomotor activity were elevated in AGRPPdk1(-/-) mice and reduced in ?256Foxo1(AGRP)Pdk1(-/-) mice. In vitro, ghrelin-induced changes in [Ca(2+)](i) and inhibition of ghrelin by leptin were significantly attenuated in AGRPPdk1(-/-) neurons compared to control neurons. However, ghrelin-induced [Ca(2+)](i) changes and leptin inhibition were restored in ?256Foxo1(AGRP)Pdk1(-/-) mice. These results suggested that PDK1 and Foxo1 signaling pathways play important roles in the control of energy homeostasis through AGRP-independent mechanisms.

SUBMITTER: Cao Y

PROVIDER: S-EPMC3072380 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

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PDK1-Foxo1 in agouti-related peptide neurons regulates energy homeostasis by modulating food intake and energy expenditure.

Cao Yongheng Y Nakata Masanori M Okamoto Shiki S Takano Eisuke E Yada Toshihiko T Minokoshi Yasuhiko Y Hirata Yukio Y Nakajima Kazunori K Iskandar Kristy K Hayashi Yoshitake Y Ogawa Wataru W Barsh Gregory S GS Hosoda Hiroshi H Kangawa Kenji K Itoh Hiroshi H Noda Tetsuo T Kasuga Masato M Nakae Jun J

PloS one 20110407 4

Insulin and leptin intracellular signaling pathways converge and act synergistically on the hypothalamic phosphatidylinositol-3-OH kinase/3-phosphoinositide-dependent protein kinase 1 (PDK1). However, little is known about whether PDK1 in agouti-related peptide (AGRP) neurons contributes to energy homeostasis. We generated AGRP neuron-specific PDK1 knockout (AGRPPdk1(-/-)) mice and mice with selective expression of transactivation-defective Foxo1 (Δ256Foxo1(AGRP)Pdk1(-/-)). The AGRPPdk1(-/-) mic ...[more]

PMID: 21694754

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Project description:Prolyl carboxypeptidase (PRCP) plays a role in the regulation of energy metabolism by inactivating hypothalamic ?-melanocyte stimulating hormone (?-MSH) levels. Although detected in the arcuate nucleus, limited PRCP expression has been observed in the arcuate POMC neurons, and its site of action in regulating metabolism is still ill-defined.We performed immunostaining to assess the localization of PRCP in arcuate Neuropeptide Y/Agouti-related Peptide (NPY/AgRP) neurons. Hypothalamic explants were then used to assess the intracellular localization of PRCP and its release at the synaptic levels. Finally, we generated a mouse model to assess the role of PRCP in NPY/AgRP neurons of the arcuate nucleus in the regulation of metabolism.Here we show that PRCP is expressed in NPY/AgRP-expressing neurons of the arcuate nucleus. In hypothalamic explants, stimulation by ghrelin increased PRCP concentration in the medium and decreased PRCP content in synaptic extract, suggesting that PRCP is released at the synaptic level. In support of this, hypothalamic explants from mice with selective deletion of PRCP in AgRP neurons (PrcpAgRPKO) showed reduced ghrelin-induced PRCP concentration in the medium compared to controls mice. Furthermore, male PrcpAgRPKO mice had decreased body weight and fat mass compared to controls. However, this phenotype was sex-specific as female PrcpAgRPKO mice show metabolic differences only when challenged by high fat diet feeding. The improved metabolism of PrcpAgRPKO mice was associated with reduced food intake and increased energy expenditure, locomotor activity, and hypothalamic ?-MSH levels. Administration of SHU9119, a potent melanocortin receptor antagonist, selectively in the PVN of PrcpAgRPKO male mice increased food intake to a level similar to that of control mice.Altogether, our data indicate that PRCP is released at the synaptic levels and that PRCP in AgRP neurons contributes to the modulation of ?-MSH degradation and related metabolic control in mice.

Dataset Information

PDK1-Foxo1 in agouti-related peptide neurons regulates energy homeostasis by modulating food intake and energy expenditure.

Publications

PDK1-Foxo1 in agouti-related peptide neurons regulates energy homeostasis by modulating food intake and energy expenditure.

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