Prolyl carboxypeptidase in Agouti-related Peptide neurons modulates food intake and body weight

Giuseppe Bruschetta,Sungho Jin,Jung Dae Kim,Sabrina Diano

doi:10.1016/j.molmet.2018.02.003

Giuseppe Bruschetta, Sungho Jin + Show 2 more

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https://doi.org/10.1016/j.molmet.2018.02.003

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Journal: Molecular Metabolism	Publication Date: Feb 8, 2018
Citations: 14	License type: cc-by

Affiliation: Yale University

Abstract

ObjectiveProlyl carboxypeptidase (PRCP) plays a role in the regulation of energy metabolism by inactivating hypothalamic α-melanocyte stimulating hormone (α-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. MethodsWe 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. ResultsHere 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 α-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. ConclusionsAltogether, our data indicate that PRCP is released at the synaptic levels and that PRCP in AgRP neurons contributes to the modulation of α-MSH degradation and related metabolic control in mice.

Highlights

The arcuate melanocortin system comprises neurons expressing either the anorexigenic pro-opiomelanocortin peptide (POMC) or the orexigenic Neuropeptide Y/Agouti-related peptide (NPY/AgRP)
Prolyl carboxypeptidase (PRCP) expression in AgRP neurons To assess whether PRCP is expressed in NPY/AgRP neurons, we performed immunostaining of PRCP in hypothalamic sections from NPY/GFP mice
Our results showed that about 77.8 Æ 2.39% of NPY neurons in the arcuate nucleus express PRCP (Figure 1AeC)

Summary

Introduction

The arcuate melanocortin system comprises neurons expressing either the anorexigenic pro-opiomelanocortin peptide (POMC) or the orexigenic Neuropeptide Y/Agouti-related peptide (NPY/AgRP). These neurons project to overlapping target areas, including the paraventricular nucleus of the hypothalamus, where AgRP antagonizes the effect of amelanocyte stimulating hormone (a-MSH), a product of the POMC gene, on melanocortin receptors (MCRs)-expressing neurons [1]. Alpha-MSH is generated by extensive posttranslational processes that involve several enzymes, such as the prohormone convertases 1 and 2. The obesity phenotype reported is associated with mutations in the human prohormone convertase 1 gene [5] and increased levels of unprocessed POMC. Studies on the regulation of these enzymes have shown that leptin, glucocorticoids, and thyroid hormones regulate PC1 and PC2 in vivo and in vitro [6e9]

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