CaMK1D signaling in AgRP neurons promotes ghrelin-mediated food intake

Hypothalamic AgRP/NPY neurons are key players in the control of feeding behavior. Ghrelin, a major hormone released under fasting conditions, activates orexigenic AgRP/NPY neurons to stimulate food intake and adiposity. However, cell-autonomous ghrelin-dependent signaling mechanisms in AgRP/NPY neurons remain poorly defined. Here we demonstrate that calcium/calmodulin-dependent protein kinase ID (CaMK1D), a genetic hot spot in type 2 diabetes, is activated in hypothalamus upon ghrelin stimulation and acts in AgRP neurons to promote ghrelin-dependent food intake. Global CaMK1D knockout mice are resistant to the orexigenic action of ghrelin, gain less body weight and are protected against high-fat diet-induced obesity. Deletion of CaMK1D in AgRP but not in POMC neurons is sufficient to recapitulate above phenotypes. Lack of CaMK1D attenuates phosphorylation of CREB and CREB-dependent expression of the orexigenic neuropeptides AgRP/NPY as well as the amount of AgRP fiber projections to the Paraventricular nucleus (PVN), while electrical activity of AgRP neurons and 5 AMP-activated protein kinase (AMPK) signaling are unaffected. Hence, CaMK1D links ghrelin action to transcriptional control of orexigenic neuropeptide availability in AgRP neurons. HighlightsO_LIWhole-body deletion of CaMK1D in mice reduces food intake, ghrelin sensitivity and protects against obesity. C_LIO_LIAgRP/NPY neuron-specific deletion of CaMK1D reduces food intake, ghrelin sensitivity, energy expenditure and protects against obesity. C_LIO_LICaMK1D is dispensable for ghrelin-stimulated electrical activity of AgRP neurons and hypothalamic AMPK signaling. C_LIO_LICaMK1D controls phosphorylation of CREB and CREB-dependent expression of the orexigenic neuropeptides AgRP and NPY. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=174 HEIGHT=200 SRC="FIGDIR/small/471546v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@40d7d7org.highwire.dtl.DTLVardef@11a8c64org.highwire.dtl.DTLVardef@1f6fad3org.highwire.dtl.DTLVardef@1cd5581_HPS_FORMAT_FIGEXP M_FIG C_FIG