Cyclin-dependent kinase 4/6 inhibitors require an arcuate-to-paraventricular hypothalamus melanocortin circuit to treat diet-induced obesity

Am J Physiol Endocrinol Metab. 2021 Mar 1;320(3):E467-E474. doi: 10.1152/ajpendo.00386.2020. Epub 2020 Dec 28.

Abstract

The arcuate nucleus (ARC) of the hypothalamus comprises two antagonistic neuron populations critical for energy balance, namely, the anorexigenic pro-opiomelanocortin (POMC) and the orexigenic agouti-related peptide (AgRP) neurons that act as agonists and antagonists, respectively, for neurons expressing the type IV melanocortin receptor (MC4R) (Andermann ML and Lowell BB. Neuron 95: 757-778, 2017). MC4R activation increases energy expenditure and decreases food intake during positive energy balance states to prevent diet-induced obesity (DIO). Work from our group identified aberrant neuronal cell cycle events both as a novel biomarker and druggable target in the ARC for the treatment of DIO, demonstrating pharmacological restoration of retinoblastoma protein function in the ARC using cyclin-dependent kinase 4/6 (CDK4/6) inhibitors could treat DIO in mice by increasing lipid oxidation to selectively decrease fat mass. However, the role of CDK4/6 inhibitors on food intake was not examined. Four-week-old Mc4r-loxTB mice were continuously administered high-fat diet (60% kcal fat). At 8 wk of age, animals were administered 60 mg/kg abemaciclib orally or a saline control and monitored every 2 wk for fat mass changes by MRI. At 11 wk of age, all animals were injected bilaterally in the paraventricular hypothalamus with AAV8 serotype virus expressing a Cre-mCherry and monitored for another 5 wk. Restoration of Mc4r expression in the paraventricular hypothalamic nucleus (PVN/PVH) reduced food intake in hyperphagic obese mice when given CDK4/6 inhibitor therapy. The reduced food intake was responsible for reduced fat mass in mice treated with abemaciclib. These results indicate that targeting POMC neurons could be an effective strategy in treating diet-related obesity.NEW & NOTEWORTHY We have defined some of the necessary components to prevent high-fat diet-induced obesity at the molecular and cellular level. Within POMC neurons, the retinoblastoma protein must remain active and prevented from phosphoinactivation by cyclin-dependent kinases. The downstream neurons within the PVH must also properly express MC4R for the circuit to appropriately regulate feeding behavior.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Arcuate Nucleus of Hypothalamus / drug effects*
  • Arcuate Nucleus of Hypothalamus / metabolism
  • Arcuate Nucleus of Hypothalamus / pathology
  • Cyclin-Dependent Kinase 4 / antagonists & inhibitors
  • Cyclin-Dependent Kinase 6 / antagonists & inhibitors
  • Diet, High-Fat
  • Male
  • Melanocortins / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Obese
  • Mice, Transgenic
  • Nerve Net / drug effects*
  • Nerve Net / metabolism
  • Nerve Net / pathology
  • Neurons / drug effects
  • Neurons / metabolism
  • Neurons / pathology
  • Obesity / drug therapy*
  • Obesity / etiology
  • Obesity / metabolism
  • Obesity / pathology
  • Paraventricular Hypothalamic Nucleus / drug effects*
  • Paraventricular Hypothalamic Nucleus / metabolism
  • Paraventricular Hypothalamic Nucleus / pathology
  • Protein Kinase Inhibitors / pharmacology
  • Protein Kinase Inhibitors / therapeutic use*
  • Receptor, Melanocortin, Type 4 / genetics
  • Signal Transduction / drug effects

Substances

  • MC4R protein, mouse
  • Melanocortins
  • Protein Kinase Inhibitors
  • Receptor, Melanocortin, Type 4
  • Cyclin-Dependent Kinase 4
  • Cyclin-Dependent Kinase 6