Deletion of Lkb1 in pro-opiomelanocortin neurons impairs peripheral glucose homeostasis in mice
Research output: Contribution to journal › Article › peer-review
Colleges, School and Institutes
- Laboratory of Diabetes and Obesity, Endocrinology and Nutrition Unit, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Hospital Clinic de Barcelona, Barcelona, Spain.
OBJECTIVE: AMP-activated protein kinase (AMPK) signaling acts as a sensor of nutrients and hormones in the hypothalamus, thereby regulating whole-body energy homeostasis. Deletion of Ampkα2 in pro-opiomelanocortin (POMC) neurons causes obesity and defective neuronal glucose sensing. LKB1, the Peutz-Jeghers syndrome gene product, and Ca(2+)-calmodulin-dependent protein kinase kinase β (CaMKKβ) are key upstream activators of AMPK. This study aimed to determine their role in POMC neurons upon energy and glucose homeostasis regulation.
RESEARCH DESIGN AND METHODS: Mice lacking either Camkkβ or Lkb1 in POMC neurons were generated, and physiological, electrophysiological, and molecular biology studies were performed.
RESULTS: Deletion of Camkkβ in POMC neurons does not alter energy homeostasis or glucose metabolism. In contrast, female mice lacking Lkb1 in POMC neurons (PomcLkb1KO) display glucose intolerance, insulin resistance, impaired suppression of hepatic glucose production, and altered expression of hepatic metabolic genes. The underlying cellular defect in PomcLkb1KO mice involves a reduction in melanocortin tone caused by decreased α-melanocyte-stimulating hormone secretion. However, Lkb1-deficient POMC neurons showed normal glucose sensing, and body weight was unchanged in PomcLkb1KO mice.
CONCLUSIONS: Our findings demonstrate that LKB1 in hypothalamic POMC neurons plays a key role in the central regulation of peripheral glucose metabolism but not body-weight control. This phenotype contrasts with that seen in mice lacking AMPK in POMC neurons with defects in body-weight regulation but not glucose homeostasis, which suggests that LKB1 plays additional functions distinct from activating AMPK in POMC neurons.
|Number of pages||11|
|Publication status||Published - Mar 2011|
- Analysis of Variance, Animals, Area Under Curve, Body Weight, Cell Count, Eating, Electrophysiology, Energy Metabolism, Female, Glucose, Glucose Clamp Technique, Homeostasis, Hypothalamus, Immunohistochemistry, Insulin Resistance, Male, Mice, Mice, Transgenic, Neurons, Pro-Opiomelanocortin, Protein-Serine-Threonine Kinases, Reverse Transcriptase Polymerase Chain Reaction, Signal Transduction, Statistics, Nonparametric, Journal Article, Research Support, Non-U.S. Gov't