8638 NEGR1 is a Mediator of Exercise-Induced Neuritogenesis in Subcutaneous White Adipose Tissue, Implications for Improved Systemic Metabolism
Authors: Nigro P , Carbone N P , Caputo T , Vamvini M , Columbus M M , Hirshman M F , Middelbeek R , Goodyear L J 
Published: October 2024

Disclosure: P. Nigro: None. N.P. Carbone: None. T. Caputo: None. M. Vamvini: None. M.M. Columbus: None. M.F. Hirshman: None. R. Middelbeek: None. L.J. Goodyear: None.

Emerging research shows that exercise training results in robust and beneficial adaptions to subcutaneous white adipose tissue (scWAT), leading to improved systemic metabolism. The mechanisms for these benefits of exercise on are not fully understood, but we have recently demonstrated that training in mouse scWAT refines nerve connections in scWAT promoting neurite outgrowth (neuritogenesis). Our multi-omics and advanced microscopy data identifies Neuronal Growth Regulator 1 (NEGR1) as a potential player in this process. Here, we determine the role of NEGR1 as a mediator of scWAT neuritogenesis and regulator of systemic metabolism. Exercise training in mice for 11 days significantly increased NEGR1 protein expression by 35% (p&lt;0.05). Next, we directly injected NEGR1 AAV into the inguinal scWAT of untrained male mice for three weeks resulting in a 43% increase in NEGR1 protein (p&lt;0.05). Overexpression of NEGR1 led to an increase in the innervation markers tyrosine hydroxylase (+38%, p&lt;0.01) and synaptophysin (+39%, p&lt;0.01), and remarkably, a 16% decrease in adipocyte cell size (p&lt;0.05), and a 15% reduction in fasting blood glucose levels (p&lt;0.05). This suggests that NEGR1 plays a fundamental role in regulating scWAT morphology and function, adaptations that improve systemic glucose homeostasis. To determine mechanisms for exercise training-induced increases in NEGR1 expression, we used in silico and cell culture experiments and found that NEGR1 is under the regulation of the Peroxisome Proliferator-Activated Receptor gamma (PPARg) transcription factor. Given that numerous natural and synthetic PPARg ligands are lipids, we used targeted lipidomics to identify exercise-induced lipids capable of binding and inducing PPARg expression in inguinal scWAT. We identified 13-oxo-octadecadienoic acid (13-oxo-ODE), an oxylipin derived from linoleic acid, as a potent agonist and inducer of PPARg expression. Exercise training increased 13-oxo-ODE by 3-fold (p&lt;0.05), and 13-hydroxyoctadecadienoic acid (13-HODE), the 13-oxo-ODE precursor was also increased by 3-fold (p&lt;0.01). To validate that 13-oxo-ODE increases NEGR1, adipocytes were incubated with 2μM of 13-oxo-ODE for 48 hours. 13-oxo-ODE increased NEGR1 expression by 27-fold (p&lt;0.0001) and NEGR1 protein by 2-fold (p&lt;0.01). In summary, NEGR1 is a novel exercise-induced molecule that regulates neuronal refinement in scWAT. Our data also suggest that the synthesis of 13-oxo-ODE leads to PPARγ activation that in turn promotes NEGR1 expression in scWAT. NEGR1 has beneficial effects on scWAT that are associated with improved systemic metabolism, making NEGR1 a novel target for treatment of obesity and cardiometabolic diseases.

Presentation: 6/1/2024