Colonic Mucosal Proteome Signature Reveals Reduced Energy Metabolism and Protein Synthesis but Activated Autophagy during Anorexia‐Induced Malnutrition in Mice

Abstract

Anorexia nervosa is an eating disorder often associated with intestinal disorders. To explore the underlying mechanisms of these disorders, the colonic proteome was evaluated during activity-based anorexia. Female C57Bl/6 mice were randomized into three groups: Control, Limited Food Access (LFA) and Activity-Based Anorexia (ABA). LFA and ABA mice had a progressive limited access to food but only ABA mice had access to an activity wheel. On colonic mucosal protein extracts, a 2D PAGE-based comparative proteomic analysis was then performed and differentially expressed proteins were identified by LC-ESI-MS/MS. Twenty-seven nonredundant proteins that were differentially expressed between Control, LFA, and ABA groups were identified. ABA mice exhibited alteration of several mitochondrial proteins involved in energy metabolism such as dihydrolipoyl dehydrogenase and 3-mercaptopyruvate sulfurtransferase. In addition, a downregulation of mammalian target of rapamycin (mTOR) pathway was observed leading, on the one hand, to the inhibition of protein synthesis, evaluated by puromycin incorporation and mediated by the increased phosphorylation of eukaryotic elongation factor 2, and on the other hand, to the activation of autophagy, assessed by the increase of the marker of autophagy, form LC3-phosphatidylethanolamine conjugate/Cytosolic form of Microtubule-associated protein 1A/1B light chain 3 (LC3II/LC3I) ratio. Colonic mucosal proteome is altered during ABA suggesting a downregulation of energy metabolism. A decrease of protein synthesis and an activation of autophagy were also observed mediated by mTOR pathway.

Glutamine, but not Branched-Chain Amino Acids, Restores Intestinal Barrier Function during Activity-Based Anorexia

“…Fluid intake was monitored each day by weighting drinking bottles. At day 17, mice received an intraperitoneal injection of 100 µL PBS containing puromycin (Sigma Aldrich, Saint Quentin Fallavier, France) at a dose of 0.040 µmol/g 20 min before euthanasia with a ketamine/xylazine solution, as previously described [21]. Blood was collected and stored in heparin-coated collecting tubes.…”

“…In the activity-based anorexia model (ABA) in mice, we previously reported in the colon an altered barrier function [14], a TLR-4 activation [20] and a reduced protein synthesis associated with specific modifications of proteome [21]. Glutamine is a conditionally essential amino acid and the main energy substrate for rapidly dividing cells [22,23].…”

Activity Based Anorexia as an Animal Model for Anorexia Nervosa–A Systematic Review

“…This was observed in the soleus muscle of ABA mice associated with reduced protein synthesis, while in the anterior tibialis no alterations were observed. Compared to controls and restrictedly fed mice, C57BL/6 ABA mice displayed a reduction in dihydrolipoyl dehydrogenase and 3-mercaptopyruvate sulfurtransferase and other mitochondrial proteins implicated in energy metabolism (192).…”

“…TLR4-deficient mice displayed a higher mortality rate in response to the ABA protocol (19), suggesting a dual effect of TLR4 in ABA: a key role in the early colonic inflammation and a protective effect, since its absence can be fatal. Noteworthy, ABA in female mice induced an alteration in the colonic mucosal proteome, especially proteins implicated in energy metabolism (192). The mammalian target of rapamycin (mTOR) pathway was decreased inhibiting protein synthesis (puromycin incorporation) and activating autophagy (192), giving rise to an alteration of colonic mucosal proteome due to the downregulation of energy metabolism.…”

“…Noteworthy, ABA in female mice induced an alteration in the colonic mucosal proteome, especially proteins implicated in energy metabolism (192). The mammalian target of rapamycin (mTOR) pathway was decreased inhibiting protein synthesis (puromycin incorporation) and activating autophagy (192), giving rise to an alteration of colonic mucosal proteome due to the downregulation of energy metabolism.…”