title: Metformin increases phagocytosis and acidifies lysosomal/endosomal compartments in AMPK-dependent manner in rat primary microglia.
abstract: Recent evidence suggests that metformin shows beneficial effects in experimental models of neuroinflammatory diseases. The aim of the present study was to determine the effect of metformin on phagocytosis and acidification of lysosomal/endosomal compartments in rat primary microglia in the presence of lipopolysaccharide (LPS) and/or beta-peptides (25-35), (1-40), and (1-42). Metformin increased the phagocytosis of fluorescent microspheres in the presence or absence of all the beta-peptides. However, the drug had no effect on the phagocytosis in LPS-stimulated microglia regardless of the presence of all the beta-peptides. Metformin acidified the lysosomal/endosomal compartments in the presence or absence of the beta-peptide 1-40 in both resting and activated microglia. To elucidate the mechanism of metformin action, we used 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside as an activator of adenosine monophosphate-activated protein kinase (AMPK) and compound C as a confirmed pharmacological inhibitor of AMPK. We have shown that metformin increased AMPK activity in microglial cells and that all observed effects are AMPK-dependent because the pretreatment of microglia with compound C reversed the effects of the drug. Since degradation of proteins in lysosomal/endosomal compartments depends largely on their phagocytosis and acidification, metformin may be beneficial in proteinopathies affecting the brain.
authors.affiliation: Department of Clinical Pharmacology, Medical University of Silesia, Medyków 18, 40-752 Katowice, Poland. labuzek@rubikon.pl
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Labuzek
authors.forename: Sebastian
authors.initials: S
authors.lastname: Liber
authors.forename: Bozena
authors.initials: B
authors.lastname: Gabryel
authors.forename: Jakub
authors.initials: J
authors.lastname: Adamczyk
authors.forename: Bogusław
authors.initials: B
authors.lastname: Okopień
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D016229:Amyloid beta-Peptides / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D011992:Endosomes / Q000187:drug effects* / Q000378:metabolism; D004789:Enzyme Activation; D006863:Hydrogen-Ion Concentration; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008247:Lysosomes / Q000187:drug effects* / Q000378:metabolism; D008687:Metformin / Q000494:pharmacology*; D017628:Microglia / Q000187:drug effects* / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology; D010587:Phagocytosis / Q000187:drug effects*; D010750:Phosphoproteins / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012265:Ribonucleotides / Q000494:pharmacology
chemical_list: D016229:Amyloid beta-Peptides; D007004:Hypoglycemic Agents; D008070:Lipopolysaccharides; D010446:Peptide Fragments; D010750:Phosphoproteins; D011720:Pyrazoles; D011743:Pyrimidines; D012265:Ribonucleotides; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42); C074636:amyloid beta-protein (25-35); C516138:dorsomorphin; D000620:Aminoimidazole Carboxamide; D008687:Metformin; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide