title: Methylene blue delays cellular senescence and enhances key mitochondrial biochemical pathways.
abstract: Methylene blue (MB) has been used clinically for about a century to treat numerous ailments. We show that MB and other diaminophenothiazines extend the life span of human IMR90 fibroblasts in tissue culture by >20 population doubling (PDLs). MB delays senescence at nM levels in IMR90 by enhancing mitochondrial function. MB increases mitochondrial complex IV by 30%, enhances cellular oxygen consumption by 37-70%, increases heme synthesis, and reverses premature senescence caused by H2O2 or cadmium. MB also induces phase-2 antioxidant enzymes in hepG2 cells. Flavin-dependent enzymes are known to use NAD(P)H to reduce MB to leucomethylene blue (MBH2), whereas cytochrome c reoxidizes MBH2 to MB. Experiments on lysates from rat liver mitochondria suggest the ratio MB/cytochrome c is important for the protective actions of MB. We propose that the cellular senescence delay caused by MB is due to cycling between MB and MBH2 in mitochondria, which may partly explain the increase in specific mitochondrial activities. Cycling of MB between oxidized and reduced forms may block oxidant production by mitochondria. Mitochondrial dysfunction and oxidative stress are thought to be key aberrations that lead to cellular senescence and aging. MB may be useful to delay mitochondrial dysfunction with aging and the decrease in complex IV in Alzheimer disease.
authors.affiliation: Nutrition & Metabolism Center, Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland, CA 94609-1673, USA. hatamna@chori.org
authors.forename: Hani
authors.initials: H
authors.lastname: Atamna
authors.forename: Andy
authors.initials: A
authors.lastname: Nguyen
authors.forename: Carla
authors.initials: C
authors.lastname: Schultz
authors.forename: Kathleen
authors.initials: K
authors.lastname: Boyle
authors.forename: Justin
authors.initials: J
authors.lastname: Newberry
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kato
authors.forename: Bruce N
authors.initials: BN
authors.lastname: Ames
mesh_terms: D000818:Animals; D002104:Cadmium / Q000037:antagonists & inhibitors / Q000633:toxicity; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects*; D045304:Cytochromes c / Q000378:metabolism; D004790:Enzyme Induction / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000037:antagonists & inhibitors / Q000633:toxicity; D008297:Male; D008751:Methylene Blue / Q000737:chemistry / Q000494:pharmacology*; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D016877:Oxidants / Q000037:antagonists & inhibitors / Q000633:toxicity; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D011808:Quinone Reductases / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D015398:Signal Transduction / Q000187:drug effects*; D054481:Thioredoxin Reductase 1 / Q000378:metabolism; D013997:Time Factors
chemical_list: D016877:Oxidants; D002104:Cadmium; D045304:Cytochromes c; D006861:Hydrogen Peroxide; D011808:Quinone Reductases; D054481:Thioredoxin Reductase 1; D010100:Oxygen; D008751:Methylene Blue