The Anti-apoptotic Action of 5-Hydroxyindole: Protection of Mitochondrial Integrity

Abstract

5-Hydroxyindole (5HI) is a metabolite of tryptophan that is involved in learning and memory as well as in central nervous system regulation, such as in blocking desensitization.1) 5HI also has anti-oxidant activity, 2,3) but its cellular targets are unclear.Oxidative stress can be induced by endogenous processes in which the balance between reductants and oxidants becomes slanted towards the oxidative side. Most oxidants are derived from oxygen and nitrogen based reactive species (RS), including reactive oxygen species (ROS) and lipid peroxidation byproducts.4) ROS cause oxidative modification and play important roles in abnormal pathological processes and biochemical functions. 5,6) ROS also can induce apoptosis in many different cell systems. 7) tert-Butylhydroperoxide (t-BHP) can cause oxidative stress and cell damage. 8) t-BHP is a strong RS inducer of lipid peroxidation, and causes glutathione (GSH) depletion and peroxynitrite (ONOO Ϫ ) generation.9,10) A short-chain analog of lipid hydroperoxides, t-BHP is used often as a model compound to establish the mechanism of cell damage initiated by oxidative stress. 8)Mitochondrial integrity is constantly threatened by the presence of RS produced in the membrane. High RS levels in the mitochondria can compromise mitochondrial membrane potential (Dym), leading to depolarization 11) and apoptotic events, including cytochrome c release and caspase activation.12) Here, we attempted to identify the cellular mechanisms of 5HI by focusing on mitochondria and associated apoptotic processes. Our findings show that 5HI treatment inhibited damage from oxidative stress and apoptosis in t-BHP-induced human fibroblast cell. These findings are supported by the data gained on GSH, lipid peroxidation, RS generation, DNA damage, decreased mitochondrial membrane potential, cytochrome c release, and caspase activity. MATERIALS AND METHODS MaterialsHuman fibroblasts were obtained from the American Type Culture Collection (ATCC, Manassas, VA, U.S.A.). 5HI and Dulbecco's modified Eagle's media (DMEM) were purchased form Sigma-Aldrich Chemical (St. Louis, MO, U.S.A.), as were all reagents unless otherwise stated. Fetal bovine serum (FBS), trypsin-ethylenediamineteraacetic acid, and penicillin-streptomycin were purchased from Gibco BRL (Ground Island, NY, U.S.A.). 3-(4,5-Dimethylthiazol-yl)-diphenyl tetrazolium bromide (MTT) was provided by DUCHEFA Biochemie (Haarlem, Netherlands). Antibodies for human cytochrome c, cleavedcaspase-3, and caspase-9 were purchased from Santa Cruz Biotechnology (Santa Cruz, CA, U.S.A.). Human a-tubulin antibody and 2Ј,7Ј-dichlorodihydrofluorescein diacetate (DCFDA) were obtained from Sigma-Aldrich (St. Louis, MO, U.S.A.) Horseradish peroxidase-conjugated goat antirabbit immunoglobulin G (IgG) and goat anti-mouse IgG was provided by Santa Cruz (Santa Cruz, CA, U.S.A.). 5HI was dissolved in dimethyl sulfoxide (DMSO), and the final concentration of DMSO was Ͻ0.1%.Cell Culture and MTT Assay Human fibroblast cells were cultured in DMEM containing 10% FBS, 2 mM gl...

Kynurenines: from the perspective of major psychiatric disorders

“…On the other hand, 5HI has antioxidant activity and protects mitochondrial integrity, which, in combination, is anti‐apoptotic [56], whereas OHK enhances formation of reactive oxygen species [57] which would further enhance the activities of IDO and KMO and shift the pathway to the OHK and QUIN side. Therefore, the synergistic action of 5HI and KYNA may contribute to a neuroprotective effect since KYNA antagonizes the toxic effect of QUIN.…”

Ferulate Protects the Epithelial Barrier by Maintaining Tight Junction Protein Expression and Preventing Apoptosis in Tert‐Butyl Hydroperoxide‐Induced Caco‐2 Cells

“…The prooxidant tert ‐butyl hydroperoxide ( t ‐BHP), a short‐chain analog of lipid hydroperoxide, has been widely used in research, and its many oxidative stress‐mediated cell damage effects have been described, for example, induction of apoptosis (Bae et al ., ), increasing lipid peroxidation (Park et al ., ), decreasing mitochondrial membrane potential (Drahota et al ., ), and depletion or oxidation of functionally important SH groups (Krukoski et al ., ). In addition, t ‐BHP is known to increase intestinal permeability through P‐glycoprotein dysfunction and TJ opening, which is ameliorated by antioxidants such as lutein and biliverdin (Nagira et al ., ).…”

Tryptophan and Cell Death

“…3HK has dual effect in redox balance depending on the metabolic demands of body cells, prooxidants or antioxidants. During the mitochondrial dysfunction, 3HK causes intracellular accumulation of peroxide and subsequent cell death (Okuda et al 1996 ;Tan et al 2012 ), whereas 5-hydroxyindoles, a class of Trp metabolites, protect cells by attenuating oxidative stress and consequently keeping them from mitochondrial dysfunction (Bae et al 2010 ). Actually, 5-hydroxyindoles consist of three different molecules: 5-hydroxytryptamine (serotonin), 5-hydroxytryptophan (5HTP), and 5-hydroxyindoleacetic acid (5HIAA).…”

“…Antioxidants block cytochrome c release and activation of caspase-3 during l -Kyn-induced apoptosis (Song et al 2011 ). Likewise, 5-hydroxyindole (5HI), a metabolite of Trp, markedly inhibits cytochrome c release and caspase-3 activation but not caspase-9 activation by attenuating oxidative stress (Bae et al 2010 ).…”