title: Insulin-like growth factor 1 specifically up-regulates expression of modifier subunit of glutamate-cysteine ligase and enhances glutathione synthesis in SH-SY5Y cells.
abstract: Glutathione is a key regulator of oxidative balance in all mammals, especially in the central nervous system. The first step of glutathione synthesis is catalyzed by glutamate-cysteine ligase (GCL), which is composed of catalytic and modifier subunits (GCLC and GCLM, respectively). In non-neural cells and tissues, insulin and insulin-like growth factor 1 (IGF-1) have been found to stimulate transcription of GCLC gene. Here we found that treatment of human neuroblastoma SH-SY5Y cells with insulin or IGF-1 increased mRNA level of GCLM, but not of GCLC, in a concentration- and time-dependent manner. In contrast, insulin did not increase GCL expression in rat C6 glioma cells. We also confirmed that IGF-1 increased protein level of GCLM and cellular glutathione content in SH-SY5Y cells. In addition, IGF-1 increased nuclear factor erythroid 2-related factor 2 (Nrf2) protein in the nuclear fraction of SH-SY5Y cells. siRNA-mediated knockdown of Nrf2 protein expression abrogated IGF-1-induced up-regulation of GCLM mRNA expression. Finally, IGF-1-induced increase in nuclear Nrf2 protein and GCLM mRNA expression was abolished by LY294002, a phosphoinositide 3-kinase inhibitor. These results indicate that insulin and IGF-1 have the ability to enhance glutathione biosynthesis in neuronal cells via specific up-regulation of GCLM expression.
authors.affiliation: Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Shuhei
authors.initials: S
authors.lastname: Takahashi
authors.affiliation: Priority Organization for Innovation and Excellence, Kumamoto University, Kumamoto, Japan; Program for Leading Graduate Schools "HIGO (Health Life Science: Interdisciplinary and Glocal Oriented) Program", Kumamoto University, Kumamoto, Japan.
authors.forename: Akinori
authors.initials: A
authors.lastname: Hisatsune
authors.affiliation: Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kurauchi
authors.affiliation: Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Seki
authors.affiliation: Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Katsuki
mesh_terms: D064413:3-Phosphoinositide-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D000818:Animals; D045744:Cell Line, Tumor; D002867:Chromones / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D005721:Glutamate-Cysteine Ligase / Q000096:biosynthesis* / Q000187:drug effects / Q000235:genetics; D005978:Glutathione / Q000096:biosynthesis*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D009025:Morpholines / Q000494:pharmacology; D051267:NF-E2-Related Factor 2 / Q000096:biosynthesis / Q000235:genetics; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D002867:Chromones; D009025:Morpholines; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D018696:Neuroprotective Agents; D034741:RNA, Small Interfering; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D007334:Insulin-Like Growth Factor I; D064413:3-Phosphoinositide-Dependent Protein Kinases; C000609392:GCLC protein, human; C546365:GCLM protein, human; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione
keywords: Extracellular signal-regulated kinase; Neuroprotection; Neurotrophic factor; Oxidative stress; PI3-kinase