title: L-cysteine reversibly inhibits glucose-induced biphasic insulin secretion and ATP production by inactivating PKM2.
abstract: Increase in the concentration of plasma L-cysteine is closely associated with defective insulin secretion from pancreatic β-cells, which results in type 2 diabetes (T2D). In this study, we investigated the effects of prolonged L-cysteine treatment on glucose-stimulated insulin secretion (GSIS) from mouse insulinoma 6 (MIN6) cells and from mouse pancreatic islets, and found that the treatment reversibly inhibited glucose-induced ATP production and resulting GSIS without affecting proinsulin and insulin synthesis. Comprehensive metabolic analyses using capillary electrophoresis time-of-flight mass spectrometry showed that prolonged L-cysteine treatment decreased the levels of pyruvate and its downstream metabolites. In addition, methyl pyruvate, a membrane-permeable form of pyruvate, rescued L-cysteine-induced inhibition of GSIS. Based on these results, we found that both in vitro and in MIN6 cells, L-cysteine specifically inhibited the activity of pyruvate kinase muscle isoform 2 (PKM2), an isoform of pyruvate kinases that catalyze the conversion of phosphoenolpyruvate to pyruvate. L-cysteine also induced PKM2 subunit dissociation (tetramers to dimers/monomers) in cells, which resulted in impaired glucose-induced ATP production for GSIS. DASA-10 (NCGC00181061, a substituted N,N'-diarylsulfonamide), a specific activator for PKM2, restored the tetramer formation and the activity of PKM2, glucose-induced ATP production, and biphasic insulin secretion in L-cysteine-treated cells. Collectively, our results demonstrate that impaired insulin secretion due to exposure to L-cysteine resulted from its direct binding and inactivation of PKM2 and suggest that PKM2 is a potential therapeutic target for T2D.
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan;
authors.forename: Daiki
authors.initials: D
authors.lastname: Nakatsu
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan;
authors.forename: Yuta
authors.initials: Y
authors.lastname: Horiuchi
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan; Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan;
authors.forename: Fumi
authors.initials: F
authors.lastname: Kano
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan;
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Noguchi
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan;
authors.forename: Taichi
authors.initials: T
authors.lastname: Sugawara
authors.affiliation: Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan;
authors.forename: Iseki
authors.initials: I
authors.lastname: Takamoto
authors.affiliation: Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan; Department of Clinical Nutrition Therapy, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan; and Laboratory for Metabolic Homeostasis, RIKEN Center for Integrative Medical Sciences, 1-7-22 Suehiro-cho, Turumi-ku, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Kubota
authors.affiliation: Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan;
authors.forename: Takashi
authors.initials: T
authors.lastname: Kadowaki
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan; mmurata@bio.c.u-tokyo.ac.jp.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Murata
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis*; D000818:Animals; D002352:Carrier Proteins / Q000037:antagonists & inhibitors*; D002460:Cell Line; D003545:Cysteine / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D008565:Membrane Proteins / Q000037:antagonists & inhibitors*; D051379:Mice; D013963:Thyroid Hormones; D000097810:Thyroid Hormone-Binding Proteins
chemical_list: D000255:Adenosine Triphosphate; D002352:Carrier Proteins; D003545:Cysteine; D005947:Glucose; D007328:Insulin; D008565:Membrane Proteins; D013963:Thyroid Hormones; D000097810:Thyroid Hormone-Binding Proteins
keywords: L-cysteine; PKM2; insulin secretion; metabolomics; type 2 diabetes