title: Overexpression of BAX INHIBITOR-1 Links Plasma Membrane Microdomain Proteins to Stress.
abstract: BAX INHIBITOR-1 (BI-1) is a cell death suppressor widely conserved in plants and animals. Overexpression of BI-1 enhances tolerance to stress-induced cell death in plant cells, although the molecular mechanism behind this enhancement is unclear. We recently found that Arabidopsis (Arabidopsis thaliana) BI-1 is involved in the metabolism of sphingolipids, such as the synthesis of 2-hydroxy fatty acids, suggesting the involvement of sphingolipids in the cell death regulatory mechanism downstream of BI-1. Here, we show that BI-1 affects cell death-associated components localized in sphingolipid-enriched microdomains of the plasma membrane in rice (Oryza sativa) cells. The amount of 2-hydroxy fatty acid-containing glucosylceramide increased in the detergent-resistant membrane (DRM; a biochemical counterpart of plasma membrane microdomains) fraction obtained from BI-1-overexpressing rice cells. Comparative proteomics analysis showed quantitative changes of DRM proteins in BI-1-overexpressing cells. In particular, the protein abundance of FLOTILLIN HOMOLOG (FLOT) and HYPERSENSITIVE-INDUCED REACTION PROTEIN3 (HIR3) markedly decreased in DRM of BI-1-overexpressing cells. Loss-of-function analysis demonstrated that FLOT and HIR3 are required for cell death by oxidative stress and salicylic acid, suggesting that the decreased levels of these proteins directly contribute to the stress-tolerant phenotypes in BI-1-overexpressing rice cells. These findings provide a novel biological implication of plant membrane microdomains in stress-induced cell death, which is negatively modulated by BI-1 overexpression via decreasing the abundance of a set of key proteins involved in cell death.
authors: Graduate School of Science and Engineering (T.I., M.K.-Y.) and Institute for Environmental Science and Technology (H.U., M.K.-Y.), Saitama University, Saitama City, Saitama 338-8570, Japan; andGraduate School of Agricultural and Life Sciences (T.A., S.Y.) and Biotechnology Research Center (S.Y.), University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors: Toshiki
authors: T
authors: Ishikawa
authors: Graduate School of Science and Engineering (T.I., M.K.-Y.) and Institute for Environmental Science and Technology (H.U., M.K.-Y.), Saitama University, Saitama City, Saitama 338-8570, Japan; andGraduate School of Agricultural and Life Sciences (T.A., S.Y.) and Biotechnology Research Center (S.Y.), University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors: Toshihiko
authors: T
authors: Aki
authors: Graduate School of Science and Engineering (T.I., M.K.-Y.) and Institute for Environmental Science and Technology (H.U., M.K.-Y.), Saitama University, Saitama City, Saitama 338-8570, Japan; andGraduate School of Agricultural and Life Sciences (T.A., S.Y.) and Biotechnology Research Center (S.Y.), University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors: Shuichi
authors: S
authors: Yanagisawa
authors: Graduate School of Science and Engineering (T.I., M.K.-Y.) and Institute for Environmental Science and Technology (H.U., M.K.-Y.), Saitama University, Saitama City, Saitama 338-8570, Japan; andGraduate School of Agricultural and Life Sciences (T.A., S.Y.) and Biotechnology Research Center (S.Y.), University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors: Hirofumi
authors: H
authors: Uchimiya
authors: Graduate School of Science and Engineering (T.I., M.K.-Y.) and Institute for Environmental Science and Technology (H.U., M.K.-Y.), Saitama University, Saitama City, Saitama 338-8570, Japan; andGraduate School of Agricultural and Life Sciences (T.A., S.Y.) and Biotechnology Research Center (S.Y.), University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan mkawai@mail.saitama-u.ac.jp.
authors: Maki
authors: M
authors: Kawai-Yamada
mesh_terms: D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects; D018506:Gene Expression Regulation, Plant; D005963:Glucosylceramides / Q000737:chemistry / Q000378:metabolism; D021962:Membrane Microdomains / Q000737:chemistry / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D012275:Oryza / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D018384:Oxidative Stress / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D040901:Proteomics / Q000379:methods; D020156:Salicylic Acid / Q000378:metabolism / Q000494:pharmacology; D013107:Sphingolipids / Q000737:chemistry / Q000378:metabolism; D013312:Stress, Physiological / Q000235:genetics
chemical_list: C491862:ATBI-1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D005963:Glucosylceramides; D008565:Membrane Proteins; D010940:Plant Proteins; D013107:Sphingolipids; D020156:Salicylic Acid