Oxygen and Conformation Dependent Protein Oxidation and Aggregation by Porphyrins in Hepatocytes and Light-Exposed Cells.

Autor:	Maitra D; Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan. Electronic address: dm1401@cabm.rutgers.edu., Carter EL; Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan., Richardson R; Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan., Rittié L; Department of Dermatology, University of Michigan, Ann Arbor, Michigan., Basrur V; Department of Pathology, University of Michigan, Ann Arbor, Michigan., Zhang H; Department of Pharmacology, University of Michigan, Ann Arbor, Michigan., Nesvizhskii AI; Department of Pathology, University of Michigan, Ann Arbor, Michigan., Osawa Y; Department of Pharmacology, University of Michigan, Ann Arbor, Michigan., Wolf MW; Department of Chemistry, University of Michigan, Ann Arbor, Michigan., Ragsdale SW; Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan., Lehnert N; Department of Chemistry, University of Michigan, Ann Arbor, Michigan; Department of Biophysics, University of Michigan, Ann Arbor, Michigan., Herrmann H; Institute of Neuropathology, University Hospital Erlangen, Erlangen, Germany; Division of Molecular Genetics, German Cancer Research Center, Heidelberg, Germany., Omary MB; Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan; Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan; Cell Biology, Faculty of Science and Technology, Åbo Akademi University, Turku, Finland.
Jazyk:	angličtina
Zdroj:	Cellular and molecular gastroenterology and hepatology [Cell Mol Gastroenterol Hepatol] 2019; Vol. 8 (4), pp. 659-682.e1. Date of Electronic Publication: 2019 Jun 04.
DOI:	10.1016/j.jcmgh.2019.05.010
Abstrakt:	Background & Aims: Porphyrias are caused by porphyrin accumulation resulting from defects in the heme biosynthetic pathway that typically lead to photosensitivity and possible end-stage liver disease with an increased risk of hepatocellular carcinoma. Our aims were to study the mechanism of porphyrin-induced cell damage and protein aggregation, including liver injury, where light exposure is absent. Methods: Porphyria was induced in vivo in mice using 3,5-diethoxycarbonyl-1,4-dihydrocollidine or in vitro by exposing human liver Huh7 cells and keratinocytes, or their lysates, to protoporphyrin-IX, other porphyrins, or to δ-aminolevulinic acid plus deferoxamine. The livers, cultured cells, or porphyrin exposed purified proteins were analyzed for protein aggregation and oxidation using immunoblotting, mass spectrometry, and electron paramagnetic resonance spectroscopy. Consequences on cell-cycle progression were assessed. Results: Porphyrin-mediated protein aggregation required porphyrin-photosensitized singlet oxygen and porphyrin carboxylate side-chain deprotonation, and occurred with site-selective native protein methionine oxidation. Noncovalent interaction of protoporphyrin-IX with oxidized proteins led to protein aggregation that was reversed by incubation with acidified n-butanol or high-salt buffer. Phototoxicity and the ensuing proteotoxicity, mimicking porphyria photosensitivity conditions, were validated in cultured keratinocytes. Protoporphyrin-IX inhibited proteasome function by aggregating several proteasomal subunits, and caused cell growth arrest and aggregation of key cell proliferation proteins. Light-independent synergy of protein aggregation was observed when porphyrin was applied together with glucose oxidase as a secondary peroxide source. Conclusions: Photo-excitable porphyrins with deprotonated carboxylates mediate protein aggregation. Porphyrin-mediated proteotoxicity in the absence of light, as in the liver, requires porphyrin accumulation coupled with a second tissue oxidative injury. These findings provide a potential mechanism for internal organ damage and photosensitivity in porphyrias. (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)
Databáze:	MEDLINE
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