The role of oxidative stress in Wolfram syndrome 1 and hypothermia
Date
2019-04-25
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Abstract
Wolframi sündroom on haruldane autosomaalne retsessiivne haigus, mida iseloomustavad juveniilne diabeet (magediabeet, tüüp I suhkrudiabeet), nägemisnärvi kahjustus, kuulmishäired, progressiivne neurodegeneratsioon, endokriinsed kahjustused ja psühhiaatrilised probleemid. Wolframi sündroom on põhjustatud mõlemas alleelis esinevatest mutatsioonidest WFS1 geenis, mille tõttu geeni produkt, wolframiin, ei oma enam tavapärast funktsiooni. Mutantse wolframiini puhul kuhjuvad voltumata valgud endoplasmaatilise retiikulumi luumenisse ning põhjustavad endoplasmaatilise retiikulumi stressi (ka oksüdatiivset stressi) ja sealse homoöstaasi häirumist ja apoptootilise raja käivitumist.
Antud töö peaeesmärgiks oli kirjeldada Wfs1-defektiga (KO) hiire metaboloomi ning oksüdatiivse stressi taset erinevates kudedes (maks, süda, neerud ja pankreas) ja biovedelikes (veri ja uriin) enne ja pärast antioksüdantide manustamist. Lisaks analüüsida missugune on hüpotermia mõju glutatiooni (GSH) süsteemile erinevates rakuliinides.
Selgus, et nooremad KO hiired kasutavad energia saamiseks eelkõige glükoosi, glükoneogeneesi ja anaeroobset glükolüüsi, kuid hilisemas vanuses kui haigus rohkem progresseerunud, eelistatult lipolüüsi. Lisaks esines noorematel KO hiirtel glükosuuria, mis tüüpiliselt diabeedi varajases staadiumis ei esine.
Näitasime, et redutseeritud GSH kontsentratsioon on üldiselt KO hiirte kudedes madalam kui metsiktüüpi (WT) liigikaaslastel. Maksakoes siiski täheldasime mõningast GSH taseme tõusu noortel hiirtel, mis viitab GSH sünteesi intensiivistumisele stressitingimustes. Antioksüdantse ensüümi GSH peroksüdaasi aktiivsus oli südames ja maksas KO hiirtel kõrgem ja GSH reduktaasi aktiivsus madalam võrreldes WT hiirtega. Neerukoes oli mõlema ensüümi aktiivsus KO hiirtel kõrgem. Antioksüdantite manustamine parandas eelkõige GSH taset südames ja maksakoes ning suurendas vanematel ja vähendas noorematel hiirtel GSH süsteemi ensüümide aktiivsust.
Hüpotermia-indutseeritud rakkudes on kõrgem totaalse GSH kontsentratsioon metsik-tüüpi hiire embrüonaalsetes fibroblastides ja HeLa rakkudes, kusjuures esimestes vähenes oksüdeeritud GSH tase ja teises jäi see muutumatuks.
The deficiency in WFS1 gene causes Wolfram syndrome (WS), which represents a valuable disease model currently available for identifying markers associated with endoplasmic reticulum (ER) stress, juvenile-onset diabetes and neurodegeneration. Another important factor is that WS arises from mutation of a single gene, which makes it a good model for teasing out the mechanisms of ER dysfunction than other multifactorial conditions like diabetes and oxidative stress. Studying oxidative stress and metabolic profiling of Wfs1-deficient mice under hyperglycemic conditions to find therapies aimed at reducing stress in patients or those at risk for developing diabetes. Also this might give new insight of the association between the Wfs1 and its functions. The metabolomic characterization of Wfs1-deficient mice (KO) revealed a broad spectrum of metabolic complications and affected glutathione redox status in the knock-out mice. At the whole organism level, the glucose use, gluconeogenesis and anaerobic glycolysis appear to be increased in the early stages of the disease, but later the energy demand is satisfied by intensified lipolysis. Furthermore, in the blood and liver tissue of KO mice, the progression of the WS exceeds hypouricemia into hyperuricemia. In the pancreas and heart tissue young mice, glycosuria preceded hyperglycemia, which implied to kidney dysfunction. The concentration of reduced glutathione (GSH) was generally decreased in Wfs1-deficient mice, but a slight upregulation of GSH in the liver is probably an attempt to control ER stress. In the liver and heart the activity of glutathione peroxidase was increased and the activity of glutathione reductase was decreased in KO mice compared to wild-type littermates. In the kidneys KO mice, the activity of both enzymes increased. The antioxidants had the highest effect improving the glutathione status in the liver and heart tissue of Wfs1-deficient mice. In the liver tissue, the studied antioxidants mainly reduced the acitivity of glutathione reductase and peroxidase in older mice and inversely in the younger littermates. Hypothermia induced the highest level of total glutathione in wild-type mouse embryonic fibroblasts and HeLa cells, whereas the concentration of oxidized glutathione was decreased or remained unchanged, respectively.
The deficiency in WFS1 gene causes Wolfram syndrome (WS), which represents a valuable disease model currently available for identifying markers associated with endoplasmic reticulum (ER) stress, juvenile-onset diabetes and neurodegeneration. Another important factor is that WS arises from mutation of a single gene, which makes it a good model for teasing out the mechanisms of ER dysfunction than other multifactorial conditions like diabetes and oxidative stress. Studying oxidative stress and metabolic profiling of Wfs1-deficient mice under hyperglycemic conditions to find therapies aimed at reducing stress in patients or those at risk for developing diabetes. Also this might give new insight of the association between the Wfs1 and its functions. The metabolomic characterization of Wfs1-deficient mice (KO) revealed a broad spectrum of metabolic complications and affected glutathione redox status in the knock-out mice. At the whole organism level, the glucose use, gluconeogenesis and anaerobic glycolysis appear to be increased in the early stages of the disease, but later the energy demand is satisfied by intensified lipolysis. Furthermore, in the blood and liver tissue of KO mice, the progression of the WS exceeds hypouricemia into hyperuricemia. In the pancreas and heart tissue young mice, glycosuria preceded hyperglycemia, which implied to kidney dysfunction. The concentration of reduced glutathione (GSH) was generally decreased in Wfs1-deficient mice, but a slight upregulation of GSH in the liver is probably an attempt to control ER stress. In the liver and heart the activity of glutathione peroxidase was increased and the activity of glutathione reductase was decreased in KO mice compared to wild-type littermates. In the kidneys KO mice, the activity of both enzymes increased. The antioxidants had the highest effect improving the glutathione status in the liver and heart tissue of Wfs1-deficient mice. In the liver tissue, the studied antioxidants mainly reduced the acitivity of glutathione reductase and peroxidase in older mice and inversely in the younger littermates. Hypothermia induced the highest level of total glutathione in wild-type mouse embryonic fibroblasts and HeLa cells, whereas the concentration of oxidized glutathione was decreased or remained unchanged, respectively.
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Keywords
oksüdatiivne stress, Wolframi sündroom, hüpotermia