Patatin-like phospholipase domain-containing protein PNPLA8, also termed Ca2+-independent phospholipase A2γ (iPLA2γ), is addressed to the mitochondrial matrix (or peroxisomes), where it may manifest its unique activity to cleave phospholipid side-chains from both sn-1 and sn-2 positions, consequently releasing either saturated or unsaturated fatty acids (FAs), including oxidized FAs. Moreover, iPLA2γ is directly stimulated by H2O2 and, hence, is activated by redox signaling or oxidative stress. This redox activation permits the antioxidant synergy with mitochondrial uncoupling proteins (UCPs) or other SLC25 mitochondrial carrier family members by FA-mediated protonophoretic activity, termed mild uncoupling, that leads to diminishing of mitochondrial superoxide formation. This mechanism allows for the maintenance of the steady-state redox status of the cell. Besides the antioxidant role, we review the relations of iPLA2γ to lipid peroxidation since iPLA2γ is alternatively activated by cardiolipin hydroperoxides and hypothetically by structural alterations of lipid bilayer due to lipid peroxidation. Other iPLA2γ roles include the remodeling of mitochondrial (or peroxisomal) membranes and the generation of specific lipid second messengers. Thus, for example, during FA β-oxidation in pancreatic β-cells, H2O2-activated iPLA2γ supplies the GPR40 metabotropic FA receptor to amplify FA-stimulated insulin secretion. Cytoprotective roles of iPLA2γ in the heart and brain are also discussed.

• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Mitochondrial uncoupling protein-2 (UCP2) mediates free fatty acid (FA)-dependent H+ translocation across the inner mitochondrial membrane (IMM), which leads to acceleration of respiration and suppression of mitochondrial superoxide formation. Redox-activated mitochondrial phospholipase A2 (mt-iPLA2γ) cleaves FAs from the IMM and has been shown to acts in synergy with UCP2. Here, we tested the mechanism of mt-iPLA2γ-dependent UCP2-mediated antioxidant protection using lipopolysaccharide (LPS)-induced pro-inflammatory and pro-oxidative responses and their acute influence on the overall oxidative stress reflected by protein carbonylation in murine lung and spleen mitochondria and tissue homogenates. We provided challenges either by blocking the mt-iPLA 2γ function by the selective inhibitor R-bromoenol lactone (R-BEL) or by removing UCP2 by genetic ablation. We found that the basal levels of protein carbonyls in lung and spleen tissues and isolated mitochondria were higher in UCP2-knockout mice relative to the wild-type (wt) controls. The administration of R-BEL increased protein carbonyl levels in wt but not in UCP2-knockout (UCP2-KO) mice. LPS further increased the protein carbonyl levels in UCP2-KO mice, which correlated with protein carbonyl levels determined in wt mice treated with R-BEL. These results are consistent with the UCP2/mt-iPLA 2γ antioxidant mechanisms in these tissues and support the existence of UCP2-synergic mt-iPLA 2γ-dependent cytoprotective mechanism in vivo.

• Publikační typ
• časopisecké články MeSH

Mitochondrial uncoupling protein-2 (UCP2) has been suggested to participate in the attenuation of the reactive oxygen species production, but the mechanism of action and the physiological significance of UCP2 activity remain controversial. Here we tested the hypothesis that UCP2 provides feedback downregulation of oxidative stress in vivo via synergy with an H2O2-activated mitochondrial calcium-independent phospholipase A2 (mt-iPLA2). Tert-butylhydroperoxide or H2O2 induced free fatty acid release from mitochondrial membranes as detected by gas chromatography/mass spectrometry, which was inhibited by r-bromoenol lactone (r-BEL) but not by its stereoisomer s-BEL, suggesting participation of mt-iPLA2γ isoform. Tert-butylhydroperoxide or H2O2 also induced increase in respiration and decrease in mitochondrial membrane potential in lung and spleen mitochondria from control but not UCP2-knockout mice. These data suggest that mt-iPLA2γ-dependent release of free fatty acids promotes UCP2-dependent uncoupling. Upon such uncoupling, mitochondrial superoxide formation decreased instantly also in the s-BEL presence, but not when mt-iPLA2 was blocked by R-BEL and not in mitochondria from UCP2-knockout mice. Mt-iPLA2γ was alternatively activated by H2O2 produced probably in conjunction with the electron-transferring flavoprotein:ubiquinone oxidoreductase (ETFQOR), acting in fatty acid β-oxidation. Palmitoyl-d,l-carnitine addition to mouse lung mitochondria, respiring with succinate plus rotenone, caused a respiration increase that was sensitive to r-BEL and insensitive to s-BEL. We thus demonstrate for the first time that UCP2, functional due to fatty acids released by redox-activated mt-iPLA2γ, suppresses mitochondrial superoxide production by its uncoupling action. In conclusion, H2O2-activated mt-iPLA2γ and UCP2 act in concert to protect against oxidative stress.

• MeSH
• antioxidancia metabolismus   MeSH
• buněčné dýchání účinky léků   MeSH
• down regulace účinky léků   MeSH
• fosfolipasy A2, skupina VI metabolismus   MeSH
• iontové kanály metabolismus   MeSH
• játra cytologie   MeSH
• mastné kyseliny sekrece   MeSH
• mitochondriální proteiny metabolismus   MeSH
• mitochondrie účinky léků   enzymologie   metabolismus   MeSH
• myši MeSH
• oxidace-redukce MeSH
• oxidační stres účinky léků   MeSH
• peroxid vodíku farmakologie   MeSH
• slezina cytologie   MeSH
• superoxidy metabolismus   MeSH
• terc-butylhydroperoxid farmakologie   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Cíl studie: Cílem studie byla longitudinální analýza progredujících dopplerometrických abnormalit u intrauterinní růstové retardace plodu (IUGR) od začátku placentální insuficience. Typ studie: Prospektivní studie. Název a sídlo pracoviště: Gynekologicko-porodnická klinika, LF UP a FN Olomouc. Metodika: Studovaný soubor tvoří 77 těhotných s intrauterinní růstovou retardací plodu placentálního původu. U 59 z nich byly dynamicky sledovány intervaly progrese od počátečních až k pokročilým dopplerometrickým abnormalitám a těhotné byly zařazeny do 3 typů placentální insuficience. Výsledky: Bylo provedeno 486 dopplerometrických měření u 77 těhotných. Podle progrese změn bylo 21 těhotných s lehkou placentální insuficienci (abnormality UA a CPR nepřesáhly 3 SD, progresivní interval byl 31 dnů), u 28 těhotných byla zjištěna progresivní placentální insuficience (celé spektrum abnormalit s progresivním intervalem 18 dnů) a 10 těhotných mělo těžkou formu placentální insuficience (časný nástup abnormalit před 30. týdnem gestace s celým spektrem abnormalit a s progresivním intervalem 8 dnů). Závěr: Gestační věk vzniku první abnormality (vzestup pulzatilního indexu UA nad 2 SD) a časový interval k další abnormalitě (pokles CPR pod 2 SD) jsou významné při posuzování závažnosti placentální insuficience. Dynamická sledování abnormit umožňují lépe vyhodnotit aktuální riziko, anticipovat další vývoj placentální insuficience a učinit včasná opatření k předcházení nepříznivým perinatálním výsledkům.

Objective: The aim of the study was the longitudinal analysis of the progression of dopplerometric abnormalities in intrauterine growth retardation (IUGR) since the onset of placental insufficiency. Design: Prospective study. Setting: Dept. of Gynaecology and Obstetrics, Medical Faculty and University Hospital, Olomouc. Methods: The study group consisted of 77 pregnat women with intrauterine growth retardation resulting from placental insufficiency. Of these, in 59 women, the intervals of progression were followed from the early to the advanced dopplerometric abnormalities. According to the findings the patients were classified into one of the three types of placental insufficiency. Results: In total, 486 dopplerometric measurements in 77 pregnant patients were performed. Mild placental insufficiency where abnormality of umbilical artery (UA) and cerebroplacental ratio (CPR) did not exceed 3 SD and the progressive interval was 31 days was found in 21 pregnat patients. Progressive placental insufficiency with a whole spectrum of abnormalities and the progressive interval of 18 days was found in 28 pregnat patients. Severe form of placental insufficiency (early onset of abnormalities before the 30th gestational week) a whole spectrum of abnormalities and progressive interval 8 days was found in 10 pregnat patients. Conclusions: Gestational week at the occurence of the first abnormality (elevation of the pulsatility index of UA over 2 SD) and the time interval to next abnormality (decrease of CPR under 2 SD) are important factors for the assessment of severity of placental insufficiency. Dynamic follow-up of abnormalities permits a better evaluation of the actual risk, the anticipation of the further development of placental insufficiency and in this way to apply suitable measures to prevent unfavourable perinatal outcomes.

• Klíčová slova
• placentální insuficience,
• MeSH
• dospělí MeSH
• interpretace statistických dat MeSH
• komplikace těhotenství prevence a kontrola   MeSH
• lidé MeSH
• longitudinální studie MeSH
• mladý dospělý MeSH
• nemoci plodu MeSH
• novorozenec MeSH
• placentární insuficience diagnóza   MeSH
• plod abnormality   MeSH
• progrese nemoci MeSH
• prospektivní studie MeSH
• růstová retardace plodu diagnóza   MeSH
• rychlost toku krve MeSH
• statistika jako téma MeSH
• ultrasonografie dopplerovská MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• novorozenec MeSH
• ženské pohlaví MeSH

• MeSH
• Escherichia coli metabolismus   MeSH
• finanční podpora výzkumu jako téma MeSH
• lidé MeSH
• mastné kyseliny chemie   metabolismus   MeSH
• membránové transportní proteiny fyziologie   metabolismus   MeSH
• mitochondriální proteiny fyziologie   MeSH
• mitochondrie fyziologie   MeSH
• transport proteinů MeSH
• Check Tag
• lidé MeSH