Průchová Pavla, Gotvaldová Klára, Smolková Katarína, Alán Lukáš, Holendová Blanka, Tauber Jan, Galkin Alexander, Ježek Petr, Jabůrek Martin
Department of Mitochondrial Physiology, No. 75, Institute of Physiology of the Czech Academy of Sciences, 142 20 Prague, Czech Republic.
Department of Biochemistry and Microbiology, Faculty of Food and Biochemical Technology, University of Chemistry and Technology, 166 28 Prague, Czech Republic.
Antioxidants (Basel). 2022 Jan 20;11(2):198. doi: 10.3390/antiox11020198.
Mitochondrial Ca-independent phospholipase Aγ (iPLAγ/PNPLA8) was previously shown to be directly activated by HO and release free fatty acids (FAs) for FA-dependent H transport mediated by the adenine nucleotide translocase (ANT) or uncoupling protein 2 (UCP2). The resulting mild mitochondrial uncoupling and consequent partial attenuation of mitochondrial superoxide production lead to an antioxidant effect. However, the antioxidant role of iPLAγ in the brain is not completely understood. Here, using wild-type and iPLAγ-KO mice, we demonstrate the ability of -butylhydroperoxide (TBHP) to activate iPLAγ in isolated brain mitochondria, with consequent liberation of FAs and lysophospholipids. The liberated FA caused an increase in respiratory rate, which was fully inhibited by carboxyatractyloside (CATR), a specific inhibitor of ANT. Employing detailed lipidomic analysis, we also demonstrate a typical cleavage pattern for TBHP-activated iPLAγ, reflecting cleavage of glycerophospholipids from both -1 and -2 positions releasing saturated FAs, monoenoic FAs, and predominant polyunsaturated FAs. The acute antioxidant role of iPLAγ-released FAs is supported by monitoring both intramitochondrial superoxide and extramitochondrial HO release. We also show that iPLAγ-KO mice were more sensitive to stimulation by pro-inflammatory lipopolysaccharide, as reflected by the concomitant increase in protein carbonyls in the brain and pro-inflammatory IL-6 release in the serum. These data support the antioxidant and anti-inflammatory role of iPLAγ in vivo. Our data also reveal a substantial decrease of several high molecular weight cardiolipin (CL) species and accumulation of low molecular weight CL species in brain mitochondria of iPLAγ-KO mice. Collectively, our results support a key role of iPLAγ in the remodeling of lower molecular weight immature cardiolipins with predominantly saturated acyl chains to high molecular weight mature cardiolipins with highly unsaturated PUFA acyl chains, typical for the brain.
线粒体钙非依赖性磷脂酶Aγ（iPLAγ/PNPLA8）先前已被证明可被血红素加氧酶（HO）直接激活，并释放游离脂肪酸（FAs），用于由腺嘌呤核苷酸转位酶（ANT）或解偶联蛋白2（UCP2）介导的FA依赖性H转运。由此产生的轻度线粒体解偶联以及随后线粒体超氧化物产生的部分减弱导致抗氧化作用。然而，iPLAγ在大脑中的抗氧化作用尚未完全了解。在这里，我们使用野生型和iPLAγ基因敲除（KO）小鼠，证明了叔丁基过氧化氢（TBHP）能够激活分离的脑线粒体中的iPLAγ，从而释放脂肪酸和溶血磷脂。释放的FA导致呼吸速率增加，这被ANT的特异性抑制剂羧基苍术苷（CATR）完全抑制。通过详细的脂质组学分析，我们还证明了TBHP激活的iPLAγ具有典型的裂解模式，反映了甘油磷脂从-1和-2位的裂解，释放出饱和FA、单烯FA和主要的多不饱和FA。通过监测线粒体内超氧化物和线粒体外HO释放，支持了iPLAγ释放的FA的急性抗氧化作用。我们还表明，iPLAγ-KO小鼠对促炎脂多糖的刺激更敏感，这反映在大脑中蛋白质羰基的同时增加和血清中促炎白细胞介素-6的释放。这些数据支持了iPLAγ在体内的抗氧化和抗炎作用。我们的数据还揭示了iPLAγ-KO小鼠脑线粒体中几种高分子量心磷脂（CL）种类的大幅减少和低分子量CL种类的积累。总的来说，我们的结果支持了iPLAγ在将主要具有饱和酰基链的低分子量未成熟心磷脂重塑为具有高度不饱和多不饱和脂肪酸（PUFA）酰基链的高分子量成熟心磷脂中的关键作用，这是大脑典型的特征。
