Lysophosphatidylcholine acyltransferase 1 controls the mitochondrial reactive oxygen species generation and survival of the retinal photoreceptor cells
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE184818 | GEO | 2022/01/01
REPOSITORIES: GEO
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Project description:Due to their high energy demands and characteristic morphology, retinal photoreceptor cells require a specialized lipid metabolism for survival and function. Accordingly, dysregulation of lipid metabolism leads to the photoreceptor cell death and retinal degeneration. Mice bearing a frameshift mutation in the gene encoding lysophosphatidylcholine acyltransferase 1 (Lpcat1), which produces saturated phosphatidylcholine (PC) composed of two saturated fatty acids, has been reported to cause spontaneous retinal degeneration in mice; however, the mechanism by which this mutation affects degeneration is unclear. In this study, we performed a detailed characterization of LPCAT1 in the retina and found that genetic deletion of Lpcat1 induces light-independent and photoreceptor-specific apoptosis in mice. Lipidomic analyses of the retina and isolated photoreceptor outer segment (OS) suggested that loss of Lpcat1 not only decreased saturated PC production but also affected membrane lipid composition, presumably by altering saturated fatty acyl-CoA availability. Furthermore, we demonstrated that Lpcat1 deletion led to increased mitochondrial reactive oxygen species levels in photoreceptor cells, but not in other retinal cells, and did not affect the OS structure or trafficking of OS-localized proteins. These results suggest that the LPCAT1-dependent production of saturated PC plays critical roles in photoreceptor maturation. Our findings highlight the therapeutic potential of saturated fatty acid metabolism in photoreceptor cell degeneration-related retinal diseases.
| S-EPMC9136105 | biostudies-literature
Project description:Due to the high energy demands and characteristic morphology, retinal photoreceptor cells require a specialized lipid metabolism for survival and function. This study focused on the roles of saturated fatty acids and their metabolism. A frameshift mutation of lysophosphatidylcholine acyltransferase 1 (Lpcat1), introducing saturated fatty acids into lysophosphatidylcholine to produce disaturated phosphatidylcholine (PC), has been reported to cause spontaneous retinal degeneration in mice (rd11 mice). In this study, we performed a detailed characterization of Lpcat1 in the retina and found that Lpcat1 deficiency induces light-independent and photoreceptor-specific apoptosis in mice. Lipidomic analyses of the retina and isolated photoreceptor outer segment (OS) suggested that loss of Lpcat1 affects disaturated PC production and the proper cellular fatty acid flux, presumably by altering saturated fatty acyl-CoA availabilities. Furthermore, we demonstrated that Lpcat1 deletion increased mitochondrial reactive oxygen species (ROS) levels in photoreceptor cells, but not in other retinal cells without affecting the OS structure and trafficking of OS-localized proteins. These results suggest that the LPCAT1-dependent production of disaturated PC is critical for metabolic adaptation during photoreceptor maturation. Our findings highlight the therapeutic potential of saturated fatty acid metabolism in photoreceptor cell degeneration-related retinal diseases.
2022-01-01 | GSE184817 | GEO
Project description:Due to the high energy demands and characteristic morphology, retinal photoreceptor cells require the specialized lipid metabolism for survival and functions. In this study, we focus on the roles of saturated fatty acids and their metabolism in these processes. Frame-shift mutation of lysophosphatidylcholine acyltransferase 1 (Lpcat1), which introduces saturated fatty acid into lysophosphatidylcholine to produce disaturated phosphatidylcholine (PC), has been reported as a causative for spontaneous retinal degeneration in mice (rd11 mice). However, the molecular basis of retinal degeneration caused by Lpcat1 mutation remains unclear. Here, we report that Lpcat1 deficiency induces light-independent and photoreceptor-specific apoptosis in mice. Lipidomic analyses of retina and isolated photoreceptor outer segment (OS) suggested that loss of Lpcat1 affects not only disaturated PC production, but also the proper cellular fatty acid flux presumably through altering saturated fatty acyl-CoA availabilities. Furthermore, we demonstrated that Lpcat1 deletion increased mitochondrial reactive oxygen species (ROS) levels in photoreceptor cells, but not in other retinal cells, without affecting the OS structure and trafficking of OS localized proteins. These results suggested that LPCAT1-dependent production of disaturated PC is critical for metabolic adaptation during photoreceptor maturation. Our findings highlight the therapeutic potential of saturated fatty acid metabolism in photoreceptor cell degeneration-related retinal diseases.
2022-01-01 | GSE184815 | GEO
Project description:Lysophosphatidylcholine acyltransferase 1 controls the mitochondrial reactive oxygen species generation and survival of the retinal photoreceptor cells
| PRJNA766595 | ENA
Project description:Lysophosphatidylcholine acyltransferase 1 controls the mitochondrial reactive oxygen species generation and survival of the retinal photoreceptor cells [P8 photoreceptor]
| PRJNA766601 | ENA
Project description:Lysophosphatidylcholine acyltransferase 1 controls the mitochondrial reactive oxygen species generation and survival of the retinal photoreceptor cells [2w Retina]
| PRJNA766600 | ENA
Project description:ObjectiveHyperlipidemia-induced endothelial cell (EC) activation is considered as an initial event responsible for monocyte recruitment in atherogenesis. However, it remains poorly defined what is the mechanism underlying hyperlipidemia-induced EC activation. Here, we tested a novel hypothesis that mitochondrial reactive oxygen species (mtROS) serve as signaling mediators for EC activation in early atherosclerosis.Approach and resultsMetabolomics and transcriptomics analyses revealed that several lysophosphatidylcholine (LPC) species, such as 16:0, 18:0, and 18:1, and their processing enzymes, including Pla2g7 and Pla2g4c, were significantly induced in the aortas of apolipoprotein E knockout mice during early atherosclerosis. Using electron spin resonance and flow cytometry, we found that LPC 16:0, 18:0, and 18:1 induced mtROS in primary human aortic ECs, independently of the activities of nicotinamide adenine dinucleotide phosphate oxidase. Mechanistically, using confocal microscopy and Seahorse XF mitochondrial analyzer, we showed that LPC induced mtROS via unique calcium entry-mediated increase of proton leak and mitochondrial O2 reduction. In addition, we found that mtROS contributed to LPC-induced EC activation by regulating nuclear binding of activator protein-1 and inducing intercellular adhesion molecule-1 gene expression in vitro. Furthermore, we showed that mtROS inhibitor MitoTEMPO suppressed EC activation and aortic monocyte recruitment in apolipoprotein E knockout mice using intravital microscopy and flow cytometry methods.ConclusionsATP synthesis-uncoupled, but proton leak-coupled, mtROS increase mediates LPC-induced EC activation during early atherosclerosis. These results indicate that mitochondrial antioxidants are promising therapies for vascular inflammation and cardiovascular diseases.
| S-EPMC4882253 | biostudies-literature
Project description:Lysophosphatidylcholine (lysoPC) evokes diverse biological responses in vascular cells including Ca(2+) mobilization, production of reactive oxygen species, and activation of the mitogen-activated protein kinases, but the mechanisms linking these events remain unclear. Here, we provide evidence that the response of mitochondria to the lysoPC-dependent increase in cytosolic Ca(2+) leads to activation of the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase through a redox signaling mechanism in human umbilical vein endothelial cells. ERK activation was attenuated by inhibitors of the electron transport chain proton pumps (rotenone and antimycin A) and an uncoupler (carbonyl cyanide p-trifluoromethoxyphenylhydrazone), suggesting that mitochondrial inner membrane potential plays a key role in the signaling pathway. ERK activation was also selectively attenuated by chain-breaking antioxidants and by vitamin E targeted to mitochondria, suggesting that transduction of the mitochondrial hydrogen peroxide signal is mediated by a lipid peroxidation product. Inhibition of ERK activation with MEK inhibitors (PD98059 or U0126) diminished induction of the antioxidant enzyme heme oxygenase-1. Taken together, these data suggest a role for mitochondrially generated reactive oxygen species and Ca(2+) in the redox cell signaling path-ways, leading to ERK activation and adaptation of the pathological stress mediated by oxidized lipids such as lysoPC.
| S-EPMC1606607 | biostudies-literature
Project description:The mitochondrial generation of reactive oxygen species (ROS) plays a central role in many cell signaling pathways, but debate still surrounds its regulation by factors, such as substrate availability, [O2] and metabolic state. Previously, we showed that in isolated mitochondria respiring on succinate, ROS generation was a hyperbolic function of [O2]. In the current study, we used a wide variety of substrates and inhibitors to probe the O2 sensitivity of mitochondrial ROS generation under different metabolic conditions. From such data, the apparent Km for O2 of putative ROS-generating sites within mitochondria was estimated as follows: 0.2, 0.9, 2.0, and 5.0 microM O2 for the complex I flavin site, complex I electron backflow, complex III QO site, and electron transfer flavoprotein quinone oxidoreductase of beta-oxidation, respectively. Differential effects of respiratory inhibitors on ROS generation were also observed at varying [O2]. Based on these data, we hypothesize that at physiological [O2], complex I is a significant source of ROS, whereas the electron transfer flavoprotein quinone oxidoreductase may only contribute to ROS generation at very high [O2]. Furthermore, we suggest that previous discrepancies in the assignment of effects of inhibitors on ROS may be due to differences in experimental [O2]. Finally, the data set (see supplemental material) may be useful in the mathematical modeling of mitochondrial metabolism.
| S-EPMC2713566 | biostudies-literature
Project description:Retinal degenerative diseases, such as retinitis pigmentosa and Leber congenital amaurosis, are a leading cause of untreatable blindness with substantive impact on the quality of life of affected individuals and their families. Mouse mutants with retinal dystrophies have provided a valuable resource to discover human disease genes and helped uncover pathways critical for photoreceptor function. Here we show that the rd11 mouse mutant and its allelic strain, B6-JR2845, exhibit rapid photoreceptor dysfunction, followed by degeneration of both rods and cones. Using linkage analysis, we mapped the rd11 locus to mouse chromosome 13. We then identified a one-nucleotide insertion (c.420-421insG) in exon 3 of the Lpcat1 gene. Subsequent screening of this gene in the B6-JR2845 strain revealed a seven-nucleotide deletion (c.14-20delGCCGCGG) in exon 1. Both sequence changes are predicted to result in a frame-shift, leading to premature truncation of the lysophosphatidylcholine acyltransferase-1 (LPCAT1) protein. LPCAT1 (also called AYTL2) is a phospholipid biosynthesis/remodeling enzyme that facilitates the conversion of palmitoyl-lysophosphatidylcholine to dipalmitoylphosphatidylcholine (DPPC). The analysis of retinal lipids from rd11 and B6-JR2845 mice showed substantially reduced DPPC levels compared with C57BL/6J control mice, suggesting a causal link to photoreceptor dysfunction. A follow-up screening of LPCAT1 in retinitis pigmentosa and Leber congenital amaurosis patients did not reveal any obvious disease-causing mutations. Previously, LPCAT1 has been suggested to be critical for the production of lung surfactant phospholipids and biosynthesis of platelet-activating factor in noninflammatory remodeling pathway. Our studies add another dimension to an essential role for LPCAT1 in retinal photoreceptor homeostasis.
| S-EPMC2932565 | biostudies-literature