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Mavuduru VA, Vadupu L, Ghosh KK, Chakrabortty S, Gulyás B, Padmanabhan P, Ball WB. Mitochondrial phospholipid transport: Role of contact sites and lipid transport proteins. Prog Lipid Res 2024; 94:101268. [PMID: 38195013 DOI: 10.1016/j.plipres.2024.101268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 01/03/2024] [Accepted: 01/05/2024] [Indexed: 01/11/2024]
Abstract
One of the major constituents of mitochondrial membranes is the phospholipids, which play a key role in maintaining the structure and the functions of the mitochondria. However, mitochondria do not synthesize most of the phospholipids in situ, necessitating the presence of phospholipid import pathways. Even for the phospholipids, which are synthesized within the inner mitochondrial membrane (IMM), the phospholipid precursors must be imported from outside the mitochondria. Therefore, the mitochondria heavily rely on the phospholipid transport pathways for its proper functioning. Since, mitochondria are not part of a vesicular trafficking network, the molecular mechanisms of how mitochondria receive its phospholipids remain a relevant question. One of the major ways that hydrophobic phospholipids can cross the aqueous barrier of inter or intraorganellar spaces is by apposing membranes, thereby decreasing the distance of transport, or by being sequestered by lipid transport proteins (LTPs). Therefore, with the discovery of LTPs and membrane contact sites (MCSs), we are beginning to understand the molecular mechanisms of phospholipid transport pathways in the mitochondria. In this review, we will present a brief overview of the recent findings on the molecular architecture and the importance of the MCSs, both the intraorganellar and interorganellar contact sites, in facilitating the mitochondrial phospholipid transport. In addition, we will also discuss the role of LTPs for trafficking phospholipids through the intermembrane space (IMS) of the mitochondria. Mechanistic insights into different phospholipid transport pathways of mitochondria could be exploited to vary the composition of membrane phospholipids and gain a better understanding of their precise role in membrane homeostasis and mitochondrial bioenergetics.
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Affiliation(s)
- Vijay Aditya Mavuduru
- Department of Biological Sciences, School of Engineering and Sciences, SRM University AP Andhra Pradesh, Guntur, Andhra Pradesh 522240, India
| | - Lavanya Vadupu
- Department of Biological Sciences, School of Engineering and Sciences, SRM University AP Andhra Pradesh, Guntur, Andhra Pradesh 522240, India
| | - Krishna Kanta Ghosh
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 59 Nanyang Drive, Singapore, 636921, Singapore
| | - Sabyasachi Chakrabortty
- Department of Chemistry, School of Engineering and Sciences, SRM University AP Andhra Pradesh, Guntur, Andhra Pradesh 522502, India
| | - Balázs Gulyás
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 59 Nanyang Drive, Singapore, 636921, Singapore; Cognitive Neuroimaging Centre, Nanyang Technological University, Singapore, 59 Nanyang Drive, 636921, Singapore; Department of Clinical Neuroscience, Karolinska Institute, Stockholm 17176, Sweden
| | - Parasuraman Padmanabhan
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 59 Nanyang Drive, Singapore, 636921, Singapore; Cognitive Neuroimaging Centre, Nanyang Technological University, Singapore, 59 Nanyang Drive, 636921, Singapore.
| | - Writoban Basu Ball
- Department of Biological Sciences, School of Engineering and Sciences, SRM University AP Andhra Pradesh, Guntur, Andhra Pradesh 522240, India.
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Flis VV, Daum G. Lipid transport between the endoplasmic reticulum and mitochondria. Cold Spring Harb Perspect Biol 2013; 5:5/6/a013235. [PMID: 23732475 DOI: 10.1101/cshperspect.a013235] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Mitochondria are partially autonomous organelles that depend on the import of certain proteins and lipids to maintain cell survival and membrane formation. Although phosphatidylglycerol, cardiolipin, and phosphatidylethanolamine are synthesized by mitochondrial enzymes, phosphatidylcholine, phosphatidylinositol, phosphatidylserine, and sterols need to be imported from other organelles. The origin of most lipids imported into mitochondria is the endoplasmic reticulum, which requires interaction of these two subcellular compartments. Recently, protein complexes that are involved in membrane contact between endoplasmic reticulum and mitochondria were identified, but their role in lipid transport is still unclear. In the present review, we describe components involved in lipid translocation between the endoplasmic reticulum and mitochondria and discuss functional as well as regulatory aspects that are important for lipid homeostasis.
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Affiliation(s)
- Vid V Flis
- Institute of Biochemistry, Graz University of Technology, A-8010 Graz, Austria
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Jacobs-Harper A, Crumbly A, Romani A. Acute effect of ethanol on hepatic reticular G6Pase and Ca2+ pool. Alcohol Clin Exp Res 2013; 37 Suppl 1:E40-51. [PMID: 22958133 PMCID: PMC3519974 DOI: 10.1111/j.1530-0277.2012.01933.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 06/21/2012] [Indexed: 11/25/2022]
Abstract
BACKGROUND Hydrolysis of glucose 6-phosphate (G6P) via glucose 6-phosphatase (G6Pase) enlarges the reticular Ca(2+) pool of the hepatocyte. Exposure of liver cells to ethanol (EtOH) impairs reticular Ca(2+) homeostasis. The present study investigated the effect of acute EtOH administration on G6P-supported Ca(2+) accumulation in liver cells. METHODS Total microsomes were isolated from rat livers acutely perfused with varying doses of EtOH (0.01, 0.1, or 1% v/v) for 8 minutes. Calcium uptake was assessed by (45) Ca redistribution. Inorganic phosphate (Pi) formation was measured as an indicator of G6Pase hydrolytic activity. RESULTS G6P-supported Ca(2+) uptake decreased in a manner directly proportional to the dose of EtOH infused in the liver, whereas Ca(2+) uptake via SERCA pumps was decreased by ~25% only at the highest dose of alcohol administered. The reduced accumulation of Ca(2+) within the microsomes resulted in a smaller inositol 1,4,5-trisphosphate (IP(3))-induced Ca(2+) release. Kinetic assessment of IP(3) and passive Ca(2+) release indicated a faster mobilization in microsomes from EtOH-treated livers, suggesting alcohol-induced alteration of Ca(2+) releasing mechanisms. Pretreatment of livers with chloromethiazole (CMZ) or dithiothreitol (DTT), but not 4-methyl-pyrazole prevented the inhibitory effect of EtOH on G6Pase activity and Ca(2+) homeostasis. CONCLUSIONS Liver G6Pase activity and IP(3) -mediated Ca(2+) release are rapidly inhibited following acute (8 minutes) exposure to EtOH, thus compromising the ability of the endoplasmic reticulum to dynamically modulate Ca(2+) homeostasis in the hepatocyte. The protective effect of CMZ and DTT suggests that the inhibitory effect of EtOH is mediated through its metabolism via reticular cyP4502E1 and consequent free radicals formation.
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Affiliation(s)
- Amy Jacobs-Harper
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, US
| | - Ashlee Crumbly
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, US
| | - Andrea Romani
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, US
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Ferguson CS, Miksys S, Palmour RM, Tyndale RF. Differential effects of nicotine treatment and ethanol self-administration on CYP2A6, CYP2B6 and nicotine pharmacokinetics in African green monkeys. J Pharmacol Exp Ther 2012; 343:628-37. [PMID: 22935730 DOI: 10.1124/jpet.112.198564] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2025] Open
Abstract
In primates, nicotine is metabolically inactivated in the liver by CYP2A6 and possibly CYP2B6. Changes in the levels of these two enzymes may affect nicotine pharmacokinetics and influence smoking behaviors. This study investigated the independent and combined effects of ethanol self-administration and nicotine treatment (0.5 mg/kg b.i.d. s.c.) on hepatic CYP2A6 and CYP2B6 levels (mRNA, protein, and enzymatic activity), in vitro nicotine metabolism, and in vivo nicotine pharmacokinetics in monkeys. CYP2A6 mRNA and protein levels and in vitro coumarin (selective CYP2A6 substrate) and nicotine metabolism were decreased by nicotine treatment but unaffected by ethanol. CYP2B6 protein levels and in vitro bupropion (selective CYP2B6 substrate) metabolism were increased by ethanol but unaffected by nicotine treatment; CYP2B6 mRNA levels were unaltered by either treatment. Combined ethanol and nicotine exposure decreased CYP2A6 mRNA and protein levels, as well as in vitro coumarin and nicotine metabolism, and increased CYP2B6 protein levels and in vitro bupropion metabolism, with no change in CYP2B6 mRNA levels. Chronic nicotine resulted in higher nicotine plasma levels achieved after nicotine administration, consistent with decreased CYP2A6. Ethanol alone, or combined with nicotine, resulted in lower nicotine plasma levels by a mechanism independent of the change in these enzymes. Thus, nicotine can decrease hepatic CYP2A6, reducing the metabolism of its substrates, including nicotine, whereas ethanol can increase hepatic CYP2B6, increasing the metabolism of CYP2B6 substrates. In vivo nicotine pharmacokinetics are differentially affected by ethanol and nicotine, but when both drugs are used in combination the effect more closely resembles ethanol alone.
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Affiliation(s)
- C S Ferguson
- Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology, and Toxicology, University of Toronto, Toronto, Canada
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