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Elustondo P, Martin LA, Karten B. Mitochondrial cholesterol import. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:90-101. [PMID: 27565112 DOI: 10.1016/j.bbalip.2016.08.012] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 08/15/2016] [Accepted: 08/19/2016] [Indexed: 02/06/2023]
Abstract
All animal subcellular membranes require cholesterol, which influences membrane fluidity and permeability, fission and fusion processes, and membrane protein function. The distribution of cholesterol among subcellular membranes is highly heterogeneous and the cholesterol content of each membrane must be carefully regulated. Compared to other subcellular membranes, mitochondrial membranes are cholesterol-poor, particularly the inner mitochondrial membrane (IMM). As a result, steroidogenesis can be controlled through the delivery of cholesterol to the IMM, where it is converted to pregnenolone. The low basal levels of cholesterol also make mitochondria sensitive to changes in cholesterol content, which can have a relatively large impact on the biophysical and functional characteristics of mitochondrial membranes. Increased mitochondrial cholesterol levels have been observed in diverse pathological conditions including cancer, steatohepatitis, Alzheimer disease and Niemann-Pick Type C1-deficiency, and are associated with increased oxidative stress, impaired oxidative phosphorylation, and changes in the susceptibility to apoptosis, among other alterations in mitochondrial function. Mitochondria are not included in the vesicular trafficking network; therefore, cholesterol transport to mitochondria is mostly achieved through the activity of lipid transfer proteins at membrane contact sites or by cytosolic, diffusible lipid transfer proteins. Here we will give an overview of the main mechanisms involved in mitochondrial cholesterol import, focusing on the steroidogenic acute regulatory protein StAR/STARD1 and other members of the StAR-related lipid transfer (START) domain protein family, and we will discuss how changes in mitochondrial cholesterol levels can arise and affect mitochondrial function. This article is part of a Special Issue entitled: Lipids of Mitochondria edited by Guenther Daum.
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Affiliation(s)
- Pia Elustondo
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Laura A Martin
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Barbara Karten
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada.
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Martin LA, Kennedy BE, Karten B. Mitochondrial cholesterol: mechanisms of import and effects on mitochondrial function. J Bioenerg Biomembr 2016; 48:137-51. [PMID: 25425472 DOI: 10.1007/s10863-014-9592-6] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 11/14/2014] [Indexed: 12/23/2022]
Abstract
Mitochondria require cholesterol for biogenesis and membrane maintenance, and for the synthesis of steroids, oxysterols and hepatic bile acids. Multiple pathways mediate the transport of cholesterol from different subcellular pools to mitochondria. In steroidogenic cells, the steroidogenic acute regulatory protein (StAR) interacts with a mitochondrial protein complex to mediate cholesterol delivery to the inner mitochondrial membrane for conversion to pregnenolone. In non-steroidogenic cells, several members of a protein family defined by the presence of a StAR-related lipid transfer (START) domain play key roles in the delivery of cholesterol to mitochondrial membranes. Subdomains of the endoplasmic reticulum (ER), termed mitochondria-associated ER membranes (MAM), form membrane contact sites with mitochondria and may contribute to the transport of ER cholesterol to mitochondria, either independently or in conjunction with lipid-transfer proteins. Model systems of mitochondria enriched with cholesterol in vitro and mitochondria isolated from cells with (patho)physiological mitochondrial cholesterol accumulation clearly demonstrate that mitochondrial cholesterol levels affect mitochondrial function. Increased mitochondrial cholesterol levels have been observed in several diseases, including cancer, ischemia, steatohepatitis and neurodegenerative diseases, and influence disease pathology. Hence, a deeper understanding of the mechanisms maintaining mitochondrial cholesterol homeostasis may reveal additional targets for therapeutic intervention. Here we give a brief overview of mitochondrial cholesterol import in steroidogenic cells, and then focus on cholesterol trafficking pathways that deliver cholesterol to mitochondrial membranes in non-steroidogenic cells. We also briefly discuss the consequences of increased mitochondrial cholesterol levels on mitochondrial function and their potential role in disease pathology.
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Marí M, Morales A, Colell A, García-Ruiz C, Fernández-Checa JC. Mitochondrial cholesterol accumulation in alcoholic liver disease: Role of ASMase and endoplasmic reticulum stress. Redox Biol 2014; 3:100-8. [PMID: 25453982 PMCID: PMC4297930 DOI: 10.1016/j.redox.2014.09.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 09/21/2014] [Accepted: 09/23/2014] [Indexed: 02/08/2023] Open
Abstract
Alcoholic liver disease (ALD) is a major cause of chronic liver disease and a growing health concern in theworld. While the pathogenesis of ALD is poorly characterized key players identified in experimental models and patients, such as perturbations in mitochondrial structure and function, selective loss of antioxidant defense and susceptibility to inflammatory cytokines, contribute to ALD progression. Both oxidative stress and mitochondrial dysfunction compromise essential cellular functions and energy generation and hence are important pathogenic mechanisms of ALD. An important process mediating the mitochondrial disruption induced by alcohol intake is the trafficking of cholesterol to mitochondria, mediated by acid sphingomyelinase-induced endoplasmic reticulum stress, which contributes to increased cholesterol synthesis and StARD1upregulation. Mitochondrial cholesterol accumulation not only sensitizes to oxidative stress but it can contribute to the metabolic reprogramming in ALD, manifested by activation of the hypoxia inducible transcription factor 1 and stimulation of glycolysis and lactate secretion. Thus, a better understanding of the mechanisms underlying alcohol-mediated mitochondrial impairment and oxidative stress may lead to the identification of novel treatments for ALD. The present review briefly summarizes current knowledge on the cellular and molecular mechanisms contributing to alcohol-induced mitochondrial dysfunction and cholesterol accumulation and provides insights for potential therapeutic targets in ALD. Alcohol perturbs mitochondria function, which modulates ROS generation and alcohol metabolism. Alcohol stimulates mitochondrial cholesterol (mChol) accumulation. MChol accumulation impairs mitochondrial function and mediates alcohol-induced lipotoxicity. ASMase promotes mitochondrial dysfunction by stimulating mChol loading.
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Affiliation(s)
- Montserrat Marí
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB-CSIC), Consejo Superior Investigaciones Científicas (CSIC), IDIBAPS, Liver Unit-Hospital Clínic, CIBEREHD, 08036 Barcelona, Spain.
| | - Albert Morales
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB-CSIC), Consejo Superior Investigaciones Científicas (CSIC), IDIBAPS, Liver Unit-Hospital Clínic, CIBEREHD, 08036 Barcelona, Spain
| | - Anna Colell
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB-CSIC), Consejo Superior Investigaciones Científicas (CSIC), IDIBAPS, Liver Unit-Hospital Clínic, CIBEREHD, 08036 Barcelona, Spain
| | - Carmen García-Ruiz
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB-CSIC), Consejo Superior Investigaciones Científicas (CSIC), IDIBAPS, Liver Unit-Hospital Clínic, CIBEREHD, 08036 Barcelona, Spain
| | - Jose C Fernández-Checa
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB-CSIC), Consejo Superior Investigaciones Científicas (CSIC), IDIBAPS, Liver Unit-Hospital Clínic, CIBEREHD, 08036 Barcelona, Spain; Research Center for Alcoholic Liver and Pancreatic Diseases, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA.
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Fernandez A, Matias N, Fucho R, Ribas V, Von Montfort C, Nuño N, Baulies A, Martinez L, Tarrats N, Mari M, Colell A, Morales A, Dubuquoy L, Mathurin P, Bataller R, Caballeria J, Elena M, Balsinde J, Kaplowitz N, Garcia-Ruiz C, Fernandez-Checa JC. ASMase is required for chronic alcohol induced hepatic endoplasmic reticulum stress and mitochondrial cholesterol loading. J Hepatol 2013; 59:805-13. [PMID: 23707365 PMCID: PMC3779525 DOI: 10.1016/j.jhep.2013.05.023] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 05/07/2013] [Accepted: 05/13/2013] [Indexed: 12/04/2022]
Abstract
BACKGROUND & AIMS The pathogenesis of alcohol-induced liver disease (ALD) is poorly understood. Here, we examined the role of acid sphingomyelinase (ASMase) in alcohol induced hepatic endoplasmic reticulum (ER) stress, a key mechanism of ALD. METHODS We examined ER stress, lipogenesis, hyperhomocysteinemia, mitochondrial cholesterol (mChol) trafficking and susceptibility to LPS and concanavalin-A in ASMase(-)(/-) mice fed alcohol. RESULTS Alcohol feeding increased SREBP-1c, DGAT-2, and FAS mRNA in ASMase(+/+) but not in ASMase(-/-) mice. Compared to ASMase(+/+) mice, ASMase(-/-) mice exhibited decreased expression of ER stress markers induced by alcohol, but the level of tunicamycin-mediated upregulation of ER stress markers and steatosis was similar in both types of mice. The increase in homocysteine levels induced by alcohol feeding was comparable in both ASMase(+/+) and ASMase(-/-) mice. Exogenous ASMase, but not neutral SMase, induced ER stress by perturbing ER Ca(2+) homeostasis. Moreover, alcohol-induced mChol loading and StARD1 overexpression were blunted in ASMase(-/-) mice. Tunicamycin upregulated StARD1 expression and this outcome was abrogated by tauroursodeoxycholic acid. Alcohol-induced liver injury and sensitization to LPS and concanavalin-A were prevented in ASMase(-/-) mice. These effects were reproduced in alcohol-fed TNFR1/R2(-/-) mice. Moreover, ASMase does not impair hepatic regeneration following partial hepatectomy. Of relevance, liver samples from patients with alcoholic hepatitis exhibited increased expression of ASMase, StARD1, and ER stress markers. CONCLUSIONS Our data indicate that ASMase is critical for alcohol-induced ER stress, and provide a rationale for further clinical investigation in ALD.
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Affiliation(s)
- Anna Fernandez
- Department of Cell Death and Proliferation, IIBB-CSIC,Liver Unit-Hospital Clinic-IDIBAPS, and CIBEREHD, Barcelona, Spain
| | - Núria Matias
- Department of Cell Death and Proliferation, IIBB-CSIC,Liver Unit-Hospital Clinic-IDIBAPS, and CIBEREHD, Barcelona, Spain
| | - Raquel Fucho
- Department of Cell Death and Proliferation, IIBB-CSIC,Liver Unit-Hospital Clinic-IDIBAPS, and CIBEREHD, Barcelona, Spain
| | - Vicente Ribas
- Department of Cell Death and Proliferation, IIBB-CSIC,Liver Unit-Hospital Clinic-IDIBAPS, and CIBEREHD, Barcelona, Spain
| | - Claudia Von Montfort
- Department of Cell Death and Proliferation, IIBB-CSIC,Liver Unit-Hospital Clinic-IDIBAPS, and CIBEREHD, Barcelona, Spain
| | - Natalia Nuño
- Department of Cell Death and Proliferation, IIBB-CSIC,Liver Unit-Hospital Clinic-IDIBAPS, and CIBEREHD, Barcelona, Spain
| | - Anna Baulies
- Department of Cell Death and Proliferation, IIBB-CSIC,Liver Unit-Hospital Clinic-IDIBAPS, and CIBEREHD, Barcelona, Spain
| | - Laura Martinez
- Department of Cell Death and Proliferation, IIBB-CSIC,Liver Unit-Hospital Clinic-IDIBAPS, and CIBEREHD, Barcelona, Spain
| | - Núria Tarrats
- Department of Cell Death and Proliferation, IIBB-CSIC,Liver Unit-Hospital Clinic-IDIBAPS, and CIBEREHD, Barcelona, Spain
| | - Montserrat Mari
- Department of Cell Death and Proliferation, IIBB-CSIC,Liver Unit-Hospital Clinic-IDIBAPS, and CIBEREHD, Barcelona, Spain
| | - Anna Colell
- Department of Cell Death and Proliferation, IIBB-CSIC,Liver Unit-Hospital Clinic-IDIBAPS, and CIBEREHD, Barcelona, Spain
| | - Albert Morales
- Department of Cell Death and Proliferation, IIBB-CSIC,Liver Unit-Hospital Clinic-IDIBAPS, and CIBEREHD, Barcelona, Spain
| | - Laurent Dubuquoy
- Université Lille Nord de France, and Service des Maladies de l'Appareil Digestif, Hôpital Huriez, Lille, France; Unité 995, Institut National de la Santé et de la Recherche Médicale, Lille, France
| | - Philippe Mathurin
- Université Lille Nord de France, and Service des Maladies de l'Appareil Digestif, Hôpital Huriez, Lille, France; Unité 995, Institut National de la Santé et de la Recherche Médicale, Lille, France
| | - Ramón Bataller
- Liver Unit-Hospital Clinic-IDIBAPS, and CIBEREHD, Barcelona, Spain
| | - Joan Caballeria
- Liver Unit-Hospital Clinic-IDIBAPS, and CIBEREHD, Barcelona, Spain
| | | | - Jesus Balsinde
- Institut of Molecular Biology and Genetics, CSIC-CIBERDEM, Valladolid, Spain
| | - Neil Kaplowitz
- Southern California Research Center for ALPD and Cirrhosis, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90033
| | - Carmen Garcia-Ruiz
- Department of Cell Death and Proliferation, IIBB-CSIC,Liver Unit-Hospital Clinic-IDIBAPS, and CIBEREHD, Barcelona, Spain,Carmen Garcia-Ruiz and Jose C Fernandez-Checa share senior authorship. Correspondence addressed to Jose C Fernandez-Checa,
| | - Jose C. Fernandez-Checa
- Department of Cell Death and Proliferation, IIBB-CSIC,Liver Unit-Hospital Clinic-IDIBAPS, and CIBEREHD, Barcelona, Spain,Southern California Research Center for ALPD and Cirrhosis, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90033,Carmen Garcia-Ruiz and Jose C Fernandez-Checa share senior authorship. Correspondence addressed to Jose C Fernandez-Checa,
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Abstract
Alcohol-induced liver disease (ALD) is a major health concern of alcohol abuse and a leading cause of liver-related morbidity and mortality. The pathogenesis of ALD is multifactorial and still ill characterized. One of the hallmarks of ALD common for both patients and experimental models is the alteration in the architecture and function of mitochondria. Due to their primordial role in energy production, metabolism and cell fate decisions, these changes in mitochondria caused by alcohol are considered an important contributory factor in ALD. A better understanding of the mechanisms underlying alcohol-mediated mitochondrial alterations may shed light on ALD pathogenesis and provide novel avenues for treatment. The purpose of the current review is to briefly update the latest developments in ALD research regarding morphological and functional mitochondrial regulation including mitochondrial dynamics and biogenesis, mitochondrial protein acetylation and evidence for an endoplasmic reticulum stress-mitochondrial cholesterol link of potential relevance for ALD.
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Affiliation(s)
- Carmen García-Ruiz
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), Consejo Superior Investigaciones Cientificas (CSIC) and Liver Unit-Hospital Clinic and CIBEREHD, Barcelona, Spain
| | - Neil Kaplowitz
- Southern California Research Center for ALPD and Cirrhosis, Keck School of Medicine of the University of Southern, California, Los Angeles, CA, USA
| | - José C Fernandez-Checa
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), Consejo Superior Investigaciones Cientificas (CSIC) and Liver Unit-Hospital Clinic and CIBEREHD, Barcelona, Spain. Southern California Research Center for ALPD and Cirrhosis, Keck School of Medicine of the University of Southern, California, Los Angeles, CA, USA
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