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Ilacqua N, Anastasia I, Aloshyn D, Ghandehari-Alavijeh R, Peluso EA, Brearley-Sholto MC, Pellegrini LV, Raimondi A, de Aguiar Vallim TQ, Pellegrini L. Expression of Synj2bp in mouse liver regulates the extent of wrappER-mitochondria contact to maintain hepatic lipid homeostasis. Biol Direct 2022; 17:37. [PMID: 36457006 PMCID: PMC9717519 DOI: 10.1186/s13062-022-00344-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 10/26/2022] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND In mouse liver hepatocytes, nearly half of the surface area of every mitochondrion is covered by wrappER, a wrapping-type of ER that is rich in fatty acids and synthesizes lipoproteins (VLDL) (Anastasia et al. in Cell Rep 34:108873, 2021; Hurtley in Science (80- ) 372:142-143, 2021; Ilacqua et al. in J Cell Sci 135:1-11, 2021). A disruption of the ultrastructure of the wrappER-mitochondria contact results in altered fatty acid flux, leading to hepatic dyslipidemia (Anastasia et al. 2021). The molecular mechanism that regulates the extent of wrappER-mitochondria contacts is unknown. METHODS We evaluated the expression level of the mitochondrial protein Synj2bp in the liver of normal and obese (ob/ob) mice. In addition, we silenced its expression in the liver using an AAV8 vector. We coupled quantitative EM morphometric analysis to proteomics and lipid analyses on these livers. RESULTS The expression level of Synj2bp in the liver positively correlates with the extent of wrappER-mitochondria contacts. A 50% reduction in wrappER-mitochondria contacts causes hepatic dyslipidemia, characterized by a gross accumulation of lipid droplets in the liver, an increased hepatic secretion of VLDL and triglycerides, a curtailed ApoE expression, and an increased capacity of mitochondrial fatty acid respiration. CONCLUSION Synj2bp regulates the extent of wrappER-mitochondria contacts in the liver, thus contributing to the control of hepatic lipid flux.
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Affiliation(s)
- Nicolò Ilacqua
- Graduate Program in Neuroscience, Faculty of Medicine, Laval University, Quebec, QC, Canada.,Mitochondria Biology Laboratory, Brain Research Center, Laval University, Quebec, QC, Canada
| | - Irene Anastasia
- Mitochondria Biology Laboratory, Brain Research Center, Laval University, Quebec, QC, Canada
| | - Danylo Aloshyn
- Mitochondria Biology Laboratory, Brain Research Center, Laval University, Quebec, QC, Canada
| | | | - Emily Ann Peluso
- Departments of Medicine/Cardiology and Biological Chemistry, University of California, Los Angeles, CA, USA
| | | | - Leonardo V Pellegrini
- Mitochondria Biology Laboratory, Brain Research Center, Laval University, Quebec, QC, Canada
| | - Andrea Raimondi
- Experimental Imaging Center, San Raffaele Scientific Institute, Milan, Italy
| | - Thomas Q de Aguiar Vallim
- Departments of Medicine/Cardiology and Biological Chemistry, University of California, Los Angeles, CA, USA
| | - Luca Pellegrini
- Mitochondria Biology Laboratory, Brain Research Center, Laval University, Quebec, QC, Canada. .,Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Quebec, QC, Canada.
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Thierer JH, Ekker SC, Farber SA. The LipoGlo reporter system for sensitive and specific monitoring of atherogenic lipoproteins. Nat Commun 2019; 10:3426. [PMID: 31366908 PMCID: PMC6668417 DOI: 10.1038/s41467-019-11259-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 06/28/2019] [Indexed: 12/18/2022] Open
Abstract
Apolipoprotein-B (ApoB) is the structural component of atherogenic lipoproteins, lipid-rich particles that drive atherosclerosis by accumulating in the vascular wall. As atherosclerotic cardiovascular disease is the leading cause of death worldwide, there is an urgent need to develop new strategies to prevent lipoproteins from causing vascular damage. Here we report the LipoGlo system, which uses a luciferase enzyme (NanoLuc) fused to ApoB to monitor several key determinants of lipoprotein atherogenicity including particle abundance, size, and localization. Using LipoGlo, we comprehensively characterize the lipoprotein profile of individual larval zebrafish and collect images of atherogenic lipoprotein localization in an intact organism. We report multiple extravascular lipoprotein localization patterns, as well as identify Pla2g12b as a potent regulator of lipoprotein size. ApoB-fusion proteins thus represent a sensitive and specific approach to study atherogenic lipoproteins and their genetic and small molecule modifiers. Atherosclerosis results from the accumulation of lipoproteins in the vascular wall. Here, Thierer et al. report the design of a chemiluminescent reporter for atherogenic lipoproteins using fusion of apolipoprotein-B to a luciferase enzyme, and find it bears potential for the identification of regulators of lipoprotein metabolism in vivo.
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Affiliation(s)
- James H Thierer
- Carnegie Institution for Science Department of Embryology, 3520 San Martin Drive, Baltimore, MD, 21218, USA.,Johns Hopkins University Department of Biology, 3400N Charles Street, Baltimore, MD, 21218, USA
| | - Stephen C Ekker
- Department of Biochemistry and Molecular Biology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Steven A Farber
- Carnegie Institution for Science Department of Embryology, 3520 San Martin Drive, Baltimore, MD, 21218, USA. .,Johns Hopkins University Department of Biology, 3400N Charles Street, Baltimore, MD, 21218, USA.
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Ercius P, Alaidi O, Rames MJ, Ren G. Electron Tomography: A Three-Dimensional Analytic Tool for Hard and Soft Materials Research. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:5638-63. [PMID: 26087941 PMCID: PMC4710474 DOI: 10.1002/adma.201501015] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 04/22/2015] [Indexed: 05/23/2023]
Abstract
Three-dimensional (3D) structural analysis is essential to understand the relationship between the structure and function of an object. Many analytical techniques, such as X-ray diffraction, neutron spectroscopy, and electron microscopy imaging, are used to provide structural information. Transmission electron microscopy (TEM), one of the most popular analytic tools, has been widely used for structural analysis in both physical and biological sciences for many decades, in which 3D objects are projected into two-dimensional (2D) images. In many cases, 2D-projection images are insufficient to understand the relationship between the 3D structure and the function of nanoscale objects. Electron tomography (ET) is a technique that retrieves 3D structural information from a tilt series of 2D projections, and is gradually becoming a mature technology with sub-nanometer resolution. Distinct methods to overcome sample-based limitations have been separately developed in both physical and biological science, although they share some basic concepts of ET. This review discusses the common basis for 3D characterization, and specifies difficulties and solutions regarding both hard and soft materials research. It is hoped that novel solutions based on current state-of-the-art techniques for advanced applications in hybrid matter systems can be motivated.
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Affiliation(s)
- Peter Ercius
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, USA
| | - Osama Alaidi
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, USA
| | - Matthew J. Rames
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, USA
| | - Gang Ren
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, USA
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