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Zhang L, Xu L, Rong A, Cui Y, Wang L, Li L, Han X, Xiao X, Wu H. Effect of Rab18 on liver injury and lipid accumulation by regulating perilipin 2 and peroxisome proliferator-activated receptor gamma in non-alcoholic fatty liver disease. J Gastroenterol Hepatol 2024; 39:2219-2227. [PMID: 39030773 DOI: 10.1111/jgh.16676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 05/29/2024] [Accepted: 06/19/2024] [Indexed: 07/22/2024]
Abstract
BACKGROUND AND AIM Nonalcoholic fatty liver disease (NAFLD) is currently one of the most common chronic liver diseases worldwide, characterized by the presence of lipid droplets. Rab18 is an important lipid droplet protein; however, its effects and mechanisms of action on NAFLD remain unclear. METHODS Free fatty acid-stimulated AML-12 cells and high-fat diet (HFD)-fed mice were used as NAFLD models. Lentiviruses overexpressing Rab18 (Rab18-OE) or knockdown (Rab18-KD) were used to generate stable cell lines for genetic analysis. Blood serum levels of alanine aminotransferase, aspartate aminotransferase, total cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, glucose, and leptin were measured using a biochemical autoanalyzer. Hematoxylin and eosin staining was performed to detect pathological damage to the liver. Lipid accumulation in the cells was assessed by Oil Red O staining. Target expression was measured using qPCR, western blotting, and immunocytochemistry. RESULTS Rab18 mRNA and protein expression levels increased in free fatty acid-stimulated AML-12 cells and the livers of HFD-fed mice. Rab18-OE increased lipid accumulation in vitro, which was attenuated by Rab18-KD. In vivo, Rab18-OE augmented liver pathological damage, serum alanine aminotransferase/aspartate aminotransferase activity, and triglyceride, total cholesterol, and low-density lipoprotein levels, whereas Rab18-KD decreased these indicators. Rab18-KD also downregulated blood glucose levels in HFD-fed mice. Mechanistically, Rab18-OE and Rab18-KD regulated the mRNA and protein expression levels of perilipin 2 (PLIN2) and peroxisome proliferator-activated receptor gamma (PPARγ) in vitro and in vivo, respectively. Immunocytochemistry revealed that Rab18 colocalized with PLIN2 and PPARγ in AML-12 cells. CONCLUSION Rab18 expression was elevated in vitro and in vivo in the NAFLD mouse model. Rab18 regulates PLIN2 and PPARγ expression to exaggerate liver injury and lipid accumulation in patients with NAFLD. Thus, Rab18 may be a crucial protein in this disease and a potential therapeutic target.
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Affiliation(s)
- Lei Zhang
- Department of Gastroenterology, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, China
| | - Lidong Xu
- Department of Gastroenterology, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, China
| | - Aimei Rong
- Department of Gastroenterology, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, China
| | - Yuanbo Cui
- Department of Translational Medicine Center, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, China
| | - Lin Wang
- Department of Gastroenterology, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, China
| | - Lu Li
- Department of Gastroenterology, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, China
| | - Xiaomeng Han
- Department of Gastroenterology, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, China
| | - Xingguo Xiao
- Department of Gastroenterology, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, China
| | - Huili Wu
- Department of Gastroenterology, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, China
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Sood C, Verma JK, Basak R, Kapoor A, Gupta S, Mukhopadhyay A. Leishmania highjack host lipid body for its proliferation in macrophages by overexpressing host Rab18 and TRAPPC9 by downregulating miR-1914-3p expression. PLoS Pathog 2024; 20:e1012024. [PMID: 38412149 PMCID: PMC10898768 DOI: 10.1371/journal.ppat.1012024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Accepted: 02/05/2024] [Indexed: 02/29/2024] Open
Abstract
Lipids stored in lipid-bodies (LBs) in host cells are potential sources of fatty acids for pathogens. However, the mechanism of recruitment of LBs from the host cells by pathogens to acquire fatty acids is not known. Here, we have found that Leishmania specifically upregulates the expression of host Rab18 and its GEF, TRAPPC9 by downregulating the expression of miR-1914-3p by reducing the level of Dicer in macrophages via their metalloprotease gp63. Our results also show that miR-1914-3p negatively regulates the expression of Rab18 and its GEF in cells. Subsequently, Leishmania containing parasitophorous vacuoles (Ld-PVs) recruit and retain host Rab18 and TRAPPC9. Leishmania infection also induces LB biogenesis in host cells and recruits LBs on Ld-PVs and acquires FLC12-labeled fatty acids from LBs. Moreover, overexpression of miR-1914-3p in macrophages significantly inhibits the recruitment of LBs and thereby suppresses the multiplication of parasites in macrophages as parasites are unable to acquire fatty acids. These results demonstrate a novel mechanism how Leishmania acquire fatty acids from LBs for their growth in macrophages.
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Affiliation(s)
- Chandni Sood
- National Institute of Immunology, New Delhi, India
| | - Jitender Kumar Verma
- Kusuma School of Biological Sciences, Indian Institute of Technology, Hauz Khas, New Delhi, India
- National Institute of Immunology, New Delhi, India
| | - Rituparna Basak
- Kusuma School of Biological Sciences, Indian Institute of Technology, Hauz Khas, New Delhi, India
| | - Anjali Kapoor
- Kusuma School of Biological Sciences, Indian Institute of Technology, Hauz Khas, New Delhi, India
| | - Swarnima Gupta
- Kusuma School of Biological Sciences, Indian Institute of Technology, Hauz Khas, New Delhi, India
| | - Amitabha Mukhopadhyay
- Kusuma School of Biological Sciences, Indian Institute of Technology, Hauz Khas, New Delhi, India
- National Institute of Immunology, New Delhi, India
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Dempsey JL, Ioannou GN, Carr RM. Mechanisms of Lipid Droplet Accumulation in Steatotic Liver Diseases. Semin Liver Dis 2023; 43:367-382. [PMID: 37799111 DOI: 10.1055/a-2186-3557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
The steatotic diseases of metabolic dysfunction-associated steatotic liver disease (MASLD), alcohol-associated liver disease (ALD), and chronic hepatitis C (HCV) account for the majority of liver disease prevalence, morbidity, and mortality worldwide. While these diseases have distinct pathogenic and clinical features, dysregulated lipid droplet (LD) organelle biology represents a convergence of pathogenesis in all three. With increasing understanding of hepatocyte LD biology, we now understand the roles of LD proteins involved in these diseases but also how genetics modulate LD biology to either exacerbate or protect against the phenotypes associated with steatotic liver diseases. Here, we review the history of the LD organelle and its biogenesis and catabolism. We also review how this organelle is critical not only for the steatotic phenotype of liver diseases but also for their advanced phenotypes. Finally, we summarize the latest attempts and challenges of leveraging LD biology for therapeutic gain in steatotic diseases. In conclusion, the study of dysregulated LD biology may lead to novel therapeutics for the prevention of disease progression in the highly prevalent steatotic liver diseases of MASLD, ALD, and HCV.
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Affiliation(s)
- Joseph L Dempsey
- Division of Gastroenterology, Department of Medicine, School of Medicine, University of Washington, Seattle, Washington
| | - George N Ioannou
- Division of Gastroenterology, Department of Medicine, School of Medicine, University of Washington, Seattle, Washington
- Division of Gastroenterology, Veterans Affairs Puget Sound Healthcare System Seattle, Washington
| | - Rotonya M Carr
- Division of Gastroenterology, Department of Medicine, School of Medicine, University of Washington, Seattle, Washington
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Sarhadi TR, Panse JS, Nagotu S. Mind the gap: Methods to study membrane contact sites. Exp Cell Res 2023; 431:113756. [PMID: 37633408 DOI: 10.1016/j.yexcr.2023.113756] [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: 03/28/2023] [Revised: 08/11/2023] [Accepted: 08/13/2023] [Indexed: 08/28/2023]
Abstract
Organelles are dynamic entities whose functions are essential for the optimum functioning of cells. It is now known that the juxtaposition of organellar membranes is essential for the exchange of metabolites and their communication. These functional apposition sites are termed membrane contact sites. Dynamic membrane contact sites between various sub-cellular structures such as mitochondria, endoplasmic reticulum, peroxisomes, Golgi apparatus, lysosomes, lipid droplets, plasma membrane, endosomes, etc. have been reported in various model systems. The burgeoning area of research on membrane contact sites has witnessed several manuscripts in recent years that identified the contact sites and components involved. Several methods have been developed to identify, measure and analyze the membrane contact sites. In this manuscript, we aim to discuss important methods developed to date that are used to study membrane contact sites.
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Affiliation(s)
- Tanveera Rounaque Sarhadi
- Organelle Biology and Cellular Ageing Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Janhavee Shirish Panse
- Organelle Biology and Cellular Ageing Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Shirisha Nagotu
- Organelle Biology and Cellular Ageing Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
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Kataoka-Hamai C, Kawakami K. Ostwald Ripening of Triacylglycerol Droplets Embedded in Glass-Supported Phospholipid Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:10001-10010. [PMID: 37433207 DOI: 10.1021/acs.langmuir.3c00835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/13/2023]
Abstract
Lipid droplets are fat storage organelles that consist of a neutral lipid core surrounded by a phospholipid monolayer. Because of their important biological functions, reconstituting model lipid droplets in synthetic phospholipid membranes is of great interest. In the present study, we investigated the incorporation of triacylglycerol droplets into glass-supported phospholipid bilayers by using fluorescence microscopy. We adsorbed triolein emulsions onto a glass surface that was partially covered with planar bilayers. After adsorption, triolein droplets were found to be immobilized in the bilayer membrane. The volume of each bound droplet varied over time. Large droplets grew, whereas small droplets shrank. Additionally, data on fluorescence recovery after photobleaching obtained for a phospholipid probe indicate that phospholipids on and near triolein droplets were fully mobile. Furthermore, photobleaching data obtained for a triacylglycerol probe indicate that triolein molecules diffused between different droplets along the planar bilayer. These results demonstrate Ostwald ripening, where triolein molecules in a small droplet dissolved in the bilayer, diffused laterally, and eventually bound to the interfaces of larger droplets. We investigated the ripening rate by using the average of the cube root of the fluorescence emission obtained for individual droplets. The ripening slowed after the addition of trilinolein to the triolein phase. Finally, we investigated the time dependence of the size distributions of the triolein droplets. The distribution was initially nearly unimodal and subsequently became bimodal.
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Affiliation(s)
- Chiho Kataoka-Hamai
- Research Center for Macromolecules and Biomaterials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Kohsaku Kawakami
- Research Center for Macromolecules and Biomaterials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
- Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan
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Singh J, Sanghavi P, Mallik R. Microtubule motor driven interactions of lipid droplets: Specificities and opportunities. Front Cell Dev Biol 2022; 10:893375. [PMID: 36200039 PMCID: PMC9527339 DOI: 10.3389/fcell.2022.893375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 09/05/2022] [Indexed: 11/29/2022] Open
Abstract
Lipid Droplets (LDs) are evolutionarily conserved cellular organelles that store neutral lipids such as triacylglycerol and cholesterol-esters. Neutral lipids are enclosed within the limiting membrane of the LD, which is a monolayer of phospholipids and is therefore fundamentally different from the bilayer membrane enclosing most other organelles. LDs have long been viewed as a storehouse of lipids needed on demand for generating energy and membranes inside cells. Outside this classical view, we are now realizing that LDs have significant roles in protein sequestration, supply of signalling lipids, viral replication, lipoprotein production and many other functions of important physiological consequence. To execute such functions, LDs must often exchange lipids and proteins with other organelles (e.g., the ER, lysosomes, mitochondria) via physical contacts. But before such exchanges can occur, how does a micron-sized LD with limited ability to diffuse around find its cognate organelle? There is growing evidence that motor protein driven motion of LDs along microtubules may facilitate such LD-organelle interactions. We will summarize some aspects of LD motion leading to LD-organelle contacts, how these change with metabolic state and pathogen infections, and also ask how these pathways could perhaps be targeted selectively in the context of disease and drug delivery. Such a possibility arises because the binding of motor proteins to the monolayer membrane on LDs could be different from motor binding to the membrane on other cellular organelles.
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Affiliation(s)
- Jagjeet Singh
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
- *Correspondence: Roop Mallik, ; Jagjeet Singh,
| | - Paulomi Sanghavi
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Roop Mallik
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
- *Correspondence: Roop Mallik, ; Jagjeet Singh,
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