1
|
Garg V, Geurten BRH. Diving deep: zebrafish models in motor neuron degeneration research. Front Neurosci 2024; 18:1424025. [PMID: 38966756 PMCID: PMC11222423 DOI: 10.3389/fnins.2024.1424025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 05/30/2024] [Indexed: 07/06/2024] Open
Abstract
In the dynamic landscape of biomedical science, the pursuit of effective treatments for motor neuron disorders like hereditary spastic paraplegia (HSP), amyotrophic lateral sclerosis (ALS), and spinal muscular atrophy (SMA) remains a key priority. Central to this endeavor is the development of robust animal models, with the zebrafish emerging as a prime candidate. Exhibiting embryonic transparency, a swift life cycle, and significant genetic and neuroanatomical congruencies with humans, zebrafish offer substantial potential for research. Despite the difference in locomotion-zebrafish undulate while humans use limbs, the zebrafish presents relevant phenotypic parallels to human motor control disorders, providing valuable insights into neurodegenerative diseases. This review explores the zebrafish's inherent traits and how they facilitate profound insights into the complex behavioral and cellular phenotypes associated with these disorders. Furthermore, we examine recent advancements in high-throughput drug screening using the zebrafish model, a promising avenue for identifying therapeutically potent compounds.
Collapse
Affiliation(s)
- Vranda Garg
- Department of Cellular Neurobiology, Georg-August-University Göttingen, Göttingen, Lower Saxony, Germany
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, QC, Canada
- Department of Neuroscience, Université de Montréal, Montreal, QC, Canada
| | | |
Collapse
|
2
|
Kumar M, Knapp JA, Gupta K, Ryan TA. Isolation and Lipidomic Profiling of Neuronal Lipid Droplets: Unveiling the Lipid Landscape for insights into Neurodegenerative Disorders. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.13.571527. [PMID: 38168251 PMCID: PMC10760103 DOI: 10.1101/2023.12.13.571527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Recent advances have expanded the role of lipid droplets (LDs) beyond passive lipid storage, implicating their involvement in various metabolic processes across mammalian tissues. Neuronal LDs, long debated in existence, have been identified in several neural structures, raising questions about their contribution to neurodegenerative disorders. Elucidating the specific chemical makeup of these organelles within neurons is critical for understanding their implication in neural pathologies. This study outlines an improved methodology to stimulate and isolate mature LDs from cultured primary neurons, offering insights into their unique lipid-protein composition. Integrating this method with high-throughput techniques may unveil disease-specific alterations in lipid metabolism, providing avenues for potential therapeutic interventions.
Collapse
Affiliation(s)
- Mukesh Kumar
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA
| | - Justin A Knapp
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Kallol Gupta
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, Maryland 20815, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA
- Nanobiology Institute, Yale University, West Haven, CT 06516, USA
| | - Timothy A. Ryan
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, Maryland 20815, USA
| |
Collapse
|
3
|
Cholesterol esters form supercooled lipid droplets whose nucleation is facilitated by triacylglycerols. Nat Commun 2023; 14:915. [PMID: 36807572 PMCID: PMC9938224 DOI: 10.1038/s41467-023-36375-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 01/27/2023] [Indexed: 02/19/2023] Open
Abstract
Cellular cholesterol can be metabolized to its fatty acid esters, cholesteryl esters (CEs), to be stored in lipid droplets (LDs). With triacylglycerols (TGs), CEs represent the main neutral lipids in LDs. However, while TG melts at ~4 °C, CE melts at ~44 °C, raising the question of how CE-rich LDs form in cells. Here, we show that CE forms supercooled droplets when the CE concentration in LDs is above 20% to TG and, in particular, liquid-crystalline phases when the fraction of CEs is above 90% at 37 °C. In model bilayers, CEs condense and nucleate droplets when the CE/phospholipid ratio reaches over 10-15%. This concentration is reduced by TG pre-clusters in the membrane that thereby facilitate CE nucleation. Accordingly, blocking TG synthesis in cells is sufficient to strongly dampen CE LD nucleation. Finally, CE LDs emerged at seipins, which cluster and nucleate TG LDs in the ER. However, when TG synthesis is inhibited, similar numbers of LDs are generated in the presence and absence of seipin, suggesting that seipin controls CE LD formation via its TG clustering capacity. Our data point to a unique model whereby TG pre-clusters, favorable at seipins, catalyze the nucleation of CE LDs.
Collapse
|
4
|
Nogueira V, Chang CK, Lan CY, Pereira C, Costa V, Teixeira V. Causative links between ER stress and oxidative damage in a yeast model of human N88S seipinopathy. Free Radic Biol Med 2022; 192:165-181. [PMID: 36126862 DOI: 10.1016/j.freeradbiomed.2022.09.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 08/02/2022] [Accepted: 09/13/2022] [Indexed: 11/29/2022]
Abstract
Seipin is encoded by the gene Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2) and FLD1/SEI1 in yeast. The gain-of-function N88S mutation in the BSCL2 gene was identified in a cohort of autosomal dominant motor neuron diseases (MNDs) collectively known as seipinopathies. Previous work has shown that this mutation disrupts N-glycosylation, leading to the formation of inclusion bodies (IBs) and contributing to severe Endoplasmic Reticulum (ER) stress and cell death. In this work, we established a humanized yeast model of N88S seipinopathy that recapitulated the formation of IBs and activation of the unfolded protein response (UPR) observed in mammalian systems. Autophagy and the Hrd1-mediated endoplasmic reticulum-associated degradation (ERAD) were fully functional in cells expressing mutant homomers and WT-mutant heteromers of seipin, discarding the possibility that mutant seipin accumulate due to impaired protein quality control systems. Importantly, the N88S seipin form IBs that appear to induce changes in ER morphology, in association with Kar2 chaperone and the Hsp104 disaggregase. For the first time, we have determined that N88S homo-oligomers expressing cells present reduced viability, decreased antioxidant activity and increased oxidative damage associated with loss of mitochondrial membrane potential, higher reactive oxygen species (ROS) levels and lipid peroxidation. This was correlated with the activation of oxidative stress sensor Yap1. Moreover, activation of ERAD and UPR quality control mechanisms were essential for proper cell growth, and crucial to prevent excessive accumulation of ROS in cells expressing N88S homomers solely. Overall, this study provides new insights into the molecular underpinnings of these rare diseases and offers novel targets for potential pharmacological intervention.
Collapse
Affiliation(s)
- Verónica Nogueira
- Yeast Signalling Networks, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Che-Kang Chang
- Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Chung-Yu Lan
- Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, 30013, Taiwan; Department of Life Science, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Clara Pereira
- Yeast Signalling Networks, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Vítor Costa
- Yeast Signalling Networks, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; ICBAS, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Vitor Teixeira
- Yeast Signalling Networks, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
| |
Collapse
|
5
|
Li Y, Yang X, Peng L, Xia Q, Zhang Y, Huang W, Liu T, Jia D. Role of Seipin in Human Diseases and Experimental Animal Models. Biomolecules 2022; 12:biom12060840. [PMID: 35740965 PMCID: PMC9221541 DOI: 10.3390/biom12060840] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/13/2022] [Accepted: 06/14/2022] [Indexed: 02/05/2023] Open
Abstract
Seipin, a protein encoded by the Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2) gene, is famous for its key role in the biogenesis of lipid droplets and type 2 congenital generalised lipodystrophy (CGL2). BSCL2 gene mutations result in genetic diseases including CGL2, progressive encephalopathy with or without lipodystrophy (also called Celia’s encephalopathy), and BSCL2-associated motor neuron diseases. Abnormal expression of seipin has also been found in hepatic steatosis, neurodegenerative diseases, glioblastoma stroke, cardiac hypertrophy, and other diseases. In the current study, we comprehensively summarise phenotypes, underlying mechanisms, and treatment of human diseases caused by BSCL2 gene mutations, paralleled by animal studies including systemic or specific Bscl2 gene knockout, or Bscl2 gene overexpression. In various animal models representing diseases that are not related to Bscl2 mutations, differential expression patterns and functional roles of seipin are also described. Furthermore, we highlight the potential therapeutic approaches by targeting seipin or its upstream and downstream signalling pathways. Taken together, restoring adipose tissue function and targeting seipin-related pathways are effective strategies for CGL2 treatment. Meanwhile, seipin-related pathways are also considered to have potential therapeutic value in diseases that are not caused by BSCL2 gene mutations.
Collapse
Affiliation(s)
- Yuying Li
- West China Pancreatitis Centre, Centre for Integrated Traditional Chinese Medicine and Western Medicine, West China-Liverpool Biomedical Research Centre, West China Hospital, Sichuan University, Chengdu 610041, China; (Y.L.); (X.Y.); (Q.X.)
| | - Xinmin Yang
- West China Pancreatitis Centre, Centre for Integrated Traditional Chinese Medicine and Western Medicine, West China-Liverpool Biomedical Research Centre, West China Hospital, Sichuan University, Chengdu 610041, China; (Y.L.); (X.Y.); (Q.X.)
| | - Linrui Peng
- Department of Endocrinology and Metabolism, West China Hospital of Sichuan University, Chengdu 610041, China; (L.P.); (Y.Z.)
| | - Qing Xia
- West China Pancreatitis Centre, Centre for Integrated Traditional Chinese Medicine and Western Medicine, West China-Liverpool Biomedical Research Centre, West China Hospital, Sichuan University, Chengdu 610041, China; (Y.L.); (X.Y.); (Q.X.)
| | - Yuwei Zhang
- Department of Endocrinology and Metabolism, West China Hospital of Sichuan University, Chengdu 610041, China; (L.P.); (Y.Z.)
| | - Wei Huang
- West China Pancreatitis Centre, Centre for Integrated Traditional Chinese Medicine and Western Medicine, West China-Liverpool Biomedical Research Centre, West China Hospital, Sichuan University, Chengdu 610041, China; (Y.L.); (X.Y.); (Q.X.)
- Institutes for Systems Genetics & Immunology and Inflammation, Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu 610041, China
- Correspondence: (W.H.); (T.L.)
| | - Tingting Liu
- West China Pancreatitis Centre, Centre for Integrated Traditional Chinese Medicine and Western Medicine, West China-Liverpool Biomedical Research Centre, West China Hospital, Sichuan University, Chengdu 610041, China; (Y.L.); (X.Y.); (Q.X.)
- Correspondence: (W.H.); (T.L.)
| | - Da Jia
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Paediatrics, West China Second University Hospital, State Key Laboratory of Biotherapy and Collaborative Innovation Center of Biotherapy, Sichuan University, Chengdu 610041, China;
| |
Collapse
|
6
|
Islimye E, Girard V, Gould AP. Functions of Stress-Induced Lipid Droplets in the Nervous System. Front Cell Dev Biol 2022; 10:863907. [PMID: 35493070 PMCID: PMC9047859 DOI: 10.3389/fcell.2022.863907] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/22/2022] [Indexed: 12/12/2022] Open
Abstract
Lipid droplets are highly dynamic intracellular organelles that store neutral lipids such as cholesteryl esters and triacylglycerols. They have recently emerged as key stress response components in many different cell types. Lipid droplets in the nervous system are mostly observed in vivo in glia, ependymal cells and microglia. They tend to become more numerous in these cell types and can also form in neurons as a consequence of ageing or stresses involving redox imbalance and lipotoxicity. Abundant lipid droplets are also a characteristic feature of several neurodegenerative diseases. In this minireview, we take a cell-type perspective on recent advances in our understanding of lipid droplet metabolism in glia, neurons and neural stem cells during health and disease. We highlight that a given lipid droplet subfunction, such as triacylglycerol lipolysis, can be physiologically beneficial or harmful to the functions of the nervous system depending upon cellular context. The mechanistic understanding of context-dependent lipid droplet functions in the nervous system is progressing apace, aided by new technologies for probing the lipid droplet proteome and lipidome with single-cell type precision.
Collapse
|
7
|
Seipin localizes at endoplasmic-reticulum-mitochondria contact sites to control mitochondrial calcium import and metabolism in adipocytes. Cell Rep 2022; 38:110213. [PMID: 35021082 DOI: 10.1016/j.celrep.2021.110213] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 10/11/2021] [Accepted: 12/14/2021] [Indexed: 12/31/2022] Open
Abstract
Deficiency of the endoplasmic reticulum (ER) protein seipin results in generalized lipodystrophy by incompletely understood mechanisms. Here, we report mitochondrial abnormalities in seipin-deficient patient cells. A subset of seipin is enriched at ER-mitochondria contact sites (MAMs) in human and mouse cells and localizes in the vicinity of calcium regulators SERCA2, IP3R, and VDAC. Seipin association with MAM calcium regulators is stimulated by fasting-like stimuli, while seipin association with lipid droplets is promoted by lipid loading. Acute seipin removal does not alter ER calcium stores but leads to defective mitochondrial calcium import accompanied by a widespread reduction in Krebs cycle metabolites and ATP levels. In mice, inducible seipin deletion leads to mitochondrial dysfunctions preceding the development of metabolic complications. Together, these data suggest that seipin controls mitochondrial energy metabolism by regulating mitochondrial calcium influx at MAMs. In seipin-deficient adipose tissue, reduced ATP production compromises adipocyte properties, contributing to lipodystrophy pathogenesis.
Collapse
|
8
|
Wilson MH, Ekker SC, Farber SA. Imaging cytoplasmic lipid droplets in vivo with fluorescent perilipin 2 and perilipin 3 knock-in zebrafish. eLife 2021; 10:e66393. [PMID: 34387191 PMCID: PMC8460263 DOI: 10.7554/elife.66393] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 08/10/2021] [Indexed: 12/26/2022] Open
Abstract
Cytoplasmic lipid droplets are highly dynamic storage organelles that are critical for cellular lipid homeostasis. While the molecular details of lipid droplet dynamics are a very active area of investigation, this work has been primarily performed in cultured cells. Taking advantage of the powerful transgenic and in vivo imaging opportunities available in zebrafish, we built a suite of tools to study lipid droplets in real time from the subcellular to the whole organism level. Fluorescently tagging the lipid droplet-associated proteins, perilipin 2 and perilipin 3, in the endogenous loci permits visualization of lipid droplets in the intestine, liver, and adipose tissue. Using these tools, we found that perilipin 3 is rapidly loaded on intestinal lipid droplets following a high-fat meal and later replaced by perilipin 2. These powerful new tools will facilitate studies on the role of lipid droplets in different tissues, under different genetic and physiological manipulations, and in a variety of human disease models.
Collapse
Affiliation(s)
- Meredith H Wilson
- Carnegie Institution for Science Department of EmbryologyBaltimoreUnited States
| | - Stephen C Ekker
- Department of Biochemistry and Molecular Biology, Mayo ClinicRochesterUnited States
| | - Steven A Farber
- Carnegie Institution for Science Department of EmbryologyBaltimoreUnited States
- Johns Hopkins University Department of BiologyBaltimoreUnited States
| |
Collapse
|
9
|
FATP4 inactivation in cultured macrophages attenuates M1- and ER stress-induced cytokine release via a metabolic shift towards triacylglycerides. Biochem J 2021; 478:1861-1877. [PMID: 33900381 DOI: 10.1042/bcj20210155] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/16/2021] [Accepted: 04/26/2021] [Indexed: 12/15/2022]
Abstract
Fatty acid transport protein 4 (FATP4) belongs to a family of acyl-CoA synthetases which activate long-chain fatty acids into acyl-CoAs subsequently used in specific metabolic pathways. Patients with FATP4 mutations and Fatp4-null mice show thick desquamating skin and other complications, however, FATP4 role on macrophage functions has not been studied. We here determined whether the levels of macrophage glycerophospholipids, sphingolipids including ceramides, triacylglycerides, and cytokine release could be altered by FATP4 inactivation. Two in vitro experimental systems were studied: FATP4 knockdown in THP-1-derived macrophages undergoing M1 (LPS + IFNγ) or M2 (IL-4) activation and bone marrow-derived macrophages (BMDMs) from macrophage-specific Fatp4-knockout (Fatp4M-/-) mice undergoing tunicamycin (TM)-induced endoplasmic reticulum stress. FATP4-deficient macrophages showed a metabolic shift towards triacylglycerides and were protected from M1- or TM-induced release of pro-inflammatory cytokines and cellular injury. Fatp4M-/- BMDMs showed specificity in attenuating TM-induced activation of inositol-requiring enzyme1α, but not other unfolded protein response pathways. Under basal conditions, FATP4/Fatp4 deficiency decreased the levels of ceramides and induced an up-regulation of mannose receptor CD206 expression. The deficiency led to an attenuation of IL-8 release in THP-1 cells as well as TNF-α and IL-12 release in BMDMs. Thus, FATP4 functions as an acyl-CoA synthetase in macrophages and its inactivation suppresses the release of pro-inflammatory cytokines by shifting fatty acids towards the synthesis of specific lipids.
Collapse
|
10
|
Tadepalle N, Rugarli EI. Lipid Droplets in the Pathogenesis of Hereditary Spastic Paraplegia. Front Mol Biosci 2021; 8:673977. [PMID: 34041268 PMCID: PMC8141572 DOI: 10.3389/fmolb.2021.673977] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 04/26/2021] [Indexed: 12/21/2022] Open
Abstract
Hereditary spastic paraplegias (HSPs) are genetically heterogeneous conditions caused by the progressive dying back of the longest axons in the central nervous system, the corticospinal axons. A wealth of data in the last decade has unraveled disturbances of lipid droplet (LD) biogenesis, maturation, turnover and contact sites in cellular and animal models with perturbed expression and function of HSP proteins. As ubiquitous organelles that segregate neutral lipid into a phospholipid monolayer, LDs are at the cross-road of several processes including lipid metabolism and trafficking, energy homeostasis, and stress signaling cascades. However, their role in brain cells, especially in neurons remains enigmatic. Here, we review experimental findings linking LD abnormalities to defective function of proteins encoded by HSP genes, and discuss arising questions in the context of the pathogenesis of HSP.
Collapse
Affiliation(s)
- Nimesha Tadepalle
- Molecular and Cell Biology Laboratory, Salk Institute of Biological Sciences, La Jolla, CA, United States
| | - Elena I Rugarli
- Institute for Genetics, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany.,Center for Molecular Medicine (CMMC),Cologne, Germany
| |
Collapse
|
11
|
Prasanna X, Salo VT, Li S, Ven K, Vihinen H, Jokitalo E, Vattulainen I, Ikonen E. Seipin traps triacylglycerols to facilitate their nanoscale clustering in the endoplasmic reticulum membrane. PLoS Biol 2021; 19:e3000998. [PMID: 33481779 PMCID: PMC7857593 DOI: 10.1371/journal.pbio.3000998] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 02/03/2021] [Accepted: 11/02/2020] [Indexed: 11/19/2022] Open
Abstract
Seipin is a disk-like oligomeric endoplasmic reticulum (ER) protein important for lipid droplet (LD) biogenesis and triacylglycerol (TAG) delivery to growing LDs. Here we show through biomolecular simulations bridged to experiments that seipin can trap TAGs in the ER bilayer via the luminal hydrophobic helices of the protomers delineating the inner opening of the seipin disk. This promotes the nanoscale sequestration of TAGs at a concentration that by itself is insufficient to induce TAG clustering in a lipid membrane. We identify Ser166 in the α3 helix as a favored TAG occupancy site and show that mutating it compromises the ability of seipin complexes to sequester TAG in silico and to promote TAG transfer to LDs in cells. While the S166D-seipin mutant colocalizes poorly with promethin, the association of nascent wild-type seipin complexes with promethin is promoted by TAGs. Together, these results suggest that seipin traps TAGs via its luminal hydrophobic helices, serving as a catalyst for seeding the TAG cluster from dissolved monomers inside the seipin ring, thereby generating a favorable promethin binding interface.
Collapse
Affiliation(s)
- Xavier Prasanna
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Veijo T. Salo
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Shiqian Li
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Katharina Ven
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Helena Vihinen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Eija Jokitalo
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Ilpo Vattulainen
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Elina Ikonen
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
- * E-mail:
| |
Collapse
|
12
|
Teixeira V, Maciel P, Costa V. Leading the way in the nervous system: Lipid Droplets as new players in health and disease. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1866:158820. [PMID: 33010453 DOI: 10.1016/j.bbalip.2020.158820] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 09/01/2020] [Accepted: 09/21/2020] [Indexed: 12/28/2022]
Abstract
Lipid droplets (LDs) are ubiquitous fat storage organelles composed of a neutral lipid core, comprising triacylglycerols (TAG) and sterol esters (SEs), surrounded by a phospholipid monolayer membrane with several decorating proteins. Recently, LD biology has come to the foreground of research due to their importance for energy homeostasis and cellular stress response. As aberrant LD accumulation and lipid depletion are hallmarks of numerous diseases, addressing LD biogenesis and turnover provides a new framework for understanding disease-related mechanisms. Here we discuss the potential role of LDs in neurodegeneration, while making some predictions on how LD imbalance can contribute to pathophysiology in the brain.
Collapse
Affiliation(s)
- Vitor Teixeira
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade of Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
| | - Patrícia Maciel
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Vítor Costa
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade of Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; ICBAS, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| |
Collapse
|
13
|
Salo VT, Hölttä-Vuori M, Ikonen E. Seipin-Mediated Contacts as Gatekeepers of Lipid Flux at the Endoplasmic Reticulum–Lipid Droplet Nexus. ACTA ACUST UNITED AC 2020. [DOI: 10.1177/2515256420945820] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Lipid droplets (LDs) are dynamic cellular hubs of lipid metabolism. While LDs contact a plethora of organelles, they have the most intimate relationship with the endoplasmic reticulum (ER). Indeed, LDs are initially assembled at specialized ER subdomains, and recent work has unraveled an increasing array of proteins regulating ER-LD contacts. Among these, seipin, a highly conserved lipodystrophy protein critical for LD growth and adipogenesis, deserves special attention. Here, we review recent insights into the role of seipin in LD biogenesis and as a regulator of ER-LD contacts. These studies have also highlighted the evolving concept of ER and LDs as a functional continuum for lipid partitioning and pinpointed a role for seipin at the ER-LD nexus in controlling lipid flux between these compartments.
Collapse
Affiliation(s)
- Veijo T. Salo
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Maarit Hölttä-Vuori
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Elina Ikonen
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| |
Collapse
|
14
|
Santinho A, Salo VT, Chorlay A, Li S, Zhou X, Omrane M, Ikonen E, Thiam AR. Membrane Curvature Catalyzes Lipid Droplet Assembly. Curr Biol 2020; 30:2481-2494.e6. [PMID: 32442467 DOI: 10.1016/j.cub.2020.04.066] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 03/24/2020] [Accepted: 04/23/2020] [Indexed: 12/20/2022]
Abstract
Lipid droplet (LD) biogenesis begins in the endoplasmic reticulum (ER) bilayer, but how the ER topology impacts this process is unclear. An early step in LD formation is nucleation, wherein free neutral lipids, mainly triacylglycerols (TGs) and sterol esters (SEs), condense into a nascent LD. How this transition occurs is poorly known. Here, we found that LDs preferably assemble at ER tubules, with higher curvature than ER sheets, independently of the LD assembly protein seipin. Indeed, the critical TG concentration required for initiating LD assembly is lower at curved versus flat membrane regions. In agreement with this finding, flat ER regions bear higher amounts of free TGs than tubular ones and present less LDs. By using an in vitro approach, we discovered that the presence of free TGs in tubules is energetically unfavorable, leading to outflow of TGs to flat membrane regions or condensation into LDs. Accordingly, in vitro LD nucleation can be achieved by the sole increase of membrane curvature. In contrast to TGs, the presence of free SEs is favored at tubules and increasing SE levels is inhibitory to the curvature-induced nucleation of TG LDs. Finally, we found that seipin is enriched at ER tubules and controls the condensation process, preventing excessive tubule-induced nucleation. The absence of seipin provokes erratic LD nucleation events determined by the abundance of ER tubules. In summary, our data indicate that membrane curvature catalyzes LD assembly.
Collapse
Affiliation(s)
- Alexandre Santinho
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
| | - Veijo T Salo
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; Minerva Foundation Institute for Medical Research, 00290 Helsinki, Finland
| | - Aymeric Chorlay
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
| | - Shiqian Li
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; Minerva Foundation Institute for Medical Research, 00290 Helsinki, Finland
| | - Xin Zhou
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; Minerva Foundation Institute for Medical Research, 00290 Helsinki, Finland
| | - Mohyeddine Omrane
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
| | - Elina Ikonen
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; Minerva Foundation Institute for Medical Research, 00290 Helsinki, Finland
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France.
| |
Collapse
|
15
|
Spastin mutations impair coordination between lipid droplet dispersion and reticulum. PLoS Genet 2020; 16:e1008665. [PMID: 32315314 PMCID: PMC7173978 DOI: 10.1371/journal.pgen.1008665] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Accepted: 02/12/2020] [Indexed: 12/22/2022] Open
Abstract
Lipid droplets (LD) are affected in multiple human disorders. These highly dynamic organelles are involved in many cellular roles. While their intracellular dispersion is crucial to ensure their function and other organelles-contact, underlying mechanisms are still unclear. Here we show that Spastin, one of the major proteins involved in Hereditary Spastic Paraplegia (HSP), controls LD dispersion. Spastin depletion in zebrafish affects metabolic properties and organelle dynamics. These functions are ensured by a conserved complex set of splice variants. M1 isoforms determine LD dispersion in the cell by orchestrating endoplasmic reticulum (ER) shape along microtubules (MTs). To further impact LD fate, Spastin modulates transcripts levels and subcellular location of other HSP key players, notably Seipin and REEP1. In pathological conditions, mutations in human Spastin M1 disrupt this mechanism and impacts LD network. Spastin depletion influences not only other key proteins but also modulates specific neutral lipids and phospholipids, revealing an impact on membrane and organelle components. Altogether our results show that Spastin and its partners converge in a common machinery that coordinates LD dispersion and ER shape along MTs. Any alteration of this system results in HSP clinical features and impacts lipids profile, thus opening new avenues for novel biomarkers of HSP.
Collapse
|
16
|
Wat LW, Chao C, Bartlett R, Buchanan JL, Millington JW, Chih HJ, Chowdhury ZS, Biswas P, Huang V, Shin LJ, Wang LC, Gauthier MPL, Barone MC, Montooth KL, Welte MA, Rideout EJ. A role for triglyceride lipase brummer in the regulation of sex differences in Drosophila fat storage and breakdown. PLoS Biol 2020; 18:e3000595. [PMID: 31961851 PMCID: PMC6994176 DOI: 10.1371/journal.pbio.3000595] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 01/31/2020] [Accepted: 01/03/2020] [Indexed: 01/26/2023] Open
Abstract
Triglycerides are the major form of stored fat in all animals. One important determinant of whole-body fat storage is whether an animal is male or female. Here, we use Drosophila, an established model for studies on triglyceride metabolism, to gain insight into the genes and physiological mechanisms that contribute to sex differences in fat storage. Our analysis of triglyceride storage and breakdown in both sexes identified a role for triglyceride lipase brummer (bmm) in the regulation of sex differences in triglyceride homeostasis. Normally, male flies have higher levels of bmm mRNA both under normal culture conditions and in response to starvation, a lipolytic stimulus. We find that loss of bmm largely eliminates the sex difference in triglyceride storage and abolishes the sex difference in triglyceride breakdown via strongly male-biased effects. Although we show that bmm function in the fat body affects whole-body triglyceride levels in both sexes, in males, we identify an additional role for bmm function in the somatic cells of the gonad and in neurons in the regulation of whole-body triglyceride homeostasis. Furthermore, we demonstrate that lipid droplets are normally present in both the somatic cells of the male gonad and in neurons, revealing a previously unrecognized role for bmm function, and possibly lipid droplets, in these cell types in the regulation of whole-body triglyceride homeostasis. Taken together, our data reveal a role for bmm function in the somatic cells of the gonad and in neurons in the regulation of male–female differences in fat storage and breakdown and identify bmm as a link between the regulation of triglyceride homeostasis and biological sex. An investigation of the genetic and physiological mechanisms underlying sex differences in fat storage and breakdown in the fruit fly Drosophila identifies previously unrecognized sex- and cell type-specific roles for the conserved triglyceride lipase brummer.
Collapse
Affiliation(s)
- Lianna W. Wat
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Charlotte Chao
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Rachael Bartlett
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Justin L. Buchanan
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Jason W. Millington
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Hui Ju Chih
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Zahid S. Chowdhury
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Puja Biswas
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Vivian Huang
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Leah J. Shin
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Lin Chuan Wang
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Marie-Pierre L. Gauthier
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Maria C. Barone
- Department of Biology, University of Rochester, Rochester, New York, United States of America
| | - Kristi L. Montooth
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Michael A. Welte
- Department of Biology, University of Rochester, Rochester, New York, United States of America
| | - Elizabeth J. Rideout
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
| |
Collapse
|
17
|
Naef V, Mero S, Fichi G, D'Amore A, Ogi A, Gemignani F, Santorelli FM, Marchese M. Swimming in Deep Water: Zebrafish Modeling of Complicated Forms of Hereditary Spastic Paraplegia and Spastic Ataxia. Front Neurosci 2019; 13:1311. [PMID: 31920481 PMCID: PMC6914767 DOI: 10.3389/fnins.2019.01311] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 11/22/2019] [Indexed: 12/13/2022] Open
Abstract
Hereditary spastic paraplegia (HSP) and hereditary ataxia (HA) are two groups of disorders characterized, respectively, by progressive dysfunction or degeneration of the pyramidal tracts (HSP) and of the Purkinje cells and spinocerebellar tracts (HA). Although HSP and HA are generally shown to have distinct clinical-genetic profiles, in several cases the clinical presentation, the causative genes, and the cellular pathways and mechanisms involved overlap between the two forms. Genetic analyses in humans in combination with in vitro and in vivo studies using model systems have greatly expanded our knowledge of spinocerebellar degenerative disorders. In this review, we focus on the zebrafish (Danio rerio), a vertebrate model widely used in biomedical research since its overall nervous system organization is similar to that of humans. A critical analysis of the literature suggests that zebrafish could serve as a powerful experimental tool for molecular and genetic dissection of both HA and HSP. The zebrafish, found to be very useful for demonstrating the causal relationship between defect and mutation, also offers a useful platform to exploit for the development of therapies.
Collapse
Affiliation(s)
- Valentina Naef
- Neurobiology and Molecular Medicine, IRCCS Stella Maris, Pisa, Italy
| | - Serena Mero
- Neurobiology and Molecular Medicine, IRCCS Stella Maris, Pisa, Italy.,Department of Biology, University of Pisa, Pisa, Italy
| | - Gianluca Fichi
- Neurobiology and Molecular Medicine, IRCCS Stella Maris, Pisa, Italy.,Struttura Complessa Toscana Sud (Sede Grosseto), Istituto Zooprofilattico Sperimentale del Lazio e Toscana M. Aleandri, Grosseto, Italy
| | - Angelica D'Amore
- Neurobiology and Molecular Medicine, IRCCS Stella Maris, Pisa, Italy.,Department of Biology, University of Pisa, Pisa, Italy.,Department of Neurology, The F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States
| | - Asahi Ogi
- Neurobiology and Molecular Medicine, IRCCS Stella Maris, Pisa, Italy.,Department of Veterinary Sciences, University of Pisa, Pisa, Italy
| | | | | | - Maria Marchese
- Neurobiology and Molecular Medicine, IRCCS Stella Maris, Pisa, Italy
| |
Collapse
|
18
|
Heybrock S, Kanerva K, Meng Y, Ing C, Liang A, Xiong ZJ, Weng X, Ah Kim Y, Collins R, Trimble W, Pomès R, Privé GG, Annaert W, Schwake M, Heeren J, Lüllmann-Rauch R, Grinstein S, Ikonen E, Saftig P, Neculai D. Lysosomal integral membrane protein-2 (LIMP-2/SCARB2) is involved in lysosomal cholesterol export. Nat Commun 2019; 10:3521. [PMID: 31387993 PMCID: PMC6684646 DOI: 10.1038/s41467-019-11425-0] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 07/12/2019] [Indexed: 11/30/2022] Open
Abstract
The intracellular transport of cholesterol is subject to tight regulation. The structure of the lysosomal integral membrane protein type 2 (LIMP-2, also known as SCARB2) reveals a large cavity that traverses the molecule and resembles the cavity in SR-B1 that mediates lipid transfer. The detection of cholesterol within the LIMP-2 structure and the formation of cholesterol-like inclusions in LIMP-2 knockout mice suggested the possibility that LIMP2 transports cholesterol in lysosomes. We present results of molecular modeling, crosslinking studies, microscale thermophoresis and cell-based assays that support a role of LIMP-2 in cholesterol transport. We show that the cavity in the luminal domain of LIMP-2 can bind and deliver exogenous cholesterol to the lysosomal membrane and later to lipid droplets. Depletion of LIMP-2 alters SREBP-2-mediated cholesterol regulation, as well as LDL-receptor levels. Our data indicate that LIMP-2 operates in parallel with Niemann Pick (NPC)-proteins, mediating a slower mode of lysosomal cholesterol export.
Collapse
Affiliation(s)
- Saskia Heybrock
- Biochemisches Institut, Christian-Albrechts-Universität Kiel, Kiel, Germany
| | - Kristiina Kanerva
- Faculty of Medicine, Anatomy and Stem Cells and Metabolism Research Program, University of Helsinki, Helsinki, Finland
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Ying Meng
- Department of Cell Biology, and Department of Pathology Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China
| | - Chris Ing
- Program in Molecular Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, M5G 0A4, Canada
- Department of Biochemistry, University of Toronto, Toronto, M5S 1A8, Canada
| | - Anna Liang
- Program in Molecular Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, M5G 0A4, Canada
- Department of Biochemistry, University of Toronto, Toronto, M5S 1A8, Canada
| | - Zi-Jian Xiong
- Department of Biochemistry, University of Toronto, Toronto, M5S 1A8, Canada
| | - Xialian Weng
- Department of Cell Biology, and Department of Pathology Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China
| | - Young Ah Kim
- Department of Chemistry and Biochemistry, Queens College, City University of New York, Flushing, New York, USA
| | - Richard Collins
- Cell Biology Program, Hospital for Sick Children, Toronto, M5G 1X8, Canada
| | - William Trimble
- Department of Biochemistry, University of Toronto, Toronto, M5S 1A8, Canada
- Cell Biology Program, Hospital for Sick Children, Toronto, M5G 1X8, Canada
- Department of Physiology, University of Toronto, Toronto, M5S 1A8, Canada
| | - Régis Pomès
- Program in Molecular Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, M5G 0A4, Canada
- Department of Biochemistry, University of Toronto, Toronto, M5S 1A8, Canada
| | - Gilbert G Privé
- Department of Biochemistry, University of Toronto, Toronto, M5S 1A8, Canada
- Princes Margaret Cancer Centre, Toronto, ON, Canada
| | - Wim Annaert
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, Leuven, Belgium
| | - Michael Schwake
- Faculty of Chemistry, Biochemistry III, University of Bielefeld, 33615, Bielefeld, Germany
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA
| | - Joerg Heeren
- Institut für Biochemie und Molekulare Zellbiologie, Zentrum für Experimentelle Medizin, Universitätsklinikum Hamburg-Eppendorf, Hamburg-Eppendorf, Germany
| | | | - Sergio Grinstein
- Department of Biochemistry, University of Toronto, Toronto, M5S 1A8, Canada.
- Cell Biology Program, Hospital for Sick Children, Toronto, M5G 1X8, Canada.
| | - Elina Ikonen
- Faculty of Medicine, Anatomy and Stem Cells and Metabolism Research Program, University of Helsinki, Helsinki, Finland.
- Minerva Foundation Institute for Medical Research, Helsinki, Finland.
| | - Paul Saftig
- Biochemisches Institut, Christian-Albrechts-Universität Kiel, Kiel, Germany.
| | - Dante Neculai
- Department of Cell Biology, and Department of Pathology Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China.
| |
Collapse
|
19
|
Salo VT, Li S, Vihinen H, Hölttä-Vuori M, Szkalisity A, Horvath P, Belevich I, Peränen J, Thiele C, Somerharju P, Zhao H, Santinho A, Thiam AR, Jokitalo E, Ikonen E. Seipin Facilitates Triglyceride Flow to Lipid Droplet and Counteracts Droplet Ripening via Endoplasmic Reticulum Contact. Dev Cell 2019; 50:478-493.e9. [PMID: 31178403 DOI: 10.1016/j.devcel.2019.05.016] [Citation(s) in RCA: 128] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 02/27/2019] [Accepted: 05/03/2019] [Indexed: 01/02/2023]
Abstract
Seipin is an oligomeric integral endoplasmic reticulum (ER) protein involved in lipid droplet (LD) biogenesis. To study the role of seipin in LD formation, we relocalized it to the nuclear envelope and found that LDs formed at these new seipin-defined sites. The sites were characterized by uniform seipin-mediated ER-LD necks. At low seipin content, LDs only grew at seipin sites, and tiny, growth-incompetent LDs appeared in a Rab18-dependent manner. When seipin was removed from ER-LD contacts within 1 h, no lipid metabolic defects were observed, but LDs became heterogeneous in size. Studies in seipin-ablated cells and model membranes revealed that this heterogeneity arises via a biophysical ripening process, with triglycerides partitioning from smaller to larger LDs through droplet-bilayer contacts. These results suggest that seipin supports the formation of structurally uniform ER-LD contacts and facilitates the delivery of triglycerides from ER to LDs. This counteracts ripening-induced shrinkage of small LDs.
Collapse
Affiliation(s)
- Veijo T Salo
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Shiqian Li
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Helena Vihinen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Maarit Hölttä-Vuori
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | | | | | - Ilya Belevich
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Johan Peränen
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | | | - Pentti Somerharju
- Department of Biochemistry, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Hongxia Zhao
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Alexandre Santinho
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Universite de Paris, Paris, France
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Universite de Paris, Paris, France.
| | - Eija Jokitalo
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
| | - Elina Ikonen
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Minerva Foundation Institute for Medical Research, Helsinki, Finland.
| |
Collapse
|
20
|
Sui X, Arlt H, Brock KP, Lai ZW, DiMaio F, Marks DS, Liao M, Farese RV, Walther TC. Cryo-electron microscopy structure of the lipid droplet-formation protein seipin. J Cell Biol 2018; 217:4080-4091. [PMID: 30327422 PMCID: PMC6279392 DOI: 10.1083/jcb.201809067] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 10/03/2018] [Accepted: 10/05/2018] [Indexed: 01/11/2023] Open
Abstract
Sui et al. report the cryo-EM structure of the conserved luminal domain of the lipid droplet (LD)-formation protein seipin. The structure reveals key features of this domain and suggests a new model for seipin’s role in LD formation. Metabolic energy is stored in cells primarily as triacylglycerols in lipid droplets (LDs), and LD dysregulation leads to metabolic diseases. The formation of monolayer-bound LDs from the endoplasmic reticulum (ER) bilayer is poorly understood, but the ER protein seipin is essential to this process. In this study, we report a cryo–electron microscopy structure and functional characterization of Drosophila melanogaster seipin. The structure reveals a ring-shaped dodecamer with the luminal domain of each monomer resolved at ∼4.0 Å. Each luminal domain monomer exhibits two distinctive features: a hydrophobic helix (HH) positioned toward the ER bilayer and a β-sandwich domain with structural similarity to lipid-binding proteins. This structure and our functional testing in cells suggest a model in which seipin oligomers initially detect forming LDs in the ER via HHs and subsequently act as membrane anchors to enable lipid transfer and LD growth.
Collapse
Affiliation(s)
- Xuewu Sui
- Department of Cell Biology, Harvard Medical School, Boston, MA.,Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA
| | - Henning Arlt
- Department of Cell Biology, Harvard Medical School, Boston, MA.,Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA
| | - Kelly P Brock
- Department of Systems Biology, Harvard Medical School, Boston, MA
| | - Zon Weng Lai
- Department of Cell Biology, Harvard Medical School, Boston, MA.,Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA
| | - Frank DiMaio
- Department of Biochemistry and Institute of Protein Design, University of Washington, Seattle, WA
| | - Debora S Marks
- Department of Systems Biology, Harvard Medical School, Boston, MA
| | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | - Robert V Farese
- Department of Cell Biology, Harvard Medical School, Boston, MA .,Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA.,Broad Institute, Massachusetts Institute of Technology and Harvard University, Cambridge, MA
| | - Tobias C Walther
- Department of Cell Biology, Harvard Medical School, Boston, MA .,Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA.,Broad Institute, Massachusetts Institute of Technology and Harvard University, Cambridge, MA.,Howard Hughes Medical Institute, Boston, MA
| |
Collapse
|
21
|
Exploring Seipin: From Biochemistry to Bioinformatics Predictions. Int J Cell Biol 2018; 2018:5207608. [PMID: 30402103 PMCID: PMC6192094 DOI: 10.1155/2018/5207608] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 08/12/2018] [Accepted: 09/03/2018] [Indexed: 01/30/2023] Open
Abstract
Seipin is a nonenzymatic protein encoded by the BSCL2 gene. It is involved in lipodystrophy and seipinopathy diseases. Named in 2001, all seipin functions are still far from being understood. Therefore, we reviewed much of the research, trying to find a pattern that could explain commonly observed features of seipin expression disorders. Likewise, this review shows how this protein seems to have tissue-specific functions. In an integrative view, we conclude by proposing a theoretical model to explain how seipin might be involved in the triacylglycerol synthesis pathway.
Collapse
|
22
|
Dantas de Medeiros JL, Carneiro Bezerra B, Brito de Araújo TA, Craveiro Sarmento AS, de Azevedo Medeiros LB, Peroni Gualdi L, Luna Cruz MDS, Xavier Nobre TT, Gomes Lima J, Araújo de Melo Campos JT. Impairment of respiratory muscle strength in Berardinelli-Seip congenital lipodystrophy subjects. Respir Res 2018; 19:173. [PMID: 30208912 PMCID: PMC6134719 DOI: 10.1186/s12931-018-0879-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 09/05/2018] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Berardinelli-Seip Congenital Generalized Lipodystrophy (BSCL) is an ultra-rare metabolic disease characterized by hypertriglyceridemia, hyperinsulinemia, hyperglycemia, hypoleptinemia, and diabetes mellitus. Although cardiovascular disturbances have been observed in BSCL patients, there are no studies regarding the Respiratory Muscle Strength (RMS) in this type of lipodystrophy. This study aimed to evaluate RMS in BSCL subjects compared with healthy subjects. METHODS Eleven individuals with BSCL and 11 healthy subjects matched for age and gender were included in this study. The Maximum Inspiratory Pressure (MIP), Maximum Expiratory Pressure (MEP), and Peripheral Muscle Strength (PMS) were measured for three consecutive years. BSCL subjects were compared to healthy individuals for MIP, MEP, and PMS. Correlations between PMS and MIP were also analyzed. The genetic diagnosis was performed, and sociodemographic and anthropometric data were also collected. RESULTS BSCL subjects showed significantly lower values for MIP and MEP (p < 0.0001 and p = 0.0002, respectively) in comparison to healthy subjects, but no changes in handgrip strength (p = 0.15). Additionally, we did not observe changes in MIP, MEP, and PMS two years after the first analysis, showing maintenance of respiratory dysfunction in BSCL subjects (p = 0.05; p = 0.45; p = 0.99). PMS and MIP were not correlated in these subjects (r = 0.56; p = 0.18). CONCLUSION BSCL subjects showed lower respiratory muscle strength when compared with healthy subjects; however, PMS was not altered. These findings were maintained at similar levels during the two years of evaluation. Our data reveal the first association of BSCL with the development of respiratory muscle weakness.
Collapse
Affiliation(s)
| | - Bruno Carneiro Bezerra
- Faculdade de Ciências da Saúde do Trairi, Universidade Federal do Rio Grande do Norte, Santa Cruz, RN Brazil
| | | | - Aquiles Sales Craveiro Sarmento
- Laboratório de Biologia Molecular e Genômica, Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN Brazil
| | - Lázaro Batista de Azevedo Medeiros
- Laboratório de Biologia Molecular e Genômica, Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN Brazil
| | - Lucien Peroni Gualdi
- Faculdade de Ciências da Saúde do Trairi, Universidade Federal do Rio Grande do Norte, Santa Cruz, RN Brazil
| | - Maria do Socorro Luna Cruz
- Faculdade de Ciências da Saúde do Trairi, Universidade Federal do Rio Grande do Norte, Santa Cruz, RN Brazil
| | | | - Josivan Gomes Lima
- Departamento de Medicina Clínica, Hospital Universitário Onofre Lopes (HUOL)/UFRN, Natal, RN Brazil
| | - Julliane Tamara Araújo de Melo Campos
- Faculdade de Ciências da Saúde do Trairi, Universidade Federal do Rio Grande do Norte, Santa Cruz, RN Brazil
- Laboratório de Biologia Molecular e Genômica, Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN Brazil
| |
Collapse
|
23
|
Abstract
Lipid droplets (LDs) are ubiquitous fat storage organelles and play key roles in lipid metabolism and energy homeostasis; in addition, they contribute to protein storage, folding, and degradation. However, a role for LDs in the nervous system remains largely unexplored. We discuss evidence supporting an intimate functional connection between LDs and motor neuron disease (MND) pathophysiology, examining how LD functions in systemic energy homeostasis, in neuron-glia metabolic coupling, and in protein folding and clearance may affect or contribute to disease pathology. An integrated understanding of LD biology and neurodegeneration may open the way for new therapeutic interventions.
Collapse
Affiliation(s)
- Giuseppa Pennetta
- Euan MacDonald Centre for Motor Neuron Disease Research, University of Edinburgh, Edinburgh EH8 9XD, UK; Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, UK.
| | - Michael A Welte
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| |
Collapse
|
24
|
Araújo-Vilar D, Domingo-Jiménez R, Ruibal Á, Aguiar P, Ibáñez-Micó S, Garrido-Pumar M, Martínez-Olmos MÁ, López-Soler C, Guillín-Amarelle C, González-Rodríguez M, Rodríguez-Núñez A, Álvarez-Escudero J, Liñares-Paz M, González-Méndez B, Rodríguez-García S, Sánchez-Iglesias S. Association of metreleptin treatment and dietary intervention with neurological outcomes in Celia's encephalopathy. Eur J Hum Genet 2018; 26:396-406. [PMID: 29367704 DOI: 10.1038/s41431-017-0052-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 11/03/2017] [Accepted: 11/13/2017] [Indexed: 12/18/2022] Open
Abstract
Celia's encephalopathy (progressive encephalopathy with/without lipodystrophy, PELD) is a recessive neurodegenerative disease that is fatal in childhood. It is caused by a c.985C>T variant in the BSCL2/seipin gene that results in an aberrant seipin protein. We evaluated neurological development before and during treatment with human recombinant leptin (metreleptin) plus a dietary intervention rich in polyunsaturated fatty acids (PUFA) in the only living patient. A 7 years and 10 months old girl affected by PELD was treated at age 3 years with metreleptin, adding at age 6 omega-3 fatty acid supplementation. Her mental age was evaluated using the Battelle Developmental Inventory Screening Test (BDI), and brain PET/MRI was performed before treatment and at age 5, 6.5, and 7.5 years. At age 7.5 years, the girl remains alive and leads a normal life for her mental age of 30 months, which increased by 4 months over the last 18 months according to BDI. PET images showed improved glucose uptake in the thalami, cerebellum, and brainstem. This patient showed a clear slowdown in neurological regression during leptin replacement plus a high PUFA diet. The aberrant BSCL2 transcript was overexpressed in SH-SY5Y cells and was treated with docosahexaenoic acid (200 µM) plus leptin (0.001 mg/ml) for 24 h. The relative expression of aberrant BSCL2 transcript was measured by qPCR. In vitro studies showed significant reduction (32%) in aberrant transcript expression. This therapeutic approach should be further studied in this devastating disease.
Collapse
Affiliation(s)
- David Araújo-Vilar
- Thyroid and Metabolic Diseases Unit, Biomedical Research Institute (CIMUS)-IDIS, School of Medicine, Universidade de Santiago de Compostela, Santiago de Compostela, Spain. .,Division of Endocrinology and Nutrition, Hospital Clínico Universitario de Santiago de Compostela, Santiago de Compostela, Spain.
| | - Rosario Domingo-Jiménez
- Section of Neuropediatrics, Division of Pediatrics, Hospital Clínico Universitario Virgen de la Arrixaca-IMIB Arrixaca, Murcia, Spain
| | - Álvaro Ruibal
- Division of Nuclear Medicine, Hospital Clínico Universitario de Santiago de Compostela, Santiago de Compostela, Spain.,Fundación Tejerina, Madrid, Spain.,Molecular Imaging and Medical Physics, Universidade de Santiago de Compostela. IDIS, Santiago de Compostela, Spain
| | - Pablo Aguiar
- Division of Nuclear Medicine, Hospital Clínico Universitario de Santiago de Compostela, Santiago de Compostela, Spain.,Molecular Imaging and Medical Physics, Universidade de Santiago de Compostela. IDIS, Santiago de Compostela, Spain
| | - Salvador Ibáñez-Micó
- Section of Neuropediatrics, Division of Pediatrics, Hospital Clínico Universitario Virgen de la Arrixaca-IMIB Arrixaca, Murcia, Spain
| | - Miguel Garrido-Pumar
- Division of Nuclear Medicine, Hospital Clínico Universitario de Santiago de Compostela, Santiago de Compostela, Spain
| | - Miguel Ángel Martínez-Olmos
- Division of Endocrinology and Nutrition, Hospital Clínico Universitario de Santiago de Compostela, Santiago de Compostela, Spain
| | | | - Cristina Guillín-Amarelle
- Thyroid and Metabolic Diseases Unit, Biomedical Research Institute (CIMUS)-IDIS, School of Medicine, Universidade de Santiago de Compostela, Santiago de Compostela, Spain.,Division of Endocrinology and Nutrition, Hospital Clínico Universitario de Santiago de Compostela, Santiago de Compostela, Spain
| | - María González-Rodríguez
- Division of Endocrinology and Nutrition, Hospital Clínico Universitario de Santiago de Compostela, Santiago de Compostela, Spain
| | - Antonio Rodríguez-Núñez
- Pediatric Intensive Care Unit, Pediatric Area, Hospital Clínico Universitario de Santiago de Compostela, Santiago de Compostela, Spain
| | - Julián Álvarez-Escudero
- Anesthesia and Reanimation Department, Hospital Clínico Universitario de Santiago de Compostela, Santiago de Compostela, Spain
| | - Mercedes Liñares-Paz
- Department of Radiology, Hospital Clínico Universitario de Santiago de Compostela, Santiago de Compostela, Spain
| | - Blanca González-Méndez
- Thyroid and Metabolic Diseases Unit, Biomedical Research Institute (CIMUS)-IDIS, School of Medicine, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Silvia Rodríguez-García
- Thyroid and Metabolic Diseases Unit, Biomedical Research Institute (CIMUS)-IDIS, School of Medicine, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Sofía Sánchez-Iglesias
- Thyroid and Metabolic Diseases Unit, Biomedical Research Institute (CIMUS)-IDIS, School of Medicine, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| |
Collapse
|
25
|
Salo VT, Belevich I, Li S, Karhinen L, Vihinen H, Vigouroux C, Magré J, Thiele C, Hölttä-Vuori M, Jokitalo E, Ikonen E. Seipin regulates ER-lipid droplet contacts and cargo delivery. EMBO J 2016; 35:2699-2716. [PMID: 27879284 PMCID: PMC5167346 DOI: 10.15252/embj.201695170] [Citation(s) in RCA: 212] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 10/22/2016] [Accepted: 10/24/2016] [Indexed: 11/10/2022] Open
Abstract
Seipin is an endoplasmic reticulum (ER) membrane protein implicated in lipid droplet (LD) biogenesis and mutated in severe congenital lipodystrophy (BSCL2). Here, we show that seipin is stably associated with nascent ER–LD contacts in human cells, typically via one mobile focal point per LD. Seipin appears critical for such contacts since ER–LD contacts were completely missing or morphologically aberrant in seipin knockout and BSCL2 patient cells. In parallel, LD mobility was increased and protein delivery from the ER to LDs to promote LD growth was decreased. Moreover, while growing LDs normally acquire lipid and protein constituents from the ER, this process was compromised in seipin‐deficient cells. In the absence of seipin, the initial synthesis of neutral lipids from exogenous fatty acid was normal, but fatty acid incorporation into neutral lipids in cells with pre‐existing LDs was impaired. Together, our data suggest that seipin helps to connect newly formed LDs to the ER and that by stabilizing ER–LD contacts seipin facilitates the incorporation of protein and lipid cargo into growing LDs in human cells.
Collapse
Affiliation(s)
- Veijo T Salo
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Ilya Belevich
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Shiqian Li
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Leena Karhinen
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Helena Vihinen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Corinne Vigouroux
- Sorbonne Universités, UPMC Univ Paris 6, Inserm UMR_S938, Saint-Antoine Research Center, Institute of Cardiometabolism And Nutrition, AP-HP, Saint-Antoine Hospital Department of Molecular Biology and Genetics, Paris, France
| | - Jocelyne Magré
- l'Institut du Thorax, INSERM CNRS UNIV Nantes, Nantes, France
| | | | - Maarit Hölttä-Vuori
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Eija Jokitalo
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Elina Ikonen
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland .,Minerva Foundation Institute for Medical Research, Helsinki, Finland
| |
Collapse
|
26
|
Hepatic BSCL2 (Seipin) Deficiency Disrupts Lipid Droplet Homeostasis and Increases Lipid Metabolism via SCD1 Activity. Lipids 2016; 52:129-150. [DOI: 10.1007/s11745-016-4210-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 10/25/2016] [Indexed: 12/11/2022]
|
27
|
Sánchez-Iglesias S, Unruh-Pinheiro A, Guillín-Amarelle C, González-Méndez B, Ruiz-Riquelme A, Rodríguez-Cañete BL, Rodríguez-García S, Guillén-Navarro E, Domingo-Jiménez R, Araújo-Vilar D. Skipped BSCL2 Transcript in Celia's Encephalopathy (PELD): New Insights on Fatty Acids Involvement, Senescence and Adipogenesis. PLoS One 2016; 11:e0158874. [PMID: 27391332 PMCID: PMC4938205 DOI: 10.1371/journal.pone.0158874] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 06/23/2016] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE PELD (Progressive Encephalopathy with or without Lipodystrophy or Celia's Encephalopathy) is a fatal and rare neurodegenerative syndrome associated with the BSCL2 mutation c.985C>T, that results in an aberrant transcript without the exon 7 (Celia seipin). The aim of this study was to evaluate both the process of cellular senescence and the effect of unsaturated fatty acids on preadipocytes from a homozygous c.985C>T patient. Also, the role of aberrant seipin isoform on adipogenesis was studied in adipose-derived human mesenchymal stem cells. MATERIAL AND METHODS Cellular senescence was evaluated using β-galactosidase staining of preadipocytes obtained from a homozygous c.985C>T patient. Moreover, these cells were cultured during 24 hours with Intralipid, a soybean oil-based commercial lipid emulsion. The expression of the different BSCL2 transcripts was measured by qPCR. Adipose-derived human mesenchymal stem cells were differentiated to a fat lineage using StemPRO adipogenesis kit, and the expression of BSCL2 transcripts and several adipogenesis-related genes was measured by qPCR. RESULTS the treatment of preadipocytes with unsaturated fatty acids significantly reduced the expression of the BSCL2 transcript without exon 7 by 34 to 63%. On the other hand, at least in preadipocytes, this mutation does not disturb cellular senescence rate. Finally, during adipocyte differentiation of adipose-derived human mesenchymal stem cells, the expression of adipogenic genes (PPARG, LPIN1, and LPL) increased significantly over 14 days, and noteworthy is that the BSCL2 transcript without exon 7 was differentially expressed by 332 to 723% when compared to day 0, suggesting an underlying role in adipogenesis. CONCLUSIONS our results suggest that Celia seipin is probably playing an underestimated role in adipocyte maturation, but not in senescence, and its expression can be modified by exogenous factors as fatty acids.
Collapse
Affiliation(s)
- Sofía Sánchez-Iglesias
- Thyroid and Metabolic Diseases Unit (U.E.T.eM.), Department of Medicine, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS)-IDIS, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Alexander Unruh-Pinheiro
- Thyroid and Metabolic Diseases Unit (U.E.T.eM.), Department of Medicine, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS)-IDIS, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Cristina Guillín-Amarelle
- Thyroid and Metabolic Diseases Unit (U.E.T.eM.), Department of Medicine, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS)-IDIS, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Blanca González-Méndez
- Thyroid and Metabolic Diseases Unit (U.E.T.eM.), Department of Medicine, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS)-IDIS, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Alejandro Ruiz-Riquelme
- Thyroid and Metabolic Diseases Unit (U.E.T.eM.), Department of Medicine, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS)-IDIS, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Blanca Leticia Rodríguez-Cañete
- Thyroid and Metabolic Diseases Unit (U.E.T.eM.), Department of Medicine, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS)-IDIS, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Silvia Rodríguez-García
- Thyroid and Metabolic Diseases Unit (U.E.T.eM.), Department of Medicine, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS)-IDIS, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Encarnación Guillén-Navarro
- Unit of Medical Genetics and Dysmorphology, Division of Pediatrics, Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain
| | - Rosario Domingo-Jiménez
- Section of Neuropediatrics, Division of Pediatrics, Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain
| | - David Araújo-Vilar
- Thyroid and Metabolic Diseases Unit (U.E.T.eM.), Department of Medicine, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS)-IDIS, University of Santiago de Compostela, Santiago de Compostela, Spain
- * E-mail:
| |
Collapse
|
28
|
Alfonso-García A, Pfisterer SG, Riezman H, Ikonen E, Potma EO. D38-cholesterol as a Raman active probe for imaging intracellular cholesterol storage. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:61003. [PMID: 26719944 PMCID: PMC4681884 DOI: 10.1117/1.jbo.21.6.061003] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 10/15/2015] [Indexed: 05/05/2023]
Abstract
We generated a highly deuterated cholesterol analog (D38-cholesterol) and demonstrated its use for selective vibrational imaging of cholesterol storage in mammalian cells. D38-cholesterol produces detectable signals in stimulated Raman scattering (SRS) imaging, is rapidly taken up by cells, and is efficiently metabolized by acyl-CoA cholesterol acyltransferase to form cholesteryl esters. Using hyperspectral SRS imaging of D38-cholesterol, we visualized cholesterol storage in lipid droplets. We found that some lipid droplets accumulated preferentially unesterified D38-cholesterol, whereas others stored D38-cholesteryl esters. In steroidogenic cells, D38-cholesteryl esters and triacylglycerols were partitioned into distinct sets of lipid droplets. Thus, hyperspectral SRS imaging of D38-cholesterol demonstrates a heterogeneous incorporation of neutral lipid species, i.e., free cholesterol, cholesteryl esters, and triacylglycerols, between individual lipid droplets in a cell.
Collapse
Affiliation(s)
- Alba Alfonso-García
- University of California, Irvine, Department of Biomedical Engineering, Irvine, California 92697, United States
| | - Simon G. Pfisterer
- University of Helsinki, Finland and Minerva Foundation Institute for Medical Research, Department of Anatomy and Research Programs Unit, Faculty of Medicine, Helsinki 00290, Finland
| | - Howard Riezman
- University of Geneva, NCCR Chemical Biology, Department of Biochemistry, CH-1211 Geneva, Switzerland
| | - Elina Ikonen
- University of Helsinki, Finland and Minerva Foundation Institute for Medical Research, Department of Anatomy and Research Programs Unit, Faculty of Medicine, Helsinki 00290, Finland
| | - Eric O. Potma
- University of California, Irvine, Department of Chemistry, Irvine, California 92697, United States
- Address all correspondence to: Eric O. Potma, E-mail:
| |
Collapse
|
29
|
Ruiz-Riquelme A, Sánchez-Iglesias S, Rábano A, Guillén-Navarro E, Domingo-Jiménez R, Ramos A, Rosa I, Senra A, Nilsson P, García Á, Araújo-Vilar D, Requena JR. Larger aggregates of mutant seipin in Celia's Encephalopathy, a new protein misfolding neurodegenerative disease. Neurobiol Dis 2015; 83:44-53. [PMID: 26282322 DOI: 10.1016/j.nbd.2015.08.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 07/18/2015] [Accepted: 08/12/2015] [Indexed: 11/19/2022] Open
Abstract
Celia's Encephalopathy (MIM #615924) is a recently discovered fatal neurodegenerative syndrome associated with a new BSCL2 mutation (c.985C>T) that results in an aberrant isoform of seipin (Celia seipin). This mutation is lethal in both homozygosity and compounded heterozygosity with a lipodystrophic BSCL2 mutation, resulting in a progressive encephalopathy with fatal outcomes at ages 6-8. Strikingly, heterozygous carriers are asymptomatic, conflicting with the gain of toxic function attributed to this mutation. Here we report new key insights about the molecular pathogenic mechanism of this new syndrome. Intranuclear inclusions containing mutant seipin were found in brain tissue from a homozygous patient suggesting a pathogenic mechanism similar to other neurodegenerative diseases featuring brain accumulation of aggregated, misfolded proteins. Sucrose gradient distribution showed that mutant seipin forms much larger aggregates as compared with wild type (wt) seipin, indicating an impaired oligomerization. On the other hand, the interaction between wt and Celia seipin confirmed by coimmunoprecipitation (CoIP) assays, together with the identification of mixed oligomers in sucrose gradient fractionation experiments can explain the lack of symptoms in heterozygous carriers. We propose that the increased aggregation and subsequent impaired oligomerization of Celia seipin leads to cell death. In heterozygous carriers, wt seipin might prevent the damage caused by mutant seipin through its sequestration into harmless mixed oligomers.
Collapse
Affiliation(s)
- Alejandro Ruiz-Riquelme
- CIMUS Biomedical Research Institute, University of Santiago de Compostela-IDIS, 15782 Santiago de Compostela, Spain
| | - Sofía Sánchez-Iglesias
- CIMUS Biomedical Research Institute, University of Santiago de Compostela-IDIS, 15782 Santiago de Compostela, Spain
| | - Alberto Rábano
- Neuropathology Department and Tissue Bank, Fundación CIEN, 28031 Madrid, Spain
| | - Encarna Guillén-Navarro
- Section of Medical Genetics Dysmorphology, Division of Pediatrics, Hospital Clínico Universitario Virgen de la Arrixaca, IMIB-Arrixaca, 30120 Murcia, Spain; UCAM-Catholic University of Murcia, CIBERER-ISCIII, Madrid, Spain
| | - Rosario Domingo-Jiménez
- Section of Neuropediatrics, Division of Pediatrics, Hospital Clínico Universitario Virgen de la Arrixaca, IMIB-Arrixaca, 30120 Murcia, Spain; CIBERER-ISCIII, Madrid, Spain
| | - Adriana Ramos
- CIMUS Biomedical Research Institute, University of Santiago de Compostela-IDIS, 15782 Santiago de Compostela, Spain
| | - Isaac Rosa
- CIMUS Biomedical Research Institute, University of Santiago de Compostela-IDIS, 15782 Santiago de Compostela, Spain; Department of Pharmacology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Ana Senra
- CIMUS Biomedical Research Institute, University of Santiago de Compostela-IDIS, 15782 Santiago de Compostela, Spain
| | - Peter Nilsson
- Affinity Proteomics, SciLifeLab, School of Biotechnology, KTH - Royal Institute of Technology, SE 171-21 Stockholm, Sweden
| | - Ángel García
- CIMUS Biomedical Research Institute, University of Santiago de Compostela-IDIS, 15782 Santiago de Compostela, Spain; Department of Pharmacology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - David Araújo-Vilar
- CIMUS Biomedical Research Institute, University of Santiago de Compostela-IDIS, 15782 Santiago de Compostela, Spain; Department of Medicine, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
| | - Jesús R Requena
- CIMUS Biomedical Research Institute, University of Santiago de Compostela-IDIS, 15782 Santiago de Compostela, Spain; Department of Medicine, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
| |
Collapse
|
30
|
Bautista G, Pfisterer SG, Huttunen MJ, Ranjan S, Kanerva K, Ikonen E, Kauranen M. Polarized THG microscopy identifies compositionally different lipid droplets in mammalian cells. Biophys J 2015; 107:2230-6. [PMID: 25418291 PMCID: PMC4241439 DOI: 10.1016/j.bpj.2014.10.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 10/01/2014] [Accepted: 10/10/2014] [Indexed: 11/27/2022] Open
Abstract
Cells store excess lipids as two major compounds, triacylglycerols (TAGs) and cholesteryl esters (CEs), inside lipid droplets (LDs). The degree of lipid ordering is considered to play a major role in the mobility and enzymatic processing of lipids in LDs. Here, we provide evidence that polarized third-harmonic generation (THG) microscopy distinguishes between native TAG- and CE-enriched LDs in cells due to the different ordering of the two lipid species. We first demonstrate that the responses from synthetic TAG- and CE-enriched LDs using THG microscopy with linear and circular polarizations differ according to their different intrinsic ordering. We then employ simulations to dissect how polarization effects influence the THG from an isotropic LD. Finally, we induce TAG- and CE-enriched LDs in murine macrophages and demonstrate that polarized THG responses increase in a nonlinear fashion with increasing CE/TAG ratio. This suggests that with an increasing CE content, there is a rather sharp transition toward increased LD ordering. Our results demonstrate that polarized THG microscopy enables label-free quantitative analysis of LD ordering and discriminates between compositionally different LDs in intact mammalian cells.
Collapse
Affiliation(s)
- Godofredo Bautista
- Department of Physics, Tampere University of Technology, Tampere, Finland.
| | - Simon G Pfisterer
- Institute of Biomedicine, Anatomy, University of Helsinki, Helsinki, Finland; Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Mikko J Huttunen
- Department of Physics, Tampere University of Technology, Tampere, Finland; COMP Centre of Excellence and Department of Applied Physics, Aalto University, Aalto, Finland
| | - Sanjeev Ranjan
- Institute of Biomedicine, Anatomy, University of Helsinki, Helsinki, Finland; Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Kristiina Kanerva
- Institute of Biomedicine, Anatomy, University of Helsinki, Helsinki, Finland; Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Elina Ikonen
- Institute of Biomedicine, Anatomy, University of Helsinki, Helsinki, Finland; Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Martti Kauranen
- Department of Physics, Tampere University of Technology, Tampere, Finland
| |
Collapse
|
31
|
Sanhueza M, Chai A, Smith C, McCray BA, Simpson TI, Taylor JP, Pennetta G. Network analyses reveal novel aspects of ALS pathogenesis. PLoS Genet 2015; 11:e1005107. [PMID: 25826266 PMCID: PMC4380362 DOI: 10.1371/journal.pgen.1005107] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 02/27/2015] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disease characterized by selective loss of motor neurons, muscle atrophy and paralysis. Mutations in the human VAMP-associated protein B (hVAPB) cause a heterogeneous group of motor neuron diseases including ALS8. Despite extensive research, the molecular mechanisms underlying ALS pathogenesis remain largely unknown. Genetic screens for key interactors of hVAPB activity in the intact nervous system, however, represent a fundamental approach towards understanding the in vivo function of hVAPB and its role in ALS pathogenesis. Targeted expression of the disease-causing allele leads to neurodegeneration and progressive decline in motor performance when expressed in the adult Drosophila, eye or in its entire nervous system, respectively. By using these two phenotypic readouts, we carried out a systematic survey of the Drosophila genome to identify modifiers of hVAPB-induced neurotoxicity. Modifiers cluster in a diverse array of biological functions including processes and genes that have been previously linked to hVAPB function, such as proteolysis and vesicular trafficking. In addition to established mechanisms, the screen identified endocytic trafficking and genes controlling proliferation and apoptosis as potent modifiers of ALS8-mediated defects. Surprisingly, the list of modifiers was mostly enriched for proteins linked to lipid droplet biogenesis and dynamics. Computational analysis reveals that most modifiers can be linked into a complex network of interacting genes, and that the human genes homologous to the Drosophila modifiers can be assembled into an interacting network largely overlapping with that in flies. Identity markers of the endocytic process were also found to abnormally accumulate in ALS patients, further supporting the relevance of the fly data for human biology. Collectively, these results not only lead to a better understanding of hVAPB function but also point to potentially relevant targets for therapeutic intervention. Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease causing loss of motor neurons and consequently a progressive deterioration of motor functions. ALS is uniformly fatal with death occurring 5 years after onset of symptoms. There is currently no effective treatment for ALS. Several mutations in a gene called hVAPB have shown that this gene is causative of a type of ALS known as ALS8. In this study we sought to identify genes and cellular processes that are involved in the toxicity conferred by the defective ALS8 allele. By using the power of Drosophila genetics, we performed a large scale genomic screen and identified a number of genes that can affect hVAPB-mediated toxicity. These modifiers cluster into functional pathways known to be involved in ALS as well as novel ones. The relevance of these modifiers and mechanisms for the human disease was confirmed by showing that the human homologues of the fly modifiers can be organized into a network that closely resembles that of the Drosophila genes. Identifying cellular processes and proteins that modulate hVAPB pathological activity can facilitate the discovery of an effective treatment for ALS.
Collapse
Affiliation(s)
- Mario Sanhueza
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
- Euan MacDonald Centre for Motor Neuron Disease Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Andrea Chai
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
- Euan MacDonald Centre for Motor Neuron Disease Research, University of Edinburgh, Edinburgh, United Kingdom
- Department of Molecular and Human Genetics, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Houston, Texas, United States of America
| | - Colin Smith
- Academic Department of Neuropathology, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Brett A. McCray
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Cambridge, Massachusetts, United States of America
| | - T. Ian Simpson
- Biomathematics and Statistics Scotland, University of Edinburgh, United Kingdom
- Institute for Adaptive and Neural Computation, School of Informatics, University of Edinburgh, United Kingdom
| | - J. Paul Taylor
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Giuseppa Pennetta
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
- Euan MacDonald Centre for Motor Neuron Disease Research, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
| |
Collapse
|
32
|
Talukder MMU, Sim MFM, O'Rahilly S, Edwardson JM, Rochford JJ. Seipin oligomers can interact directly with AGPAT2 and lipin 1, physically scaffolding critical regulators of adipogenesis. Mol Metab 2015; 4:199-209. [PMID: 25737955 PMCID: PMC4338318 DOI: 10.1016/j.molmet.2014.12.013] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 12/21/2014] [Accepted: 12/27/2014] [Indexed: 01/30/2023] Open
Abstract
OBJECTIVE Disruption of the genes encoding either seipin or 1-acylglycerol-3-phosphate O-acyltransferase 2 (AGPAT2) causes severe congenital generalized lipodystrophy (CGL) in humans. However, the function of seipin in adipogenesis remains poorly defined. We demonstrated recently that seipin can bind the key adipogenic phosphatidic acid (PA) phosphatase lipin 1 and that seipin forms stable dodecamers. As AGPAT2 generates PA, the substrate for lipin 1, we investigated whether seipin might bind both enzymes of this lipid biosynthetic pathway, which is required for adipogenesis to occur. METHODS We employed co-immunoprecipitation and immunofluorescence methods to determine whether seipin can interact with AGPAT2 and the consequences of this in developing adipocytes. Atomic force microscopy was used to determine whether these interactions involved direct association of the proteins and to define the molecular architecture of these complexes. RESULTS Our data reveal that seipin can bind AGPAT2 during adipogenesis and that stabilizing this interaction during adipogenesis can increase the nuclear accumulation of PPARγ. Both AGPAT2 and lipin 1 can directly associate with seipin dodecamers, and a single seipin complex can simultaneously bind both AGPAT2 and lipin with a defined orientation. CONCLUSIONS Our study provides the first direct molecular link between seipin and AGPAT2, two proteins whose disruption causes CGL. Moreover, it provides the first example of an interaction between seipin and another protein that causally influences a key aspect of adipogenesis. Together our data suggest that the critical role of seipin in adipogenesis may involve its capacity to juxtapose important regulators of this process in a multi-protein complex.
Collapse
Affiliation(s)
| | - M F Michelle Sim
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Stephen O'Rahilly
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | | | - Justin J Rochford
- Rowett Institute of Nutrition and Health, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| |
Collapse
|
33
|
Ruhanen H, Perttilä J, Hölttä-Vuori M, Zhou Y, Yki-Järvinen H, Ikonen E, Käkelä R, Olkkonen VM. PNPLA3 mediates hepatocyte triacylglycerol remodeling. J Lipid Res 2014; 55:739-46. [PMID: 24511104 DOI: 10.1194/jlr.m046607] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The I148M substitution in patatin-like phospholipase domain containing 3 (PNPLA3(I148M)) determines a genetic form of nonalcoholic fatty liver disease. To elucidate the mode of PNPLA3 action in human hepatocytes, we studied effects of WT PNPLA3 (PNPLA3(WT)) and PNPLA3(I148M) on HuH7 cell lipidome after [(13)C]glycerol labeling, cellular turnover of oleic acid labeled with 17 deuterium atoms ([D17]oleic acid) in triacylglycerols (TAGs), and subcellular distribution of the protein variants. PNPLA3(I148M) induced a net accumulation of unlabeled TAGs, but not newly synthesized total [(13)C]TAGs. Principal component analysis (PCA) revealed that both PNPLA3(WT) and PNPLA3(I148M) induced a relative enrichment of TAGs with saturated FAs or MUFAs, with concurrent enrichment of polyunsaturated phosphatidylcholines. PNPLA3(WT) associated in PCA with newly synthesized [(13)C]TAGs, particularly 52:1 and 50:1, while PNPLA3(I148M) associated with similar preexisting TAGs. PNPLA3(WT) overexpression resulted in increased [D17]oleic acid labeling of TAGs during 24 h, and after longer incubations their turnover was accelerated, effects not detected with PNPLA3(I148M). PNPLA3(I148M) localized more extensively to lipid droplets (LDs) than PNPLA3(WT), suggesting that the substitution alters distribution of PNPLA3 between LDs and endoplasmic reticulum/cytosol. This study reveals a function of PNPLA3 in FA-selective TAG remodeling, resulting in increased TAG saturation. A defect in TAG remodeling activity likely contributes to the TAG accumulation observed in cells expressing PNPLA3(I148M).
Collapse
Affiliation(s)
- Hanna Ruhanen
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, FI-00290 Helsinki, Finland
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Vatier C, Bidault G, Briand N, Guénantin AC, Teyssières L, Lascols O, Capeau J, Vigouroux C. What the genetics of lipodystrophy can teach us about insulin resistance and diabetes. Curr Diab Rep 2013; 13:757-67. [PMID: 24026869 DOI: 10.1007/s11892-013-0431-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Genetic lipodystrophic syndromes are rare diseases characterized by generalized or partial fat atrophy (lipoatrophy) associated with severe metabolic complications such as insulin resistance (IR), diabetes, dyslipidemia, nonalcoholic fatty liver disease, and ovarian hyperandrogenism. During the last 15 years, mutations in several genes have been shown to be responsible for monogenic forms of lipodystrophic syndromes, of autosomal dominant or recessive transmission. Although the molecular basis of lipodystrophies is heterogeneous, most mutated genes lead to impaired adipogenesis, adipocyte lipid storage, and/or formation or maintenance of the adipocyte lipid droplet (LD), showing that primary alterations of adipose tissue (AT) can result in severe systemic metabolic and endocrine consequences. The reduced expandability of AT alters its ability to buffer excess caloric intake, leading to ectopic lipid storage that impairs insulin signaling and other cellular functions ("lipotoxicity"). Genetic studies have also pointed out the close relationships between ageing, inflammatory processes, lipodystrophy, and IR.
Collapse
Affiliation(s)
- Camille Vatier
- INSERM UMR_S938, Centre de Recherche Saint-Antoine, 75012, Paris, France
| | | | | | | | | | | | | | | |
Collapse
|