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Neuhaus M, Fryklund C, Taylor H, Borreguero-Muñoz A, Kopietz F, Ardalani H, Rogova O, Stirrat L, Bremner SK, Spégel P, Bryant NJ, Gould GW, Stenkula KG. EHD2 regulates plasma membrane integrity and downstream insulin receptor signaling events. Mol Biol Cell 2023; 34:ar124. [PMID: 37703099 PMCID: PMC10846623 DOI: 10.1091/mbc.e23-03-0078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 09/07/2023] [Accepted: 09/08/2023] [Indexed: 09/14/2023] Open
Abstract
Adipocyte dysfunction is a crucial driver of insulin resistance and type 2 diabetes. We identified EH domain-containing protein 2 (EHD2) as one of the most highly upregulated genes at the early stage of adipose-tissue expansion. EHD2 is a dynamin-related ATPase influencing several cellular processes, including membrane recycling, caveolae dynamics, and lipid metabolism. Here, we investigated the role of EHD2 in adipocyte insulin signaling and glucose transport. Using C57BL6/N EHD2 knockout mice under short-term high-fat diet conditions and 3T3-L1 adipocytes we demonstrate that EHD2 deficiency is associated with deterioration of insulin signal transduction and impaired insulin-stimulated GLUT4 translocation. Furthermore, we show that lack of EHD2 is linked with altered plasma membrane lipid and protein composition, reduced insulin receptor expression, and diminished insulin-dependent SNARE protein complex formation. In conclusion, these data highlight the importance of EHD2 for the integrity of the plasma membrane milieu, insulin receptor stability, and downstream insulin receptor signaling events, involved in glucose uptake and ultimately underscore its role in insulin resistance and obesity.
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Affiliation(s)
- Mathis Neuhaus
- Department of Experimental Medical Science, Lund University, 22184 Lund, Sweden
| | - Claes Fryklund
- Department of Experimental Medical Science, Lund University, 22184 Lund, Sweden
| | - Holly Taylor
- Strathclyde Institute for Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, UK
| | | | - Franziska Kopietz
- Department of Experimental Medical Science, Lund University, 22184 Lund, Sweden
| | - Hamidreza Ardalani
- Department of Chemistry, Centre for Analysis and Synthesis, Lund University, 22241 Lund, Sweden
| | - Oksana Rogova
- Department of Chemistry, Centre for Analysis and Synthesis, Lund University, 22241 Lund, Sweden
| | - Laura Stirrat
- Strathclyde Institute for Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, UK
| | - Shaun K. Bremner
- Strathclyde Institute for Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, UK
| | - Peter Spégel
- Department of Chemistry, Centre for Analysis and Synthesis, Lund University, 22241 Lund, Sweden
| | - Nia J. Bryant
- Department of Biology and York Biomedical Research Institute, University of York, York YO10 5DD, UK
| | - Gwyn W. Gould
- Strathclyde Institute for Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, UK
| | - Karin G. Stenkula
- Department of Experimental Medical Science, Lund University, 22184 Lund, Sweden
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2
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Fryklund C, Morén B, Neuhaus M, Periwal V, Stenkula KG. Rosiglitazone treatment enhances intracellular actin dynamics and glucose transport in hypertrophic adipocytes. Life Sci 2022; 299:120537. [PMID: 35398016 DOI: 10.1016/j.lfs.2022.120537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 03/28/2022] [Accepted: 04/02/2022] [Indexed: 10/18/2022]
Abstract
AIMS To accommodate surplus energy, adipose tissue expands by increasing both adipose cell size (hypertrophy) and cell number (hyperplasia). Enlarged, hypertrophic adipocytes are known to have reduced insulin response and impaired glucose transport, which negatively influence whole-body glucose homeostasis. Rosiglitazone is a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, known to stimulate hyperplasia and to efficiently improve insulin sensitivity. Still, a limited amount of research has investigated the effects of rosiglitazone in mature, hypertrophic adipocytes. Therefore, the objective of this study was to examine rosiglitazone's effect on insulin-stimulated glucose uptake in hypertrophic adipocytes. MAIN METHODS C57BL/6J male mice were subjected to 2 weeks of high-fat diet (HFD) followed by 1 week of HFD combined with daily administration of rosiglitazone (10 mg/kg). Adipose cell-size distribution and gene expression were analysed in intact adipose tissue, and glucose uptake, insulin response, and protein expression were examined using primary adipocytes isolated from epididymal and inguinal adipose tissue. KEY FINDINGS HFD-feeding induced an accumulation of hypertrophic adipocytes, which was not affected by rosiglitazone-treatment. Still, rosiglitazone efficiently improved insulin-stimulated glucose transport without restoring insulin signaling or GLUT4 expression in similar-sized adipocytes. This improvement occurred concurrently with extracellular matrix remodelling and restored intracellular levels of targets involved in actin turnover. SIGNIFICANCE These results demonstrate that rosiglitazone improves glucose transport in hypertrophic adipocytes, and highlights the importance of the cytoskeleton and extracellular matrix as potential therapeutic targets.
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Affiliation(s)
- Claes Fryklund
- Department of Experimental Medical Science, Lund University, Sweden.
| | - Björn Morén
- Department of Experimental Medical Science, Lund University, Sweden
| | | | - Vipul Periwal
- Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, USA
| | - Karin G Stenkula
- Department of Experimental Medical Science, Lund University, Sweden
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3
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Heckmann M, Klanert G, Sandner G, Lanzerstorfer P, Auer M, Weghuber J. Fluorescence Microscopy-Based Quantitation of GLUT4 Translocation. Methods Appl Fluoresc 2022; 10. [PMID: 35008072 DOI: 10.1088/2050-6120/ac4998] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 01/10/2022] [Indexed: 11/11/2022]
Abstract
Postprandial insulin-stimulated glucose uptake into target tissue is crucial for the maintenance of normal blood glucose homeostasis. This step is rate-limited by the number of facilitative glucose transporters type 4 (GLUT4) present in the plasma membrane. Since insulin resistance and impaired GLUT4 translocation are associated with the development of metabolic disorders such as type 2 diabetes, this transporter has become an important target of antidiabetic drug research. The application of screening approaches that are based on the analysis of GLUT4 translocation to the plasma membrane to identify substances with insulinomimetic properties has gained global research interest in recent years. Here, we review methods that have been implemented to quantitate the translocation of GLUT4 to the plasma membrane. These methods can be broadly divided into two sections: microscopy-based technologies (e.g., immunoelectron, confocal or total internal reflection fluorescence microscopy) and biochemical and spectrometric approaches (e.g., membrane fractionation, photoaffinity labeling or flow cytometry). In this review, we discuss the most relevant approaches applied to GLUT4 thus far, highlighting the advantages and disadvantages of these approaches, and we provide a critical discussion and outlook into new methodological opportunities.
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Affiliation(s)
- Mara Heckmann
- University of Applied Sciences Upper Austria, Stelzhamerstrasse 23, Wels, Oberösterreich, 4600, AUSTRIA
| | - Gerald Klanert
- FFoQSI GmbH-Austrian Competence Centre for Feed and Food Quality, Safety and Innovation, Technopark 1C, Tulln, 3430, AUSTRIA
| | - Georg Sandner
- University of Applied Sciences Upper Austria, Stelzhamerstrasse 23, Wels, Oberösterreich, 4600, AUSTRIA
| | - Peter Lanzerstorfer
- University of Applied Sciences Upper Austria, Stelzhamerstrasse 23, Wels, Oberösterreich, 4600, AUSTRIA
| | - Manfred Auer
- Division of Pathway Medicine, University of Edinburgh, University of Edinburgh Medical School, The Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, Edinburgh, EH8 9AB, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Julian Weghuber
- University of Applied Sciences Upper Austria, Stelzhamerstrasse 23, Wels, Oberösterreich, 4600, AUSTRIA
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Fryklund C, Morén B, Shah S, Grossi M, Degerman E, Matthaeus C, Stenkula KG. EH Domain-Containing 2 Deficiency Restricts Adipose Tissue Expansion and Impairs Lipolysis in Primary Inguinal Adipocytes. Front Physiol 2021; 12:740666. [PMID: 34630160 PMCID: PMC8497890 DOI: 10.3389/fphys.2021.740666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 08/25/2021] [Indexed: 11/21/2022] Open
Abstract
Lipid uptake can be facilitated via caveolae, specific plasma membrane invaginations abundantly expressed in adipocytes. The dynamin-related protein EH domain-containing 2 (EHD2) stabilizes caveolae at the cell surface. Here, we have examined the importance of EHD2 for lipid handling using primary adipocytes isolated from EHD2 knockout (Ehd2−/−) C57BL6/N mice. Following high-fat diet (HFD) feeding, we found a clear impairment of epididymal, but not inguinal, adipose tissue expansion in Ehd2−/− compared with Ehd2+/+ (WT) mice. Cell size distribution analysis revealed that Ehd2−/− mice had a lower proportion of small adipocytes, and an accumulation of medium-sized adipocytes in both epididymal and inguinal adipose tissue. Further, PPARγ activity, FABP4 and caveolin-1 expression were decreased in adipocytes isolated from Ehd2−/− mice. Inguinal adipocytes isolated from Ehd2−/− mice displayed reduced lipolysis in response to beta adrenergic receptor agonist, which was associated with reduced phosphorylation of perilipin-1 and hormone sensitive lipase (HSL). This impairment could not be rescued using a cAMP analog, indicating that impaired lipolysis in Ehd2−/− primary adipocytes likely occurs at the level of, or downstream of, protein kinase A (PKA). Altogether, these findings pinpoint the importance of EHD2 for maintained intracellular lipid metabolism, and emphasize differences in mechanisms regulating lipid handling in various adipose-tissue depots.
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Affiliation(s)
- Claes Fryklund
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Björn Morén
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Shrenika Shah
- School of Biomedical, Nutritional and Sport Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Mario Grossi
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Eva Degerman
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Claudia Matthaeus
- National Heart, Lung and Blood Institute, NIH, Bethesda, MD, United States
| | - Karin G Stenkula
- Department of Experimental Medical Science, Lund University, Lund, Sweden
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Morén B, Fryklund C, Stenkula K. Surface-associated lipid droplets: an intermediate site for lipid transport in human adipocytes? Adipocyte 2020; 9:636-648. [PMID: 33108251 PMCID: PMC7595579 DOI: 10.1080/21623945.2020.1838684] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Adipose tissue plays a major role in regulating whole-body energy metabolism. While the biochemical processes regulating storage and release of excess energy are well known, the temporal organization of these events is much less defined. In this study, we have characterized the presence of small surface-associated lipid droplets, distinct from the central droplet, in primary human adipocytes. Based on microscopy analyses, we illustrate the distribution of mitochondria, endoplasmic reticulum and lysosomes in the vicinity of these specialized lipid droplets. Ultrastructure analysis confirmed the presence of small droplets in intact adipose tissue. Further, CIDEC, known to bind and regulate lipid droplet expansion, clearly localized at these lipid droplets. Neither acute or prolonged stimulation with insulin or isoprenaline, or pharmacologic intervention to suppress lipid flux, affected the presence of these lipid droplets. Still, phosphorylated perilipin and hormone-sensitive lipase accumulated at these droplets following adrenergic stimuli, which supports metabolic activity at these locations. Altogether, we propose these lipid droplet clusters represent an intermediate site involved in lipid transport in primary adipocytes.
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Affiliation(s)
- Björn Morén
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Claes Fryklund
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Karin Stenkula
- Department of Experimental Medical Science, Lund University, Lund, Sweden
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6
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Hansson B, Morén B, Fryklund C, Vliex L, Wasserstrom S, Albinsson S, Berger K, Stenkula KG. Adipose cell size changes are associated with a drastic actin remodeling. Sci Rep 2019; 9:12941. [PMID: 31506540 PMCID: PMC6736966 DOI: 10.1038/s41598-019-49418-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 08/23/2019] [Indexed: 12/21/2022] Open
Abstract
Adipose tissue plays a major role in regulating whole-body insulin sensitivity and energy metabolism. To accommodate surplus energy, the tissue rapidly expands by increasing adipose cell size (hypertrophy) and cell number (hyperplasia). Previous studies have shown that enlarged, hypertrophic adipocytes are less responsive to insulin, and that adipocyte size could serve as a predictor for the development of type 2 diabetes. In the present study, we demonstrate that changes in adipocyte size correlate with a drastic remodeling of the actin cytoskeleton. Expansion of primary adipocytes following 2 weeks of high-fat diet (HFD)-feeding in C57BL6/J mice was associated with a drastic increase in filamentous (F)-actin as assessed by fluorescence microscopy, increased Rho-kinase activity, and changed expression of actin-regulating proteins, favoring actin polymerization. At the same time, increased cell size was associated with impaired insulin response, while the interaction between the cytoskeletal scaffolding protein IQGAP1 and insulin receptor substrate (IRS)-1 remained intact. Reversed feeding from HFD to chow restored cell size, insulin response, expression of actin-regulatory proteins and decreased the amount of F-actin filaments. Together, we report a drastic cytoskeletal remodeling during adipocyte expansion, a process which could contribute to deteriorating adipocyte function.
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Affiliation(s)
- Björn Hansson
- Lund University, Department of Experimental Medical Science, Lund, Sweden
| | - Björn Morén
- Lund University, Department of Experimental Medical Science, Lund, Sweden
| | - Claes Fryklund
- Lund University, Department of Experimental Medical Science, Lund, Sweden
| | - Lars Vliex
- Lund University, Department of Experimental Medical Science, Lund, Sweden.,Maastricht University, Faculty of Health, Medicine and Life Sciences, Maastricht, The Netherlands
| | | | | | - Karin Berger
- Lund University, Department of Experimental Medical Science, Lund, Sweden
| | - Karin G Stenkula
- Lund University, Department of Experimental Medical Science, Lund, Sweden.
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7
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Morén B, Hansson B, Negoita F, Fryklund C, Lundmark R, Göransson O, Stenkula KG. EHD2 regulates adipocyte function and is enriched at cell surface-associated lipid droplets in primary human adipocytes. Mol Biol Cell 2019; 30:1147-1159. [PMID: 30811273 PMCID: PMC6724522 DOI: 10.1091/mbc.e18-10-0680] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Adipocytes play a central role in energy balance, and dysfunctional adipose tissue severely affects systemic energy homeostasis. The ATPase EH domain–containing 2 (EHD2) has previously been shown to regulate caveolae, plasma membrane-specific domains that are involved in lipid uptake and signal transduction. Here, we investigated the role of EHD2 in adipocyte function. We demonstrate that EHD2 protein expression is highly up-regulated at the onset of triglyceride accumulation during adipocyte differentiation. Small interfering RNA–mediated EHD2 silencing affected the differentiation process and impaired insulin sensitivity, lipid storage capacity, and lipolysis. Fluorescence imaging revealed localization of EHD2 to caveolae, close to cell surface–associated lipid droplets in primary human adipocytes. These lipid droplets stained positive for glycerol transporter aquaporin 7 and phosphorylated perilipin-1 following adrenergic stimulation. Further, EHD2 overexpression in human adipocytes increased the lipolytic signaling and suppressed the activity of transcription factor PPARγ. Overall, these data suggest that EHD2 plays a key role for adipocyte function.
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Affiliation(s)
- Björn Morén
- Department of Experimental Medical Science, Lund University, 223 84 Lund, Sweden
| | - Björn Hansson
- Department of Experimental Medical Science, Lund University, 223 84 Lund, Sweden
| | - Florentina Negoita
- Department of Experimental Medical Science, Lund University, 223 84 Lund, Sweden
| | - Claes Fryklund
- Department of Experimental Medical Science, Lund University, 223 84 Lund, Sweden
| | - Richard Lundmark
- Medical Biochemistry and Biophysics, Umeå University, 901 87 Umeå, Sweden
| | - Olga Göransson
- Department of Experimental Medical Science, Lund University, 223 84 Lund, Sweden
| | - Karin G Stenkula
- Department of Experimental Medical Science, Lund University, 223 84 Lund, Sweden
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