1
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Kim AT, Park Y. Esculetin Inhibits Fat Accumulation Through Insulin/Insulin-like Growth Factor- and AMP-Activated Protein Kinase-Dependent Pathways in Caenorhabditis elegans. Nutrients 2025; 17:1565. [PMID: 40362874 PMCID: PMC12073564 DOI: 10.3390/nu17091565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2025] [Revised: 04/29/2025] [Accepted: 04/29/2025] [Indexed: 05/15/2025] Open
Abstract
Background: Esculetin, 6,7-dihydroxycoumarin, is a bioactive compound found in various herbal plants, and is known to have health-beneficial properties including anti-obesity effects. However, there is a lack of in vivo studies to clearly determine esculetin's role in lipid metabolism. Objectives: In this study, we studied esculetin's effect on lipid accumulation using Caenorhabditis elegans and its underlying mechanisms. Methods:C. elegans were treated with esculetin (100 or 200 μM) for 48 h, and their triglyceride and protein levels were measured. Additionally, behavioral patterns such as pharyngeal pumping rate, body bending rate, body sizes, and locomotive activity were analyzed. Genetic dependencies were examined by utilizing mutant worms and testing relative gene expressions. Results:C. elegans treated with esculetin displayed significantly reduced fat accumulation compared to the controls without effects on the pharyngeal pumping rate, body bending rate, or locomotive activity. Esculetin's fat-lowering effect was dependent on DAF-2 (insulin/insulin-like growth factor-1 [IGF-1] receptor homolog), DAF-16 (Forkhead box protein O homolog), and AAK-2 (5'-adenosine monophosphate-activated protein kinase [AMPK] catalytic subunit α2) in the mutant experiments. Esculetin also significantly increased the relative expression of downstream targets of DAF-16 (hsp-16.2 and sod-3), AMPK-related genes (aak-1 and aak-2), a sirtuin gene, sir-2.1, and a lipolysis-related gene, atgl-1. Conclusions: These findings suggest that esculetin inhibited fat accumulation in C. elegans and this effect was dependent on the insulin/IGF-1 and 5'-adenosine monophosphate-activated protein kinase signaling pathways.
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Affiliation(s)
| | - Yeonhwa Park
- Department of Food Science, University of Massachusetts, Amherst, MA 01003, USA;
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2
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Smith TJ. Controversies Surrounding IGF-I Receptor Involvement in Thyroid-Associated Ophthalmopathy. Thyroid 2025; 35:232-244. [PMID: 39909461 DOI: 10.1089/thy.2024.0606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2025]
Abstract
Background: Thyroid-associated ophthalmopathy (TAO, aka thyroid eye disease [TED], Graves' orbitopathy) remains poorly understood and inadequately treated since its initial description. It is disfiguring, can threaten vision, and represents an autoimmune process closely associated with thyroid disease. Unambiguous connections linking TAO to the glandular maladies of Graves' disease (GD) remain incompletely clarified. Detecting the thyrotropin receptor (TSHR) in periocular tissues suggests that this cell-surface protein represents a shared autoantigen with the thyroid gland, but we now know that its expression is ubiquitous. Most patients with TAO have relatively high circulating levels of activating anti-TSHR autoantibodies. Emerging more recently is the importance of insulin-like growth factor I receptor (IGF-IR) in the pathogenesis of TAO. The TSHR/IGF-IR signaling complex apparently drives circulating fibrocytes and the unique phenotypes of fibroblasts inhabiting the TAO orbit (GD-OF). Methods: The PubMed database was scanned for articles dating back to the earliest time periods covered. Keywords used for primary searches included thyroid-associated ophthalmopathy, Graves' orbitopathy, TED, orbit, TSH receptor, IGF-I receptor, and autoimmune thyroid disease. Secondary searches used numerous other search terms. Results: GD-OF have been characterized extensively as being particularly responsive to the immunological factors and key effectors in TAO pathogenesis. Both TSHR and IGF-IR are overexpressed by GD-OF and CD34+ fibrocytes and form a signaling complex. They are activated through this TSHR/IGF-IR complex to produce large amounts of hyaluronan and express multiple cytokines. This complex mediates cellular responses to pathogenic IgGs in TAO. CD34+ fibrocytes and CD34+ OF also express relatively high levels of multiple thyroid autoantigens. Identifying IGF-IR as a key component of a receptor complex and its intertwining signaling activities with those of TSHR has led to a targeted medical therapy for TAO. This therapy involves the selective systemic inhibition of IGF-IR. Conclusions: Much has been learned over the preceding decades about the pathogenesis of TAO. Among these is the identification of IGF-IR as a pivotal component underpinning the disease. This has led directly to development of an effective targeted therapy. Important gaps in our understanding persist, and current therapies have limitations. Thus, despite these advancements, considerably more remains to be achieved.
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Affiliation(s)
- Terry J Smith
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, Ann Arbor, Michigan, USA
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
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3
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Myers CG, Viswambharan H, Haywood NJ, Bridge K, Turvey S, Armstrong T, Lunn L, Meakin PJ, Porter KE, Clavane EM, Beech DJ, Cubbon RM, Wheatcroft SB, McPhillie MJ, Issad T, Fishwick CW, Kearney MT, Simmons KJ. Small molecule modulation of insulin receptor-insulin like growth factor-1 receptor heterodimers in human endothelial cells. Mol Cell Endocrinol 2024; 594:112387. [PMID: 39419341 DOI: 10.1016/j.mce.2024.112387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 09/26/2024] [Accepted: 10/12/2024] [Indexed: 10/19/2024]
Abstract
OBJECTIVES The insulin receptor (IR) and insulin like growth factor-1 receptor (IGF-1R) are heterodimers consisting of two extracellular α-subunits and two transmembrane β -subunits. Insulin αβ and insulin like growth factor-1 αβ hemi-receptors can heterodimerize to form hybrids composed of one IR αβ and one IGF-1R αβ. The function of hybrids in the endothelium is unclear. We sought insight by developing a small molecule capable of reducing hybrid formation in endothelial cells. METHODS We performed a high-throughput small molecule screening, based on a homology model of the apo hybrid structure. Endothelial cells were studied using western blotting and qPCR to determine the effects of small molecules that reduced hybrid formation. RESULTS Our studies unveil a first-in-class quinoline-containing heterocyclic small molecule that reduces hybrids by >50% in human umbilical vein endothelial cells (HUVECs) with no effects on IR or IGF-1R. This small molecule reduced expression of the negative regulatory p85α subunit of phosphatidylinositol 3-kinase, increased basal phosphorylation of the downstream target Akt and enhanced insulin/insulin-like growth factor-1 and shear stress-induced serine phosphorylation of Akt. In primary saphenous vein endothelial cells (SVEC) from patients with type 2 diabetes mellitus undergoing coronary artery bypass (CABG) surgery, hybrid receptor expression was greater than in patients without type 2 diabetes mellitus. The small molecule significantly reduced hybrid expression in SVEC from patients with type 2 diabetes mellitus. CONCLUSIONS We identified a small molecule that decreases the formation of IR: IGF-1R hybrid receptors in human endothelial cells, without significant impact on the overall expression of IR or IGF-1R. In HUVECs, reduction of IR: IGF-1R hybrid receptors leads to an increase in insulin-induced serine phosphorylation of the critical downstream signalling kinase, Akt. The underpinning mechanism appears, at least in part to involve the attenuation of the inhibitory effect of IR: IGF-1R hybrid receptors on PI3-kinase signalling.
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Affiliation(s)
- Chloe G Myers
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Hema Viswambharan
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Natalie J Haywood
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Katherine Bridge
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Samuel Turvey
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Tom Armstrong
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Lydia Lunn
- Department of Chemistry University of Leeds, Leeds, United Kingdom
| | - Paul J Meakin
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Karen E Porter
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Eva M Clavane
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - David J Beech
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom; National Institute for Health and Care Research Leeds Biomedical Research Centre, Leeds, United Kingdom
| | - Richard M Cubbon
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom; National Institute for Health and Care Research Leeds Biomedical Research Centre, Leeds, United Kingdom
| | - Stephen B Wheatcroft
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | | | - Tarik Issad
- Université Paris Cité, CNRS, INSERM, Institut Cochin, F-75014, Paris, France
| | | | - Mark T Kearney
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom; National Institute for Health and Care Research Leeds Biomedical Research Centre, Leeds, United Kingdom.
| | - Katie J Simmons
- School of Biomedical Sciences, Faculty of Biological Sciences & Astbury Centre, University of Leeds, United Kingdom
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4
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Turvey S, Muench SP, Issad T, Fishwick CWG, Kearney MT, Simmons KJ. Using site-directed mutagenesis to further the understanding of insulin receptor-insulin like growth factor-1 receptor heterodimer structure. Growth Horm IGF Res 2024; 77:101607. [PMID: 39033666 DOI: 10.1016/j.ghir.2024.101607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 06/26/2024] [Accepted: 07/17/2024] [Indexed: 07/23/2024]
Abstract
Type 2 diabetes is characterised by the disruption of insulin and insulin-like growth factor (IGF) signalling. The key hubs of these signalling cascades - the Insulin receptor (IR) and Insulin-like growth factor 1 receptor (IGF1R) - are known to form functional IR-IGF1R hybrid receptors which are insulin resistant. However, the mechanisms underpinning IR-IGF1R hybrid formation are not fully understood, hindering the ability to modulate this for future therapies targeting this receptor. To pinpoint suitable sites for intervention, computational hotspot prediction was utilised to identify promising epitopes for targeting with point mutagenesis. Specific IGF1R point mutations F450A, R391A and D555A show reduced affinity of the hybrid receptor in a BRET based donor-saturation assay, confirming hybrid formation could be modulated at this interface. These data provide the basis for rational design of more effective hybrid receptor modulators, supporting the prospect of identifying a small molecule that specifically interacts with this target.
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Affiliation(s)
- Samuel Turvey
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Stephen P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences & Astbury Centre, University of Leeds, UK
| | - Tarik Issad
- Université Paris Cité, CNRS, INSERM, Institut Cochin, F-75014 Paris, France
| | | | - Mark T Kearney
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Katie J Simmons
- School of Biomedical Sciences, Faculty of Biological Sciences & Astbury Centre, University of Leeds, UK.
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5
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Martin-Solana E, Carter SD, Donahue EK, Ning J, Glausier JR, Preisegger MA, Eisenman L, Joseph PN, Bouchet-Marquis C, Wu K, Mobini CL, Frantz AN, Puig S, Hampton CM, Kabbani N, Jensen GJ, Watkins SC, Deisseroth K, Fenno LE, Gold MS, Wills ZP, Burkewitz K, Das S, Freyberg Z. Ribosome-Associated Vesicles promote activity-dependent local translation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.07.598007. [PMID: 38895376 PMCID: PMC11185778 DOI: 10.1101/2024.06.07.598007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Local protein synthesis in axons and dendrites underpins synaptic plasticity. However, the composition of the protein synthesis machinery in distal neuronal processes and the mechanisms for its activity-driven deployment to local translation sites remain unclear. Here, we employed cryo-electron tomography, volume electron microscopy, and live-cell imaging to identify Ribosome-Associated Vesicles (RAVs) as a dynamic platform for moving ribosomes to distal processes. Stimulation via chemically-induced long-term potentiation causes RAV accumulation in distal sites to drive local translation. We also demonstrate activity-driven changes in RAV generation and dynamics in vivo, identifying tubular ER shaping proteins in RAV biogenesis. Together, our work identifies a mechanism for ribosomal delivery to distal sites in neurons to promote activity-dependent local translation.
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Affiliation(s)
- Eva Martin-Solana
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Stephen D. Carter
- MRC-University of Glasgow Centre for Virus Research, University of Glasgow, Glasgow, UK
| | - Eric K.F. Donahue
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Jiying Ning
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jill R. Glausier
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | | | - Leanna Eisenman
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Paul N. Joseph
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | | | - Ken Wu
- Materials and Structural Analysis, Thermo Fisher Scientific, Hillsboro, OR, USA
| | | | - Amber N. Frantz
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Stephanie Puig
- Department of Psychiatry, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Cheri M. Hampton
- UES, Inc., Dayton, OH, USA
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, OH, USA
| | - Nadine Kabbani
- Interdisciplinary Program in Neuroscience, George Mason University, Fairfax, VA, USA
- School of Systems Biology, George Mason University, Fairfax, VA, USA
| | - Grant J. Jensen
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
| | - Simon C. Watkins
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Karl Deisseroth
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford, CA, USA
| | - Lief E. Fenno
- Departments of Psychiatry and Neuroscience, University of Texas Austin Dell Medical School, Austin, TX, USA
| | - Michael S. Gold
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Zachary P. Wills
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Kristopher Burkewitz
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Sulagna Das
- Department of Cell Biology, Albert Einstein College of Medicine, NY
- Department of Cell Biology, Emory University, Atlanta, GA, USA
- Department of Human Genetics, Emory University, Atlanta, GA, USA
| | - Zachary Freyberg
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA
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6
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Torzone SK, Breen PC, Cohen NR, Simmons KN, Dowen RH. The TWK-26 potassium channel governs nutrient absorption in the C. elegans intestine. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.06.592787. [PMID: 38766028 PMCID: PMC11100751 DOI: 10.1101/2024.05.06.592787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Ion channels are necessary for proper water and nutrient absorption in the intestine, which supports cellular metabolism and organismal growth. While a role for Na + co-transporters and pumps in intestinal nutrient absorption is well defined, how individual K + uniporters function to maintain ion homeostasis is poorly understood. Using Caenorhabditis elegans , we show that a gain-of-function mutation in twk-26 , which encodes a two-pore domain K + ion channel orthologous to human KCNK3, facilitates nutrient absorption and suppresses the metabolic and developmental defects displayed by impaired intestinal MAP Kinase (MAPK) signaling. Mutations in drl-1 and flr-4, which encode two components of this MAPK pathway, cause severe growth defects, reduced lipid storage, and a dramatic increase in autophagic lysosomes, which mirror dietary restriction phenotypes. Additionally, these MAPK mutants display structural defects of the intestine and an impaired defecation motor program. We find that activation of TWK-26 reverses the dietary restriction-like state of the MAPK mutants by restoring intestinal nutrient absorption without correcting the intestinal bloating or defecation defects. This study provides unique insight into the mechanisms by which intestinal K + ion channels support intestinal metabolic homeostasis.
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7
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Imrie H, Viswambharan H, Haywood NJ, Bridge KI, Yuldasheva NY, Galloway S, Simmons KJ, Cubbon RM, Sukumar P, Watt NT, Lichtenstein L, Wyatt JI, Kudo H, Goldin R, Rode B, Wheatcroft SB, Kearney MT. Cixutumumab reveals a critical role for IGF-1 in adipose and hepatic tissue remodelling during the development of diet-induced obesity. Adipocyte 2022; 11:366-378. [PMID: 35734881 PMCID: PMC9235901 DOI: 10.1080/21623945.2022.2089394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
High fat diet (HFD)-induced obesity leads to perturbation in the storage function of white adipose tissue (WAT) resulting in deposition of lipids in tissues ill-equipped to deal with this challenge. The role of insulin like growth factor-1 (IGF-1) in the systemic and organ-specific responses to HFD is unclear. Using cixutumumab, a monoclonal antibody that internalizes and degrades cell surface IGF-1 receptors (IGF-1 R), leaving insulin receptor expression unchanged we aimed to establish the role of IGF-1 R in the response to a HFD. Mice treated with cixutumumab fed standard chow developed mild hyperinsulinemia with no change in WAT. When challenged by HFD mice treated with cixutumumab had reduced weight gain, reduced WAT expansion, and reduced hepatic lipid vacuole formation. In HFD-fed mice, cixutumumab led to reduced levels of genes encoding proteins important in fatty acid metabolism in WAT and liver. Cixutumumab protected against blunting of insulin-stimulated phosphorylation of Akt in liver of HFD fed mice. These data reveal an important role for IGF-1 R in the WAT and hepatic response to short-term nutrient excess. IGF-1 R inhibition during HFD leads to a lipodystrophic phenotype with a failure of WAT lipid storage and protection from HFD-induced hepatic insulin resistance.
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Affiliation(s)
- Helen Imrie
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Hema Viswambharan
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Natalie J Haywood
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Katherine I Bridge
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Nadira Y Yuldasheva
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Stacey Galloway
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Katie J Simmons
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Richard M Cubbon
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Piruthivi Sukumar
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Nicole T Watt
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Laeticia Lichtenstein
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Judy I Wyatt
- Department of Pathology, Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom
| | - Hiromi Kudo
- Department of Metabolism, Digestion and Reproduction, Imperial College, London, United Kingdom
| | - Robert Goldin
- Department of Metabolism, Digestion and Reproduction, Imperial College, London, United Kingdom
| | - Baptiste Rode
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Stephen B Wheatcroft
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Mark T Kearney
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
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8
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Turvey SJ, McPhillie MJ, Kearney MT, Muench SP, Simmons KJ, Fishwick CWG. Recent developments in the structural characterisation of the IR and IGF1R: implications for the design of IR-IGF1R hybrid receptor modulators. RSC Med Chem 2022; 13:360-374. [PMID: 35647546 PMCID: PMC9020618 DOI: 10.1039/d1md00300c] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 01/12/2022] [Indexed: 12/16/2022] Open
Abstract
The insulin receptor (IR) and insulin-like growth factor 1 receptor (IGF1R) are dimeric disulfide-linked receptor tyrosine kinases, whose actions regulate metabolic and mitogenic signalling pathways inside the cell. It is well documented that in tissues co-expressing the IR and IGF1R, their respective monomers can heterodimerise to form IR-IGF1R hybrid receptors. Increased populations of the IR-IGF1R hybrid receptors are associated with several disease states, including type 2 diabetes and cancer. Recently, progress in the structural biology of IR and IGF1R has given insights into their structure-function relationships and mechanism of action. However, challenges in isolating IR-IGF1R hybrid receptors mean that their structural properties remain relatively unexplored. This review discusses the advances in the structural understanding of the IR and IGF1R, and how these discoveries can inform the design of small-molecule modulators of the IR-IGF1R hybrid receptors to understand their role in cell biology.
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Affiliation(s)
- Samuel J Turvey
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds UK
| | | | - Mark T Kearney
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds UK
| | - Stephen P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences & Astbury Centre, University of Leeds UK
| | - Katie J Simmons
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds UK
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9
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Hou X, Zhu C, Xu M, Chen X, Sun C, Nashan B, Guang S, Feng X. The SNAPc complex mediates starvation-induced trans-splicing in Caenorhabditis elegans. J Genet Genomics 2022; 49:952-964. [DOI: 10.1016/j.jgg.2022.02.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 02/20/2022] [Accepted: 02/22/2022] [Indexed: 11/16/2022]
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10
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Viswambharan H, Yuldasheva NY, Imrie H, Bridge K, Haywood NJ, Skromna A, Hemmings KE, Clark ER, Gatenby VK, Cordell P, Simmons KJ, Makava N, Abudushalamu Y, Endesh N, Brown J, Walker AMN, Futers ST, Porter KE, Cubbon RM, Naseem K, Shah AM, Beech DJ, Wheatcroft SB, Kearney MT, Sukumar P. Novel Paracrine Action of Endothelium Enhances Glucose Uptake in Muscle and Fat. Circ Res 2021; 129:720-734. [PMID: 34420367 PMCID: PMC8448413 DOI: 10.1161/circresaha.121.319517] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
[Figure: see text].
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Affiliation(s)
- Hema Viswambharan
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Nadira Y Yuldasheva
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Helen Imrie
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Katherine Bridge
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Natalie J Haywood
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Anna Skromna
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Karen E Hemmings
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Emily R Clark
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - V Kate Gatenby
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Paul Cordell
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Katie J Simmons
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Natallia Makava
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Yilizila Abudushalamu
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Naima Endesh
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Jane Brown
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Andrew M N Walker
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Simon T Futers
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Karen E Porter
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Richard M Cubbon
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Khalid Naseem
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Ajay M Shah
- British Heart Foundation Centre of Research Excellence, King's College London (A.M.S.)
| | - David J Beech
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Stephen B Wheatcroft
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Mark T Kearney
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
| | - Piruthivi Sukumar
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, United Kingdom (H.V., N.Y.Y., H.I., K.B., N.J.H., A.S., K.E.H., E.R.C., V.K.G., P.C., K.J.S., N.M., Y.A., N.E., J.B., A.M.N.W., S.T.F., K.E.P., R.M.C., K.N., D.J.B., S.B.W., M.T.K., P.S.)
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11
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Baugh LR, Hu PJ. Starvation Responses Throughout the Caenorhabditiselegans Life Cycle. Genetics 2020; 216:837-878. [PMID: 33268389 PMCID: PMC7768255 DOI: 10.1534/genetics.120.303565] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 08/17/2020] [Indexed: 02/07/2023] Open
Abstract
Caenorhabditis elegans survives on ephemeral food sources in the wild, and the species has a variety of adaptive responses to starvation. These features of its life history make the worm a powerful model for studying developmental, behavioral, and metabolic starvation responses. Starvation resistance is fundamental to life in the wild, and it is relevant to aging and common diseases such as cancer and diabetes. Worms respond to acute starvation at different times in the life cycle by arresting development and altering gene expression and metabolism. They also anticipate starvation during early larval development, engaging an alternative developmental program resulting in dauer diapause. By arresting development, these responses postpone growth and reproduction until feeding resumes. A common set of signaling pathways mediates systemic regulation of development in each context but with important distinctions. Several aspects of behavior, including feeding, foraging, taxis, egg laying, sleep, and associative learning, are also affected by starvation. A variety of conserved signaling, gene regulatory, and metabolic mechanisms support adaptation to starvation. Early life starvation can have persistent effects on adults and their descendants. With its short generation time, C. elegans is an ideal model for studying maternal provisioning, transgenerational epigenetic inheritance, and developmental origins of adult health and disease in humans. This review provides a comprehensive overview of starvation responses throughout the C. elegans life cycle.
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Affiliation(s)
- L Ryan Baugh
- Department of Biology, Center for Genomic and Computational Biology, Duke University, Durham, North Carolina 27708 and
| | - Patrick J Hu
- Departments of Medicine and Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
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12
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Li Y, Ding W, Li CY, Liu Y. HLH-11 modulates lipid metabolism in response to nutrient availability. Nat Commun 2020; 11:5959. [PMID: 33235199 PMCID: PMC7686365 DOI: 10.1038/s41467-020-19754-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 10/27/2020] [Indexed: 02/06/2023] Open
Abstract
The ability of organisms to sense nutrient availability and tailor their metabolic states to withstand nutrient deficiency is critical for survival. To identify previously unknown regulators that couple nutrient deficiency to body fat utilization, we performed a cherry-picked RNAi screen in C. elegans and found that the transcription factor HLH-11 regulates lipid metabolism in response to food availability. In well-fed worms, HLH-11 suppresses transcription of lipid catabolism genes. Upon fasting, the HLH-11 protein level is reduced through lysosome- and proteasome-mediated degradation, thus alleviating the inhibitory effect of HLH-11, activating the transcription of lipid catabolism genes, and utilizing fat. Additionally, lipid profiling revealed that reduction in the HLH-11 protein level remodels the lipid landscape in C. elegans. Moreover, TFAP4, the mammalian homolog of HLH-11, plays an evolutionarily conserved role in regulating lipid metabolism in response to starvation. Thus, TFAP4 may represent a potential therapeutic target for lipid storage disorders. Organismal metabolism fluctuates depending on nutritional conditions. Here, the authors show that, in C. elegans, HLH-11 negatively regulates lipid metabolism genes in the presence of nutrients and that its abundance decreased in response to starvation, thereby promoting fat utilization.
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Affiliation(s)
- Yi Li
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, Peking University, 100871, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Peking University, 100871, Beijing, China.,Academy for Advanced Interdisciplinary Studies, Peking University, 100871, Beijing, China
| | - Wanqiu Ding
- Laboratory of Bioinformatics and Genomic Medicine, Institute of Molecular Medicine, Peking University, 100871, Beijing, China
| | - Chuan-Yun Li
- Laboratory of Bioinformatics and Genomic Medicine, Institute of Molecular Medicine, Peking University, 100871, Beijing, China
| | - Ying Liu
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, Peking University, 100871, Beijing, China. .,Peking-Tsinghua Center for Life Sciences, Peking University, 100871, Beijing, China. .,Beijing Advanced Innovation Center for Genomics, Peking University, 100871, Beijing, China.
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13
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Macedo F, Romanatto T, Gomes de Assis C, Buis A, Kowaltowski AJ, Aguilaniu H, Marques da Cunha F. Lifespan-extending interventions enhance lipid-supported mitochondrial respiration in Caenorhabditis elegans. FASEB J 2020; 34:9972-9981. [PMID: 32609395 DOI: 10.1096/fj.201901880r] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 04/02/2020] [Accepted: 05/05/2020] [Indexed: 11/11/2022]
Abstract
Dietary restriction and reduced reproduction have been linked to long lifespans in the vast majority of species tested. Although decreased mitochondrial mass and/or function are hallmarks of aging, little is known about the mechanisms by which these organelles contribute to physiological aging or to the effects of lifespan-extending interventions, particularly with respect to oxidative phosphorylation and energy production. Here, we employed the nematode Caenorhabditis elegans to examine the effects of inhibition of germline proliferation and dietary restriction, both of which extend the lifespan of C. elegans, on mitochondrial respiratory activity in whole animals and isolated organelles. We found that oxygen consumption rates and mitochondrial mass were reduced in wild-type (WT) C. elegans subjected to bacterial deprivation (BD) compared with animals fed ad libitum (AL). In contrast, BD decreased the rate of oxygen uptake but not mitochondrial mass in germline-less glp-1(e2144ts) mutants. Interestingly, mitochondria isolated from animals subjected to BD and/or inhibition of germline proliferation showed no differences in complex I-mediated respiratory activity compared to control mitochondria, whereas both interventions enhanced the efficiency with which mitochondria utilized lipids as respiratory substrates. Notably, the combination of BD and inhibition of germline proliferation further increased mitochondrial lipid oxidation compared to either intervention alone. We also detected a striking correlation between lifespan extension in response to BD and/or inhibition of germline proliferation and the capacity of C. elegans to generate ATP from lipids. Our results thus suggest that the ability to oxidize lipids may be determinant in enhanced longevity.
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Affiliation(s)
- Felipe Macedo
- Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Talita Romanatto
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Carolina Gomes de Assis
- Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Alexia Buis
- Institut de Génomique Fonctionnelle de Lyon, Lyon, France
| | - Alicia J Kowaltowski
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Hugo Aguilaniu
- Institut de Génomique Fonctionnelle de Lyon, Lyon, France.,Instituto Serrapilheira, Rio de Janeiro, Brazil.,Centre National de la Recherche Scientifique, France
| | - Fernanda Marques da Cunha
- Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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14
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Chou W, Lin Y, Lee Y. Short-term starvation stress at young adult stages enhances meiotic activity of germ cells to maintain spermatogenesis in aged male Caenorhabditis elegans. Aging Cell 2019; 18:e12930. [PMID: 30816005 PMCID: PMC6516166 DOI: 10.1111/acel.12930] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 01/26/2019] [Accepted: 01/31/2019] [Indexed: 12/27/2022] Open
Abstract
To survive and reproduce, living organisms must evolve numerous mechanisms to re‐adjust their physiology when encountering adverse conditions that subject them to severe stress. We found that short‐term starvation (STS) stress in young adult male Caenorhabditis elegans can significantly improve their vitality (relative to nonstressed males) when they are aged. In addition, we found that stress‐treated aged males maintained reproductive activity equivalent to young males, whereas nonstressed aged males quickly lost reproductive ability. STS stress can preserve sperm number and quality in aged male worms. Spermatogenesis involves germ cell mitosis and meiosis. We found that germ cell meiotic activity is more sensitive to aging than mitotic activity and is declining rapidly with age. We examined the role of numerous factors important for spermatogenesis on STS‐preserved spermatogenesis during aging. Our results show that mutant strains deficient in anaphase‐promoting complex/cyclosome (APC/C) function fail to exhibit the STS stress‐enhanced spermatogenesis found in wild‐type N2 worms, suggesting that the mechanism underlying starvation‐induced spermatogenesis involves the APC/C complex, a conserved ubiquitin‐protein ligase E3 complex. Furthermore, transgenic expression of FZY‐1/CDC‐20, a coactivator of APC/C, ameliorated the age‐associated decline of meiosis, similar to the hormetic effect of STS.
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Affiliation(s)
- Wan‐Yi Chou
- Laboratory of Molecular Pathology, Institute of Molecular Biology Academia Sinica Taipei Taiwan
| | - Yu‐Chun Lin
- Laboratory of Molecular Pathology, Institute of Molecular Biology Academia Sinica Taipei Taiwan
| | - Ying‐Hue Lee
- Laboratory of Molecular Pathology, Institute of Molecular Biology Academia Sinica Taipei Taiwan
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15
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Mughal RS, Bridge K, Buza I, Slaaby R, Worm J, Klitgaard-Povlsen G, Hvid H, Schiødt M, Cubbon R, Yuldasheva N, Skromna A, Makava N, Skytte-Olsen G, Kearney MT. Effects of obesity on insulin: insulin-like growth factor 1 hybrid receptor expression and Akt phosphorylation in conduit and resistance arteries. Diab Vasc Dis Res 2019; 16:160-170. [PMID: 30295509 PMCID: PMC6484231 DOI: 10.1177/1479164118802550] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Insulin and insulin-like growth factor-1 stimulate specific responses in arteries, which may be disrupted by diet-induced obesity. We examined (1) temporal effects of high-fat diet compared to low-fat diet in mice on insulin receptor, insulin-like growth factor-1 receptor, insulin receptor/insulin-like growth factor-1 receptor hybrid receptor expression and insulin/insulin-like growth factor-1-mediated Akt phosphorylation in aorta; and (2) effects of high-fat diet on insulin and insulin-like growth factor-1-mediated Akt phosphorylation and vascular tone in resistance arteries. Medium-term high-fat diet (5 weeks) decreased insulin-like growth factor-1 receptor expression and increased hybrid expression (~30%) only. After long-term (16 weeks) high-fat diet, insulin receptor expression was reduced by ~30%, insulin-like growth factor-1 receptor expression decreased a further ~40% and hybrid expression increased a further ~60%. Independent correlates of hybrid receptor expression were high-fat diet, duration of high-fat diet and plasma insulin-like growth factor-1 (all p < 0.05). In aorta, insulin was a more potent activator of Akt than insulin-like growth factor-1, whereas in resistance arteries, insulin-like growth factor-1 was more potent than insulin. High-fat diet blunted insulin-mediated vasorelaxation ( p < 0.01) but had no effect on insulin-like growth factor-1-mediated vasorelaxation in resistance arteries. Our findings support the possibility that hybrid receptor level is influenced by nutritional and metabolic cues. Moreover, vessel-dependent effects of insulin and insulin-like growth factor-1 on vascular tone and Akt activation may have implications in treating obesity-related vascular disease.
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MESH Headings
- Animals
- Antigens, CD/metabolism
- Aorta/drug effects
- Aorta/enzymology
- Cells, Cultured
- Diet, Fat-Restricted
- Diet, High-Fat
- Disease Models, Animal
- Enzyme Activation
- Human Umbilical Vein Endothelial Cells/drug effects
- Human Umbilical Vein Endothelial Cells/enzymology
- Humans
- Insulin/pharmacology
- Insulin-Like Growth Factor I/pharmacology
- Male
- Mesenteric Arteries/drug effects
- Mesenteric Arteries/enzymology
- Mesenteric Arteries/physiopathology
- Mice, Inbred C57BL
- Obesity/blood
- Obesity/enzymology
- Obesity/physiopathology
- Phosphorylation
- Proto-Oncogene Proteins c-akt/metabolism
- Receptor, IGF Type 1/genetics
- Receptor, IGF Type 1/metabolism
- Receptor, Insulin/metabolism
- Receptors, Somatomedin/metabolism
- Signal Transduction/drug effects
- Vascular Resistance/drug effects
- Vasodilation/drug effects
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Affiliation(s)
- Romana S Mughal
- Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds, UK
| | - Katherine Bridge
- Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds, UK
| | - Irma Buza
- Global Research, Novo Nordisk A/S, Malov, Denmark
| | - Rita Slaaby
- Global Research, Novo Nordisk A/S, Malov, Denmark
| | - Jesper Worm
- Global Research, Novo Nordisk A/S, Malov, Denmark
| | | | - Henning Hvid
- Global Research, Novo Nordisk A/S, Malov, Denmark
| | | | - Richard Cubbon
- Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds, UK
| | - Nadira Yuldasheva
- Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds, UK
| | - Anna Skromna
- Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds, UK
| | - Natallia Makava
- Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds, UK
| | | | - Mark T Kearney
- Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds, UK
- Mark T Kearney, Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds LS2 9JT, UK.
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16
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Mousa U, Anil C, Demir CC, Bozkus Y, Ozturk K, Bascil Tutuncu N, Gursoy A. Thyroid Nodules Are More Prevalent in Subjects with Colon Polyps, Independent of Insulin Resistance. Med Princ Pract 2019; 28:418-424. [PMID: 30861528 PMCID: PMC6771071 DOI: 10.1159/000499527] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 03/12/2019] [Indexed: 12/26/2022] Open
Abstract
OBJECTIVE Colorectal polyps and thyroid nodules are common disorders linked to hyperinsulinemia and metabolic syndrome (Mets). The direct association between these two diseases is not clear. We aimed to analyze the prevalence of thyroid nodules in subjects with and without colorectal polyps. The secondary aim was to establish the prevalence of Mets and its parameters in both disorders and to determine if insulin resistance and hyperinsulinemia are common underlying pathophysiological mechanisms. SUBJECTS AND METHODS One hundred and five subjects with colorectal polyps (71 males, 34 females) and 68 controls (28 males, 40 females) were enrolled. The parameters of Mets together with TSH, insulin, low-density lipoprotein cholesterol, and homeostasis model for assessment of insulin resistance levels were calculated. We performed thyroid ultrasonography in all participants. RESULTS The prevalence of Mets was similar in the colorectal polyp and control groups (37.1 vs. 37.3%, p = 0.982). The prevalence of Mets was nonsignificantly higher in subjects with a documented thyroid nodule compared to subjects without a thyroid nodule (43.0 vs. 32.6%, p = 0.205). The prevalence of thyroid nodules in subjects with colorectal polyps was significantly higher than in subjects without polyps (52.9 vs. 35.3%, p = 0.017). Compared to subjects with no colorectal polyps, we established a significant increase in the odds of having thyroid nodules (OR 2.05; 95% CI: 1.097-3.860, p = 0.017). The presence of colorectal polyps and age in the adjusted model were established to be independent risk factors for having thyroid nodules (p = 0.025 and p = 0.007, respectively). CONCLUSION These results may support the presence of other common mechanisms in the development of these two pathologies other than insulin resistance and hyperinsulinemia.
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Affiliation(s)
- Umut Mousa
- Department of Endocrinology and Metabolism, Baskent University Faculty of Medicine, Ankara, Turkey,
| | - Cuneyd Anil
- Department of Endocrinology and Metabolism, Guven Hospital, Ankara, Turkey
| | - Canan Cicek Demir
- Department of Endocrinology and Metabolism, Baskent University Faculty of Medicine, Ankara, Turkey
| | - Yusuf Bozkus
- Department of Endocrinology and Metabolism, Baskent University Faculty of Medicine, Ankara, Turkey
| | - Kubra Ozturk
- Department of Internal Medicine Baskent University Faculty of Medicine, Ankara, Turkey
| | - Neslihan Bascil Tutuncu
- Department of Endocrinology and Metabolism, Baskent University Faculty of Medicine, Ankara, Turkey
| | - Alptekin Gursoy
- Department of Endocrinology and Metabolism, Guven Hospital, Ankara, Turkey
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17
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Barr MM, García LR, Portman DS. Sexual Dimorphism and Sex Differences in Caenorhabditis elegans Neuronal Development and Behavior. Genetics 2018; 208:909-935. [PMID: 29487147 PMCID: PMC5844341 DOI: 10.1534/genetics.117.300294] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 01/05/2018] [Indexed: 01/05/2023] Open
Abstract
As fundamental features of nearly all animal species, sexual dimorphisms and sex differences have particular relevance for the development and function of the nervous system. The unique advantages of the nematode Caenorhabditis elegans have allowed the neurobiology of sex to be studied at unprecedented scale, linking ultrastructure, molecular genetics, cell biology, development, neural circuit function, and behavior. Sex differences in the C. elegans nervous system encompass prominent anatomical dimorphisms as well as differences in physiology and connectivity. The influence of sex on behavior is just as diverse, with biological sex programming innate sex-specific behaviors and modifying many other aspects of neural circuit function. The study of these differences has provided important insights into mechanisms of neurogenesis, cell fate specification, and differentiation; synaptogenesis and connectivity; principles of circuit function, plasticity, and behavior; social communication; and many other areas of modern neurobiology.
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Affiliation(s)
- Maureen M Barr
- Department of Genetics, Rutgers University, Piscataway, New Jersey 08854-8082
| | - L Rene García
- Department of Biology, Texas A&M University, College Station, Texas 77843-3258
| | - Douglas S Portman
- Department of Biomedical Genetics, University of Rochester, New York 14642
- Department of Neuroscience, University of Rochester, New York 14642
- Department of Biology, University of Rochester, New York 14642
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18
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Lipid droplet protein LID-1 mediates ATGL-1-dependent lipolysis during fasting in Caenorhabditis elegans. Mol Cell Biol 2014; 34:4165-76. [PMID: 25202121 DOI: 10.1128/mcb.00722-14] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lipolysis is a delicate process involving complex signaling cascades and sequential enzymatic activations. In Caenorhabditis elegans, fasting induces various physiological changes, including a dramatic decrease in lipid contents through lipolysis. Interestingly, C. elegans lacks perilipin family genes which play a crucial role in the regulation of lipid homeostasis in other species. Here, we demonstrate that in the intestinal cells of C. elegans, a newly identified protein, lipid droplet protein 1 (C25A1.12; LID-1), modulates lipolysis by binding to adipose triglyceride lipase 1 (C05D11.7; ATGL-1) during nutritional deprivation. In fasted worms, lipid droplets were decreased in intestinal cells, whereas suppression of ATGL-1 via RNA interference (RNAi) resulted in retention of stored lipid droplets. Overexpression of ATGL-1 markedly decreased lipid droplets, whereas depletion of LID-1 via RNAi prevented the effect of overexpressed ATGL-1 on lipolysis. In adult worms, short-term fasting increased cyclic AMP (cAMP) levels, which activated protein kinase A (PKA) to stimulate lipolysis via ATGL-1 and LID-1. Moreover, ATGL-1 protein stability and LID-1 binding were augmented by PKA activation, eventually leading to increased lipolysis. These data suggest the importance of the concerted action of lipase and lipid droplet protein in the response to fasting signals via PKA to maintain lipid homeostasis.
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García LR. Regulation of sensory motor circuits used in C. elegans male intromission behavior. Semin Cell Dev Biol 2014; 33:42-9. [DOI: 10.1016/j.semcdb.2014.05.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 04/25/2014] [Accepted: 05/07/2014] [Indexed: 11/15/2022]
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Ito TK, Yokoyama M, Yoshida Y, Nojima A, Kassai H, Oishi K, Okada S, Kinoshita D, Kobayashi Y, Fruttiger M, Aiba A, Minamino T. A crucial role for CDC42 in senescence-associated inflammation and atherosclerosis. PLoS One 2014; 9:e102186. [PMID: 25057989 PMCID: PMC4109913 DOI: 10.1371/journal.pone.0102186] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 06/16/2014] [Indexed: 12/19/2022] Open
Abstract
Risk factors for atherosclerosis accelerate the senescence of vascular endothelial cells and promote atherogenesis by inducing vascular inflammation. A hallmark of endothelial senescence is the persistent up-regulation of pro-inflammatory genes. We identified CDC42 signaling as a mediator of chronic inflammation associated with endothelial senescence. Inhibition of CDC42 or NF-κB signaling attenuated the sustained up-regulation of pro-inflammatory genes in senescent human endothelial cells. Endothelium-specific activation of the p53/p21 pathway, a key mediator of senescence, also resulted in up-regulation of pro-inflammatory molecules in mice, which was reversed by Cdc42 deletion in endothelial cells. Likewise, endothelial-specific deletion of Cdc42 significantly attenuated chronic inflammation and plaque formation in atherosclerotic mice. While inhibition of NF-κB suppressed the pro-inflammatory responses in acute inflammation, the influence of Cdc42 deletion was less marked. Knockdown of cdc-42 significantly down-regulated pro-inflammatory gene expression and restored the shortened lifespan to normal in mutant worms with enhanced inflammation. These findings indicate that the CDC42 pathway is critically involved in senescence-associated inflammation and could be a therapeutic target for chronic inflammation in patients with age-related diseases without compromising host defenses.
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Affiliation(s)
- Takashi K. Ito
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Masataka Yokoyama
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Yohko Yoshida
- Department of Cardiovascular Biology and Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Aika Nojima
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Hidetoshi Kassai
- Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Kengo Oishi
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Sho Okada
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Daisuke Kinoshita
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Yoshio Kobayashi
- Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Marcus Fruttiger
- Institute of Ophthalmology, University College London, London, United Kingdom
| | - Atsu Aiba
- Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Tohru Minamino
- Department of Cardiovascular Biology and Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
- PRESTO, Japan Science and Technology Agency, Saitama, Japan
- * E-mail:
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Guo X, García LR. SIR-2.1 integrates metabolic homeostasis with the reproductive neuromuscular excitability in early aging male Caenorhabditis elegans. eLife 2014; 3:e01730. [PMID: 24755287 PMCID: PMC3989601 DOI: 10.7554/elife.01730] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 03/16/2014] [Indexed: 01/29/2023] Open
Abstract
The decline of aging C. elegans male's mating behavior is correlated with the increased excitability of the cholinergic circuitry that executes copulation. In this study, we show that the mating circuits' functional durability depends on the metabolic regulator SIR-2.1, a NAD(+)-dependent histone deacetylase. Aging sir-2.1(0) males display accelerated mating behavior decline due to premature hyperexcitability of cholinergic circuits used for intromission and ejaculation. In sir-2.1(0) males, the hypercontraction of the spicule-associated muscles pinch the vas deferens opening, thus blocking sperm release. The hyperexcitability is aggravated by reactive oxygen species (ROS). Our genetic, pharmacological, and behavioral analyses suggest that in sir-2.1(0) and older wild-type males, enhanced catabolic enzymes expression, coupled with the reduced expression of ROS-scavengers contribute to the behavioral decline. However, as a compensatory response to reduce altered catabolism/ROS production, anabolic enzymes expression levels are also increased, resulting in higher gluconeogenesis and lipid synthesis. DOI: http://dx.doi.org/10.7554/eLife.01730.001.
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Affiliation(s)
- Xiaoyan Guo
- Department of Biology, Texas A&M University, College Station, United States
| | - L René García
- Department of Biology, Texas A&M University, College Station, United States
- Howard Hughes Medical Institute, Texas A&M University, Texas, United States
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Reina A, Subramaniam AB, Laromaine A, Samuel ADT, Whitesides GM. Shifts in the distribution of mass densities is a signature of caloric restriction in Caenorhabditis elegans. PLoS One 2013; 8:e69651. [PMID: 23922767 PMCID: PMC3726776 DOI: 10.1371/journal.pone.0069651] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 06/13/2013] [Indexed: 12/30/2022] Open
Abstract
Although the starvation response of the model multicellular organism Caenorhabditis elegans is a subject of much research, there is no convenient phenotypic readout of caloric restriction that can be applicable to large numbers of worms. This paper describes the distribution of mass densities of populations of C. elegans, from larval stages up to day one of adulthood, using isopycnic centrifugation, and finds that density is a convenient, if complex, phenotypic readout in C. elegans. The density of worms in synchronized populations of wildtype N2 C. elegans grown under standard solid-phase culture conditions was normally distributed, with distributions peaked sharply at a mean of 1.091 g/cm3 for L1, L2 and L3 larvae, 1.087 g/cm3 for L4 larvae, 1.081 g/cm3 for newly molted adults, and 1.074 g/cm3 at 24 hours of adulthood. The density of adult worms under starvation stress fell well outside this range, falling to a mean value of 1.054 g/cm3 after eight hours of starvation. This decrease in density correlated with the consumption of stored glycogen in the food-deprived worms. The density of the worms increased when deprived of food for longer durations, corresponding to a shift in the response of the worms: worms sacrifice their bodies by retaining larvae, which consume the adults from within. Density-based screens with the drug Ivermectin on worms cultured on single plates resulted in a clear bimodal (double-peaked) distribution of densities corresponding to drug exposed and non-exposed worms. Thus, measurements of changes in density could be used to conduct screens on the effects of drugs on several populations of worms cultured on single plates.
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Affiliation(s)
- Alfonso Reina
- Department of Chemistry and Chemical Biology, Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, Massachusetts, United States of America
| | - Anand Bala Subramaniam
- Department of Chemistry and Chemical Biology, Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, Massachusetts, United States of America
| | - Anna Laromaine
- Department of Chemistry and Chemical Biology, Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, Massachusetts, United States of America
| | - Aravinthan D. T. Samuel
- Department of Physics and Center for Brain Science, Harvard University, Cambridge, Massachusetts, United States of America
| | - George M. Whitesides
- Department of Chemistry and Chemical Biology, Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, Massachusetts, United States of America
- * E-mail:
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Miersch C, Döring F. Sex differences in body composition, fat storage, and gene expression profile in Caenorhabditis elegans in response to dietary restriction. Physiol Genomics 2013; 45:539-51. [PMID: 23715261 DOI: 10.1152/physiolgenomics.00007.2013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The metabolic and health-promoting effects of dietary restriction (DR) have been extensively studied in several species. The response to DR with respect to sex is essentially unknown. To address this question, we used the model organism Caenorhabditis elegans to analyze body composition and gene expression in males and hermaphrodites in response to DR. Unexpectedly, DR increased the fat-to-fat-free mass ratio and enlarged lipid droplets in both sexes to a similar extent. These effects were linked to a downregulation of the lipase-like 5 (lipl-5) gene in both sexes at two developmental stages. By contrast, the reductions in body size, protein content, and total RNA content in response to DR were more pronounced in hermaphrodites than in males. Functional enrichment analysis of gene expression data showed a DR-induced downregulation of several embryogenesis-associated genes concomitant with an ongoing expression of sperm-associated genes in hermaphrodites. In conclusion, DR increases fat stores in both sexes of C. elegans in the form of large and possibly lipolysis-resistant lipid droplets and markedly alters the reproductive program in hermaphrodites but not in males.
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Affiliation(s)
- Claudia Miersch
- Department of Molecular Prevention, Institute of Human Nutrition and Food Science, Christian-Albrechts-University of Kiel, Germany
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MXL-3 and HLH-30 transcriptionally link lipolysis and autophagy to nutrient availability. Nat Cell Biol 2013; 15:668-76. [PMID: 23604316 DOI: 10.1038/ncb2741] [Citation(s) in RCA: 258] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Accepted: 03/22/2013] [Indexed: 11/08/2022]
Abstract
Fat is stored or mobilized according to food availability. Malfunction of the mechanisms that ensure this coordination underlie metabolic diseases in humans. In mammals, lysosomal and autophagic function is required for normal fat storage and mobilization in the presence or absence of food. Autophagy is tightly linked to nutrients. However, if and how lysosomal lipolysis is coupled to nutritional status remains to be determined. Here we identify MXL-3 and HLH-30 (TFEB orthologue) [corrected] as transcriptional switches coupling lysosomal lipolysis and autophagy to nutrient availability and controlling fat storage and ageing in Caenorhabditis elegans. Transcriptional coupling of lysosomal lipolysis and autophagy to nutrients is also observed in mammals. Thus, MXL-3 and HLH-30 orchestrate an adaptive and conserved cellular response to nutritional status and regulate lifespan.
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The mitochondrial unfolded protein response activator ATFS-1 protects cells from inhibition of the mevalonate pathway. Proc Natl Acad Sci U S A 2013; 110:5981-6. [PMID: 23530189 DOI: 10.1073/pnas.1218778110] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Statins are cholesterol-lowering drugs that inhibit 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase, the rate-limiting enzyme in the synthesis of cholesterol via the mevalonate pathway. This pathway also produces coenzyme Q (a component of the respiratory chain), dolichols (important for protein glycosylation), and isoprenoids (lipid moieties responsible for the membrane association of small GTPases). We previously showed that the nematode Caenorhabditis elegans is useful to study the noncholesterol effects of statins because its mevalonate pathway lacks the sterol synthesis branch but retains all other branches. Here, from a screen of 150,000 mutagenized genomes, we isolated four C. elegans mutants resistant to statins by virtue of gain-of-function mutations within the first six amino acids of the protein ATFS-1, the key regulator of the mitochondrial unfolded protein response that includes activation of the chaperones HSP-6 and HSP-60. The atfs-1 gain-of-function mutants are also resistant to ibandronate, an inhibitor of an enzyme downstream of HMG-CoA reductase, and to gliotoxin, an inhibitor acting on a subbranch of the pathway important for protein prenylation, and showed improved mitochondrial function and protein prenylation in the presence of statins. Additionally, preinduction of the mitochondrial unfolded protein response in wild-type worms using ethidium bromide or paraquat triggered statin resistance, and similar observations were made in Schizosaccharomyces pombe and in a mammalian cell line. We conclude that statin resistance through maintenance of mitochondrial homeostasis is conserved across species, and that the cell-lethal effects of statins are caused primarily through impaired protein prenylation that results in mitochondria dysfunction.
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Physiological control of germline development. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 757:101-31. [PMID: 22872476 DOI: 10.1007/978-1-4614-4015-4_5] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The intersection between developmental programs and environmental conditions that alter physiology is a growing area of research interest. The C. elegans germ line is emerging as a particularly sensitive and powerful model for these studies. The germ line is subject to environmentally regulated diapause points that allow worms to withstand harsh conditions both prior to and after reproduction commences. It also responds to more subtle changes in physiological conditions. Recent studies demonstrate that different aspects of germ line development are sensitive to environmental and physiological changes and that conserved signaling pathways such as the AMPK, Insulin/IGF, TGFβ, and TOR-S6K, and nuclear hormone receptor pathways mediate this sensitivity. Some of these pathways genetically interact with but appear distinct from previously characterized mechanisms of germline cell fate control such as Notch signaling. Here, we review several aspects of hermaphrodite germline development in the context of "feasting," "food-limited," and "fasting" conditions. We also consider connections between lifespan, metabolism and the germ line, and we comment on special considerations for examining germline development under altered environmental and physiological conditions. Finally, we summarize the major outstanding questions in the field.
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