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Savage TM, Fortson KT, de Los Santos-Alexis K, Oliveras-Alsina A, Rouanne M, Rae SS, Gamarra JR, Shayya H, Kornberg A, Cavero R, Li F, Han A, Haeusler RA, Adam J, Schwabe RF, Arpaia N. Amphiregulin from regulatory T cells promotes liver fibrosis and insulin resistance in non-alcoholic steatohepatitis. Immunity 2024; 57:303-318.e6. [PMID: 38309273 PMCID: PMC10922825 DOI: 10.1016/j.immuni.2024.01.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 11/20/2023] [Accepted: 01/10/2024] [Indexed: 02/05/2024]
Abstract
Production of amphiregulin (Areg) by regulatory T (Treg) cells promotes repair after acute tissue injury. Here, we examined the function of Treg cells in non-alcoholic steatohepatitis (NASH), a setting of chronic liver injury. Areg-producing Treg cells were enriched in the livers of mice and humans with NASH. Deletion of Areg in Treg cells, but not in myeloid cells, reduced NASH-induced liver fibrosis. Chronic liver damage induced transcriptional changes associated with Treg cell activation. Mechanistically, Treg cell-derived Areg activated pro-fibrotic transcriptional programs in hepatic stellate cells via epidermal growth factor receptor (EGFR) signaling. Deletion of Areg in Treg cells protected mice from NASH-dependent glucose intolerance, which also was dependent on EGFR signaling on hepatic stellate cells. Areg from Treg cells promoted hepatocyte gluconeogenesis through hepatocyte detection of hepatic stellate cell-derived interleukin-6. Our findings reveal a maladaptive role for Treg cell-mediated tissue repair functions in chronic liver disease and link liver damage to NASH-dependent glucose intolerance.
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Affiliation(s)
- Thomas M Savage
- Department of Microbiology & Immunology, Columbia University, New York, NY, USA
| | - Katherine T Fortson
- Department of Microbiology & Immunology, Columbia University, New York, NY, USA
| | | | | | - Mathieu Rouanne
- Department of Microbiology & Immunology, Columbia University, New York, NY, USA
| | - Sarah S Rae
- Department of Microbiology & Immunology, Columbia University, New York, NY, USA
| | | | - Hani Shayya
- Mortimer B. Zuckerman Mind, and Brain and Behavior Institute, Columbia University, New York, NY, USA
| | - Adam Kornberg
- Department of Microbiology & Immunology, Columbia University, New York, NY, USA; Columbia Center for Translational Immunology, Columbia University, New York, NY, USA
| | - Renzo Cavero
- Department of Microbiology & Immunology, Columbia University, New York, NY, USA
| | - Fangda Li
- Department of Microbiology & Immunology, Columbia University, New York, NY, USA
| | - Arnold Han
- Department of Microbiology & Immunology, Columbia University, New York, NY, USA; Columbia Center for Translational Immunology, Columbia University, New York, NY, USA; Department of Medicine, Columbia University, New York, NY, USA
| | - Rebecca A Haeusler
- Naomi Berrie Diabetes Center, Columbia University, New York, NY, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | - Julien Adam
- Pathology Department, Hopital Paris Saint-Joseph, Paris, France; INSERM U1186, Gustave Roussy, Villejuif, France
| | | | - Nicholas Arpaia
- Department of Microbiology & Immunology, Columbia University, New York, NY, USA; Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.
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Park J, Hall C, Hubbard B, LaMoia T, Gaspar R, Nasiri A, Li F, Zhang H, Kim J, Haeusler RA, Accili D, Shulman GI, Yu H, Choi E. MAD2-Dependent Insulin Receptor Endocytosis Regulates Metabolic Homeostasis. Diabetes 2023; 72:1781-1794. [PMID: 37725942 PMCID: PMC10658066 DOI: 10.2337/db23-0314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 09/12/2023] [Indexed: 09/21/2023]
Abstract
Insulin activates insulin receptor (IR) signaling and subsequently triggers IR endocytosis to attenuate signaling. Cell division regulators MAD2, BUBR1, and p31comet promote IR endocytosis on insulin stimulation. Here, we show that genetic ablation of the IR-MAD2 interaction in mice delays IR endocytosis, increases IR levels, and prolongs insulin action at the cell surface. This in turn causes a defect in insulin clearance and increases circulating insulin levels, unexpectedly increasing glucagon levels, which alters glucose metabolism modestly. Disruption of the IR-MAD2 interaction increases serum fatty acid concentrations and hepatic fat accumulation in fasted male mice. Furthermore, disruption of the IR-MAD2 interaction distinctly changes metabolic and transcriptomic profiles in the liver and adipose tissues. Our findings establish the function of cell division regulators in insulin signaling and provide insights into the metabolic functions of IR endocytosis. ARTICLE HIGHLIGHTS The physiological role of IR endocytosis in insulin sensitivity remains unclear. Disruption of the IR-MAD2 interaction delays IR endocytosis and prolongs insulin signaling. IR-MAD2 controls insulin clearance and glucose metabolism. IR-MAD2 maintains energy homeostasis.
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Affiliation(s)
- Junhee Park
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
| | - Catherine Hall
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
| | - Brandon Hubbard
- Departments of Internal Medicine and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT
| | - Traci LaMoia
- Departments of Internal Medicine and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT
| | - Rafael Gaspar
- Departments of Internal Medicine and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT
| | - Ali Nasiri
- Departments of Internal Medicine and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT
| | - Fang Li
- Cardiometabolic Genomics Program, Division of Cardiology, Department of Medicine, Columbia University Irving Medical Center, New York, NY
| | - Hanrui Zhang
- Cardiometabolic Genomics Program, Division of Cardiology, Department of Medicine, Columbia University Irving Medical Center, New York, NY
| | - Jiyeon Kim
- Department of Urology and Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT
| | - Rebecca A Haeusler
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
- Naomi Berrie Diabetes Center, Columbia University, New York, NY
- Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
| | - Domenico Accili
- Naomi Berrie Diabetes Center, Columbia University, New York, NY
- Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
| | - Gerald I Shulman
- Departments of Internal Medicine and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT
| | - Hongtao Yu
- School of Life Sciences, Westlake University, Hangzhou, Zhejiang Province, China
| | - Eunhee Choi
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
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Izquierdo MC, Harris M, Shanmugarajah N, Zhong K, Ozcan L, Fredman G, Haeusler RA. Insulin sensitization by hepatic FoxO deletion is insufficient to lower atherosclerosis in mice. bioRxiv 2023:2023.10.14.562366. [PMID: 37905094 PMCID: PMC10614776 DOI: 10.1101/2023.10.14.562366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Background– Type 2 diabetes is associated with an increased risk of atherosclerotic cardiovascular disease. It has been suggested that insulin resistance underlies this link, possibly by altering the functions of cells in the artery wall. We aimed to test whether improving systemic insulin sensitivity reduces atherosclerosis. Methods– We used mice that are established to have improved systemic insulin sensitivity: those lacking FoxO transcription factors in hepatocytes. Three hepatic FoxO isoforms (FoxO1, FoxO3, and FoxO4) function together to promote hepatic glucose output, and ablating them lowers glucose production, lowers circulating glucose and insulin, and improves systemic insulin sensitivity. We made these mice susceptible to atherosclerosis in two different ways, by injecting them with gain-of-function AAV8.mPcsk9D377Y and by crossing with Ldlr-/- mice. Results– We verified that hepatic FoxO ablation improves systemic insulin sensitivity in these atherosclerotic settings. We observed that FoxO deficiency caused no reductions in atherosclerosis, and in some cases increased atherosclerosis. These phenotypes coincided with large increases in circulating triglycerides in FoxO-ablated mice. Conclusions– These findings suggest that systemic insulin sensitization is insufficient to reduce atherosclerosis.
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Affiliation(s)
- María Concepción Izquierdo
- Naomi Berrie Diabetes Center; Columbia University College of Physicians and Surgeons; New York, NY, 10032; USA
- Department of Pathology and Cell Biology; Columbia University College of Physicians and Surgeons; New York, NY, 10032; USA
| | - Michael Harris
- Naomi Berrie Diabetes Center; Columbia University College of Physicians and Surgeons; New York, NY, 10032; USA
| | - Niroshan Shanmugarajah
- Naomi Berrie Diabetes Center; Columbia University College of Physicians and Surgeons; New York, NY, 10032; USA
- Department of Pathology and Cell Biology; Columbia University College of Physicians and Surgeons; New York, NY, 10032; USA
| | - Kendra Zhong
- Naomi Berrie Diabetes Center; Columbia University College of Physicians and Surgeons; New York, NY, 10032; USA
| | - Lale Ozcan
- Department of Medicine; Columbia University College of Physicians and Surgeons; New York, NY, 10032; USA
| | - Gabrielle Fredman
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY, 12208; USA
| | - Rebecca A. Haeusler
- Naomi Berrie Diabetes Center; Columbia University College of Physicians and Surgeons; New York, NY, 10032; USA
- Department of Pathology and Cell Biology; Columbia University College of Physicians and Surgeons; New York, NY, 10032; USA
- Department of Medicine; Columbia University College of Physicians and Surgeons; New York, NY, 10032; USA
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Higuchi S, Wood C, Nasiri RH, Giddla LJ, Molina V, Diarra R, DiPatrizio NV, Kawamura A, Haeusler RA. The 16α-hydroxylated Bile Acid, Pythocholic Acid Decreases Food Intake and Increases Oleoylethanolamide in Male Mice. Endocrinology 2023; 164:bqad116. [PMID: 37490843 PMCID: PMC10407715 DOI: 10.1210/endocr/bqad116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 07/20/2023] [Accepted: 07/21/2023] [Indexed: 07/27/2023]
Abstract
Modulation of bile acid (BA) structure is a potential strategy for obesity and metabolic disease treatment. BAs act not only as signaling molecules involved in energy expenditure and glucose homeostasis, but also as regulators of food intake. The structure of BAs, particularly the position of the hydroxyl groups of BAs, impacts food intake partly by intestinal effects: (1) modulating the activity of N-acyl phosphatidylethanolamine phospholipase D, which produces the anorexigenic bioactive lipid oleoylethanolamide (OEA) or (2) regulating lipid absorption and the gastric emptying-satiation pathway. We hypothesized that 16α-hydroxylated BAs uniquely regulate food intake because of the long intermeal intervals in snake species in which these BAs are abundant. However, the effects of 16α-hydroxylated BAs in mammals are completely unknown because they are not naturally found in mammals. To test the effect of 16α-hydroxylated BAs on food intake, we isolated the 16α-hydroxylated BA pythocholic acid from ball pythons (Python regius). Pythocholic acid or deoxycholic acid (DCA) was given by oral gavage in mice. DCA is known to increase N-acyl phosphatidylethanolamine phospholipase D activity better than other mammalian BAs. We evaluated food intake, OEA levels, and gastric emptying in mice. We successfully isolated pythocholic acid from ball pythons for experimental use. Pythocholic acid treatment significantly decreased food intake in comparison to DCA treatment, and this was associated with increased jejunal OEA, but resulted in no change in gastric emptying or lipid absorption. The exogenous BA pythocholic acid is a novel regulator of food intake and the satiety signal for OEA in the mouse intestine.
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Affiliation(s)
- Sei Higuchi
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, Queens, NY 11439, USA
- Naomi Berrie Diabetes Center and Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Courtney Wood
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA
| | - Raidah H Nasiri
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, Queens, NY 11439, USA
| | - Leela J Giddla
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, Queens, NY 11439, USA
| | - Valentina Molina
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, Queens, NY 11439, USA
| | - Rokia Diarra
- Department of Biological Sciences, St. John's University, Queens, NY 11439, USA
| | - Nicholas V DiPatrizio
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA
| | - Akira Kawamura
- Department of Chemistry, Hunter College of CUNY, New York, NY 10065, USA
| | - Rebecca A Haeusler
- Naomi Berrie Diabetes Center and Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
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Bini S, D'Erasmo L, Astiarraga B, Minicocci I, Palumbo M, Pecce V, Polito L, Di Costanzo A, Haeusler RA, Arca M, Ferrannini E, Camastra S. Differential effects of bariatric surgery on plasma levels of ANGPTL3 and ANGPTL4. Nutr Metab Cardiovasc Dis 2022; 32:2647-2654. [PMID: 36163215 PMCID: PMC10018753 DOI: 10.1016/j.numecd.2022.08.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 08/12/2022] [Accepted: 08/23/2022] [Indexed: 01/21/2023]
Abstract
BACKGROUND AND AIM Angiopoietin-like 3 (ANGPTL3) and 4 (ANGPTL4) are regulators of triglyceride storage and utilization. Bariatric surgery (BS) leads to profound changes in adipose tissue composition and energy metabolism. We evaluated the impact of BS on plasma levels of ANGPTL3 and ANGPTL4. METHODS AND RESULTS Twenty-seven subjects affected by morbid obesity with or without type 2 diabetes (T2D) underwent Roux-en-Y gastric bypass (RYGB) and 18 patients with advanced T2D received Biliopancreatic Diversion (BPD). Fasting ANGPTL proteins levels, insulin sensitivity (evaluated by euglycemic hyperinsulinemic clamp), total bile acids (TBA) and free fatty acids (FFA) were measured at baseline and 1 year after surgery. Both surgical procedures resulted in the loss of fat mass, improved glucose control, and a ∼2-fold increase of insulin sensitivity. ANGPTL4 levels decreased significantly with both RYGB (26.6 ± 0.6 to 24.4 ± 0.3 ng/mL, p = 0.001) and BPD (27.9 ± 1.5 to 24.0 ± 0.5 ng/mL, p = 0.003). In contrast, ANGPTL3 concentrations did not change after RYGB but rose following BPD (225 ± 20 to 300 ± 15 ng/mL, p = 0.003). By multiple regression analysis, changes after BS in ANGPTL4 were independently associated with changes in blood glucose, (p = 0.0169) whereas changes in ANGPTL3 were associated with variations in FFA (p = 0.008) and insulin sensitivity (p = 0.043). CONCLUSION Circulating ANGPTL4 is reduced by BS, probably due to the loss of fat mass and improved insulin sensitivity. Conversely, ANGPTL3 levels increased after BPD, but not after RYGB, presumably because of the metabolic changes induced by the malabsorptive effect of BPD.
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Affiliation(s)
- Simone Bini
- Department of Translational and Precision Medicine, Sapienza University of Rome, Italy.
| | - Laura D'Erasmo
- Department of Translational and Precision Medicine, Sapienza University of Rome, Italy
| | - Brenno Astiarraga
- Department of Clinical and Experimental Medicine, University of Pisa, Italy; Pere Virgili Institute for Health Research (IISPV), Terragona, Spain
| | - Ilenia Minicocci
- Department of Translational and Precision Medicine, Sapienza University of Rome, Italy
| | - Maria Palumbo
- Department of Clinical and Experimental Medicine, University of Pisa, Italy
| | - Valeria Pecce
- Department of Translational and Precision Medicine, Sapienza University of Rome, Italy
| | - Luca Polito
- Department of Translational and Precision Medicine, Sapienza University of Rome, Italy
| | - Alessia Di Costanzo
- Department of Translational and Precision Medicine, Sapienza University of Rome, Italy
| | - Rebecca A Haeusler
- Naomi Berrie Diabetes Center and Department of Pathology and Cell Biology, Columbia University, New York, USA
| | - Marcello Arca
- Department of Translational and Precision Medicine, Sapienza University of Rome, Italy
| | | | - Stefania Camastra
- Department of Clinical and Experimental Medicine, University of Pisa, Italy.
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Cook JR, Kohan AB, Haeusler RA. An Updated Perspective on the Dual-Track Model of Enterocyte Fat Metabolism. J Lipid Res 2022; 63:100278. [PMID: 36100090 PMCID: PMC9593242 DOI: 10.1016/j.jlr.2022.100278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 08/08/2022] [Accepted: 08/31/2022] [Indexed: 02/04/2023] Open
Abstract
The small intestinal epithelium has classically been envisioned as a conduit for nutrient absorption, but appreciation is growing for a larger and more dynamic role for enterocytes in lipid metabolism. Considerable gaps remain in our knowledge of this physiology, but it appears that the enterocyte's structural polarization dictates its behavior in fat partitioning, treating fat differently based on its absorption across the apical versus the basolateral membrane. In this review, we synthesize existing data and thought on this dual-track model of enterocyte fat metabolism through the lens of human integrative physiology. The apical track includes the canonical pathway of dietary lipid absorption across the apical brush-border membrane, leading to packaging and secretion of those lipids as chylomicrons. However, this track also reserves a portion of dietary lipid within cytoplasmic lipid droplets for later uses, including the "second-meal effect," which remains poorly understood. At the same time, the enterocyte takes up circulating fats across the basolateral membrane by mechanisms that may include receptor-mediated import of triglyceride-rich lipoproteins or their remnants, local hydrolysis and internalization of free fatty acids, or enterocyte de novo lipogenesis using basolaterally absorbed substrates. The ultimate destinations of basolateral-track fat may include fatty acid oxidation, structural lipid synthesis, storage in cytoplasmic lipid droplets, or ultimate resecretion, although the regulation and purposes of this basolateral track remain mysterious. We propose that the enterocyte integrates lipid flux along both of these tracks in order to calibrate its overall program of lipid metabolism.
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Affiliation(s)
- Joshua R. Cook
- Naomi Berrie Diabetes Center, Columbia University College of Physicians and Surgeons, New York, NY, USA,Division of Endocrinology, Diabetes & Metabolism, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Alison B. Kohan
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Rebecca A. Haeusler
- Naomi Berrie Diabetes Center, Columbia University College of Physicians and Surgeons, New York, NY, USA,Department of Pathology and Cell Biology; Columbia University College of Physicians and Surgeons, New York, NY, USA,For correspondence: Rebecca A. Haeusler
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7
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Emiliano AB, Lopatinsky NR, Kraljević M, Higuchi S, He Y, Haeusler RA, Schwartz GJ. Sex-specific differences in metabolic outcomes after sleeve gastrectomy and intermittent fasting in obese middle-aged mice. Am J Physiol Endocrinol Metab 2022; 323:E107-E121. [PMID: 35658544 PMCID: PMC9273270 DOI: 10.1152/ajpendo.00017.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 05/19/2022] [Accepted: 05/19/2022] [Indexed: 01/21/2023]
Abstract
Despite the high prevalence of obesity among middle-aged subjects, it is unclear if sex differences in middle age affect the metabolic outcomes of obesity therapies. Accordingly, in this study, middle-aged obese female and male mice were randomized to one of three groups: sleeve gastrectomy (SG), sham surgery ad libitum (SH-AL), or sham surgery with weight matching to SG through intermittent fasting with calorie restriction (SH-IF). Comprehensive measures of energy and glucose homeostasis, including energy intake, body weight, energy expenditure, glucose and insulin tolerance, and interscapular brown adipose tissue (iBAT) sympathetic innervation density were obtained. At the end of 8 wk, SG and SH-IF females had better metabolic outcomes than their male counterparts. SG females had improved weight loss maintenance, preservation of fat-free mass (FFM), higher total energy expenditure (TEE), normal locomotor activity, and reduced plasma insulin and white adipose tissue (WAT) inflammatory markers. SH-IF females also had lower plasma insulin and WAT inflammatory markers, and higher TEE than SH-IF males, despite their lower FFM. In addition, SH-IF females had higher iBAT sympathetic nerve density than SG and SH-AL females, whereas there were no differences among males. Notably, SH-IF mice of both sexes had the most improved glucose tolerance, highlighting the benefits of fasting, irrespective of weight loss. Results from this study demonstrate that in middle-aged obese mice, female sex is associated with better metabolic outcomes after SG or IF with calorie restriction. Clinical studies are needed to determine if sex differences should guide the choice of obesity therapies.NEW & NOTEWORTHY SG or IF with calorie restriction produces better metabolic outcomes in females than in males. IF with calorie restriction prevents metabolic adaptation, even in the face of fat-free mass loss. IF with calorie restriction in females only, is associated with increased iBAT sympathetic innervation, which possibly mitigates reductions in energy expenditure secondary to fat-free mass loss. Lastly, IF leads to better glucose homeostasis than SG, irrespective of sex.
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Affiliation(s)
| | | | - Marko Kraljević
- Columbia University Medical Center, New York, New York
- Clarunis University Center for Gastrointestinal and Liver Diseases, St. Clara Hospital and University Hospital, Basel, Switzerland
| | - Sei Higuchi
- Columbia University Medical Center, New York, New York
| | - Ying He
- Columbia University Medical Center, New York, New York
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8
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McKimpson WM, Kuo T, Kitamoto T, Higuchi S, Mills JC, Haeusler RA, Accili D. FOXO1 Is Present in Stomach Epithelium and Determines Gastric Cell Distribution. Gastro Hep Adv 2022; 1:733-745. [PMID: 36117550 PMCID: PMC9481069 DOI: 10.1016/j.gastha.2022.05.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
BACKGROUND AND AIMS Stomach cells can be converted to insulin-producing cells by Neurog3, MafA, and Pdxl over-expression. Enteroendocrine cells can be similarly made to produce insulin by the deletion of FOXO1. Characteristics and functional properties of FOXO1-expressing stomach cells are not known. METHODS Using mice bearing a FOXO1-GFP knock-in allele and primary cell cultures, we examined the identity of FOXO1-expressing stomach cells and analyzed their features through loss-of-function studies with red-to-green fluorescent reporters. RESULTS FOXO1 localizes to a subset of Neurog3 and parietal cells. FOXO1 deletion ex vivo or in vivo using Neurog3-cre or Atp4b-cre increased numbers of parietal cells, generated insulin- and C-peptide-immunoreactive cells, and raised Neurog3 messenger RNA. Gene expression and ChIP- seq experiments identified the cell cycle regulator cyclin E1 (CCNE1) as a FOXO1 target. CONCLUSION FOXO1 is expressed in a subset of stomach cells. Its ablation increases parietal cells and yields insulin-immunoreactive cells, consistent with a role in lineage determination.
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Affiliation(s)
- Wendy M. McKimpson
- Division of Endocrinology, Department of Medicine, Columbia University, New York, New York
- Naomi Berrie Diabetes Center, Columbia University, New York, New York
| | - Taiyi Kuo
- Division of Endocrinology, Department of Medicine, Columbia University, New York, New York
- Naomi Berrie Diabetes Center, Columbia University, New York, New York
| | - Takumi Kitamoto
- Division of Endocrinology, Department of Medicine, Columbia University, New York, New York
- Naomi Berrie Diabetes Center, Columbia University, New York, New York
| | - Sei Higuchi
- Naomi Berrie Diabetes Center, Columbia University, New York, New York
- Department of Pathology and Cell Biology, Columbia University, New York, New York
| | - Jason C. Mills
- Section of Gastroenterology and Hepatology, Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Rebecca A. Haeusler
- Naomi Berrie Diabetes Center, Columbia University, New York, New York
- Department of Pathology and Cell Biology, Columbia University, New York, New York
| | - Domenico Accili
- Division of Endocrinology, Department of Medicine, Columbia University, New York, New York
- Naomi Berrie Diabetes Center, Columbia University, New York, New York
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9
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Izquierdo MC, Shanmugarajah N, Lee SX, Kraakman MJ, Westerterp M, Kitamoto T, Harris M, Cook JR, Gusarova GA, Zhong K, Marbuary E, O-Sullivan I, Rasmus NF, Camastra S, Unterman TG, Ferrannini E, Hurwitz BE, Haeusler RA. Hepatic FoxOs link insulin signaling with plasma lipoprotein metabolism through an apolipoprotein M/sphingosine-1-phosphate pathway. J Clin Invest 2022; 132:146219. [PMID: 35104242 PMCID: PMC8970673 DOI: 10.1172/jci146219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 01/28/2022] [Indexed: 11/17/2022] Open
Abstract
Multiple beneficial cardiovascular effects of HDL depend on sphingosine-1-phosphate (S1P). S1P associates with HDL by binding to apolipoprotein M (ApoM). Insulin resistance is a major driver of dyslipidemia and cardiovascular risk. However, the mechanisms linking alterations in insulin signaling with plasma lipoprotein metabolism are incompletely understood. The insulin-repressible FoxO transcription factors mediate key effects of hepatic insulin action on glucose and lipoprotein metabolism. This work tested whether hepatic insulin signaling regulates HDL-S1P and aimed to identify the underlying molecular mechanisms. We report that insulin-resistant, nondiabetic individuals had decreased HDL-S1P levels, but no change in total plasma S1P. This also occurred in insulin-resistant db/db mice, which had low ApoM and a specific reduction of S1P in the HDL fraction, with no change in total plasma S1P levels. Using mice lacking hepatic FoxOs (L-FoxO1,3,4), we found that hepatic FoxOs were required for ApoM expression. Total plasma S1P levels were similar to those in controls, but S1P was nearly absent from HDL and was instead increased in the lipoprotein-depleted plasma fraction. This phenotype was restored to normal by rescuing ApoM in L-FoxO1,3,4 mice. Our findings show that insulin resistance in humans and mice is associated with decreased HDL-associated S1P. Our study shows that hepatic FoxO transcription factors are regulators of the ApoM/S1P pathway.
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Affiliation(s)
- María Concepción Izquierdo
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, United States of America
| | - Niroshan Shanmugarajah
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, United States of America
| | - Samuel X Lee
- Naomi Berrie Diabetes Center, Columbia University College of Physicians and Surgeons, New York, United States of America
| | - Michael J Kraakman
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, United States of America
| | - Marit Westerterp
- Department of Pediatrics, University of Groningen, Groningen, Netherlands
| | - Takumi Kitamoto
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, United States of America
| | - Michael Harris
- Naomi Berrie Diabetes Center, Columbia University College of Physicians and Surgeons, New York, United States of America
| | - Joshua R Cook
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, United States of America
| | - Galina A Gusarova
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, United States of America
| | - Kendra Zhong
- Naomi Berrie Diabetes Center, Columbia University College of Physicians and Surgeons, New York, United States of America
| | - Elijah Marbuary
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, United States of America
| | - InSug O-Sullivan
- Department of Medicine, University of Illinois at Chicago College of Medicine, Chicago, United States of America
| | - Nikolaus F Rasmus
- Naomi Berrie Diabetes Center, Columbia University College of Physicians and Surgeons, New York, United States of America
| | - Stefania Camastra
- Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy
| | - Terry G Unterman
- Department of Medicine, University of Illinois at Chicago College of Medicine, Chicago, United States of America
| | - Ele Ferrannini
- Department of Internal Medicine, CNR Institute of Clinical Physiology, Pisa, Italy
| | - Barry E Hurwitz
- Department of Psychology, University of Miami, Miami, United States of America
| | - Rebecca A Haeusler
- Naomi Berrie Diabetes Center, Columbia University College of Physicians and Surgeons, New York, United States of America
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10
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Oteng AB, Higuchi S, Banks AS, Haeusler RA. Cyp2c-deficiency depletes muricholic acids and protects against high-fat diet-induced obesity in male mice but promotes liver damage. Mol Metab 2021; 53:101326. [PMID: 34438105 PMCID: PMC8449133 DOI: 10.1016/j.molmet.2021.101326] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 08/08/2021] [Accepted: 08/18/2021] [Indexed: 01/07/2023] Open
Abstract
Objective Murine-specific muricholic acids (MCAs) are reported to protect against obesity and associated metabolic disorders. However, the response of mice with genetic depletion of MCA to an obesogenic diet has not been evaluated. We used Cyp2c-deficient (Cyp2c−/−) mice, which lack MCAs and thus have a human-like bile acid (BA) profile, to directly investigate the potential role of MCAs in diet-induced obesity. Methods Male and female Cyp2c−/− mice and wild-type (WT) littermate controls were fed a standard chow diet or a high-fat diet (HFD) for 18 weeks. We measured BA composition from a pool of liver, gallbladder, and intestine, as well as weekly body weight, food intake, lean and fat mass, systemic glucose homeostasis, energy expenditure, intestinal lipid absorption, fecal lipid, and energy content. Results Cyp2c-deficiency depleted MCAs and caused other changes in BA composition, namely a decrease in the ratio of 12α-hydroxylated (12α-OH) BAs to non-12α-OH BAs, without altering the total BA levels. While WT male mice became obese after HFD feeding, Cyp2c−/− male mice were protected from obesity and associated metabolic dysfunctions. Cyp2c−/− male mice also showed reduced intestinal lipid absorption and increased lipid excretion, which was reversed by oral gavage with the 12α-OH BA and taurocholic acid (TCA). Cyp2c−/− mice also showed increased liver damage, which appeared stronger in females. Conclusions MCA does not protect against diet-induced obesity but may protect against liver injury. Reduced lipid absorption in Cyp2c-deficient male mice is potentially due to a reduced ratio of 12α-OH/non-12α-OH BAs. Presence of MCA does not necessarily protect against diet-induced obesity. Cyp2c deficiency promotes resistance to diet-induced obesity in males. Cyp2c-knockout mice have decreased the ratio of 12α-OH/non-12α-OH BAs that promotes decreased intestinal lipid absorption. Cyp2c-knockout mice have improved glucose homeostasis. Cyp2c-deficiency promotes mild and severe liver injury in male and female mice, respectively.
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Affiliation(s)
- Antwi-Boasiako Oteng
- Naomi Berrie Diabetes Center, Columbia University Medical Center, New York, NY, USA; Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA
| | - Sei Higuchi
- Naomi Berrie Diabetes Center, Columbia University Medical Center, New York, NY, USA; Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA
| | - Alexander S Banks
- Division of Endocrinology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Rebecca A Haeusler
- Naomi Berrie Diabetes Center, Columbia University Medical Center, New York, NY, USA; Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA.
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11
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Abstract
Hepatic de novo lipogenesis is a major contributor to nonalcoholic fatty liver disease (NAFLD). In this issue of the JCI, Liu and Lin et al. identified Slug as an epigenetic regulator of lipogenesis. Their findings suggest that Slug is stabilized by insulin signaling, and that it promotes lipogenesis by recruiting the histone demethylase Lsd1 to the fatty acid synthase gene promoter. On the other hand, genetic deletion or acute depletion of Slug, or Lsd1 inhibition, reduced lipogenesis and protected against obesity-associated NAFLD and insulin resistance in mice. This study advances our understanding of how lipogenesis is regulated downstream of insulin signaling in health and disease.
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12
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Higuchi S, Ahmad TR, Argueta DA, Perez PA, Zhao C, Schwartz GJ, DiPatrizio NV, Haeusler RA. Bile acid composition regulates GPR119-dependent intestinal lipid sensing and food intake regulation in mice. Gut 2020; 69:1620-1628. [PMID: 32111630 PMCID: PMC7423635 DOI: 10.1136/gutjnl-2019-319693] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 01/21/2020] [Accepted: 02/06/2020] [Indexed: 12/23/2022]
Abstract
OBJECTIVES Lipid mediators in the GI tract regulate satiation and satiety. Bile acids (BAs) regulate the absorption and metabolism of dietary lipid in the intestine, but their effects on lipid-regulated satiation and satiety are completely unknown. Investigating this is challenging because introducing excessive BAs or eliminating BAs strongly impacts GI functions. We used a mouse model (Cyp8b1-/- mice) with normal total BA levels, but alterations in the composition of the BA pool that impact multiple aspects of intestinal lipid metabolism. We tested two hypotheses: BAs affect food intake by (1) regulating production of the bioactive lipid oleoylethanolamide (OEA), which enhances satiety; or (2) regulating the quantity and localisation of hydrolysed fat in small intestine, which controls gastric emptying and satiation. DESIGN We evaluated OEA levels, gastric emptying and food intake in wild-type and Cyp8b1-/- mice. We assessed the role of the fat receptor GPR119 in these effects using Gpr119-/- mice. RESULTS Cyp8b1-/- mice on a chow diet showed mild hypophagia. Jejunal OEA production was blunted in Cyp8b1-/- mice, thus these data do not support a role for this pathway in the hypophagia of Cyp8b1-/- mice. On the other hand, Cyp8b1 deficiency decreased gastric emptying, and this was dependent on dietary fat. GPR119 deficiency normalised the gastric emptying, gut hormone levels, food intake and body weight of Cyp8b1-/- mice. CONCLUSION BAs regulate gastric emptying and satiation by determining fat-dependent GPR119 activity in distal intestine.
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Affiliation(s)
- Sei Higuchi
- Pathology and Cell Biology, Columbia University Medical Center, New York, New York, USA
| | - Tiara R Ahmad
- Pathology and Cell Biology, Columbia University Medical Center, New York, New York, USA
| | - Donovan A Argueta
- Division of Biomedical Sciences, University of California Riverside, Riverside, California, USA
| | - Pedro A Perez
- Division of Biomedical Sciences, University of California Riverside, Riverside, California, USA
| | - Chen Zhao
- Institute of Human Nutrition, Columbia University, New York, New York, USA
| | - Gary J Schwartz
- Departments of Medicine and Neuroscience, Yeshiva University Albert Einstein College of Medicine, Bronx, New York, USA
| | - Nicholas V DiPatrizio
- Division of Biomedical Sciences, University of California Riverside, Riverside, California, USA
| | - Rebecca A Haeusler
- Pathology and Cell Biology, Columbia University Medical Center, New York, New York, USA
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13
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Liu Q, Yu J, Wang L, Tang Y, Zhou Q, Ji S, Wang Y, Santos L, Haeusler RA, Que J, Rajbhandari P, Lei X, Valenti L, Pajvani UB, Qin J, Qiang L. Inhibition of PU.1 ameliorates metabolic dysfunction and non-alcoholic steatohepatitis. J Hepatol 2020; 73:361-370. [PMID: 32135178 DOI: 10.1016/j.jhep.2020.02.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 02/14/2020] [Accepted: 02/17/2020] [Indexed: 02/06/2023]
Abstract
BACKGROUND & AIMS Obesity is a well-established risk factor for type 2 diabetes (T2D) and non-alcoholic steatohepatitis (NASH), but the underlying mechanisms remain incompletely understood. Herein, we aimed to identify novel pathogenic factors (and possible therapeutic targets) underlying metabolic dysfunction in the liver. METHODS We applied a tandem quantitative proteomics strategy to enrich and identify transcription factors (TFs) induced in the obese liver. We used flow cytometry of liver cells to analyze the source of the induced TFs. We employed conditional knockout mice, shRNA, and small-molecule inhibitors to test the metabolic consequences of the induction of identified TFs. Finally, we validated mouse data in patient liver biopsies. RESULTS We identified PU.1/SPI1, the master hematopoietic regulator, as one of the most upregulated TFs in livers from diet-induced obese (DIO) and genetically obese (db/db) mice. Targeting PU.1 in the whole liver, but not hepatocytes alone, significantly improved glucose homeostasis and suppressed liver inflammation. Consistently, treatment with the PU.1 inhibitor DB1976 markedly reduced inflammation and improved glucose homeostasis and dyslipidemia in DIO mice, and strongly suppressed glucose intolerance, liver steatosis, inflammation, and fibrosis in a dietary NASH mouse model. Furthermore, hepatic PU.1 expression was positively correlated with insulin resistance and inflammation in liver biopsies from patients. CONCLUSIONS These data suggest that the elevated hematopoietic factor PU.1 promotes liver metabolic dysfunction, and may be a useful therapeutic target for obesity, insulin resistance/T2D, and NASH. LAY SUMMARY Expression of the immune regulator PU.1 is increased in livers of obese mice and people. Blocking PU.1 improved glucose homeostasis, and reduced liver steatosis, inflammation and fibrosis in mouse models of non-alcoholic steatohepatitis. Inhibition of PU.1 is thus a potential therapeutic strategy for treating obesity-associated liver dysfunction and metabolic diseases.
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Affiliation(s)
- Qiongming Liu
- Naomi Berrie Diabetes Center, Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, 10032, USA; State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, National Center for Protein Sciences (The PHOENIX Center at Beijing), Beijing 102206, China
| | - Junjie Yu
- Naomi Berrie Diabetes Center, Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York, 10032, USA
| | - Liheng Wang
- Naomi Berrie Diabetes Center, Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York, 10032, USA
| | - Yuliang Tang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Quan Zhou
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, National Center for Protein Sciences (The PHOENIX Center at Beijing), Beijing 102206, China
| | - Shuhui Ji
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, National Center for Protein Sciences (The PHOENIX Center at Beijing), Beijing 102206, China
| | - Yi Wang
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Luis Santos
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, United States
| | - Rebecca A Haeusler
- Naomi Berrie Diabetes Center, Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, 10032, USA
| | - Jianwen Que
- Columbia Center for Human Development and Department of Medicine, Columbia University, New York, NY 10032
| | - Prashant Rajbhandari
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, United States
| | - Xiaoguang Lei
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Luca Valenti
- Department of Pathophysiology and Transplantation, Università degli Studi Milano, and Internal Medicine and Metabolic Diseases, Fondazione IRCCS Ca' Granda Ospedale Policlinico, Milan, Italy
| | - Utpal B Pajvani
- Naomi Berrie Diabetes Center, Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York, 10032, USA.
| | - Jun Qin
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, National Center for Protein Sciences (The PHOENIX Center at Beijing), Beijing 102206, China; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, 77030, USA.
| | - Li Qiang
- Naomi Berrie Diabetes Center, Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, 10032, USA.
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14
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Ahmad TR, Higuchi S, Bertaggia E, Hung A, Shanmugarajah N, Guilz NC, Gamarra JR, Haeusler RA. Bile acid composition regulates the manganese transporter Slc30a10 in intestine. J Biol Chem 2020; 295:12545-12558. [PMID: 32690612 DOI: 10.1074/jbc.ra120.012792] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 07/10/2020] [Indexed: 12/11/2022] Open
Abstract
Bile acids (BAs) comprise heterogenous amphipathic cholesterol-derived molecules that carry out physicochemical and signaling functions. A major site of BA action is the terminal ileum, where enterocytes actively reuptake BAs and express high levels of BA-sensitive nuclear receptors. BA pool size and composition are affected by changes in metabolic health, and vice versa. One of several factors that differentiate BAs is the presence of a hydroxyl group on C12 of the steroid ring. 12α-Hydroxylated BAs (12HBAs) are altered in multiple disease settings, but the consequences of 12HBA abundance are incompletely understood. We employed mouse primary ileum organoids to investigate the transcriptional effects of varying 12HBA abundance in BA pools. We identified Slc30a10 as one of the top genes differentially induced by BA pools with varying 12HBA abundance. SLC30A10 is a manganese efflux transporter critical for whole-body manganese excretion. We found that BA pools, especially those low in 12HBAs, induce cellular manganese efflux and that Slc30a10 induction by BA pools is driven primarily by lithocholic acid signaling via the vitamin D receptor. Administration of lithocholic acid or a vitamin D receptor agonist resulted in increased Slc30a10 expression in mouse ileum epithelia. These data demonstrate a previously unknown role for BAs in intestinal control of manganese homeostasis.
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Affiliation(s)
- Tiara R Ahmad
- Department of Pathology and Cell Biology, Columbia University, New York, New York, USA.,Naomi Berrie Diabetes Center, Columbia University, New York, New York, USA
| | - Sei Higuchi
- Department of Pathology and Cell Biology, Columbia University, New York, New York, USA.,Naomi Berrie Diabetes Center, Columbia University, New York, New York, USA
| | - Enrico Bertaggia
- Department of Pathology and Cell Biology, Columbia University, New York, New York, USA.,Naomi Berrie Diabetes Center, Columbia University, New York, New York, USA
| | - Allison Hung
- Naomi Berrie Diabetes Center, Columbia University, New York, New York, USA
| | - Niroshan Shanmugarajah
- Department of Pathology and Cell Biology, Columbia University, New York, New York, USA.,Naomi Berrie Diabetes Center, Columbia University, New York, New York, USA
| | - Nicole C Guilz
- Naomi Berrie Diabetes Center, Columbia University, New York, New York, USA
| | - Jennifer R Gamarra
- Naomi Berrie Diabetes Center, Columbia University, New York, New York, USA
| | - Rebecca A Haeusler
- Department of Pathology and Cell Biology, Columbia University, New York, New York, USA .,Naomi Berrie Diabetes Center, Columbia University, New York, New York, USA
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15
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Abstract
Of all the novel glucoregulatory molecules discovered in the past 20 years, bile acids (BAs) are notable for the fact that they were hiding in plain sight. BAs were well known for their requirement in dietary lipid absorption and biliary cholesterol secretion, due to their micelle-forming properties. However, it was not until 1999 that BAs were discovered to be endogenous ligands for the nuclear receptor FXR. Since that time, BAs have been shown to act through multiple receptors (PXR, VDR, TGR5 and S1PR2), as well as to have receptor-independent mechanisms (membrane dynamics, allosteric modulation of N-acyl phosphatidylethanolamine phospholipase D). We now also have an appreciation of the range of physiological, pathophysiological and therapeutic conditions in which endogenous BAs are altered, raising the possibility that BAs contribute to the effects of these conditions on glycaemia. In this Review, we highlight the mechanisms by which BAs regulate glucose homeostasis and the settings in which endogenous BAs are altered, and provide suggestions for future research.
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Affiliation(s)
- Tiara R Ahmad
- Naomi Berrie Diabetes Center, Columbia University Medical Center, New York, NY, USA
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA
| | - Rebecca A Haeusler
- Naomi Berrie Diabetes Center, Columbia University Medical Center, New York, NY, USA.
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA.
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16
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Hoogerland JA, Lei Y, Wolters JC, de Boer JF, Bos T, Bleeker A, Mulder NL, van Dijk TH, Kuivenhoven JA, Rajas F, Mithieux G, Haeusler RA, Verkade HJ, Bloks VW, Kuipers F, Oosterveer MH. Glucose-6-Phosphate Regulates Hepatic Bile Acid Synthesis in Mice. Hepatology 2019; 70:2171-2184. [PMID: 31102537 PMCID: PMC6859192 DOI: 10.1002/hep.30778] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 05/15/2019] [Indexed: 12/22/2022]
Abstract
It is well established that, besides facilitating lipid absorption, bile acids act as signaling molecules that modulate glucose and lipid metabolism. Bile acid metabolism, in turn, is controlled by several nutrient-sensitive transcription factors. Altered intrahepatic glucose signaling in type 2 diabetes associates with perturbed bile acid synthesis. We aimed to characterize the regulatory role of the primary intracellular metabolite of glucose, glucose-6-phosphate (G6P), on bile acid metabolism. Hepatic gene expression patterns and bile acid composition were analyzed in mice that accumulate G6P in the liver, that is, liver-specific glucose-6-phosphatase knockout (L-G6pc-/- ) mice, and mice treated with a pharmacological inhibitor of the G6P transporter. Hepatic G6P accumulation induces sterol 12α-hydroxylase (Cyp8b1) expression, which is mediated by the major glucose-sensitive transcription factor, carbohydrate response element-binding protein (ChREBP). Activation of the G6P-ChREBP-CYP8B1 axis increases the relative abundance of cholic-acid-derived bile acids and induces physiologically relevant shifts in bile composition. The G6P-ChREBP-dependent change in bile acid hydrophobicity associates with elevated plasma campesterol/cholesterol ratio and reduced fecal neutral sterol loss, compatible with enhanced intestinal cholesterol absorption. Conclusion: We report that G6P, the primary intracellular metabolite of glucose, controls hepatic bile acid synthesis. Our work identifies hepatic G6P-ChREBP-CYP8B1 signaling as a regulatory axis in control of bile acid and cholesterol metabolism.
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Affiliation(s)
- Joanne A. Hoogerland
- Department of PediatricsUniversity Medical Center GroningenGroningenThe Netherlands
| | - Yu Lei
- Department of PediatricsUniversity Medical Center GroningenGroningenThe Netherlands
| | - Justina C. Wolters
- Department of PediatricsUniversity Medical Center GroningenGroningenThe Netherlands
| | - Jan Freark de Boer
- Department of PediatricsUniversity Medical Center GroningenGroningenThe Netherlands,Laboratory MedicineUniversity of Groningen, University Medical Center GroningenGroningenThe Netherlands
| | - Trijnie Bos
- Department of PediatricsUniversity Medical Center GroningenGroningenThe Netherlands
| | - Aycha Bleeker
- Department of PediatricsUniversity Medical Center GroningenGroningenThe Netherlands
| | - Niels L. Mulder
- Department of PediatricsUniversity Medical Center GroningenGroningenThe Netherlands
| | - Theo H. van Dijk
- Laboratory MedicineUniversity of Groningen, University Medical Center GroningenGroningenThe Netherlands
| | - Jan A. Kuivenhoven
- Department of PediatricsUniversity Medical Center GroningenGroningenThe Netherlands
| | - Fabienne Rajas
- Institut National de la Santé et de la Recherche Médicale, U1213Université Claude Bernard LyonVilleurbanneFrance
| | - Gilles Mithieux
- Institut National de la Santé et de la Recherche Médicale, U1213Université Claude Bernard LyonVilleurbanneFrance
| | - Rebecca A. Haeusler
- Department of Pathology and Cell BiologyColumbia University College of Physicians and SurgeonsNew YorkNY
| | - Henkjan J. Verkade
- Department of PediatricsUniversity Medical Center GroningenGroningenThe Netherlands
| | - Vincent W. Bloks
- Department of PediatricsUniversity Medical Center GroningenGroningenThe Netherlands
| | - Folkert Kuipers
- Department of PediatricsUniversity Medical Center GroningenGroningenThe Netherlands,Laboratory MedicineUniversity of Groningen, University Medical Center GroningenGroningenThe Netherlands
| | - Maaike H. Oosterveer
- Department of PediatricsUniversity Medical Center GroningenGroningenThe Netherlands
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17
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Kanter JE, Shao B, Kramer F, Barnhart S, Shimizu-Albergine M, Vaisar T, Graham MJ, Crooke RM, Manuel CR, Haeusler RA, Mar D, Bomsztyk K, Hokanson JE, Kinney GL, Snell-Bergeon JK, Heinecke JW, Bornfeldt KE. Increased apolipoprotein C3 drives cardiovascular risk in type 1 diabetes. J Clin Invest 2019; 129:4165-4179. [PMID: 31295146 DOI: 10.1172/jci127308] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Type 1 diabetes mellitus (T1DM) increases the risk of atherosclerotic cardiovascular disease (CVD) in humans by poorly understood mechanisms. Using mouse models of T1DM-accelerated atherosclerosis, we found that relative insulin deficiency rather than hyperglycemia elevated levels of apolipoprotein C3 (APOC3), an apolipoprotein that prevents clearance of triglyceride-rich lipoproteins (TRLs) and their remnants. We then showed that serum APOC3 levels predict incident CVD events in subjects with T1DM in the Coronary Artery Calcification in Type 1 Diabetes (CACTI) study. To explore underlying mechanisms, we investigated the impact of Apoc3 antisense oligonucleotides (ASOs) on lipoprotein metabolism and atherosclerosis in a mouse model of T1DM. Apoc3 ASO treatment abolished the increased hepatic Apoc3 expression in diabetic mice - resulting in lower levels of TRLs - without improving glycemic control. APOC3 suppression also prevented arterial accumulation of APOC3-containing lipoprotein particles, macrophage foam cell formation, and the accelerated atherosclerosis in diabetic mice. Our observations demonstrate that relative insulin deficiency increases APOC3 and that this results in elevated levels of TRLs and accelerated atherosclerosis in a mouse model of T1DM. Because serum levels of APOC3 predicted incident CVD events in the CACTI study, inhibiting APOC3 might reduce CVD risk in T1DM patients.
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Affiliation(s)
- Jenny E Kanter
- Department of Medicine, UW Medicine Diabetes Institute, University of Washington, Seattle, Washington, USA
| | - Baohai Shao
- Department of Medicine, UW Medicine Diabetes Institute, University of Washington, Seattle, Washington, USA
| | - Farah Kramer
- Department of Medicine, UW Medicine Diabetes Institute, University of Washington, Seattle, Washington, USA
| | - Shelley Barnhart
- Department of Medicine, UW Medicine Diabetes Institute, University of Washington, Seattle, Washington, USA
| | - Masami Shimizu-Albergine
- Department of Medicine, UW Medicine Diabetes Institute, University of Washington, Seattle, Washington, USA
| | - Tomas Vaisar
- Department of Medicine, UW Medicine Diabetes Institute, University of Washington, Seattle, Washington, USA
| | | | | | - Clarence R Manuel
- Department of Pathology and Cell Biology, Columbia University, New York, New York, USA
| | - Rebecca A Haeusler
- Department of Pathology and Cell Biology, Columbia University, New York, New York, USA
| | - Daniel Mar
- Department of Medicine, Division of Allergy and Infectious Disease, University of Washington, Seattle, Washington, USA
| | - Karol Bomsztyk
- Department of Medicine, Division of Allergy and Infectious Disease, University of Washington, Seattle, Washington, USA
| | - John E Hokanson
- Department of Epidemiology, Colorado School of Public Health, University of Colorado Denver, Aurora, Colorado, USA
| | - Gregory L Kinney
- Department of Epidemiology, Colorado School of Public Health, University of Colorado Denver, Aurora, Colorado, USA
| | - Janet K Snell-Bergeon
- Barbara Davis Center for Diabetes, School of Medicine, University of Colorado Denver, Aurora, Colorado, USA
| | - Jay W Heinecke
- Department of Medicine, UW Medicine Diabetes Institute, University of Washington, Seattle, Washington, USA
| | - Karin E Bornfeldt
- Department of Medicine, UW Medicine Diabetes Institute, University of Washington, Seattle, Washington, USA.,Department of Pathology, University of Washington, Seattle, Washington, USA
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18
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Langlet F, Tarbier M, Haeusler RA, Camastra S, Ferrannini E, Friedländer MR, Accili D. microRNA-205-5p is a modulator of insulin sensitivity that inhibits FOXO function. Mol Metab 2018; 17:49-60. [PMID: 30174230 PMCID: PMC6197154 DOI: 10.1016/j.molmet.2018.08.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 08/07/2018] [Indexed: 12/20/2022] Open
Abstract
Objectives Hepatic insulin resistance is a hallmark of type 2 diabetes and obesity. Insulin receptor signaling through AKT and FOXO has important metabolic effects that have traditionally been ascribed to regulation of gene expression. However, whether all the metabolic effects of FOXO arise from its regulation of protein-encoding mRNAs is unknown. Methods To address this question, we obtained expression profiles of FOXO-regulated murine hepatic microRNAs (miRNAs) during fasting and refeeding using mice lacking Foxo1, 3a, and 4 in liver (L-Foxo1,3a, 4). Results Out of 439 miRNA analyzed, 175 were differentially expressed in Foxo knockouts. Their functions were associated with insulin, Wnt, Mapk signaling, and aging. Among them, we report a striking increase of miR-205-5p expression in L-Foxo1,3a,4 knockouts, as well as in obese mice. We show that miR-205-5p gain-of-function increases AKT phosphorylation and decreases SHIP2 in primary hepatocytes, resulting in FOXO inhibition. This results in decreased hepatocyte glucose production. Consistent with these observations, miR-205-5p gain-of-function in mice lowered glucose levels and improved pyruvate tolerance. Conclusions These findings reveal a homeostatic miRNA loop regulating insulin signaling, with potential implications for in vivo glucose metabolism. A comprehensive analysis of Foxo-dependent miRNA. miRNAs recapitulate the transcriptional effects of Foxo on insulin signaling. Foxo regulates miRNA transcription during the fasting/refeeding transition. miR205 regulates insulin sensitivity through a homeostatic loop with Foxo.
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Affiliation(s)
- Fanny Langlet
- Naomi Berrie Diabetes Center and Departments of Medicine, Columbia University, New York, 10032, USA
| | - Marcel Tarbier
- Science for Life Laboratory, Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 17121, Stockholm, Sweden
| | - Rebecca A Haeusler
- Naomi Berrie Diabetes Center and Departments of Pathology and Cell Biology, Columbia University, New York, 10032, USA
| | - Stefania Camastra
- Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy
| | - Eleuterio Ferrannini
- Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy; CNR Institute of Clinical Physiology, Pisa, Italy
| | - Marc R Friedländer
- Science for Life Laboratory, Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 17121, Stockholm, Sweden
| | - Domenico Accili
- Naomi Berrie Diabetes Center and Departments of Medicine, Columbia University, New York, 10032, USA.
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19
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Abstract
PURPOSE OF REVIEW Type 2 diabetes is associated with a characteristic dyslipidemia that may exacerbate cardiovascular risk. The causes of, and the effects of new antihyperglycemia medications on, this dyslipidemia, are under investigation. In an unexpected reciprocal manner, lowering LDL-cholesterol with statins slightly increases the risk of diabetes. Here we review the latest findings. RECENT FINDINGS The inverse relationship between LDL-cholesterol and diabetes has now been confirmed by multiple lines of evidence. This includes clinical trials, genetic instruments using aggregate single nucleotide polymorphisms, as well as at least eight individual genes - HMGCR, NPC1L1, HNF4A, GCKR, APOE, PCKS9, TM6SF2, and PNPLA3 - support this inverse association. Genetic and pharmacologic evidence suggest that HDL-cholesterol may also be inversely associated with diabetes risk. Regarding the effects of diabetes on lipoproteins, new evidence suggests that insulin resistance but not diabetes per se may explain impaired secretion and clearance of VLDL-triglycerides. Weight loss, bariatric surgery, and incretin-based therapies all lower triglycerides, whereas SGLT2 inhibitors may slightly increase HDL-cholesterol and LDL-cholesterol. SUMMARY Diabetes and lipoproteins are highly interregulated. Further research is expected to uncover new mechanisms governing the metabolism of glucose, fat, and cholesterol. This topic has important implications for treating type 2 diabetes and cardiovascular disease.
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MESH Headings
- Animals
- Cholesterol, HDL/genetics
- Cholesterol, HDL/metabolism
- Cholesterol, LDL/genetics
- Cholesterol, LDL/metabolism
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/therapy
- Dyslipidemias/genetics
- Dyslipidemias/metabolism
- Dyslipidemias/therapy
- Humans
- Lipoproteins, VLDL/genetics
- Lipoproteins, VLDL/metabolism
- Polymorphism, Single Nucleotide
- Triglycerides/genetics
- Triglycerides/metabolism
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Affiliation(s)
- Sei Higuchi
- Columbia University College of Physicians & Surgeons, Naomi Berrie Diabetes Center
- Department of Pathology and Cell Biology, New York, NY
| | - M Concepción Izquierdo
- Columbia University College of Physicians & Surgeons, Naomi Berrie Diabetes Center
- Department of Pathology and Cell Biology, New York, NY
| | - Rebecca A Haeusler
- Columbia University College of Physicians & Surgeons, Naomi Berrie Diabetes Center
- Department of Pathology and Cell Biology, New York, NY
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20
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Molusky MM, Hsieh J, Lee SX, Ramakrishnan R, Tascau L, Haeusler RA, Accili D, Tall AR. Metformin and AMP Kinase Activation Increase Expression of the Sterol Transporters ABCG5/8 (ATP-Binding Cassette Transporter G5/G8) With Potential Antiatherogenic Consequences. Arterioscler Thromb Vasc Biol 2018; 38:1493-1503. [PMID: 29853564 PMCID: PMC6039406 DOI: 10.1161/atvbaha.118.311212] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 05/16/2018] [Indexed: 11/16/2022]
Abstract
OBJECTIVE The mechanisms underlying the cardiovascular benefit of the anti-diabetic drug metformin are poorly understood. Recent studies have suggested metformin may upregulate macrophage reverse cholesterol transport. The final steps of reverse cholesterol transport are mediated by the sterol transporters, ABCG5 (ATP-binding cassette transporter G5) and ABCG8 (ATP-binding cassette transporter G8), which facilitate hepato-biliary transport of cholesterol. This study was undertaken to assess the possibility that metformin induces Abcg5 and Abcg8 expression in liver and to elucidate the underlying mechanisms. APPROACH AND RESULTS Metformin-treated mouse or human primary hepatocytes showed increased expression of Abcg5/8 and the bile salt export pump, Bsep. Administration of metformin to Western-type diet-fed mice showed significant upregulation of Abcg5/8 and Bsep. This resulted in increased initial clearance of 3H-cholesteryl ester HDL (high-density lipoprotein) from plasma. However, fecal 3H-cholesterol output was only marginally increased, possibly reflecting increased hepatic Ldlr (low-density lipoprotein receptor) expression, which would increase nonradiolabeled cholesterol uptake. Abcg5/8 undergo strong circadian variation. Available chromatin immunoprecipitation-Seq data suggested multiple binding sites for Period 2, a transcriptional repressor, within the Abcg5/8 locus. Addition of AMPK (5' adenosine monophosphate-activated protein kinase) agonists decreased Period 2 occupancy, suggesting derepression of Abcg5/8. Inhibition of ATP citrate lyase, which generates acetyl-CoA from citrate, also decreased Period 2 occupancy, with concomitant upregulation of Abcg5/8. This suggests a mechanistic link between feeding-induced acetyl-CoA production and decreased cholesterol excretion via Period 2, resulting in inhibition of Abcg5/8 expression. CONCLUSIONS Our findings provide partial support for the concept that metformin may provide cardiovascular benefit via increased reverse cholesterol transport but also indicate increased Ldlr expression as a potential additional mechanism. AMPK activation or ATP citrate lyase inhibition may mediate antiatherogenic effects through increased ABCG5/8 expression.
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Affiliation(s)
- Matthew M Molusky
- From the Division of Molecular Medicine, Department of Medicine (M.M.M, J.H., L.T., A.R.T.)
| | - Joanne Hsieh
- From the Division of Molecular Medicine, Department of Medicine (M.M.M, J.H., L.T., A.R.T.)
| | - Samuel X Lee
- Naomi Berrie Diabetes Center, College of Physicians and Surgeons (S.X.L., R.A.H.)
| | | | - Liana Tascau
- From the Division of Molecular Medicine, Department of Medicine (M.M.M, J.H., L.T., A.R.T.)
| | - Rebecca A Haeusler
- Naomi Berrie Diabetes Center, College of Physicians and Surgeons (S.X.L., R.A.H.).,Department of Pathology and Cell Biology (R.A.H.)
| | - Domenico Accili
- Department of Medicine and Naomi Berrie Diabetes Center (D.A.), Columbia University, New York
| | - Alan R Tall
- From the Division of Molecular Medicine, Department of Medicine (M.M.M, J.H., L.T., A.R.T.)
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21
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Xu H, Kaul S, Proudfoot S, Schill RL, Fatema K, Thomas MJ, Kallinger R, Civelek M, Haeusler RA, Remaley AT, Neufeld EB, Malide DA, Sahoo D, Sorci-Thomas MG. Abstract 045: SR-BI and PCPE2 Modulate Lipid Trafficking in Adipocytes. Arterioscler Thromb Vasc Biol 2018. [DOI: 10.1161/atvb.38.suppl_1.045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Adipose tissue undergoes distinct structural remodeling in response to increases in fat mass, as in obesity. During this process, the extracellular matrix (ECM) plays a pivotal role with respect to both adipocyte receptor signaling and structural remodeling. One ECM protein, procollagen endopeptidase enhancer 2 (PCPE2), has been shown by our lab to work in partnership with the scavenger receptor class B type I (SR-BI) to regulate adipocyte cholesterol homeostasis. To investigate the functional impact of the partnership between SR-BI and PCPE2, we studied mature adipocytes differentiated from murine embryonic fibroblasts (MEF) and compared to our adipose specific PCPE2 knockout mice. Our studies showed the presence of an SR-BI-PCPE2 protein complex based on the co-immunoprecipitation of PCPE2 with SR-BI in both differentiated MEFs and mouse adipose tissue. Furthermore, stimulated emission depletion (STED) microscopy showed SR-BI and PCPE2 localized on the lipid droplet surface separated by distances ranging from 24 – 90 nm, suggesting that the SR-BI-PCPE2 complex may contain other proteins. Most significantly, a loss of SR-BI function was shown in PCPE2-deficient adipocytes by the SR-BI mediated HDL binding and cholesteryl ester (CE) uptake assays. Compared to differentiated MEFs from
Ldlr
-/-
mice, binding of HDL to differentiated MEFs from
Ldlr
-/-
Pcpe2
-/-
mice was reduced by 75%, and HDL cholesteryl oleyl ether uptake was reduced by 50%. Disruption of adipocyte SR-BI function in the absence of PCPE2 also reduced free cholesterol efflux indicating substantial disruption to intracellular cholesterol homeostasis. Moreover, analysis of RNAseq from several human clinical studies show that PCPE2 mRNA expression is positively correlated with fat mass in specific adipose depots, while negatively correlated with plasma insulin, glucose and triglyceride levels, with the latter two more robust in type 2 diabetic populations (FDR < 0.004). Overall, these results suggest that the partnership between SR-BI and PCPE2 in adipocytes plays an important role in cholesterol trafficking and homeostasis which influences fat mass expansion, glucose tolerance and insulin resistance.
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Affiliation(s)
- Hao Xu
- Med College Wisconsin, Milwaukee, WI
| | | | | | | | | | | | | | | | | | - Alan T Remaley
- National Heart, Lung, and Blood Institute, Translational Vascular Medicine Branch, Bethesda, MD
| | - Edward B Neufeld
- National Heart, Lung, and Blood Institute, Translational Vascular Medicine Branch, Bethesda, MD
| | - Daniela A Malide
- National Heart, Lung, and Blood Institute, Translational Vascular Medicine Branch, Bethesda, MD
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22
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Kim K, Goldberg IJ, Graham MJ, Sundaram M, Bertaggia E, Lee SX, Qiang L, Haeusler RA, Metzger D, Chambon P, Yao Z, Ginsberg HN, Pajvani UB. γ-Secretase Inhibition Lowers Plasma Triglyceride-Rich Lipoproteins by Stabilizing the LDL Receptor. Cell Metab 2018; 27:816-827.e4. [PMID: 29576536 PMCID: PMC5884729 DOI: 10.1016/j.cmet.2018.02.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 12/14/2017] [Accepted: 02/14/2018] [Indexed: 12/31/2022]
Abstract
Excess plasma triglycerides (TGs) are a key component of obesity-induced metabolic syndrome. We have shown that γ-secretase inhibitor (GSI) treatment improves glucose tolerance due to inhibition of hepatic Notch signaling but found additional Notch-independent reduction of plasma TG-rich lipoproteins (TRLs) in GSI-treated, as well as hepatocyte-specific, γ-secretase knockout (L-Ncst) mice, which suggested a primary effect on hepatocyte TRL uptake. Indeed, we found increased VLDL and LDL particle uptake in L-Ncst hepatocytes and Ncst-deficient hepatoma cells, in part through reduced γ-secretase-mediated low-density lipoprotein receptor (LDLR) cleavage and degradation. To exploit this novel finding, we generated a liver-selective Nicastrin ASO, which recapitulated glucose and lipid improvements of L-Ncst mice, with increased levels of hepatocyte LDLR. Collectively, these results identify the role of hepatic γ-secretase to regulate LDLR and suggest that liver-specific GSIs may simultaneously improve multiple aspects of the metabolic syndrome.
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Affiliation(s)
- KyeongJin Kim
- Department of Medicine, Columbia University, New York, NY, USA
| | - Ira J Goldberg
- Department of Medicine, New York University, New York, NY, USA
| | | | - Meenakshi Sundaram
- Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON, Canada
| | - Enrico Bertaggia
- Departments of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | - Samuel X Lee
- Departments of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | - Li Qiang
- Departments of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | - Rebecca A Haeusler
- Departments of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | | | | | - Zemin Yao
- Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON, Canada
| | | | - Utpal B Pajvani
- Department of Medicine, Columbia University, New York, NY, USA.
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23
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Lee SX, Heine M, Schlein C, Ramakrishnan R, Liu J, Belnavis G, Haimi I, Fischer AW, Ginsberg HN, Heeren J, Rinninger F, Haeusler RA. FoxO transcription factors are required for hepatic HDL cholesterol clearance. J Clin Invest 2018; 128:1615-1626. [PMID: 29408809 DOI: 10.1172/jci94230] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 02/01/2018] [Indexed: 12/15/2022] Open
Abstract
Insulin resistance and type 2 diabetes are associated with low levels of high-density lipoprotein cholesterol (HDL-C). The insulin-repressible FoxO transcription factors are potential mediators of the effect of insulin on HDL-C. FoxOs mediate a substantial portion of insulin-regulated transcription, and poor FoxO repression is thought to contribute to the excessive glucose production in diabetes. In this work, we show that mice with liver-specific triple FoxO knockout (L-FoxO1,3,4), which are known to have reduced hepatic glucose production, also have increased HDL-C. This was associated with decreased expression of the HDL-C clearance factors scavenger receptor class B type I (SR-BI) and hepatic lipase and defective selective uptake of HDL cholesteryl ester by the liver. The phenotype could be rescued by re-expression of SR-BI. These findings demonstrate that hepatic FoxOs are required for cholesterol homeostasis and HDL-mediated reverse cholesterol transport to the liver.
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Affiliation(s)
- Samuel X Lee
- Naomi Berrie Diabetes Center, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | - Markus Heine
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Christian Schlein
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Rajasekhar Ramakrishnan
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | - Jing Liu
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | - Gabriella Belnavis
- Naomi Berrie Diabetes Center, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | - Ido Haimi
- Naomi Berrie Diabetes Center, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | - Alexander W Fischer
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Henry N Ginsberg
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | - Joerg Heeren
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Franz Rinninger
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg Eppendorf, Hamburg, Germany.,Department of Internal Medicine III, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Rebecca A Haeusler
- Naomi Berrie Diabetes Center, Columbia University College of Physicians and Surgeons, New York, New York, USA.,Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, USA
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Abstract
The mechanism of insulin action is a central theme in biology and medicine. In addition to the rather rare condition of insulin deficiency caused by autoimmune destruction of pancreatic β-cells, genetic and acquired abnormalities of insulin action underlie the far more common conditions of type 2 diabetes, obesity and insulin resistance. The latter predisposes to diseases ranging from hypertension to Alzheimer disease and cancer. Hence, understanding the biochemical and cellular properties of insulin receptor signalling is arguably a priority in biomedical research. In the past decade, major progress has led to the delineation of mechanisms of glucose transport, lipid synthesis, storage and mobilization. In addition to direct effects of insulin on signalling kinases and metabolic enzymes, the discovery of mechanisms of insulin-regulated gene transcription has led to a reassessment of the general principles of insulin action. These advances will accelerate the discovery of new treatment modalities for diabetes.
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Affiliation(s)
- Rebecca A Haeusler
- Columbia University College of Physicians and Surgeons, Department of Pathology and Cell Biology, New York, New York 10032, USA
| | - Timothy E McGraw
- Weill Cornell Medicine, Departments of Biochemistry and Cardiothoracic Surgery, New York, New York 10065, USA
| | - Domenico Accili
- Columbia University College of Physicians & Surgeons, Department of Medicine, New York, New York 10032, USA
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25
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Bertaggia E, Jensen KK, Castro-Perez J, Xu Y, Di Paolo G, Chan RB, Wang L, Haeusler RA. Cyp8b1 ablation prevents Western diet-induced weight gain and hepatic steatosis because of impaired fat absorption. Am J Physiol Endocrinol Metab 2017; 313:E121-E133. [PMID: 28377401 PMCID: PMC5582885 DOI: 10.1152/ajpendo.00409.2016] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 03/28/2017] [Accepted: 03/29/2017] [Indexed: 01/05/2023]
Abstract
Bile acids (BAs) are cholesterol derivatives that regulate lipid metabolism, through their dual abilities to promote lipid absorption and activate BA receptors. However, different BA species have varying abilities to perform these functions. Eliminating 12α-hydroxy BAs in mice via Cyp8b1 knockout causes low body weight and improved glucose tolerance. The goal of this study was to determine mechanisms of low body weight in Cyp8b1-/- mice. We challenged Cyp8b1-/- mice with a Western-type diet and assessed body weight and composition. We measured energy expenditure, fecal calories, and lipid absorption and performed lipidomic studies on feces and intestine. We investigated the requirement for dietary fat in the phenotype using a fat-free diet. Cyp8b1-/- mice were resistant to Western diet-induced body weight gain, hepatic steatosis, and insulin resistance. These changes were associated with increased fecal calories, due to malabsorption of hydrolyzed dietary triglycerides. This was reversed by treating the mice with taurocholic acid, the major 12α-hydroxylated BA species. The improvements in body weight and steatosis were normalized by feeding mice a fat-free diet. The effects of BA composition on intestinal lipid handling are important for whole body energy homeostasis. Thus modulating BA composition is a potential tool for obesity or diabetes therapy.
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Affiliation(s)
- Enrico Bertaggia
- Department of Pathology and Cell Biology, Columbia University, New York, New York
| | - Kristian K Jensen
- Diabetes Department, Merck Research Laboratories, Kenilworth, New Jersey; and
| | - Jose Castro-Perez
- Diabetes Department, Merck Research Laboratories, Kenilworth, New Jersey; and
| | - Yimeng Xu
- Department of Pathology and Cell Biology, Columbia University, New York, New York
| | - Gilbert Di Paolo
- Department of Pathology and Cell Biology, Columbia University, New York, New York
- Denali Therapeutics, Incorporated, South San Francisco, California
| | - Robin B Chan
- Department of Pathology and Cell Biology, Columbia University, New York, New York
| | - Liangsu Wang
- Diabetes Department, Merck Research Laboratories, Kenilworth, New Jersey; and
| | - Rebecca A Haeusler
- Department of Pathology and Cell Biology, Columbia University, New York, New York;
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26
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Bertaggia E, Jensen KK, Castro-Perez J, Xu Y, Chan RB, Wang L, Haeusler RA. Abstract 186: Cyp8b1 Ablation Prevents Western Diet-Induced Weight Gain and Hepatic Steatosis due to Impaired Fat Absorption. Arterioscler Thromb Vasc Biol 2017. [DOI: 10.1161/atvb.37.suppl_1.186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Bile acids (BAs) are cholesterol derivatives that are well-known for their role in facilitating intestinal lipid absorption. Furthermore, they can regulate glucose and lipid metabolism by activating nuclear and cell surface receptors. Insulin resistance is correlated with alterations in bile acid composition, in particular higher levels of 12α-hydroxylated BAs. These BA species are generated by the enzyme Cyp8b1. We hypothesized that elevated levels of 12α-hydroxylated BAs could be a link between insulin resistance and defects of lipid metabolism. To study the role of Cyp8b1 in the regulation of lipid metabolism, we used Cyp8b1 deficient mice-which are unable to produce 12α-hydroxy BAs-and challenged them with a western type diet. We found that Cyp8b1-/- mice gained less weight compared to controls, which was entirely accounted for by fat mass. Triglyceride and cholesterol accumulation in the liver of Cyp8b1-/- mice were also strongly reduced. We found that these improvements were due to reduced lipid absorption in the intestine of Cyp8b1-/- mice, which could be rescued by replenishing the pool with taurocholic acid. The lipid malabsorption resulted in higher caloric excretion in the feces, due to excess excretion of hydrolyzed dietary lipids. When we fed the mice with a fat-free diet, these differences between genotypes were normalized, confirming the central role of BA composition-not just overall levels-in intestinal lipid absorption and whole-body lipid homeostasis. Based on these findings, it is possible that reducing 12α-hydroxy BAs could be a therapeutic option for the control of obesity and lipid homeostasis.
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Dutia R, Embrey M, O'Brien S, Haeusler RA, Agénor KK, Homel P, McGinty J, Vincent RP, Alaghband-Zadeh J, Staels B, le Roux CW, Yu J, Laferrère B. Temporal changes in bile acid levels and 12α-hydroxylation after Roux-en-Y gastric bypass surgery in type 2 diabetes. Int J Obes (Lond) 2016; 40:554. [PMID: 26952775 DOI: 10.1038/ijo.2015.250] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Since the publication of the above article it has been noted that the author S O'Brien should have been listed as CS O'Brien. The authors should therefore appear as follows: R Dutia, M Embrey, CS O'Brien, RA Haeusler, KK Agénor, P Homel, J McGinty, RP Vincent, J Alaghband-Zadeh, B Staels, CW le Roux, J Yu and B Laferrère The corrected article html and online pdf versions have been amended. The authors wish to apologise for any inconvenience caused.
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Haeusler RA, Camastra S, Nannipieri M, Astiarraga B, Castro-Perez J, Xie D, Wang L, Chakravarthy M, Ferrannini E. Increased Bile Acid Synthesis and Impaired Bile Acid Transport in Human Obesity. J Clin Endocrinol Metab 2016; 101:1935-44. [PMID: 26684275 PMCID: PMC4870845 DOI: 10.1210/jc.2015-2583] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
CONTEXT Alterations in bile acid (BA) synthesis and transport have the potential to affect multiple metabolic pathways in the pathophysiology of obesity. OBJECTIVE The objective of the study was to investigate the effects of obesity on serum fluctuations of BAs and markers of BA synthesis. DESIGN We measured BA fluctuations in 11 nonobese and 32 obese subjects and BA transporter expression in liver specimens from 42 individuals and specimens of duodenum, jejunum, ileum, colon, and pancreas from nine individuals. MAIN OUTCOME MEASURES We analyzed serum BAs and markers of BA synthesis after overnight fasting, during a hyperinsulinemic-euglycemic clamp, or a mixed-meal tolerance test and the association of BA transporter expression with body mass index. RESULTS BA synthesis markers were 2-fold higher (P < .01) and preferentially 12α-hydroxylated (P < .05) in obese subjects, and both measures were correlated with clamp-derived insulin sensitivity (r = -0.62, P < .0001, and r = -0.39, P = .01, respectively). Insulin infusion acutely reduced serum BAs in nonobese subjects, but this effect was blunted in obese subjects (δBAs -44.2% vs -4.2%, P < .05). The rise in serum BAs postprandially was also relatively blunted in obese subjects (δBAs +402% vs +133%, P < .01). Liver expression of the Na+-taurocholate cotransporting polypeptide and the bile salt export pump were negatively correlated with body mass index (r = -0.37, P = .02, and r = -0.48, P = .001, respectively). CONCLUSIONS Obesity is associated with increased BA synthesis, preferential 12α-hydroxylation, and impaired serum BA fluctuations. The findings reveal new pathophysiological aspects of BA action in obesity that may lend themselves to therapeutic targeting in metabolic disease.
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Affiliation(s)
- Rebecca A Haeusler
- Department of Pathology and Cell Biology (R.A.H.), Columbia University, New York, New York 10032; Department of Clinical and Experimental Medicine (S.C., M.N., B.A., E.F.), University of Pisa School of Medicine, 56100 Pisa, Italy; Merck Research Laboratories (J.C.-P., D.X., L.W., M.C.), Cardiometabolic Disease, Kenilworth, New Jersey 07033; and CNR Institute of Clinical Physiology (E.F.), 56100 Pisa, Italy
| | - Stefania Camastra
- Department of Pathology and Cell Biology (R.A.H.), Columbia University, New York, New York 10032; Department of Clinical and Experimental Medicine (S.C., M.N., B.A., E.F.), University of Pisa School of Medicine, 56100 Pisa, Italy; Merck Research Laboratories (J.C.-P., D.X., L.W., M.C.), Cardiometabolic Disease, Kenilworth, New Jersey 07033; and CNR Institute of Clinical Physiology (E.F.), 56100 Pisa, Italy
| | - Monica Nannipieri
- Department of Pathology and Cell Biology (R.A.H.), Columbia University, New York, New York 10032; Department of Clinical and Experimental Medicine (S.C., M.N., B.A., E.F.), University of Pisa School of Medicine, 56100 Pisa, Italy; Merck Research Laboratories (J.C.-P., D.X., L.W., M.C.), Cardiometabolic Disease, Kenilworth, New Jersey 07033; and CNR Institute of Clinical Physiology (E.F.), 56100 Pisa, Italy
| | - Brenno Astiarraga
- Department of Pathology and Cell Biology (R.A.H.), Columbia University, New York, New York 10032; Department of Clinical and Experimental Medicine (S.C., M.N., B.A., E.F.), University of Pisa School of Medicine, 56100 Pisa, Italy; Merck Research Laboratories (J.C.-P., D.X., L.W., M.C.), Cardiometabolic Disease, Kenilworth, New Jersey 07033; and CNR Institute of Clinical Physiology (E.F.), 56100 Pisa, Italy
| | - Jose Castro-Perez
- Department of Pathology and Cell Biology (R.A.H.), Columbia University, New York, New York 10032; Department of Clinical and Experimental Medicine (S.C., M.N., B.A., E.F.), University of Pisa School of Medicine, 56100 Pisa, Italy; Merck Research Laboratories (J.C.-P., D.X., L.W., M.C.), Cardiometabolic Disease, Kenilworth, New Jersey 07033; and CNR Institute of Clinical Physiology (E.F.), 56100 Pisa, Italy
| | - Dan Xie
- Department of Pathology and Cell Biology (R.A.H.), Columbia University, New York, New York 10032; Department of Clinical and Experimental Medicine (S.C., M.N., B.A., E.F.), University of Pisa School of Medicine, 56100 Pisa, Italy; Merck Research Laboratories (J.C.-P., D.X., L.W., M.C.), Cardiometabolic Disease, Kenilworth, New Jersey 07033; and CNR Institute of Clinical Physiology (E.F.), 56100 Pisa, Italy
| | - Liangsu Wang
- Department of Pathology and Cell Biology (R.A.H.), Columbia University, New York, New York 10032; Department of Clinical and Experimental Medicine (S.C., M.N., B.A., E.F.), University of Pisa School of Medicine, 56100 Pisa, Italy; Merck Research Laboratories (J.C.-P., D.X., L.W., M.C.), Cardiometabolic Disease, Kenilworth, New Jersey 07033; and CNR Institute of Clinical Physiology (E.F.), 56100 Pisa, Italy
| | - Manu Chakravarthy
- Department of Pathology and Cell Biology (R.A.H.), Columbia University, New York, New York 10032; Department of Clinical and Experimental Medicine (S.C., M.N., B.A., E.F.), University of Pisa School of Medicine, 56100 Pisa, Italy; Merck Research Laboratories (J.C.-P., D.X., L.W., M.C.), Cardiometabolic Disease, Kenilworth, New Jersey 07033; and CNR Institute of Clinical Physiology (E.F.), 56100 Pisa, Italy
| | - Ele Ferrannini
- Department of Pathology and Cell Biology (R.A.H.), Columbia University, New York, New York 10032; Department of Clinical and Experimental Medicine (S.C., M.N., B.A., E.F.), University of Pisa School of Medicine, 56100 Pisa, Italy; Merck Research Laboratories (J.C.-P., D.X., L.W., M.C.), Cardiometabolic Disease, Kenilworth, New Jersey 07033; and CNR Institute of Clinical Physiology (E.F.), 56100 Pisa, Italy
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Ferrannini E, Camastra S, Astiarraga B, Nannipieri M, Castro-Perez J, Xie D, Wang L, Chakravarthy M, Haeusler RA. Increased Bile Acid Synthesis and Deconjugation After Biliopancreatic Diversion. Diabetes 2015; 64:3377-85. [PMID: 26015549 PMCID: PMC4587641 DOI: 10.2337/db15-0214] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 05/21/2015] [Indexed: 12/19/2022]
Abstract
Biliopancreatic diversion (BPD) improves insulin sensitivity and decreases serum cholesterol out of proportion with weight loss. Mechanisms of these effects are unknown. One set of proposed contributors to metabolic improvements after bariatric surgeries is bile acids (BAs). We investigated the early and late effects of BPD on plasma BA levels, composition, and markers of BA synthesis in 15 patients with type 2 diabetes (T2D). We compared these to the early and late effects of Roux-en-Y gastric bypass (RYGB) in 22 patients with T2D and 16 with normal glucose tolerance. Seven weeks after BPD, insulin sensitivity had doubled and serum cholesterol had halved. At this time, BA synthesis markers and total plasma BAs, particularly unconjugated BAs, had markedly risen; this effect could not be entirely explained by low FGF19. In contrast, after RYGB, insulin sensitivity improved gradually with weight loss and cholesterol levels declined marginally; BA synthesis markers were decreased at an early time point (2 weeks) after surgery and returned to the normal range 1 year later. These findings indicate that BA synthesis contributes to the decreased serum cholesterol after BPD. Moreover, they suggest a potential role for altered enterohepatic circulation of BAs in improving insulin sensitivity and cholesterol metabolism after BPD.
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Affiliation(s)
- Ele Ferrannini
- Institute of Clinical Physiology, National Research Council, Pisa, Italy
| | - Stefania Camastra
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Brenno Astiarraga
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Monica Nannipieri
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Jose Castro-Perez
- Cardiometabolic Disease, Merck Research Laboratories, Kenilworth, NJ
| | - Dan Xie
- Cardiometabolic Disease, Merck Research Laboratories, Kenilworth, NJ
| | - Liangsu Wang
- Cardiometabolic Disease, Merck Research Laboratories, Kenilworth, NJ
| | - Manu Chakravarthy
- Cardiometabolic Disease, Merck Research Laboratories, Kenilworth, NJ
| | - Rebecca A Haeusler
- Department of Pathology and Cell Biology, Columbia University, New York, NY
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Dutia R, Embrey M, O'Brien CS, O'Brien S, Haeusler RA, Agénor KK, Homel P, McGinty J, Vincent RP, Alaghband-Zadeh J, Staels B, le Roux CW, Yu J, Laferrère B. Temporal changes in bile acid levels and 12α-hydroxylation after Roux-en-Y gastric bypass surgery in type 2 diabetes. Int J Obes (Lond) 2015; 39:806-13. [PMID: 25599611 DOI: 10.1038/ijo.2015.1] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2014] [Revised: 11/26/2014] [Accepted: 12/25/2014] [Indexed: 12/18/2022]
Abstract
INTRODUCTION Gastric bypass surgery (GBP) leads to sustained weight loss and significant improvement in type 2 diabetes (T2DM). Bile acids (BAs), signaling molecules which influence glucose metabolism, are a potential mediator for the improvement in T2DM after GBP. This study sought to investigate the effect of GBP on BA levels and composition in individuals with T2DM. METHODS Plasma BA levels and composition and fibroblast growth factor (FGF)-19 levels were measured during fasting and in response to an oral glucose load before and at 1 month and 2 years post GBP in 13 severely obese women with T2DM. RESULTS A striking temporal change in BA levels and composition was observed after GBP. During the fasted state, BA concentrations were generally reduced at 1 month, but increased 2 years post GBP. Postprandial BA levels were unchanged 1 month post GBP, but an exaggerated postprandial peak was observed 2 years after the surgery. A significant increase in the 12α-hydroxylated/non12α-hydroxylated BA ratio during fasting and postprandially at 2 years, but not 1 month, post GBP was observed. Significant correlations between BAs vs FGF-19, body weight, the incretin effect and peptide YY (PYY) were also found. CONCLUSIONS This study provides evidence that GBP temporally modifies the concentration and composition of circulating BAs in individuals with T2DM, and suggests that BAs may be linked to the improvement in T2DM after GBP.
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Affiliation(s)
- R Dutia
- New York Obesity Nutrition Research Center, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - M Embrey
- New York Obesity Nutrition Research Center, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | | | - S O'Brien
- New York Obesity Nutrition Research Center, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - R A Haeusler
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - K K Agénor
- New York Obesity Nutrition Research Center, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - P Homel
- Department of Medicine, Albert Einstein School of Medicine, New York, NY, USA
| | - J McGinty
- Division of Bariatric and Minimally Invasive Surgery, Department of Surgery, Mount Sinai, St. Luke's Roosevelt Hospitals, New York, NY, USA
| | - R P Vincent
- Department of Clinical Biochemistry, King's College Hospital NHS Foundation Trust Denmark Hill, London, UK
| | - J Alaghband-Zadeh
- Department of Clinical Biochemistry, Guy's & St Thomas' NHS Foundation Trust, London, UK
| | - B Staels
- European Genomic Institute for Diabetes (EGID), Université Lille 2, Inserm UMR 1011, Institut Pasteur de Lille, Lille, France
| | - C W le Roux
- Diabetes Complications Research Center, Conway Institute, University College, Dublin, Ireland
| | - J Yu
- New York Obesity Nutrition Research Center, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - B Laferrère
- New York Obesity Nutrition Research Center, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY, USA
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Haeusler RA, Camastra S, Astiarraga B, Nannipieri M, Anselmino M, Ferrannini E. Decreased expression of hepatic glucokinase in type 2 diabetes. Mol Metab 2014; 4:222-6. [PMID: 25737948 PMCID: PMC4338311 DOI: 10.1016/j.molmet.2014.12.007] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 12/10/2014] [Accepted: 12/12/2014] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND/OBJECTIVES Increased endogenous glucose production is a hallmark of type 2 diabetes. Evidence from animal models has suggested that a likely cause of this is increased mRNA expression of glucose 6-phosphatase and phosphoenolpyruvate carboxykinase (encoded by G6PC, PCK1 and PCK2). But another contributing factor may be decreased liver glucokinase (encoded by GCK). METHODS We examined expression of these enzymes in liver biopsies from 12 nondiabetic and 28 diabetic individuals. Diabetic patients were further separated into those with HbA1c lower or higher than 7.0. RESULTS In diabetic subjects with HbA1c > 7.0, we found that gluconeogenic enzymes were expressed normally, but GCK was suppressed more than 60%. Moreover, HbA1c and fasting glucose were negatively correlated with GCK, but showed no correlation with G6PC, PCK1, or PCK2. CONCLUSION These findings suggest an underlying dysregulation of hepatic GCK expression during frank diabetes, which has implications for the therapeutic use of glucokinase activators in this population.
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Affiliation(s)
- Rebecca A. Haeusler
- Columbia University, Department of Pathology and Cell Biology, New York, NY, USA
- Corresponding author.
| | - Stefania Camastra
- Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy
| | - Brenno Astiarraga
- Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy
| | - Monica Nannipieri
- Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy
| | - Marco Anselmino
- Division of Bariatric Surgery, Santa Chiara Hospital, Pisa, Italy
| | - Ele Ferrannini
- Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy
- CNR Institute of Clinical Physiology, Italy
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Haeusler RA, Hartil K, Vaitheesvaran B, Arrieta-Cruz I, Knight CM, Cook JR, Kammoun HL, Febbraio MA, Gutierrez-Juarez R, Kurland IJ, Accili D. Integrated control of hepatic lipogenesis versus glucose production requires FoxO transcription factors. Nat Commun 2014; 5:5190. [PMID: 25307742 PMCID: PMC4197140 DOI: 10.1038/ncomms6190] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 09/08/2014] [Indexed: 12/28/2022] Open
Abstract
Insulin integrates hepatic glucose and lipid metabolism, directing nutrients to storage as glycogen and triglyceride. In type 2 diabetes, levels of the former are low and the latter are exaggerated, posing a pathophysiologic and therapeutic conundrum. A branching model of insulin signaling, with FoxO1 presiding over glucose production and Srebp–1c regulating lipogenesis, provides a potential explanation. Here we illustrate an alternative mechanism that integrates glucose production and lipogenesis under the unifying control of FoxO. Liver–specific ablation of three FoxOs (L–FoxO1,3,4) prevents the induction of glucose–6–phosphatase and the repression of glucokinase during fasting, thus increasing lipogenesis at the expense of glucose production. We document a similar pattern in the early phases of diet-induced insulin resistance, and propose that FoxOs are required to enable the liver to direct nutritionally derived carbons to glucose vs. lipid metabolism. Our data underscore the heterogeneity of hepatic insulin resistance during progression from the metabolic syndrome to overt diabetes, and the conceptual challenge of designing therapies that curtail glucose production without promoting hepatic lipid accumulation.
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Affiliation(s)
- Rebecca A Haeusler
- 1] Department of Pathology and Cell Biology, Columbia University, New York, New York 10032, USA [2] Department of Medicine, Columbia University, New York, New York 10032, USA
| | - Kirsten Hartil
- Department of Medicine, Albert Einstein University, Bronx, New York 10461, USA
| | | | - Isabel Arrieta-Cruz
- Department of Medicine, Albert Einstein University, Bronx, New York 10461, USA
| | - Colette M Knight
- Department of Medicine, Albert Einstein University, Bronx, New York 10461, USA
| | - Joshua R Cook
- Department of Medicine, Columbia University, New York, New York 10032, USA
| | - Helene L Kammoun
- Cellular and Molecular Metabolism Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria 3004, Australia
| | - Mark A Febbraio
- Cellular and Molecular Metabolism Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria 3004, Australia
| | | | - Irwin J Kurland
- Department of Medicine, Albert Einstein University, Bronx, New York 10461, USA
| | - Domenico Accili
- Department of Medicine, Columbia University, New York, New York 10032, USA
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Abstract
Bile acids (BAs) exert pleiotropic metabolic effects, and physicochemical properties of different BAs affect their function. In rodents, insulin regulates BA composition, in part by regulating the BA 12α-hydroxylase CYP8B1. However, it is unclear whether a similar effect occurs in humans. To address this question, we examined the relationship between clamp-measured insulin sensitivity and plasma BA composition in a cohort of 200 healthy subjects and 35 type 2 diabetic (T2D) patients. In healthy subjects, insulin resistance (IR) was associated with increased 12α-hydroxylated BAs (cholic acid, deoxycholic acid, and their conjugated forms). Furthermore, ratios of 12α-hydroxylated/non-12α-hydroxylated BAs were associated with key features of IR, including higher insulin, proinsulin, glucose, glucagon, and triglyceride (TG) levels and lower HDL cholesterol. In T2D patients, BAs were nearly twofold elevated, and more hydrophobic, compared with healthy subjects, although we did not observe disproportionate increases in 12α-hydroxylated BAs. In multivariate analysis of the whole dataset, controlling for sex, age, BMI, and glucose tolerance status, higher 12α-hydroxy/non-12α-hydroxy BA ratios were associated with lower insulin sensitivity and higher plasma TGs. These findings suggest a role for 12α-hydroxylated BAs in metabolic abnormalities in the natural history of T2D and raise the possibility of developing insulin-sensitizing therapeutics based on manipulations of BA composition.
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Affiliation(s)
- Rebecca A. Haeusler
- Department of Medicine, Columbia University, New York, New York
- Corresponding author: Rebecca A. Haeusler,
| | - Brenno Astiarraga
- Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy
| | - Stefania Camastra
- Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy
| | - Domenico Accili
- Department of Medicine, Columbia University, New York, New York
| | - Ele Ferrannini
- Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy
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35
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Haeusler RA, Pratt-Hyatt M, Welch CL, Klaassen CD, Accili D. Impaired generation of 12-hydroxylated bile acids links hepatic insulin signaling with dyslipidemia. Cell Metab 2012; 15:65-74. [PMID: 22197325 PMCID: PMC3253887 DOI: 10.1016/j.cmet.2011.11.010] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 10/06/2011] [Accepted: 11/28/2011] [Indexed: 12/27/2022]
Abstract
The association of type 2 diabetes with elevated plasma triglyceride (TG) and very low-density lipoproteins (VLDL), and intrahepatic lipid accumulation represents a pathophysiological enigma and an unmet therapeutic challenge. Here, we uncover a link between insulin action through FoxO1, bile acid (BA) composition, and altered lipid homeostasis that brings new insight to this longstanding conundrum. FoxO1 ablation brings about two signature lipid abnormalities of diabetes and the metabolic syndrome, elevated liver and plasma TG. These changes are associated with deficiency of 12α-hydroxylated BAs and their synthetic enzyme, Cyp8b1, that hinders the TG-lowering effects of the BA receptor, Fxr. Accordingly, pharmacological activation of Fxr with GW4064 overcomes the BA imbalance, restoring hepatic and plasma TG levels of FoxO1-deficient mice to normal levels. We propose that generation of 12α-hydroxylated products of BA metabolism represents a signaling mechanism linking hepatic lipid abnormalities with type 2 diabetes, and a treatment target for this condition.
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36
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Abstract
Hepatic glucose production (HGP) plays a vital role in maintaining the supply of glucose to the body, and transcription factor FoxO1 is known to confer hormone responsiveness onto HGP. Mice with a liver-specific FoxO1 deletion (L-FoxO1) show reduced HGP and reduced expression of glucose production genes. To determine the contribution of additional transcription factors to HGP, we created double and triple liver-specific knock-outs lacking FoxO1, FoxO3, and FoxO4 or the related protein FoxA2. We show that, when compared with single knock-out of FoxO1, triple ablation of FoxO genes causes more pronounced fasting hypoglycemia, increased glucose tolerance, and enhanced insulin sensitivity, with decreased plasma insulin levels. In contrast, combined ablation of FoxO1 and FoxA2 phenocopied the single knock-out of FoxO1. These data indicate that FoxOs work in concert to regulate multiple aspects of hepatic glucose metabolism.
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Affiliation(s)
- Rebecca A. Haeusler
- From the Department of Medicine, Columbia University, New York, New York 10032 and the Department of Genetics, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Klaus H. Kaestner
- From the Department of Medicine, Columbia University, New York, New York 10032 and the Department of Genetics, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Domenico Accili
- From the Department of Medicine, Columbia University, New York, New York 10032 and the Department of Genetics, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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37
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Abstract
Patients with diabetes suffer disproportionately from impaired lipid metabolism and cardiovascular disease, but the relevant roles of insulin resistance and hyperglycemia in these processes are unclear. Transcription factor FoxO1 is regulated dually by insulin and nutrients. In this study, we addressed the hypothesis that, in addition to its established role to regulate hepatic glucose production, FoxO1 controls aspects of lipid metabolism in the diabetic liver. Mice with a liver-specific deletion of FoxO1 (L-FoxO1) and their control littermates were rendered hyperglycemic by streptozotocin administration. Subsequently, we monitored serum lipids, liver VLDL secretion, and hepatic expression of genes related to lipid metabolism. Hepatic FoxO1 ablation resulted in increased VLDL secretion, increased cholesterol, and increased plasma free fatty acids, three hallmarks of the diabetic state. l-FoxO1 mice expressed increased levels of SREBP-2 and FGF21 without affecting lipogenic genes. We propose that FoxO1 fine tunes lipolysis through its actions on FGF21 and that hepatic FoxO1 ablation increases availability of substrates for hepatic triglyceride and cholesterol synthesis and VLDL secretion. The implications of these findings are that FoxO1 protects against excessive hepatic lipid production during hyperglycemia and that its inhibition by intensive insulin treatment may exacerbate paradoxically the lipid abnormalities of diabetes.
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Affiliation(s)
| | - Seongah Han
- Department of Medicine, Columbia University, New York, New York 10032
| | - Domenico Accili
- Department of Medicine, Columbia University, New York, New York 10032.
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Haeusler RA, Pratt-Hyatt M, Good PD, Gipson TA, Engelke DR. Clustering of yeast tRNA genes is mediated by specific association of condensin with tRNA gene transcription complexes. Genes Dev 2008; 22:2204-14. [PMID: 18708579 DOI: 10.1101/gad.1675908] [Citation(s) in RCA: 187] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The 274 tRNA genes in Saccharomyces cerevisiae are scattered throughout the linear maps of the 16 chromosomes, but the genes are clustered at the nucleolus when compacted in the nucleus. This clustering is dependent on intact nucleolar organization and contributes to tRNA gene-mediated (tgm) silencing of RNA polymerase II transcription near tRNA genes. After examination of the localization mechanism, we find that the chromosome-condensing complex, condensin, is involved in the clustering of tRNA genes. Conditionally defective mutations in all five subunits of condensin, which we confirm is bound to active tRNA genes in the yeast genome, lead to loss of both pol II transcriptional silencing near tRNA genes and nucleolar clustering of the genes. Furthermore, we show that condensin physically associates with a subcomplex of RNA polymerase III transcription factors on the tRNA genes. Clustering of tRNA genes by condensin appears to be a separate mechanism from their nucleolar localization, as microtubule disruption releases tRNA gene clusters from the nucleolus, but does not disperse the clusters. These observations suggest a widespread role for condensin in gene organization and packaging of the interphase yeast nucleus.
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Affiliation(s)
- Rebecca A Haeusler
- Department of Biological Chemistry, The University of Michigan, Ann Arbor, MI 48109, USA
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Moir RD, Lee J, Haeusler RA, Desai N, Engelke DR, Willis IM. Protein kinase A regulates RNA polymerase III transcription through the nuclear localization of Maf1. Proc Natl Acad Sci U S A 2006; 103:15044-9. [PMID: 17005718 PMCID: PMC1622776 DOI: 10.1073/pnas.0607129103] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Maf1 is an essential and specific mediator of transcriptional repression in the RNA polymerase (pol) III system. Maf1-dependent repression occurs in response to a wide range of conditions, suggesting that the protein itself is targeted by the major nutritional and stress-signaling pathways. We show that Maf1 is a substrate for cAMP-dependent PKA in vitro and is differentially phosphorylated on PKA sites in vivo under normal versus repressing conditions. PKA activity negatively regulates Maf1 function because strains with unregulated high PKA activity block repression of pol III transcription in vivo, and strains lacking all PKA activity are hyperrepressible. Nuclear accumulation of Maf1 is required for transcriptional repression and is regulated by two nuclear localization sequences in the protein. An analysis of PKA phosphosite mutants shows that the localization of Maf1 is affected via the N-terminal nuclear localization sequence. In particular, mutations that prevent phosphorylation at PKA consensus sites promote nuclear accumulation of Maf1 without inducing repression. These results indicate that negative regulation of Maf1 by PKA is achieved by inhibiting its nuclear import and suggest that a PKA-independent activation step is required for nuclear Maf1 to function in the repression of pol III transcription. Finally, we report a previously undescribed phenotype for Maf1 in tRNA gene-mediated silencing of nearby RNA pol II transcription.
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Affiliation(s)
- Robyn D. Moir
- *Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461; and
| | - JaeHoon Lee
- *Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461; and
| | - Rebecca A. Haeusler
- Department of Biological Chemistry, University of Michigan Medical School, 3200 MSRB III, Ann Arbor, MI 48109-0606
| | - Neelam Desai
- *Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461; and
| | - David R. Engelke
- Department of Biological Chemistry, University of Michigan Medical School, 3200 MSRB III, Ann Arbor, MI 48109-0606
| | - Ian M. Willis
- *Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461; and
- To whom correspondence should be addressed. E-mail:
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Abstract
RNA polymerase III (pol III) transcribes many essential, small, noncoding RNAs, including the 5S rRNAs and tRNAs. While most pol III-transcribed genes are found scattered throughout the linear chromosome maps or in multiple linear clusters, there is increasing evidence that many of these genes prefer to be spatially clustered, often at or near the nucleolus. This association could create an environment that fosters the coregulation of transcription by pol III with transcription of the large ribosomal RNA repeats by RNA polymerase I (pol I) within the nucleolus. Given the high number of pol III-transcribed genes in all eukaryotic genomes, the spatial organization of these genes is likely to affect a large portion of the other genes in a genome. In this Survey and Summary we analyze the reports regarding the spatial organization of pol III genes and address the potential influence of this organization on transcriptional regulation.
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Affiliation(s)
| | - David R. Engelke
- To whom correspondence should be addressed. Tel: +1 734 763 0641; Fax:+1 734 763 7799;
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41
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Abstract
Transcription by RNA polymerase II is antagonized by the presence of a nearby tRNA gene in Saccharomyces cerevisiae. To test hypotheses concerning the mechanism of this tRNA gene-mediated (tgm) silencing, the effects of specific gene deletions were determined. The results show that the mechanism of silencing near tRNA genes is fundamentally different from other forms of transcriptional silencing in yeast. Rather, tgm silencing is dependent on the ability to cluster the dispersed tRNA genes in or near the nucleolus, constituting a form of three-dimensional gene control.
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Affiliation(s)
- Li Wang
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0606
- Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109-1055
| | - Rebecca A. Haeusler
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0606
| | - Paul D. Good
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0606
| | - Martin Thompson
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931-129
| | - Sapna Nagar
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0606
| | - David R. Engelke
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0606
- To whom correspondence should be addressed: Dept. of Biological Chemistry, University of Michigan, 1150 W. Medical Center Dr., 3200 MSRB III, Ann Arbor, MI, 48109-0606. Tel.: 734-763-0641; Fax: 734-763-7799;
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Chan EY, Goncalves NM, Haeusler RA, Hatch AJ, Larson JW, Maletta AM, Yantz GR, Carstea ED, Fuchs M, Wong GG, Gullans SR, Gilmanshin R. DNA mapping using microfluidic stretching and single-molecule detection of fluorescent site-specific tags. Genome Res 2004; 14:1137-46. [PMID: 15173119 PMCID: PMC419792 DOI: 10.1101/gr.1635204] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We have developed a rapid molecular mapping technology--Direct Linear Analysis (DLA)--on the basis of the analysis of individual DNA molecules bound with sequence-specific fluorescent tags. The apparatus includes a microfluidic device for stretching DNA molecules in elongational flow that is coupled to a multicolor detection system capable of single-fluorophore sensitivity. Double-stranded DNA molecules were tagged at sequence-specific motif sites with fluorescent bisPNA (Peptide Nucleic Acid) tags. The DNA molecules were then stretched in the microfluidic device and driven in a flow stream past confocal fluorescence detectors. DLA provided the spatial locations of multiple specific sequence motifs along individual DNA molecules, and thousands of individual molecules could be analyzed per minute. We validated this technology using the 48.5 kb lambda phage genome with different 8-base and 7-base sequence motif tags. The distance between the sequence motifs was determined with an accuracy of +/-0.8 kb, and these tags could be localized on the DNA with an accuracy of +/-2 kb. Thus, DLA is a rapid mapping technology, suitable for analysis of long DNA molecules.
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Affiliation(s)
- Eugene Y Chan
- U.S. Genomics, Inc., Woburn, Massachusetts 01801, USA.
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Haeusler RA, Engelke DR. Genome organization in three dimensions: thinking outside the line. Cell Cycle 2004; 3:273-5. [PMID: 14726665 PMCID: PMC3746017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023] Open
Abstract
Gene organization on nuclear chromosomes is usually depicted as a linear array, but at least some regions of the genome are localized to specific subnuclear positions in interphase nuclei. Studies in yeast have found that centromeres and telomeres are found around the nuclear periphery, and that tRNA genes are gathered at the nucleolus, along with the ribosomal RNA gene cluster. These 325 loci alone impose significant constraints on the three dimensional organization of chromosomes in the nucleus, and there is mounting experimental evidence that transcription by RNA polymerase II is strongly affected by proximity to these regions. Given these observations, one consideration in understanding nuclear gene regulation might be the degree to which spatial positioning affects at least a subset of gene families.
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Affiliation(s)
| | - David R. Engelke
- Correspondence to: Department of Biological Chemistry; University of Michigan; Ann Arbor, Michigan 48109-0606 USA; Tel.: 734.763.0641; Fax: 734.763.7799;
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44
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Abstract
Early transfer RNA (tRNA) processing events in Saccharomyces cerevisiae are coordinated in the nucleolus, the site normally associated with ribosome biosynthesis. To test whether spatial organization of the tRNA pathway begins with nucleolar clustering of the genes, we have probed the subnuclear location of five different tRNA gene families. The results show that tRNA genes, though dispersed in the linear genome, colocalize with 5S ribosomal DNA and U14 small nucleolar RNA at the nucleolus. Nucleolar localization requires tRNA gene transcription-complex formation, because inactivation of the promoter at a single locus removes its nucleolar association. This organization of tRNA genes must profoundly affect the spatial packaging of the genome and raises the question of whether gene types might be coordinated in three dimensions to regulate transcription.
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MESH Headings
- Cell Nucleolus/genetics
- DNA Polymerase II/metabolism
- DNA Polymerase III/metabolism
- DNA, Ribosomal/analysis
- DNA, Ribosomal/genetics
- Genes, Fungal
- Genes, rRNA
- Genome, Fungal
- Introns
- Multigene Family
- Promoter Regions, Genetic
- RNA, Fungal/genetics
- RNA, Ribosomal/biosynthesis
- RNA, Ribosomal, 5S/genetics
- RNA, Small Nucleolar/analysis
- RNA, Transfer/genetics
- RNA, Transfer, Gln/genetics
- RNA, Transfer, Glu/genetics
- RNA, Transfer, Gly/genetics
- RNA, Transfer, Leu/genetics
- RNA, Transfer, Lys/genetics
- Saccharomyces cerevisiae/genetics
- Transcription, Genetic
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Affiliation(s)
- Martin Thompson
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109–0606, USA
| | - Rebecca A. Haeusler
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109–0606, USA
| | - Paul D. Good
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109–0606, USA
| | - David R. Engelke
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109–0606, USA
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