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Guan S, Qu X, Wang J, Zhang D, Lu J. 3-Monochloropropane-1,2-diol esters induce HepG2 cells necroptosis via CTSB/TFAM/ROS pathway. Food Chem Toxicol 2024; 186:114525. [PMID: 38408632 DOI: 10.1016/j.fct.2024.114525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 02/14/2024] [Accepted: 02/18/2024] [Indexed: 02/28/2024]
Abstract
3-monochloropropane-1,2-diol esters (3-MCPDE) are toxic substances that form in food thermal processing and have a diverse range of toxicities. In this study, we found that 3-MCPDE triggered necroptosis by RIPK1/RIPK3/MLKL pathway in HepG2 cells. Previous studies have shown that ROS is an important activator of RIPK1 and RIPK3. The data showed that 3-MCPDE induced excessive ROS production through mitochondrial damage. After treatment with ROS inhibitor N-acetylcysteine (NAC), 3-MCPDE-induced necroptosis was relieved. Further, we explored how 3-MCPDE destroys mitochondria. The data suggested that 3-MCPDE induced mitochondrial dysfunction through the CTSB/TFAM pathway. Overall, the results indicated that 3-MCPDE induced necroptosis through CTSB/TFAM/ROS pathway in HepG2 cells. Our study provided a new mechanism for 3-MCPDE hepatotoxicity.
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Affiliation(s)
- Shuang Guan
- College of Food Science and Engineering, Jilin University, Changchun, Jilin, 130062, People's Republic of China; Key Laboratory of Zoonosis, Ministry of Education College of Veterinary Medicine, Jilin University, Changchun, Jilin, 130062, People's Republic of China
| | - Xiao Qu
- College of Food Science and Engineering, Jilin University, Changchun, Jilin, 130062, People's Republic of China
| | - Jianfeng Wang
- Key Laboratory of Zoonosis, Ministry of Education College of Veterinary Medicine, Jilin University, Changchun, Jilin, 130062, People's Republic of China
| | - Duoduo Zhang
- Department of Thoracic Surgery, The First Hospital of Jilin University, Changchun, Jilin, 130021, People's Republic of China.
| | - Jing Lu
- College of Food Science and Engineering, Jilin University, Changchun, Jilin, 130062, People's Republic of China; Key Laboratory of Zoonosis, Ministry of Education College of Veterinary Medicine, Jilin University, Changchun, Jilin, 130062, People's Republic of China.
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2
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Shim B, Stokum JA, Moyer M, Tsymbalyuk N, Tsymbalyuk O, Keledjian K, Ivanova S, Tosun C, Gerzanich V, Simard JM. Canagliflozin, an Inhibitor of the Na +-Coupled D-Glucose Cotransporter, SGLT2, Inhibits Astrocyte Swelling and Brain Swelling in Cerebral Ischemia. Cells 2023; 12:2221. [PMID: 37759444 PMCID: PMC10527352 DOI: 10.3390/cells12182221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 08/28/2023] [Accepted: 09/05/2023] [Indexed: 09/29/2023] Open
Abstract
Brain swelling is a major cause of death and disability in ischemic stroke. Drugs of the gliflozin class, which target the Na+-coupled D-glucose cotransporter, SGLT2, are approved for type 2 diabetes mellitus (T2DM) and may be beneficial in other conditions, but data in cerebral ischemia are limited. We studied murine models of cerebral ischemia with middle cerebral artery occlusion/reperfusion (MCAo/R). Slc5a2/SGLT2 mRNA and protein were upregulated de novo in astrocytes. Live cell imaging of brain slices from mice following MCAo/R showed that astrocytes responded to modest increases in D-glucose by increasing intracellular Na+ and cell volume (cytotoxic edema), both of which were inhibited by the SGLT2 inhibitor, canagliflozin. The effect of canagliflozin was studied in three mouse models of stroke: non-diabetic and T2DM mice with a moderate ischemic insult (MCAo/R, 1/24 h) and non-diabetic mice with a severe ischemic insult (MCAo/R, 2/24 h). Canagliflozin reduced infarct volumes in models with moderate but not severe ischemic insults. However, canagliflozin significantly reduced hemispheric swelling and improved neurological function in all models tested. The ability of canagliflozin to reduce brain swelling regardless of an effect on infarct size has important translational implications, especially in large ischemic strokes.
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Affiliation(s)
- Bosung Shim
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (B.S.); (J.A.S.); (M.M.); (N.T.); (O.T.); (K.K.); (S.I.); (C.T.); (V.G.)
| | - Jesse A. Stokum
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (B.S.); (J.A.S.); (M.M.); (N.T.); (O.T.); (K.K.); (S.I.); (C.T.); (V.G.)
| | - Mitchell Moyer
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (B.S.); (J.A.S.); (M.M.); (N.T.); (O.T.); (K.K.); (S.I.); (C.T.); (V.G.)
| | - Natalya Tsymbalyuk
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (B.S.); (J.A.S.); (M.M.); (N.T.); (O.T.); (K.K.); (S.I.); (C.T.); (V.G.)
| | - Orest Tsymbalyuk
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (B.S.); (J.A.S.); (M.M.); (N.T.); (O.T.); (K.K.); (S.I.); (C.T.); (V.G.)
| | - Kaspar Keledjian
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (B.S.); (J.A.S.); (M.M.); (N.T.); (O.T.); (K.K.); (S.I.); (C.T.); (V.G.)
| | - Svetlana Ivanova
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (B.S.); (J.A.S.); (M.M.); (N.T.); (O.T.); (K.K.); (S.I.); (C.T.); (V.G.)
| | - Cigdem Tosun
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (B.S.); (J.A.S.); (M.M.); (N.T.); (O.T.); (K.K.); (S.I.); (C.T.); (V.G.)
| | - Volodymyr Gerzanich
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (B.S.); (J.A.S.); (M.M.); (N.T.); (O.T.); (K.K.); (S.I.); (C.T.); (V.G.)
| | - J. Marc Simard
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (B.S.); (J.A.S.); (M.M.); (N.T.); (O.T.); (K.K.); (S.I.); (C.T.); (V.G.)
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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3
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Hoşnut FÖ, Janecke AR, Şahin G, Vogel GF, Lafcı NG, Bichler P, Müller T, Huber LA, Valovka T, Aksu AÜ. SLC5A1 Variants in Turkish Patients with Congenital Glucose-Galactose Malabsorption. Genes (Basel) 2023; 14:1359. [PMID: 37510265 PMCID: PMC10379334 DOI: 10.3390/genes14071359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 06/02/2023] [Accepted: 06/20/2023] [Indexed: 07/30/2023] Open
Abstract
Congenital glucose-galactose malabsorption is a rare autosomal recessive disorder caused by mutations in SLC5A1 encoding the apical sodium/glucose cotransporter SGLT1. We present clinical and molecular data from eleven affected individuals with congenital glucose-galactose malabsorption from four unrelated, consanguineous Turkish families. Early recognition and timely management by eliminating glucose and galactose from the diet are fundamental for affected individuals to survive and develop normally. We identified novel SLC5A1 missense variants, p.Gly43Arg and p.Ala92Val, which were linked to disease in two families. Stable expression in CaCo-2 cells showed that the p.Ala92Val variant did not reach the plasma membrane, but was retained in the endoplasmic reticulum. The p.Gly43Arg variant, however, displayed processing and plasma membrane localization comparable to wild-type SGLT1. Glycine-43 displays nearly invariant conservation in the relevant structural family of cotransporters and exchangers, and localizes to SGLT1 transmembrane domain TM0. p.Gly43Arg represents the first disease-associated variant in TM0; however, the role of TM0 in the SGLT1 function has not been established. In summary, we are expanding the mutational spectrum of this rare disorder.
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Affiliation(s)
- Ferda Ö. Hoşnut
- Department of Pediatric Gastroenterology, Hepatology and Nutrition, Dr. Sami Ulus Maternity and Child Health and Diseases Training and Research Hospital, University of Health Sciences, 06080 Ankara, Turkey
| | - Andreas R. Janecke
- Department of Pediatrics I, Medical University of Innsbruck, 6020 Innsbruck, Austria (T.V.)
- Institute of Human Genetics, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Gülseren Şahin
- Department of Pediatric Gastroenterology, Hepatology and Nutrition, Dr. Sami Ulus Maternity and Child Health and Diseases Training and Research Hospital, University of Health Sciences, 06080 Ankara, Turkey
| | - Georg F. Vogel
- Department of Pediatrics I, Medical University of Innsbruck, 6020 Innsbruck, Austria (T.V.)
- Institute of Cell Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Naz G. Lafcı
- Department of Medical Genetics, Faculty of Medicine, Hacettepe University, 06230 Ankara, Turkey
- Department of Medical Genetics, Dr. Sami Ulus Maternity and Child Health and Diseases Training and Research Hospital, University of Health Sciences, 06080 Ankara, Turkey
| | - Paul Bichler
- Department of Pediatrics I, Medical University of Innsbruck, 6020 Innsbruck, Austria (T.V.)
- Institute of Cell Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Thomas Müller
- Department of Pediatrics I, Medical University of Innsbruck, 6020 Innsbruck, Austria (T.V.)
| | - Lukas A. Huber
- Institute of Cell Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Taras Valovka
- Department of Pediatrics I, Medical University of Innsbruck, 6020 Innsbruck, Austria (T.V.)
- Institute of Cell Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Aysel Ü. Aksu
- Department of Pediatric Gastroenterology, Hepatology and Nutrition, Ankara Bilkent Hospital, University of Health Sciences, 06800 Ankara, Turkey;
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4
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Maeda K, Zachos NC, Orzalli MH, Schmieder SS, Chang D, Bugda Gwilt K, Doucet M, Baetz NW, Lee S, Crawford SE, Estes MK, Kagan JC, Turner JR, Lencer WI. Depletion of the apical endosome in response to viruses and bacterial toxins provides cell-autonomous host defense at mucosal surfaces. Cell Host Microbe 2022; 30:216-231.e5. [PMID: 35143768 PMCID: PMC8852832 DOI: 10.1016/j.chom.2021.12.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 10/28/2021] [Accepted: 12/17/2021] [Indexed: 11/22/2022]
Abstract
Polarized epithelial cells form an essential barrier against infection at mucosal surfaces. Many pathogens breach this barrier to cause disease, often by co-opting cellular endocytosis mechanisms to enter the cell through the lumenal (apical) cell surface. We recently discovered that the loss of the cell polarity gene PARD6B selectively diminishes apical endosome function. Here, we find that in response to the entry of certain viruses and bacterial toxins into the epithelial cells via the apical membrane, PARD6B and aPKC, two components of the PARD6B-aPKC-Cdc42 apical polarity complex, undergo rapid proteasome-dependent degradation. The perturbation of apical membrane glycosphingolipids by toxin- or virus-binding initiates degradation of PARD6B. The loss of PARD6B causes the depletion of apical endosome function and renders the cell resistant to further infection from the lumenal cell surface, thus enabling a form of cell-autonomous host defense.
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Affiliation(s)
- Keiko Maeda
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Nicholas C Zachos
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Megan H Orzalli
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Stefanie S Schmieder
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Denis Chang
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Katlynn Bugda Gwilt
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Michele Doucet
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Nicholas W Baetz
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Sun Lee
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Sue E Crawford
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, One Baylor Plaza, MS: BCM-385, Houston, TX 77030, USA
| | - Mary K Estes
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, One Baylor Plaza, MS: BCM-385, Houston, TX 77030, USA; Department of Medicine, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Jonathan C Kagan
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA; Harvard Digestive Diseases Center, Harvard Medical School, Boston, MA 02115, USA
| | - Jerrold R Turner
- Harvard Digestive Diseases Center, Harvard Medical School, Boston, MA 02115, USA; Department of Pathology, University of Chicago, Chicago, IL 60637, USA
| | - Wayne I Lencer
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA; Harvard Digestive Diseases Center, Harvard Medical School, Boston, MA 02115, USA.
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5
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Han L, Qu Q, Aydin D, Panova O, Robertson MJ, Xu Y, Dror RO, Skiniotis G, Feng L. Structure and mechanism of the SGLT family of glucose transporters. Nature 2021; 601:274-279. [PMID: 34880492 DOI: 10.1038/s41586-021-04211-w] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 11/04/2021] [Indexed: 12/24/2022]
Abstract
Glucose is a primary energy source in living cells. The discovery in 1960s that a sodium gradient powers the active uptake of glucose in the intestine1 heralded the concept of a secondary active transporter that can catalyse the movement of a substrate against an electrochemical gradient by harnessing energy from another coupled substrate. Subsequently, coupled Na+/glucose transport was found to be mediated by sodium-glucose cotransporters2,3 (SGLTs). SGLTs are responsible for active glucose and galactose absorption in the intestine and for glucose reabsorption in the kidney4, and are targeted by multiple drugs to treat diabetes5. Several members within the SGLT family transport key metabolites other than glucose2. Here we report cryo-electron microscopy structures of the prototypic human SGLT1 and a related monocarboxylate transporter SMCT1 from the same family. The structures, together with molecular dynamics simulations and functional studies, define the architecture of SGLTs, uncover the mechanism of substrate binding and selectivity, and shed light on water permeability of SGLT1. These results provide insights into the multifaceted functions of SGLTs.
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Affiliation(s)
- Lei Han
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Qianhui Qu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.,Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA.,Shanghai Stomatological Hospital, Institutes of Biomedical Science, Department of Systems Biology for Medicine, Fudan University, Shanghai, China
| | - Deniz Aydin
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.,Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA.,Department of Computer Science, Stanford University, Stanford, CA, USA.,Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
| | - Ouliana Panova
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.,Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Michael J Robertson
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.,Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Yan Xu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Ron O Dror
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.,Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA.,Department of Computer Science, Stanford University, Stanford, CA, USA.,Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
| | - Georgios Skiniotis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA.
| | - Liang Feng
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA.
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Drosophila Solute Carrier 5A5 Regulates Systemic Glucose Homeostasis by Mediating Glucose Absorption in the Midgut. Int J Mol Sci 2021; 22:ijms222212424. [PMID: 34830305 PMCID: PMC8617630 DOI: 10.3390/ijms222212424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 11/12/2021] [Accepted: 11/15/2021] [Indexed: 11/25/2022] Open
Abstract
The small intestine is the initial site of glucose absorption and thus represents the first of a continuum of events that modulate normal systemic glucose homeostasis. A better understanding of the regulation of intestinal glucose transporters is therefore pertinent to our efforts in curbing metabolic disorders. Using molecular genetic approaches, we investigated the role of Drosophila Solute Carrier 5A5 (dSLC5A5) in regulating glucose homeostasis by mediating glucose uptake in the fly midgut. By genetically knocking down dSLC5A5 in flies, we found that systemic and circulating glucose and trehalose levels are significantly decreased, which correlates with an attenuation in glucose uptake in the enterocytes. Reciprocally, overexpression of dSLC5A5 significantly increases systemic and circulating glucose and trehalose levels and promotes glucose uptake in the enterocytes. We showed that dSLC5A5 undergoes apical endocytosis in a dynamin-dependent manner, which is essential for glucose uptake in the enterocytes. Furthermore, we showed that the dSLC5A5 level in the midgut is upregulated by glucose and that dSLC5A5 critically directs systemic glucose homeostasis on a high-sugar diet. Together, our studies have uncovered the first Drosophila glucose transporter in the midgut and revealed new mechanisms that regulate glucose transporter levels and activity in the enterocyte apical membrane.
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7
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Role of Caveolin-1 in Diabetes and Its Complications. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:9761539. [PMID: 32082483 PMCID: PMC7007939 DOI: 10.1155/2020/9761539] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 12/10/2019] [Accepted: 12/26/2019] [Indexed: 12/25/2022]
Abstract
It is estimated that in 2017 there were 451 million people with diabetes worldwide. These figures are expected to increase to 693 million by 2045; thus, innovative preventative programs and treatments are a necessity to fight this escalating pandemic disorder. Caveolin-1 (CAV1), an integral membrane protein, is the principal component of caveolae in membranes and is involved in multiple cellular functions such as endocytosis, cholesterol homeostasis, signal transduction, and mechanoprotection. Previous studies demonstrated that CAV1 is critical for insulin receptor-mediated signaling, insulin secretion, and potentially the development of insulin resistance. Here, we summarize the recent progress on the role of CAV1 in diabetes and diabetic complications.
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A high-throughput screen identifies that CDK7 activates glucose consumption in lung cancer cells. Nat Commun 2019; 10:5444. [PMID: 31784510 PMCID: PMC6884612 DOI: 10.1038/s41467-019-13334-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 11/04/2019] [Indexed: 02/06/2023] Open
Abstract
Elevated glucose consumption is fundamental to cancer, but selectively targeting this pathway is challenging. We develop a high-throughput assay for measuring glucose consumption and use it to screen non-small-cell lung cancer cell lines against bioactive small molecules. We identify Milciclib that blocks glucose consumption in H460 and H1975, but not in HCC827 or A549 cells, by decreasing SLC2A1 (GLUT1) mRNA and protein levels and by inhibiting glucose transport. Milciclib blocks glucose consumption by targeting cyclin-dependent kinase 7 (CDK7) similar to other CDK7 inhibitors including THZ1 and LDC4297. Enhanced PIK3CA signaling leads to CDK7 phosphorylation, which promotes RNA Polymerase II phosphorylation and transcription. Milciclib, THZ1, and LDC4297 lead to a reduction in RNA Polymerase II phosphorylation on the SLC2A1 promoter. These data indicate that our high-throughput assay can identify compounds that regulate glucose consumption and that CDK7 is a key regulator of glucose consumption in cells with an activated PI3K pathway. Many cancer cells have increased glucose consumption compared to normal cells, a feature that can be exploited therapeutically. Here, the authors carry out a chemical screen and identify compounds that selectively blocks glucose metabolism in non-small-cell lung cancer cell lines.
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9
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Ghezzi C, Calmettes G, Morand P, Ribalet B, John S. Real-time imaging of sodium glucose transporter (SGLT1) trafficking and activity in single cells. Physiol Rep 2018; 5:5/3/e13062. [PMID: 28193781 PMCID: PMC5309568 DOI: 10.14814/phy2.13062] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 11/07/2016] [Indexed: 01/12/2023] Open
Abstract
The processes controlling targeting of glucose transporters to apical and basolateral membranes of polarized cells are complex and not-well understood. We have engineered SGLT1 and GLUT4 constructs linked to fluorescent proteins to highlight the differences in transporter expression and trafficking, in real time, in different cell types. Activity was assessed in parallel using a FRET glucose sensor. In COS cells and HEK cells, SGLT1 was distributed between the plasma membrane and intracellular compartments, but there was little expression in CHO cells. Trafficking was investigated using the lysosome inhibitors NH4Cl (10 mmol/L) and chloroquine (150 μmol/L) and the proteasome inhibitors MG-262 (1 μmol/L) and lactacystin (5 μmol/L). Lysosome inhibitors caused SGLT1 accumulation into intracellular bodies, whereas proteasome inhibitors induced SGLT1 accumulation in the plasma membrane, even in CHO cells. Our data suggest that a fraction of SGLT1 is rapidly degraded by lysosomes and never reached the plasma membrane; another fraction reaches the membrane and is subsequently degraded by lysosomes following internalization. The latter process is regulated by the ubiquitin/proteasome pathway, acting at a late stage of the lysosomal pathway. Using the cholesterol inhibitor MβCD (3 mmol/L), a dominant negative dynamin (K44A) and caveolin, we showed that SGLT1 internalization is lipid raft-mediated, but caveolin-independent. In contrast, GLUT4 internalization is dynamin-dependent, but cholesterol-independent. The physiological relevance of these data is discussed in terms of differential membrane compartmentalization of the transporters and expression under stress conditions.
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Affiliation(s)
- Chiara Ghezzi
- Departments of Physiology and Medicine and the Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Guillaume Calmettes
- Departments of Physiology and Medicine and the Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Pauline Morand
- Departments of Physiology and Medicine and the Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Bernard Ribalet
- Departments of Physiology and Medicine and the Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Scott John
- Departments of Physiology and Medicine and the Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, California
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10
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Brownlee IA, Gill S, Wilcox MD, Pearson JP, Chater PI. Starch digestion in the upper gastrointestinal tract of humans. STARCH-STARKE 2018. [DOI: 10.1002/star.201700111] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Iain A. Brownlee
- Human Nutrition Research CentreNewcastle Research and Innovation InstituteNewcastle UniversitySingaporeSingapore
| | - Saloni Gill
- Human Nutrition Research CentreNewcastle Research and Innovation InstituteNewcastle UniversitySingaporeSingapore
| | - Matt D. Wilcox
- Institute for Cell and Molecular BiosciencesThe Medical SchoolNewcastle UniversityNewcastle Upon TyneUnited Kingdom
| | - Jeff P. Pearson
- Institute for Cell and Molecular BiosciencesThe Medical SchoolNewcastle UniversityNewcastle Upon TyneUnited Kingdom
| | - Peter I. Chater
- Institute for Cell and Molecular BiosciencesThe Medical SchoolNewcastle UniversityNewcastle Upon TyneUnited Kingdom
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