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Liu X, Cai YD, Chiu JC. Regulation of protein O-GlcNAcylation by circadian, metabolic, and cellular signals. J Biol Chem 2024; 300:105616. [PMID: 38159854 PMCID: PMC10810748 DOI: 10.1016/j.jbc.2023.105616] [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: 07/24/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 01/03/2024] Open
Abstract
O-linked β-N-acetylglucosamine (O-GlcNAcylation) is a dynamic post-translational modification that regulates thousands of proteins and almost all cellular processes. Aberrant O-GlcNAcylation has been associated with numerous diseases, including cancer, neurodegenerative diseases, cardiovascular diseases, and type 2 diabetes. O-GlcNAcylation is highly nutrient-sensitive since it is dependent on UDP-GlcNAc, the end product of the hexosamine biosynthetic pathway (HBP). We previously observed daily rhythmicity of protein O-GlcNAcylation in a Drosophila model that is sensitive to the timing of food consumption. We showed that the circadian clock is pivotal in regulating daily O-GlcNAcylation rhythms given its control of the feeding-fasting cycle and hence nutrient availability. Interestingly, we reported that the circadian clock also modulates daily O-GlcNAcylation rhythm by regulating molecular mechanisms beyond the regulation of food consumption time. A large body of work now indicates that O-GlcNAcylation is likely a generalized cellular status effector as it responds to various cellular signals and conditions, such as ER stress, apoptosis, and infection. In this review, we summarize the metabolic regulation of protein O-GlcNAcylation through nutrient availability, HBP enzymes, and O-GlcNAc processing enzymes. We discuss the emerging roles of circadian clocks in regulating daily O-GlcNAcylation rhythm. Finally, we provide an overview of other cellular signals or conditions that impact O-GlcNAcylation. Many of these cellular pathways are themselves regulated by the clock and/or metabolism. Our review highlights the importance of maintaining optimal O-GlcNAc rhythm by restricting eating activity to the active period under physiological conditions and provides insights into potential therapeutic targets of O-GlcNAc homeostasis under pathological conditions.
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Affiliation(s)
- Xianhui Liu
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California, Davis, California, USA
| | - Yao D Cai
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California, Davis, California, USA
| | - Joanna C Chiu
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California, Davis, California, USA.
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2
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Paneque A, Fortus H, Zheng J, Werlen G, Jacinto E. The Hexosamine Biosynthesis Pathway: Regulation and Function. Genes (Basel) 2023; 14:genes14040933. [PMID: 37107691 PMCID: PMC10138107 DOI: 10.3390/genes14040933] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 04/13/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
The hexosamine biosynthesis pathway (HBP) produces uridine diphosphate-N-acetyl glucosamine, UDP-GlcNAc, which is a key metabolite that is used for N- or O-linked glycosylation, a co- or post-translational modification, respectively, that modulates protein activity and expression. The production of hexosamines can occur via de novo or salvage mechanisms that are catalyzed by metabolic enzymes. Nutrients including glutamine, glucose, acetyl-CoA, and UTP are utilized by the HBP. Together with availability of these nutrients, signaling molecules that respond to environmental signals, such as mTOR, AMPK, and stress-regulated transcription factors, modulate the HBP. This review discusses the regulation of GFAT, the key enzyme of the de novo HBP, as well as other metabolic enzymes that catalyze the reactions to produce UDP-GlcNAc. We also examine the contribution of the salvage mechanisms in the HBP and how dietary supplementation of the salvage metabolites glucosamine and N-acetylglucosamine could reprogram metabolism and have therapeutic potential. We elaborate on how UDP-GlcNAc is utilized for N-glycosylation of membrane and secretory proteins and how the HBP is reprogrammed during nutrient fluctuations to maintain proteostasis. We also consider how O-GlcNAcylation is coupled to nutrient availability and how this modification modulates cell signaling. We summarize how deregulation of protein N-glycosylation and O-GlcNAcylation can lead to diseases including cancer, diabetes, immunodeficiencies, and congenital disorders of glycosylation. We review the current pharmacological strategies to inhibit GFAT and other enzymes involved in the HBP or glycosylation and how engineered prodrugs could have better therapeutic efficacy for the treatment of diseases related to HBP deregulation.
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Affiliation(s)
- Alysta Paneque
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Harvey Fortus
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Julia Zheng
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Guy Werlen
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Estela Jacinto
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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3
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Liu X, Chiu JC. Nutrient-sensitive protein O-GlcNAcylation shapes daily biological rhythms. Open Biol 2022; 12:220215. [PMID: 36099933 PMCID: PMC9470261 DOI: 10.1098/rsob.220215] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 08/17/2022] [Indexed: 11/12/2022] Open
Abstract
O-linked-N-acetylglucosaminylation (O-GlcNAcylation) is a nutrient-sensitive protein modification that alters the structure and function of a wide range of proteins involved in diverse cellular processes. Similar to phosphorylation, another protein modification that targets serine and threonine residues, O-GlcNAcylation occupancy on cellular proteins exhibits daily rhythmicity and has been shown to play critical roles in regulating daily rhythms in biology by modifying circadian clock proteins and downstream effectors. We recently reported that daily rhythm in global O-GlcNAcylation observed in Drosophila tissues is regulated via the integration of circadian and metabolic signals. Significantly, mistimed feeding, which disrupts coordination of these signals, is sufficient to dampen daily O-GlcNAcylation rhythm and is predicted to negatively impact animal biological rhythms and health span. In this review, we provide an overview of published and potential mechanisms by which metabolic and circadian signals regulate hexosamine biosynthetic pathway metabolites and enzymes, as well as O-GlcNAc processing enzymes to shape daily O-GlcNAcylation rhythms. We also discuss the significance of functional interactions between O-GlcNAcylation and other post-translational modifications in regulating biological rhythms. Finally, we highlight organ/tissue-specific cellular processes and molecular pathways that could be modulated by rhythmic O-GlcNAcylation to regulate time-of-day-specific biology.
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Affiliation(s)
- Xianhui Liu
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, Davis, CA, USA
- Department of Pharmacology, School of Medicine, University of California Davis, Davis, CA, USA
| | - Joanna C. Chiu
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, Davis, CA, USA
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Linhorst A, Lübke T. The Human Ntn-Hydrolase Superfamily: Structure, Functions and Perspectives. Cells 2022; 11:cells11101592. [PMID: 35626629 PMCID: PMC9140057 DOI: 10.3390/cells11101592] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/05/2022] [Accepted: 05/06/2022] [Indexed: 01/27/2023] Open
Abstract
N-terminal nucleophile (Ntn)-hydrolases catalyze the cleavage of amide bonds in a variety of macromolecules, including the peptide bond in proteins, the amide bond in N-linked protein glycosylation, and the amide bond linking a fatty acid to sphingosine in complex sphingolipids. Ntn-hydrolases are all sharing two common hallmarks: Firstly, the enzymes are synthesized as inactive precursors that undergo auto-proteolytic self-activation, which, as a consequence, reveals the active site nucleophile at the newly formed N-terminus. Secondly, all Ntn-hydrolases share a structural consistent αββα-fold, notwithstanding the total lack of amino acid sequence homology. In humans, five subclasses of the Ntn-superfamily have been identified so far, comprising relevant members such as the catalytic active subunits of the proteasome or a number of lysosomal hydrolases, which are often associated with lysosomal storage diseases. This review gives an updated overview on the structural, functional, and (patho-)physiological characteristics of human Ntn-hydrolases, in particular.
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Wang L, Yang Y, Ma H, Xie Y, Xu J, Near D, Wang H, Garbutt T, Li Y, Liu J, Qian L. Single-cell dual-omics reveals the transcriptomic and epigenomic diversity of cardiac non-myocytes. Cardiovasc Res 2022; 118:1548-1563. [PMID: 33839759 PMCID: PMC9074971 DOI: 10.1093/cvr/cvab134] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 04/08/2021] [Indexed: 12/24/2022] Open
Abstract
AIMS The precise cellular identity and molecular features of non-myocytes (non-CMs) in a mammalian heart at a single-cell level remain elusive. Depiction of epigenetic landscape with transcriptomic signatures using the latest single-cell multi-omics has the potential to unravel the molecular programs underlying the cellular diversity of cardiac non-myocytes. Here, we characterized the molecular and cellular features of cardiac non-CM populations in the adult murine heart at the single-cell level. METHODS AND RESULTS Through single-cell dual omics analysis, we mapped the epigenetic landscapes, characterized the transcriptomic profiles and delineated the molecular signatures of cardiac non-CMs in the adult murine heart. Distinct cis-regulatory elements and trans-acting factors for the individual major non-CM cell types (endothelial cells, fibroblast, pericytes, and immune cells) were identified. In particular, unbiased sub-clustering and functional annotation of cardiac fibroblasts (FBs) revealed extensive FB heterogeneity and identified FB sub-types with functional states related to the cellular response to stimuli, cytoskeleton organization, and immune regulation, respectively. We further explored the function of marker genes Hsd11b1 and Gfpt2 that label major FB subpopulations and determined the distribution of Hsd11b1+ and Gfp2+ FBs in murine healthy and diseased hearts. CONCLUSIONS In summary, we characterized the non-CM cellular identity at the transcriptome and epigenome levels using single-cell omics approaches and discovered previously unrecognized cardiac fibroblast subpopulations with unique functional states.
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Affiliation(s)
- Li Wang
- Department of Pathology and Laboratory Medicine, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
| | - Yuchen Yang
- Department of Pathology and Laboratory Medicine, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Hong Ma
- Department of Pathology and Laboratory Medicine, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
| | - Yifang Xie
- Department of Pathology and Laboratory Medicine, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jun Xu
- Department of Pathology and Laboratory Medicine, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
| | - David Near
- Department of Pathology and Laboratory Medicine, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
| | - Haofei Wang
- Department of Pathology and Laboratory Medicine, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
| | - Tiffany Garbutt
- Department of Pathology and Laboratory Medicine, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
| | - Yun Li
- Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Biostatistics, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Computer Science, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jiandong Liu
- Department of Pathology and Laboratory Medicine, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
| | - Li Qian
- Department of Pathology and Laboratory Medicine, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, 111 Mason Farm Rd, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
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Nabeebaccus AA, Verma S, Zoccarato A, Emanuelli G, Santos CX, Streckfuss-Bömeke K, Shah AM. Cardiomyocyte protein O-GlcNAcylation is regulated by GFAT1 not GFAT2. Biochem Biophys Res Commun 2021; 583:121-127. [PMID: 34735873 PMCID: PMC8606754 DOI: 10.1016/j.bbrc.2021.10.056] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 10/22/2021] [Indexed: 12/29/2022]
Abstract
In response to cardiac injury, increased activity of the hexosamine biosynthesis pathway (HBP) is linked with cytoprotective as well as adverse effects depending on the type and duration of injury. Glutamine-fructose amidotransferase (GFAT; gene name gfpt) is the rate-limiting enzyme that controls flux through HBP. Two protein isoforms exist in the heart called GFAT1 and GFAT2. There are conflicting data on the relative importance of GFAT1 and GFAT2 during stress-induced HBP responses in the heart. Using neonatal rat cardiac cell preparations, targeted knockdown of GFPT1 and GFPT2 were performed and HBP activity measured. Immunostaining with specific GFAT1 and GFAT2 antibodies was undertaken in neonatal rat cardiac preparations and murine cardiac tissues to characterise cell-specific expression. Publicly available human heart single cell sequencing data was interrogated to determine cell-type expression. Western blots for GFAT isoform protein expression were performed in human cardiomyocytes derived from induced pluripotent stem cells (iPSCs). GFPT1 but not GFPT2 knockdown resulted in a loss of stress-induced protein O-GlcNAcylation in neonatal cardiac cell preparations indicating reduced HBP activity. In rodent cells and tissue, immunostaining for GFAT1 identified expression in both cardiac myocytes and fibroblasts whereas immunostaining for GFAT2 was only identified in fibroblasts. Further corroboration of findings in human heart cells identified an enrichment of GFPT2 gene expression in cardiac fibroblasts but not ventricular myocytes whereas GFPT1 was expressed in both myocytes and fibroblasts. In human iPSC-derived cardiomyocytes, only GFAT1 protein was expressed with an absence of GFAT2. In conclusion, these results indicate that GFAT1 is the primary cardiomyocyte isoform and GFAT2 is only present in cardiac fibroblasts. Cell-specific isoform expression may have differing effects on cell function and should be considered when studying HBP and GFAT functions in the heart.
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Affiliation(s)
- Adam A Nabeebaccus
- BHF Centre of Excellence King's College London, The James Black Centre, 125 Coldharbour Lane, London, SE5 9NU, UK.
| | - Sharwari Verma
- BHF Centre of Excellence King's College London, The James Black Centre, 125 Coldharbour Lane, London, SE5 9NU, UK
| | - Anna Zoccarato
- BHF Centre of Excellence King's College London, The James Black Centre, 125 Coldharbour Lane, London, SE5 9NU, UK
| | - Giulia Emanuelli
- BHF Centre of Excellence King's College London, The James Black Centre, 125 Coldharbour Lane, London, SE5 9NU, UK
| | - Celio Xc Santos
- BHF Centre of Excellence King's College London, The James Black Centre, 125 Coldharbour Lane, London, SE5 9NU, UK
| | - Katrin Streckfuss-Bömeke
- German Centre for Cardiovascular Research, 10785 Berlin, partnersite Göttingen, Germany; Institute of Pharmacology and Toxicology, University of Würzburg, 97078 Würzburg, Germany
| | - Ajay M Shah
- BHF Centre of Excellence King's College London, The James Black Centre, 125 Coldharbour Lane, London, SE5 9NU, UK
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Consumption of a high fat diet promotes protein O-GlcNAcylation in mouse retina via NR4A1-dependent GFAT2 expression. Biochim Biophys Acta Mol Basis Dis 2018; 1864:3568-3576. [PMID: 30254013 DOI: 10.1016/j.bbadis.2018.09.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 08/29/2018] [Accepted: 09/08/2018] [Indexed: 01/30/2023]
Abstract
The incidence of type 2 diabetes, the most common cause of diabetic retinopathy (DR), is rapidly on the rise in developed countries due to overconsumption of calorie rich diets. Using an animal model of diet-induced obesity/pre-diabetes, we evaluated the impact of a diet high in saturated fat (HFD) on O-GlcNAcylation of retinal proteins, as dysregulated O-GlcNAcylation contributes to diabetic complications and evidence supports a role in DR. Protein O-GlcNAcylation was increased in the retina of mice fed a HFD as compared to littermates receiving control chow. Similarly, O-GlcNAcylation was elevated in retinal Müller cells in culture exposed to the saturated fatty acid palmitate or the ceramide analog Cer6. One potential mechanism responsible for elevated O-GlcNAcylation is increased flux through the hexosamine biosynthetic pathway (HBP). Indeed, inhibition of the pathway's rate-limiting enzyme glutamine-fructose-6-phosphate amidotransferase (GFAT) prevented Cer6-induced O-GlcNAcylation. Importantly, expression of the mRNA encoding GFAT2, but not GFAT1 was elevated in both the retina of mice fed a HFD and in retinal cells in culture exposed to palmitate or Cer6. Notably, expression of nuclear receptor subfamily 4 group A member 1 (NR4A1) was increased in the retina of mice fed a HFD and NR4A1 expression was sufficient to promote GFAT2 mRNA expression and O-GlcNAcylation in retinal cells in culture. Whereas palmitate or Cer6 addition to culture medium enhanced NR4A1 and GFAT2 expression, chemical inhibition of NR4A1 transactivation repressed Cer6-induced GFAT2 mRNA expression. Overall, the results support a model wherein HFD increases retinal protein O-GlcNAcylation by promoting NR4A1-dependent GFAT2 expression.
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Wang A, Ren J, Wang CP, Hascall VC. Heparin prevents intracellular hyaluronan synthesis and autophagy responses in hyperglycemic dividing mesangial cells and activates synthesis of an extensive extracellular monocyte-adhesive hyaluronan matrix after completing cell division. J Biol Chem 2014; 289:9418-29. [PMID: 24482224 DOI: 10.1074/jbc.m113.541441] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Growth-arrested rat mesangial cells (RMCs) at a G0/G1 interphase stimulated to divide in hyperglycemic medium initiate intracellular hyaluronan synthesis that induces autophagy/cyclin D3-induced formation of a monocyte-adhesive extracellular hyaluronan matrix after completing cell division. This study shows that heparin inhibits the intracellular hyaluronan synthesis and autophagy responses, but at the end of cell division it induces synthesis of a much larger extracellular monocyte-adhesive hyaluronan matrix. Heparin bound to RMC surfaces by 1 h, internalizes into the Golgi/endoplasmic reticulum region by 2 h, and was nearly gone by 4 h. Treatment by heparin for only the first 4 h was sufficient for its function. Streptozotocin diabetic rats treated daily with heparin showed similar results. Glomeruli in sections of diabetic kidneys showed extensive accumulation of autophagic RMCs, increased hyaluronan matrix, and influx of macrophages over 6 weeks. Hyaluronan staining in the glomeruli of heparin-treated diabetic rats was very high at week 1 and decreased to near control level by 6 weeks without any RMC autophagy. However, the influx of macrophages by 6 weeks was as pronounced as in diabetic glomeruli. The results are as follows: 1) heparin blocks synthesis of hyaluronan in intracellular compartments, which prevents the autophagy and cyclin D3 responses thereby allowing RMCs to complete cell division and sustain function; 2) interaction of heparin with RMCs in early G1 phase is sufficient to induce signaling pathway(s) for its functions; and 3) influxed macrophages effectively remove the hyaluronan matrix without inducing pro-fibrotic responses that lead to nephropathy and proteinurea in diabetic kidneys.
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Affiliation(s)
- Aimin Wang
- From the Department of Biomedical Engineering, Cleveland Clinic, Cleveland, Ohio 44195
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9
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Molecular characterization, chromosomal location, alternative splicing and polymorphism of porcine GFAT1 gene. Mol Biol Rep 2009; 37:2711-7. [PMID: 19757168 DOI: 10.1007/s11033-009-9805-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Accepted: 09/02/2009] [Indexed: 10/20/2022]
Abstract
Glutamine: fructose-6-phosphate amidotransferase (GFAT) is the rate-limiting enzyme of the hexosamine synthesis pathway, which plays important roles in insulin resistance and glucose toxicity. GFAT1 is one of the two isoenzymes of GFAT. In the present study, we cloned cDNA sequence of the porcine GFAT1 gene and identified a GFAT1 splice variant (designed GFAT1-L) that contains a 54 bp insertion within the coding region. Nested RT-PCR revealed that GFAT1 was ubiquitously expressed in all tested tissues, but GFAT1-L was only expressed in skeletal muscle and heart, not in liver, spleen, lung, kidney, small intestine, stomach and fat tissue, suggested that GFAT1-L was selectively expressed in striate muscle in pig. Using both the somatic cell hybrid panel and radiation hybrid panel, the GFAT1 gene was mapped to porcine chromosome 3q21-q27, in which several significant QTLs for carcass traits were found. Among the SNPs we found in porcine GFAT1 gene, only the g. 101A>G polymorphism which located in intron 8 was polymorphic in two pig populations we investigated in the study. Association analyses revealed that the g. 101A>G polymorphism has a significant effect on lean meat percentage (P < 0.05), corrected backfat thickness (P < 0.05) and backfat at the rump (P < 0.05).
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Durand P, Golinelli-Pimpaneau B, Mouilleron S, Badet B, Badet-Denisot MA. Highlights of glucosamine-6P synthase catalysis. Arch Biochem Biophys 2008; 474:302-17. [PMID: 18279655 DOI: 10.1016/j.abb.2008.01.026] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Revised: 01/30/2008] [Accepted: 01/31/2008] [Indexed: 10/22/2022]
Abstract
L-Glutamine:d-fructose-6-phosphate amidotransferase, also known as glucosamine-6-phosphate synthase (GlcN6P synthase), which catalyzes the first step in a pathway leading to the formation of uridine 5'-diphospho-N-acetyl-d-glucosamine (UDP-GlcNAc), is a key point in the metabolic control of the biosynthesis of amino sugar-containing macromolecules. The molecular mechanism of the reaction catalyzed by GlcN6P synthase is complex and involves amide bond cleavage followed by ammonia channeling and sugar isomerization. This article provides a comprehensive overview of the present knowledge on this multi-faceted enzyme emphasizing the progress made during the last five years.
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Affiliation(s)
- Philippe Durand
- Institut de Chimie des Substances Naturelles-CNRS, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette, France
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11
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Zitzler J, Link D, Schäfer R, Liebetrau W, Kazinski M, Bonin-Debs A, Behl C, Buckel P, Brinkmann U. High-throughput functional genomics identifies genes that ameliorate toxicity due to oxidative stress in neuronal HT-22 cells: GFPT2 protects cells against peroxide. Mol Cell Proteomics 2004; 3:834-40. [PMID: 15181156 DOI: 10.1074/mcp.m400054-mcp200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We describe a novel genetic screen that is performed by transfecting every individual clone of an expression clone collection into a separate population of cells in a high-throughput mode. We combined high-throughput functional genomics with experimental validation to discover human genes that ameliorate cytotoxic responses of neuronal HT-22 cells upon exposure to oxidative stress. A collection of 5,000 human cDNAs in mammalian expression vectors were individually transfected into HT-22 cells, which were then exposed to H(2)O(2). Five genes were found that are known to be involved in pathways of detoxification of peroxide (catalase, glutathione peroxidase-1, peroxiredoxin-1, peroxiredoxin-5, and nuclear factor erythroid-derived 2-like 2). The presence of those genes in our "hit list" validates our screening platform. In addition, a set of candidate genes was found that has not been previously described as involved in detoxification of peroxide. One of these genes, which was consistently found to reduce H(2)O(2) -induced toxicity in HT-22, was GFPT2. This gene is expressed at significant levels in the central nervous system (CNS) and encodes glutamine-fructose-6-phosphate transaminase (GFPT) 2, a rate-limiting enzyme in hexosamine biosynthesis. GFPT has recently also been shown to ameliorate the toxicity of methylmercury in Saccharomyces cerevisiae. Methylmercury causes neuronal cell death in part by protein modification as well as enhancing the production of reactive oxygen species (ROS). The protective effect of GFPT2 against H(2)O(2) toxicity in neuronal HT-22 cells may be similar to its protection against methylmercury in yeast. Thus, GFPT appears to be conserved among yeast and men as a critical target of methylmercury and ROS-induced cytotoxicity.
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Affiliation(s)
- Jürgen Zitzler
- Xantos Biomedicine AG, Max-Lebsche Platz 31, D-81377 Munich, Germany
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12
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Milewski S. Glucosamine-6-phosphate synthase--the multi-facets enzyme. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1597:173-92. [PMID: 12044898 DOI: 10.1016/s0167-4838(02)00318-7] [Citation(s) in RCA: 197] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
L-Glutamine: D-fructose-6-phosphate amidotransferase, known under trivial name of glucosamine-6-phosphate synthase, as the only member of the amidotransferase subfamily of enzymes, does not display any ammonia-dependent activity. This enzyme, catalysing the first committed step in a pathway leading to the eventual formation of uridine 5'-diphospho-N-acetyl-D-glucosamine (UDP-GlcNAc), is an important point of metabolic control in biosynthesis of amino sugar-containing macromolecules. The molecular mechanism of reaction catalysed by GlcN-6-P synthase is complex and involves both amino transfer and sugar isomerisation. Substantial alterations to the enzyme structure and properties have been detected in different neoplastic tissues. GlcN-6-P synthase is inflicted in phenomenon of hexosamine-induced insulin resistance in diabetes. Finally, this enzyme has been proposed as a promising target in antifungal chemotherapy. Most of these issues, especially their molecular aspects, have been extensively studied in recent years. This article provides a comprehensive overview of the present knowledge on this multi-facets enzyme.
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Affiliation(s)
- Sławomir Milewski
- Department of Pharmaceutical Technology and Biochemistry, Technical University of Gdańsk, ul. Narutowicza 11/12, 80-952 Gdańsk, Poland.
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