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Walter LA, Blake LP, Gallot YS, Arends CJ, Sozio RS, Onifer SM, Bohnert KR. Effect of Denervation on XBP1 in Skeletal Muscle and the Neuromuscular Junction. Int J Mol Sci 2021; 23:ijms23010169. [PMID: 35008595 PMCID: PMC8745577 DOI: 10.3390/ijms23010169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 12/19/2021] [Accepted: 12/20/2021] [Indexed: 12/30/2022] Open
Abstract
Denervation of skeletal muscle is a debilitating consequence of injury of the peripheral nervous system, causing skeletal muscle to experience robust atrophy. However, the molecular mechanisms controlling the wasting of skeletal muscle due to denervation are not well understood. Here, we demonstrate that transection of the sciatic nerve in Sprague–Dawley rats induced robust skeletal muscle atrophy, with little effect on the neuromuscular junction (NMJ). Moreover, the following study indicates that all three arms of the unfolded protein response (UPR) are activated in denervated skeletal muscle. Specifically, ATF4 and ATF6 are elevated in the cytoplasm of skeletal muscle, while XBP1 is elevated in the nuclei of skeletal muscle. Moreover, XBP1 is expressed in the nuclei surrounding the NMJ. Altogether, these results endorse a potential role of the UPR and, specifically, XBP1 in the maintenance of both skeletal muscle and the NMJ following sciatic nerve transection. Further investigations into a potential therapeutic role concerning these mechanisms are needed.
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Affiliation(s)
- Lisa A. Walter
- Department of Kinesiology, St. Ambrose University, Davenport, IA 52803, USA; (L.A.W.); (L.P.B.)
| | - Lauren P. Blake
- Department of Kinesiology, St. Ambrose University, Davenport, IA 52803, USA; (L.A.W.); (L.P.B.)
| | - Yann S. Gallot
- LBEPS, Univ Evry, IRBA, Université Paris Saclay, 91025 Evry, France;
| | - Charles J. Arends
- Palmer Center for Chiropractic Research, Palmer College of Chiropractic, Davenport, IA 52803, USA; (C.J.A.); (R.S.S.); (S.M.O.)
| | - Randall S. Sozio
- Palmer Center for Chiropractic Research, Palmer College of Chiropractic, Davenport, IA 52803, USA; (C.J.A.); (R.S.S.); (S.M.O.)
| | - Stephen M. Onifer
- Palmer Center for Chiropractic Research, Palmer College of Chiropractic, Davenport, IA 52803, USA; (C.J.A.); (R.S.S.); (S.M.O.)
| | - Kyle R. Bohnert
- Department of Kinesiology, St. Ambrose University, Davenport, IA 52803, USA; (L.A.W.); (L.P.B.)
- Correspondence: ; Tel.: +1-563-333-5743
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Walter LA, Lin YH, Halbrook CJ, Chuh KN, He L, Pedowitz NJ, Batt AR, Brennan CK, Stiles BL, Lyssiotis CA, Pratt MR. Inhibiting the Hexosamine Biosynthetic Pathway Lowers O-GlcNAcylation Levels and Sensitizes Cancer to Environmental Stress. Biochemistry 2019; 59:3169-3179. [PMID: 31625393 DOI: 10.1021/acs.biochem.9b00560] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The amounts of the intracellular glycosylation, O-GlcNAc modification, are increased in essentially all tumors when compared to healthy tissue, and lowering O-GlcNAcylation levels results in reduced tumorigenesis and increased cancer cell death. Therefore, the pharmacological reduction of O-GlcNAc may represent a therapeutic vulnerability. The most direct approach to this goal is the inhibition of O-GlcNAc transferase (OGT), the enzyme that directly adds the modification to proteins. However, despite some recent success, this enzyme has proven difficult to inhibit. An alternative strategy involves starving OGT of its sugar substrate UDP-GlcNAc by targeting enzymes of the hexosamine biosynthetic pathway (HBP). Here, we explore the potential of the rate-determining enzyme of this pathway, glutamine fructose-6-phosphate amidotransferase (GFAT). We first show that CRISPR-mediated knockout of GFAT results in inhibition of cancer cell growth in vitro and a xenograft model that correlates with O-GlcNAcylation levels. We then demonstrate that pharmacological inhibition of GFAT sensitizes a small panel of cancer cells to undergo apoptosis in response to diamide-induced oxidative stress. Finally, we find that GFAT expression and O-GlcNAc levels are increased in a spontaneous mouse model of liver cancer. Together these experiments support the further development of inhibitors of the HBP as an indirect approach to lowering O-GlcNAcylation levels in cancer.
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Walter LA, Batt AR, Darabedian N, Zaro BW, Pratt MR. Azide- and Alkyne-Bearing Metabolic Chemical Reporters of Glycosylation Show Structure-Dependent Feedback Inhibition of the Hexosamine Biosynthetic Pathway. Chembiochem 2018; 19:1918-1921. [PMID: 29979493 PMCID: PMC6261355 DOI: 10.1002/cbic.201800280] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [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: 05/24/2018] [Indexed: 12/18/2022]
Abstract
Metabolic chemical reporters (MCRs) of protein glycosylation are analogues of natural monosaccharides that bear reactive groups, like azides and alkynes. When they are added to living cells and organisms, these small molecules are biosynthetically transformed into nucleotide donor sugars and then used by glycosyltransferases to modify proteins. Subsequent installation of tags by bioorthogonal chemistries can then enable the visualization and enrichment of these glycoproteins. Although this two-step procedure is powerful, the use of MCRs has the potential to change the endogenous production of the natural repertoire of donor sugars. A major route for the generation of these glycosyltransferase substrates is the hexosamine biosynthetic pathway (HBP), which results in uridine diphosphate N-acetylglucosamine (UDP-GlcNAc). Interestingly, the rate-determining enzyme of the HBP, glutamine fructose-6-phosphate amidotransferase (GFAT), is feedback inhibited by UDP-GlcNAc. This raises the possibility that a build-up of UDP-MCRs would block the biosynthesis of UDP-GlcNAc, resulting in off target effects. Here, we directly test this possibility with recombinant human GFAT and a small panel of synthetic UDP-MCRs. We find that MCRs with larger substitutions at the N-acetyl position do not inhibit GFAT, whereas those with modifications of the 2- or 6-hydroxy group do. These results further illuminate the considerations that should be applied to the use of MCRs.
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Affiliation(s)
- Lisa A. Walter
- Department of Chemistry, University of Southern California 840 Downey Way, LJS 250, Los Angeles, CA, 90089 (USA)
| | - Anna R. Batt
- Department of Chemistry, University of Southern California 840 Downey Way, LJS 250, Los Angeles, CA, 90089 (USA)
| | - Narek Darabedian
- Department of Chemistry, University of Southern California 840 Downey Way, LJS 250, Los Angeles, CA, 90089 (USA)
| | - Balyn W. Zaro
- Department of Chemistry, University of Southern California 840 Downey Way, LJS 250, Los Angeles, CA, 90089 (USA)
| | - Matthew R. Pratt
- Department of Chemistry, University of Southern California 840 Downey Way, LJS 250, Los Angeles, CA, 90089 (USA)
- Department of Biological Sciences, University of Southern California 840 Downey Way, LJS 250, Los Angeles, CA, 90089 (USA)
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Petlura C, Walter LA, Werstuck GH. Examining the Hexosamine Biosynthetic Pathway and Its Role in the Development of Diabetes-Associated Atherosclerosis: A Metabolomic Approach. Can J Cardiol 2013. [DOI: 10.1016/j.cjca.2013.07.258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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Sage AT, Walter LA, Shi Y, Khan MI, Kaneto H, Capretta A, Werstuck GH. Hexosamine biosynthesis pathway flux promotes endoplasmic reticulum stress, lipid accumulation, and inflammatory gene expression in hepatic cells. Am J Physiol Endocrinol Metab 2010; 298:E499-511. [PMID: 19952345 DOI: 10.1152/ajpendo.00507.2009] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [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: 11/22/2022]
Abstract
There is increasing evidence that endoplasmic reticulum (ER) stress contributes to the development of atherosclerosis in diabetes mellitus. The purpose of this study was to determine the effects of increased hexosamine biosynthesis pathway (HBP) flux on ER stress levels and the complications of ER stress associated with diabetes and atherosclerosis in hepatic cells. Glutamine:fructose-6-phosphate amidotransferase (GFAT), the rate-limiting enzyme of the HBP, was overexpressed in HepG2 cells by use of an adenoviral expression system. The ER stress response and downstream effects, including activation of lipid and inflammatory pathways, were determined using real-time PCR, immunoblot analysis, and cell staining techniques. GFAT overexpression resulted in increased expression of ER stress markers, including Grp78, Grp94, calreticulin, and GADD153, relative to cells infected with an empty adenoviral vector. In addition, GFAT overexpression promoted lipid, but not cholesterol, accumulation in hepatic cells as well as inflammatory pathway activation. Treatment with 6-diazo-5-oxo-norleucine, a GFAT antagonist, blocked the effects of GFAT overexpression. Consistent with our in vitro data, hyperglycemic mice presented with elevated markers of hepatic ER stress, glucosamine and lipid accumulation. Together, these data suggest that HBP flux-induced ER stress plays a role in the development of hepatic steatosis and atherosclerosis under conditions of hyperglycemia.
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Affiliation(s)
- Andrew T Sage
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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Abstract
1,5-Ethano-2,3,4,5-tetrahydro-1H-3-benzazepine, from the LiA1H4 reduction of 2-benzyloxy-1,5-ethano-4-oxo-2,3,4,5-tetrahydro-1H-3-benzazepine, was converted to N-alkyl, aralkyl, cycloalkyl, and alkenyl derivatives which were inactive as morphine type analgetics in mice. The LiA1H4 reduction of 2-benzyloxy-1,5-etheno-4-oxo-2,3,4,5-tetrahydro-1H-3-benzazepine gave unstable products from which only the skeletally rearranged dihydro- and tetrahydrobenzo[e]isoindolines, were isolated.
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Walter LA, Chang WK, Kenney J, Douvan I. Synthesis and central nervous system activity of 1,2,3,4-tetrahydro-1-amino-4-phenylnaphthalenes. J Med Chem 1974; 17:459-63. [PMID: 4830546 DOI: 10.1021/jm00250a021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Abstract
The effect of sodium fluoride on lactose metabolism and o-nitrophenyl-beta-d-galactopyranoside (ONPG) hydrolysis by Streptococcus lactis strains 7962 and C(2)F suggested that different mechanisms of lactose utilization existed in the two strains. Sodium fluoride prevented lactose utilization and ONPG hydrolysis by whole cells of S. lactis C(2)F but had no effect on S. lactis 7962. Although hydrolysis of ONPG by toluene-treated cells of S. lactis 7962 occurred without addition of phospho-enolpyruvate (PEP), toluene-treated cells of S. lactis C(2)F required the presence of this cofactor. Concentrated cell extracts of S. lactis C(2)F hydrolyzed ONPG; this hydrolysis was inhibited by NaF, but the addition of PEP, in the presence of NaF, restored maximal activity. Addition of acetyl-phosphate, carbamyl-phosphate, adenosine-5'-triphosphate, guanosine-5'-triphosphate, or uridine-5'-triphosphate did not stimulate activity. The presence of cofactors did not stimulate and NaF did not inhibit the hydrolysis in extracts of S. lactis 7962. To confirm the operation of two mechanisms, S. lactis 7962 was shown to hydrolyze lactose to glucose and galactose, whereas S. lactis C(2)F was unable to split the disaccharide. In addition, whole cells of S. lactis C(2)F rapidly accumulated a phosphorylated derivative of thiomethyl-beta-d-galactoside (TMG) which behaved chromatographically and electrophoretically like TMG-PO(4). Unexpectedly, S. lactis 7962 also accumulated a TMG derivative, although the rate was extremely low. These data indicate that different mechanisms of lactose utilization exist in the two strains, with a phosphorylation step dependent on PEP involved in S. lactis C(2)F.
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