PMID- 38192280 OWN - NLM STAT- PubMed-not-MEDLINE LR - 20240210 IS - 1663-4365 (Print) IS - 1663-4365 (Electronic) IS - 1663-4365 (Linking) VI - 15 DP - 2023 TI - O-GlcNAc regulates the mitochondrial integrated stress response by regulating ATF4. PG - 1326127 LID - 10.3389/fnagi.2023.1326127 [doi] LID - 1326127 AB - BACKGROUND: Accumulation of mitochondrial dysfunctional is a hallmark of age-related neurodegeneration including Alzheimer's disease (AD). Impairment of mitochondrial quality control mechanisms leading to the accumulation of damaged mitochondria and increasing neuronal stress. Therefore, investigating the basic mechanisms of how mitochondrial homeostasis is regulated is essential. Herein, we investigate the role of O-GlcNAcylation, a single sugar post-translational modification, in controlling mitochondrial stress-induced transcription factor Activating Transcription Factor 4 (ATF4). Mitochondrial dysfunction triggers the integrated stress response (ISR(mt)), in which the phosphorylation of eukaryotic translation initiation factor 2alpha results in the translation of ATF4. METHODS: We used patient-derived induced pluripotent stem cells, a transgenic mouse model of AD, SH-SY5Y neuroblastoma and HeLa cell-lines to examine the effect of sustained O-GlcNAcase inhibition by Thiamet-G (TMG) on ISR(mt) using biochemical analyses. RESULTS: We show that TMG elevates ATF4 protein levels upon mitochondrial stress in SH-SY5Y neuroblastoma and HeLa cell-lines. An indirect downstream target of ATF4 mitochondrial chaperone glucose-regulated protein 75 (GRP75) is significantly elevated. Interestingly, knock-down of O-GlcNAc transferase (OGT), the enzyme that adds O-GlcNAc, in SH-SY5Y increases ATF4 protein and mRNA expression. Additionally, ATF4 target gene Activating Transcription Factor 5 (ATF5) is significantly elevated at both the protein and mRNA level. Brains isolated from TMG treated mice show elevated levels of ATF4 and GRP75. Importantly, ATF4 occupancy increases at the ATF5 promoter site in brains isolated from TMG treated mice suggesting that O-GlcNAc is regulating ATF4 targeted gene expression. Interestingly, ATF4 and GRP75 are not induced in TMG treated familial Alzheimer's Disease mice model. The same results are seen in a human in vitro model of AD. CONCLUSION: Together, these results indicate that in healthy conditions, O-GlcNAc regulates the ISRmt through regulating ATF4, while manipulating O-GlcNAc in AD has no effect on ISR(mt). CI - Copyright (c) 2023 Alghusen, Carman, Wilkins, Ephrame, Qiang, Dias, Fedosyuk, Denson, Swerdlow and Slawson. FAU - Alghusen, Ibtihal M AU - Alghusen IM AD - School of Medicine, Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, United States. FAU - Carman, Marisa S AU - Carman MS AD - School of Medicine, Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, United States. FAU - Wilkins, Heather AU - Wilkins H AD - School of Medicine, Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, United States. AD - Department of Neurology, University of Kansas Medical Center, Kansas City, KS, United States. AD - University of Kansas Alzheimer's Disease Research Center, University of Kansas Medical Center, Kansas City, KS, United States. FAU - Ephrame, Sophiya John AU - Ephrame SJ AD - School of Medicine, Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, United States. FAU - Qiang, Amy AU - Qiang A AD - School of Medicine, Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, United States. FAU - Dias, Wagner B AU - Dias WB AD - School of Medicine, Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, United States. FAU - Fedosyuk, Halyna AU - Fedosyuk H AD - School of Medicine, Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, United States. FAU - Denson, Aspin R AU - Denson AR AD - School of Medicine, Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, United States. FAU - Swerdlow, Russell H AU - Swerdlow RH AD - School of Medicine, Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, United States. AD - Department of Neurology, University of Kansas Medical Center, Kansas City, KS, United States. AD - University of Kansas Alzheimer's Disease Research Center, University of Kansas Medical Center, Kansas City, KS, United States. FAU - Slawson, Chad AU - Slawson C AD - School of Medicine, Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, United States. AD - University of Kansas Alzheimer's Disease Research Center, University of Kansas Medical Center, Kansas City, KS, United States. LA - eng GR - P30 AG072973/AG/NIA NIH HHS/United States GR - R01 AG064227/AG/NIA NIH HHS/United States PT - Journal Article DEP - 20231218 PL - Switzerland TA - Front Aging Neurosci JT - Frontiers in aging neuroscience JID - 101525824 PMC - PMC10773771 OTO - NOTNLM OT - Alzheimer's disease OT - O-GlcNAc OT - activating transcription factor 4 (ATF4) OT - integrated stress response OT - mitochondrial stress COIS- The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision. EDAT- 2024/01/09 06:41 MHDA- 2024/01/09 06:42 PMCR- 2023/01/01 CRDT- 2024/01/09 03:44 PHST- 2023/10/22 00:00 [received] PHST- 2023/11/27 00:00 [accepted] PHST- 2024/01/09 06:42 [medline] PHST- 2024/01/09 06:41 [pubmed] PHST- 2024/01/09 03:44 [entrez] PHST- 2023/01/01 00:00 [pmc-release] AID - 10.3389/fnagi.2023.1326127 [doi] PST - epublish SO - Front Aging Neurosci. 2023 Dec 18;15:1326127. doi: 10.3389/fnagi.2023.1326127. eCollection 2023.