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HIF-1α Causes LCMT1/PP2A Deficiency and Mediates Tau Hyperphosphorylation and Cognitive Dysfunction during Chronic Hypoxia. Int J Mol Sci 2022; 23:ijms232416140. [PMID: 36555780 PMCID: PMC9783654 DOI: 10.3390/ijms232416140] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 12/01/2022] [Accepted: 12/02/2022] [Indexed: 12/23/2022] Open
Abstract
Chronic hypoxia is a risk factor for Alzheimer's disease (AD), and the neurofibrillary tangle (NFT) formed by hyperphosphorylated tau is one of the two major pathological changes in AD. However, the effect of chronic hypoxia on tau phosphorylation and its mechanism remains unclear. In this study, we investigated the role of HIF-1α (the functional subunit of hypoxia-inducible factor 1) in tau pathology. It was found that in Sprague-Dawley (SD) rats, global hypoxia (10% O2, 6 h per day) for one month induced cognitive impairments. Meanwhile it induced HIF-1α increase, tau hyperphosphorylation, and protein phosphatase 2A (PP2A) deficiency with leucine carboxyl methyltransferase 1(LCMT1, increasing PP2A activity) decrease in the rats' hippocampus. The results were replicated by hypoxic treatment in primary hippocampal neurons and C6/tau cells (rat C6 glioma cells stably expressing human full-length tau441). Conversely, HIF-1α silencing impeded the changes induced by hypoxia, both in primary neurons and SD rats. The result of dual luciferase assay proved that HIF-1α acted as a transcription factor of LCMT1. Unexpectedly, HIF-1α decreased the protein level of LCMT1. Further study uncovered that both overexpression of HIF-1α and hypoxia treatment resulted in a sizable degradation of LCMT1 via the autophagy--lysosomal pathway. Together, our data strongly indicated that chronic hypoxia upregulates HIF-1α, which obviously accelerated LCMT1 degradation, thus counteracting its transcriptional expression. The increase in HIF-1α decreases PP2A activity, finally resulting in tau hyperphosphorylation and cognitive dysfunction. Lowering HIF-1α in chronic hypoxia conditions may be useful in AD prevention.
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Disbrow E, Stokes KY, Ledbetter C, Patterson J, Kelley R, Pardue S, Reekes T, Larmeu L, Batra V, Yuan S, Cvek U, Trutschl M, Kilgore P, Alexander JS, Kevil CG. Plasma hydrogen sulfide: A biomarker of Alzheimer's disease and related dementias. Alzheimers Dement 2021; 17:1391-1402. [PMID: 33710769 PMCID: PMC8451930 DOI: 10.1002/alz.12305] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 10/29/2020] [Accepted: 01/15/2021] [Indexed: 12/17/2022]
Abstract
While heart disease remains a common cause of mortality, cerebrovascular disease also increases with age, and has been implicated in Alzheimer's disease and related dementias (ADRD). We have described hydrogen sulfide (H2S), a signaling molecule important in vascular homeostasis, as a biomarker of cardiovascular disease. We hypothesize that plasma H2S and its metabolites also relate to vascular and cognitive dysfunction in ADRD. We used analytical biochemical methods to measure plasma H2S metabolites and MRI to evaluate indicators of microvascular disease in ADRD. Levels of total H2S and specific metabolites were increased in ADRD versus controls. Cognition and microvascular disease indices were correlated with H2S levels. Total plasma sulfide was the strongest indicator of ADRD, and partially drove the relationship between cognitive dysfunction and white matter lesion volume, an indicator of microvascular disease. Our findings show that H2S is dysregulated in dementia, providing a potential biomarker for diagnosis and intervention.
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Affiliation(s)
- Elizabeth Disbrow
- Department of Neurology, LSU Health Shreveport, Shreveport, Louisiana, USA.,Center for Brain Health, LSU Health Shreveport, Shreveport, Louisiana, USA.,Center for Cardiovascular Diseases and Sciences, LSU Health Shreveport, Shreveport, Louisiana, USA.,Department of Pharmacology, LSU Health Shreveport, Shreveport, Louisiana, USA
| | - Karen Y Stokes
- Center for Brain Health, LSU Health Shreveport, Shreveport, Louisiana, USA.,Center for Cardiovascular Diseases and Sciences, LSU Health Shreveport, Shreveport, Louisiana, USA.,Department of Molecular and Cellular Physiology, LSU Health Shreveport, Shreveport, Louisiana, USA
| | - Christina Ledbetter
- Center for Brain Health, LSU Health Shreveport, Shreveport, Louisiana, USA.,Department of Neurosurgery, LSU Health Shreveport, Shreveport, Louisiana, USA
| | - James Patterson
- Center for Brain Health, LSU Health Shreveport, Shreveport, Louisiana, USA.,Department of Psychiatry and Behavioral Medicine, LSU Health Shreveport, Shreveport, Louisiana, USA
| | - Roger Kelley
- Department of Neurology, LSU Health Shreveport, Shreveport, Louisiana, USA.,Center for Brain Health, LSU Health Shreveport, Shreveport, Louisiana, USA
| | - Sibile Pardue
- Center for Cardiovascular Diseases and Sciences, LSU Health Shreveport, Shreveport, Louisiana, USA
| | - Tyler Reekes
- Center for Brain Health, LSU Health Shreveport, Shreveport, Louisiana, USA.,Department of Pharmacology, LSU Health Shreveport, Shreveport, Louisiana, USA
| | - Lana Larmeu
- Center for Brain Health, LSU Health Shreveport, Shreveport, Louisiana, USA.,Department of Neurosurgery, LSU Health Shreveport, Shreveport, Louisiana, USA
| | - Vinita Batra
- Center for Brain Health, LSU Health Shreveport, Shreveport, Louisiana, USA.,Department of Psychiatry and Behavioral Medicine, LSU Health Shreveport, Shreveport, Louisiana, USA
| | - Shuai Yuan
- Vascular Medicine Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - Urska Cvek
- Dept. of Computer Science, Laboratory for Advanced Biomedical Informatics, Louisiana State University Shreveport, Shreveport, Louisiana, USA
| | - Marjan Trutschl
- Dept. of Computer Science, Laboratory for Advanced Biomedical Informatics, Louisiana State University Shreveport, Shreveport, Louisiana, USA
| | - Phillip Kilgore
- Dept. of Computer Science, Laboratory for Advanced Biomedical Informatics, Louisiana State University Shreveport, Shreveport, Louisiana, USA
| | - J Steven Alexander
- Department of Neurology, LSU Health Shreveport, Shreveport, Louisiana, USA.,Center for Brain Health, LSU Health Shreveport, Shreveport, Louisiana, USA.,Center for Cardiovascular Diseases and Sciences, LSU Health Shreveport, Shreveport, Louisiana, USA.,Department of Molecular and Cellular Physiology, LSU Health Shreveport, Shreveport, Louisiana, USA
| | - Christopher G Kevil
- Center for Brain Health, LSU Health Shreveport, Shreveport, Louisiana, USA.,Center for Cardiovascular Diseases and Sciences, LSU Health Shreveport, Shreveport, Louisiana, USA.,Department of Pathology and Translational Pathobiology, Department of Pathology, and Cell Biology and Anatomy, LSU Health Shreveport, Shreveport, Louisiana, USA
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Adav SS, Sze SK. Hypoxia-Induced Degenerative Protein Modifications Associated with Aging and Age-Associated Disorders. Aging Dis 2020; 11:341-364. [PMID: 32257546 PMCID: PMC7069466 DOI: 10.14336/ad.2019.0604] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 06/04/2019] [Indexed: 12/18/2022] Open
Abstract
Aging is an inevitable time-dependent decline of various physiological functions that finally leads to death. Progressive protein damage and aggregation have been proposed as the root cause of imbalance in regulatory processes and risk factors for aging and neurodegenerative diseases. Oxygen is a modulator of aging. The oxygen-deprived conditions (hypoxia) leads to oxidative stress, cellular damage and protein modifications. Despite unambiguous evidence of the critical role of spontaneous non-enzymatic Degenerative Protein Modifications (DPMs) such as oxidation, glycation, carbonylation, carbamylation, and deamidation, that impart deleterious structural and functional protein alterations during aging and age-associated disorders, the mechanism that mediates these modifications is poorly understood. This review summarizes up-to-date information and recent developments that correlate DPMs, aging, hypoxia, and age-associated neurodegenerative diseases. Despite numerous advances in the study of the molecular hallmark of aging, hypoxia, and degenerative protein modifications during aging and age-associated pathologies, a major challenge remains there to dissect the relative contribution of different DPMs in aging (either natural or hypoxia-induced) and age-associated neurodegeneration.
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Affiliation(s)
- Sunil S Adav
- School of Biological Sciences, Nanyang Technological University, Singapore
- Singapore Phenome Centre, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Siu Kwan Sze
- School of Biological Sciences, Nanyang Technological University, Singapore
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Saura CA. Presenilin/gamma-Secretase and Inflammation. Front Aging Neurosci 2010; 2:16. [PMID: 20559464 PMCID: PMC2887037 DOI: 10.3389/fnagi.2010.00016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Accepted: 04/08/2010] [Indexed: 01/02/2023] Open
Abstract
Presenilins (PS) are the catalytic components of γ-secretase, an aspartyl protease that regulates through proteolytic processing the function of multiple signaling proteins. Specially relevant is the γ-secretase-dependent cleavage of the β-amyloid precursor protein (APP) since generates the β-amyloid (Aβ) peptides that aggregate and accumulate in the brain of Alzheimer's disease (AD) patients. Abnormal processing and/or accumulation of Aβ disrupt synaptic and metabolic processes leading to neuron dysfunction and neurodegeneration. Studies in presenilin conditional knockout mice have revealed that presenilin-1 is essential for age-dependent Aβ accumulation and inflammation. By contrast, mutations in the presenilin genes responsible for early onset familial AD cause rapid disease progression and accentuate clinical and pathological features including inflammation. In addition, a number of loss of function mutations in presenilin-1 have been recently associated to non-Alzheimer's dementias including frontotemporal dementia and dementia with Lewy bodies. In agreement, total loss of presenilin function in the brain results in striking neurodegeneration and inflammation, which includes activation of glial cells and induction of proinflammatory genes, besides altered inflammatory responses in the periphery. Interestingly, some non-steroidal anti-inflammatory drugs that slow cognitive decline and reduce the risk of AD, decrease amyloidogenic Aβ42 levels by modulating allosterically PS/γ-secretase. In this review, I present current evidence supporting a role of presenilin/γ-secretase signaling on gliogenesis and gliosis in normal and pathological conditions. Understanding the cellular mechanisms regulated by presenilin/γ-secretase during chronic inflammatory processes may provide new approaches for the development of effective therapeutic strategies for AD.
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Affiliation(s)
- Carlos A Saura
- Institut de Neurociències, Departament Bioquímica i Biologia Molecular, Centro de Investigación Biomédica en Red Enfermedades Neurodegenerativas (CIBERNED), Universitat Autònoma de Barcelona Bellaterra, Spain
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Fletcher EL, Downie LE, Ly A, Ward MM, Batcha AH, Puthussery T, Yee P, Hatzopoulos KM. A review of the role of glial cells in understanding retinal disease. Clin Exp Optom 2008; 91:67-77. [PMID: 18045252 DOI: 10.1111/j.1444-0938.2007.00204.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Retinal vascular diseases such as diabetic retinopathy and retinopathy of prematurity are major causes of visual loss. Although the focus of a great deal of research has been on the aetiology of vascular growth, it is now emerging that anomalies in other retinal cell types, especially glial cells, occur very early in the course of the disease. Glial cells have major roles in every stage of disease, from the earliest subtle variations in neural function, to the development of epi-retinal membranes and tractional detachment. Therefore, having a firm understanding of the function of retinal glia is important in our understanding of retinal disease and is crucial for the development of new treatment strategies.
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Affiliation(s)
- Erica L Fletcher
- Department of Anatomy and Cell Biology, The University of Melbourne, Victoria, Australia.
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Boycott HE, Dallas M, Boyle JP, Pearson HA, Peers C. Hypoxia suppresses astrocyte glutamate transport independently of amyloid formation. Biochem Biophys Res Commun 2007; 364:100-4. [PMID: 17927959 DOI: 10.1016/j.bbrc.2007.09.102] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Accepted: 09/25/2007] [Indexed: 11/15/2022]
Abstract
Sustained hypoxia alters the expression of numerous proteins and predisposes individuals to Alzheimer's disease (AD). We have previously shown that hypoxia in vitro alters Ca2+ homeostasis in astrocytes and promotes increased production of amyloid beta peptides (Abeta) of AD. Indeed, alteration of Ca2+ homeostasis requires amyloid formation. Here, we show that electrogenic glutamate uptake by astrocytes is suppressed by hypoxia (1% O2, 24h) in a manner that is independent of amyloid beta peptide formation. Thus, hypoxic suppression of glutamate uptake and expression levels of glutamate transporter proteins EAAT1 and EAAT2 were not mimicked by exogenous application of amyloid beta peptide, or by prevention of endogenous amyloid peptide formation (using inhibitors of either beta or gamma secretase). Thus, dysfunction in glutamate homeostasis in hypoxic conditions is independent of Abeta production, but will likely contribute to neuronal damage and death associated with AD following hypoxic events.
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Affiliation(s)
- Hannah E Boycott
- School of Medicine, University of Leeds, Worsley Building, Leeds LS2 9JT, UK
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