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Hepatitis Viruses Control Host Immune Responses by Modifying the Exosomal Biogenesis Pathway and Cargo. Int J Mol Sci 2022; 23:ijms231810862. [PMID: 36142773 PMCID: PMC9505460 DOI: 10.3390/ijms231810862] [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: 08/11/2022] [Revised: 09/13/2022] [Accepted: 09/15/2022] [Indexed: 11/17/2022] Open
Abstract
The development of smart immune evasion mechanisms is crucial for the establishment of acute and chronic viral hepatitis. Hepatitis is a major health problem worldwide arising from different causes, such as pathogens, metabolic disorders, and xenotoxins, with the five hepatitis viruses A, B, C, D, and E (HAV, HBV, HCV, HDV, and HEV) representing the majority of the cases. Most of the hepatitis viruses are considered enveloped. Recently, it was reported that the non-enveloped HAV and HEV are, in reality, quasi-enveloped viruses exploiting exosomal-like biogenesis mechanisms for budding. Regardless, all hepatitis viruses use exosomes to egress, regulate, and eventually escape from the host immune system, revealing another key function of exosomes apart from their recognised role in intercellular communication. This review will discuss how the hepatitis viruses exploit exosome biogenesis and transport capacity to establish successful infection and spread. Then, we will outline the contribution of exosomes in viral persistence and liver disease progression.
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Yi JH, Brown C, Whitehead G, Piers T, Lee YS, Perez CM, Regan P, Whitcomb DJ, Cho K. Glucocorticoids activate a synapse weakening pathway culminating in tau phosphorylation in the hippocampus. Pharmacol Res 2017; 121:42-51. [PMID: 28416463 DOI: 10.1016/j.phrs.2017.04.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Indexed: 12/19/2022]
Abstract
Evidence suggests that the stress hormones glucocorticoids (GCs) can cause cognitive deficits and neurodegeneration. Previous studies have found GCs facilitate physiological synapse weakening, termed long-term depression (LTD), though the precise mechanisms underlying this are poorly understood. Here we show that GCs activate glycogen synthase kinase-3 (GSK-3), a kinase crucial to synapse weakening signals. Critically, this ultimately leads to phosphorylation of the microtubule associated protein tau, specifically at the serine 396 residue, and this is a causal factor in the GC-mediated impairment of synaptic function. These findings reveal the link between GCs and synapse weakening signals, and the potential for stress-induced priming of neurodegeneration. This could have important implications for our understanding of how stress can lead to neurodegenerative disease.
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Affiliation(s)
- Jee Hyun Yi
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, Faculty of Health Sciences, University of Bristol, Whitson Street, Bristol, BS1 3NY, United Kingdom
| | - Christopher Brown
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, Faculty of Health Sciences, University of Bristol, Whitson Street, Bristol, BS1 3NY, United Kingdom; Chonnam-Bristol Frontier Laboratory, Biomedical Research Institute, Chonnam National University Hospital, Gwangju 501-757, South Korea
| | - Garry Whitehead
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, Faculty of Health Sciences, University of Bristol, Whitson Street, Bristol, BS1 3NY, United Kingdom
| | - Thomas Piers
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, Faculty of Health Sciences, University of Bristol, Whitson Street, Bristol, BS1 3NY, United Kingdom; Chonnam-Bristol Frontier Laboratory, Biomedical Research Institute, Chonnam National University Hospital, Gwangju 501-757, South Korea; Centre for Synaptic Plasticity, University of Bristol, Whitson Street, Bristol, BS1 3NY, United Kingdom
| | - Young Seok Lee
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, Faculty of Health Sciences, University of Bristol, Whitson Street, Bristol, BS1 3NY, United Kingdom; Department of Life Sciences, Imperial College, London, SW7 2AZ, United Kingdom
| | - Celia Martinez Perez
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, Faculty of Health Sciences, University of Bristol, Whitson Street, Bristol, BS1 3NY, United Kingdom
| | - Philip Regan
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, Faculty of Health Sciences, University of Bristol, Whitson Street, Bristol, BS1 3NY, United Kingdom; Centre for Synaptic Plasticity, University of Bristol, Whitson Street, Bristol, BS1 3NY, United Kingdom
| | - Daniel J Whitcomb
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, Faculty of Health Sciences, University of Bristol, Whitson Street, Bristol, BS1 3NY, United Kingdom; Centre for Synaptic Plasticity, University of Bristol, Whitson Street, Bristol, BS1 3NY, United Kingdom
| | - Kwangwook Cho
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, Faculty of Health Sciences, University of Bristol, Whitson Street, Bristol, BS1 3NY, United Kingdom; Centre for Synaptic Plasticity, University of Bristol, Whitson Street, Bristol, BS1 3NY, United Kingdom.
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Yu UY, Yoo BC, Ahn JH. Regulatory B Subunits of Protein Phosphatase 2A Are Involved in Site-specific Regulation of Tau Protein Phosphorylation. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2014; 18:155-61. [PMID: 24757378 PMCID: PMC3994303 DOI: 10.4196/kjpp.2014.18.2.155] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 02/12/2014] [Accepted: 02/28/2014] [Indexed: 11/15/2022]
Abstract
Overexpression of amyloid precursor protein with the Swedish mutation causes abnormal hyperphosphorylation of the microtubule-associated protein tau. Hyperphosphorylated isoforms of tau are major components of neurofibrillary tangles, which are histopathological hallmarks of Alzheimer's disease. Protein phosphatase 2A (PP2A), a major tau protein phosphatase, consists of a structural A subunit, catalytic C subunit, and a variety of regulatory B subunits. The B subunits have been reported to modulate function of the PP2A holoenzyme by regulating substrate binding, enzyme activity, and subcellular localization. In the current study, we characterized regulatory B subunit-specific regulation of tau protein phosphorylation. We showed that the PP2A B subunit PPP2R2A mediated dephosphorylation of tau protein at Ser-199, Ser-202/Thr-205, Thr-231, Ser-262, and Ser-422. Down-regulation of PPP2R5D expression decreased tau phosphorylation at Ser-202/Thr-205, Thr-231, and Ser-422, which indicates activation of the tau kinase glycogen synthase kinase 3 beta (GSK3β) by PP2A with PPP2R5D subunit. The level of activating phosphorylation of the GSK3β kinase Akt at Thr-308 and Ser-473 were both increased by PPP2R5D knockdown. We also characterized B subunit-specific phosphorylation sites in tau using mass spectrometric analysis. Liquid chromatography-mass spectrometry revealed that the phosphorylation status of the tau protein may be affected by PP2A, depending on the specific B subunits. These studies further our understanding of the function of various B subunits in mediating site-specific regulation of tau protein phosphorylation.
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Affiliation(s)
- Un Young Yu
- Department of Biochemistry, Ewha Womans University College of Medicine, Seoul 158-710, Korea
| | - Byong Chul Yoo
- Colorectal Cancer Branch, Research Institute, National Cancer Center, Goyang 410-768, Korea
| | - Jung-Hyuck Ahn
- Department of Biochemistry, Ewha Womans University College of Medicine, Seoul 158-710, Korea
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Rose AJ, Herzig S. Metabolic control through glucocorticoid hormones: an update. Mol Cell Endocrinol 2013; 380:65-78. [PMID: 23523966 DOI: 10.1016/j.mce.2013.03.007] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 02/21/2013] [Accepted: 03/08/2013] [Indexed: 01/28/2023]
Abstract
In the past decades, glucocorticoid (GC) hormones and their cognate, intracellular receptor, the glucocorticoid receptor (GR), have been well established as critical checkpoints in mammalian energy homeostasis. Whereas many aspects in healthy nutrient metabolism require physiological levels and/or action of GC, aberrant GC/GR signalling has been linked to severe metabolic dysfunction, including obesity, insulin resistance and type 2 diabetes. Consequently, studies of the molecular mechanisms within the GC signalling axis have become a major focus in biomedical research, up-to-date particularly focusing on systemic glucose and lipid handling. However, with the availability of novel high throughput technologies and more sophisticated metabolic phenotyping capabilities, as-yet non-appreciated, metabolic functions of GC have been recently discovered, including regulatory roles of the GC/GR axis in protein and bile acid homeostasis as well as metabolic inter-organ communication. Therefore, this review summarises recent advances in GC/GR biology, and summarises findings relevant for basic and translational metabolic research.
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Affiliation(s)
- Adam J Rose
- Joint Research Division, Molecular Metabolic Control, German Cancer Research Center (DKFZ) Heidelberg, Center for Molecular Biology (ZMBH), Heidelberg University, Network Aging Research, University Hospital Heidelberg, Germany
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Suwanjang W, Abramov AY, Govitrapong P, Chetsawang B. Melatonin attenuates dexamethasone toxicity-induced oxidative stress, calpain and caspase activation in human neuroblastoma SH-SY5Y cells. J Steroid Biochem Mol Biol 2013; 138:116-22. [PMID: 23688838 DOI: 10.1016/j.jsbmb.2013.04.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 04/11/2013] [Accepted: 04/15/2013] [Indexed: 02/02/2023]
Abstract
Glucocorticoids (GCs) have a significant role in the adaptive response of the brain to stress. Increasing evidence has demonstrated that an increase of GC levels may induce neuronal cell death via apoptotic pathways. There is a correlation between over-production of reactive oxygen species (ROS) and an elevation in cytosolic calcium that causes a subsequent increase in the calcium-dependent death-process activation in GC-induced toxicity. Consequently, melatonin, via its antioxidant activity, exhibits a neuroprotective effect against apoptosis induced by intracellular calcium overload. Therefore, in the present study, we explored the protective effect of melatonin in GC-induced toxicity in dopaminergic SH-SY5Y cells. Cellular treatment with the synthetic GCs, dexamethasone (DEX), resulted in a marked decrease in cell viability and in the level of the calpain-inhibitor protein, calpastatin. DEX-induced toxicity also caused an increase in ROS production and the activation of the calcium-dependent cysteine protease, calpain, along with an increase in caspase-3 activation. Pretreatment of the cells with melatonin substantially prevented the decrease in cell viability, over-production of ROS and the activation of calpain and caspase-3, and reversed the depletion in calpastatin levels. These results suggest that melatonin may exert its protective effects against the calpain- and caspase-dependent death process in DEX-induced neurotoxicity.
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Affiliation(s)
- Wilasinee Suwanjang
- Research Center for Neuroscience, Institute of Molecular Biosciences, Mahidol University, Nakhonpathom, Thailand
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