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Tsatsanis A, Dickens S, Kwok JCF, Wong BX, Duce JA. Post Translational Modulation of β-Amyloid Precursor Protein Trafficking to the Cell Surface Alters Neuronal Iron Homeostasis. Neurochem Res 2019; 44:1367-1374. [PMID: 30796750 PMCID: PMC6525264 DOI: 10.1007/s11064-019-02747-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 01/30/2019] [Accepted: 01/31/2019] [Indexed: 12/16/2022]
Abstract
Cell surface β-Amyloid precursor protein (APP) is known to have a functional role in iron homeostasis through stabilising the iron export protein ferroportin (FPN). Mechanistic evidence of this role has previously only been provided through transcriptional or translational depletion of total APP levels. However, numerous post-translational modifications of APP are reported to regulate the location and trafficking of this protein to the cell surface. Stable overexpressing cell lines were generated that overexpressed APP with disrupted N-glycosylation (APPN467K and APPN496K) or ectodomain phosphorylation (APPS206A); sites selected for their proximity to the FPN binding site on the E2 domain of APP. We hypothesise that impaired N-glycosylation or phosphorylation of APP disrupts the functional location on the cell surface or binding to FPN to consequentially alter intracellular iron levels through impaired cell surface FPN stability. Outcomes confirm that these post-translational modifications are essential for the correct location of APP on the cell surface and highlight a novel mechanism by which the cell can modulate iron homeostasis. Further interrogation of other post-translational processes to APP is warranted in order to fully understand how each modification plays a role on regulating intracellular iron levels in health and disease.
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Affiliation(s)
- Andrew Tsatsanis
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, West Yorkshire, UK
| | - Stuart Dickens
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, West Yorkshire, UK
| | - Jessica C F Kwok
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, West Yorkshire, UK
| | - Bruce X Wong
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, West Yorkshire, UK
- The ALBORADO Drug Discovery Institute, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge, UK
| | - James A Duce
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, West Yorkshire, UK.
- The ALBORADO Drug Discovery Institute, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge, UK.
- Melbourne Dementia Research Centre, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia.
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Tao PF, Huang HC. Regulation of AβPP Glycosylation Modification and Roles of Glycosylation on AβPP Cleavage in Alzheimer's Disease. ACS Chem Neurosci 2019; 10:2115-2124. [PMID: 30802027 DOI: 10.1021/acschemneuro.8b00574] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The presence of senile plaques in the gray matter of the brain is one of the major pathologic features of Alzheimer's disease (AD), and amyloid-β (Aβ) is the main component of extracellular deposits of the senile plaques. Aβ derives from amyloid-β precursor protein (AβPP) cleaved by β-secretase (BACE1) and γ-secretase, and the abnormal cleavage of AβPP is an important event leading to overproduction and aggregation of Aβ species. After translation, AβPP undergoes post-translational modifications (PTMs) including glycosylation and phosphorylation in the endoplasmic reticulum (ER) and Golgi apparatus, and these modifications play an important role in regulating the cleavage of this protein. In this Review, we summarize research progress on the modification of glycosylation, especially O-GlcNAcylation and mucin-type O-linked glycosylation (also known as O-GalNAcylation), on the regulation of AβPP cleavage and on the influence of AβPP's glycosylation in the pathogenesis of AD.
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Affiliation(s)
- Peng-Fei Tao
- Beijing Key Laboratory of Bioactive Substances and Functional Foods, Beijing Union University, Beijing, 100191, China
| | - Han-Chang Huang
- Beijing Key Laboratory of Bioactive Substances and Functional Foods, Beijing Union University, Beijing, 100191, China
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Akasaka-Manya K, Kawamura M, Tsumoto H, Saito Y, Tachida Y, Kitazume S, Hatsuta H, Miura Y, Hisanaga SI, Murayama S, Hashimoto Y, Manya H, Endo T. Excess APPO-glycosylation by GalNAc-T6 decreases Aβ production. J Biochem 2016; 161:99-111. [DOI: 10.1093/jb/mvw056] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 08/19/2016] [Indexed: 11/13/2022] Open
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Strating JRPM, Bouw G, Hafmans TGM, Martens GJM. p24 Proteins from the same subfamily are functionally nonredundant. Biochimie 2010; 93:528-32. [PMID: 21118709 DOI: 10.1016/j.biochi.2010.11.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2010] [Accepted: 11/22/2010] [Indexed: 11/17/2022]
Abstract
The p24 proteins function in early secretory pathway transport processes, but their exact role is unclear. In physiologically activated Xenopus melanotrope cells, a representative of each p24 subfamily (p24α(3), -β(1), -γ(3), -δ(2)) is upregulated coordinately with the major melanotrope cargo, proopiomelanocortin (POMC), whereas two other p24s (p24γ(2) and -δ(1)) are also expressed, but not coordinately with POMC. Using melanotrope-specific transgene expression, we here find that the roles of both p24γ(2) and p24δ(1) in the transport, glycosylation, sulphation and cleavage of POMC are different from those of their upregulated subfamily relatives (p24γ(3) and p24δ(2), respectively). Thus, even p24 proteins from the same subfamily have distinct functions in secretory cargo biosynthesis.
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Affiliation(s)
- Jeroen R P M Strating
- Donders Institute for Brain, Cognition and Behaviour, Centre for Neuroscience, and Nijmegen Centre for Molecular Life Sciences (NCMLS), 282 Department of Molecular Animal Physiology, Radboud University Nijmegen, Geert Grooteplein Zuid 28, Nijmegen, The Netherlands
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Strating JR, Hafmans TG, Martens GJ. COP-binding sites in p24δ2 are necessary for proper secretory cargo biosynthesis. Int J Biochem Cell Biol 2009; 41:1619-27. [DOI: 10.1016/j.biocel.2009.02.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Revised: 02/10/2009] [Accepted: 02/12/2009] [Indexed: 01/24/2023]
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Abstract
BACKGROUND INFORMATION The p24 protein family plays an important but unclear role at the ER (endoplasmic reticulum)-Golgi interface. A p24 member from each subfamily (p24alpha(3), beta(1), gamma(3) and delta(2)) is upregulated with the prohormone POMC (pro-opiomelanocortin) when Xenopus laevis intermediate pituitary melanotrope cells are physiologically activated. Here we explored the role of p24 by generating and analysing Xenopus with melanotrope cell-specific transgene expression of p24beta(1) or p24gamma(3), two of the p24 proteins coexpressed with POMC, and compared the results with those previously reported for the two other coexpressed p24s (p24alpha(3) and p24delta(2)). RESULTS The transgene expression of p24beta(1) or p24gamma(3) did not affect the endogenous p24 proteins or affected only endogenous p24gamma(3) respectively, whereas in transgenics expressing p24alpha(3) and p24delta(2), the levels of all endogenous p24 proteins were strongly decreased. Nevertheless, as for p24alpha(3) but albeit to a lesser extent, in the p24beta(1)-transgenic melanotrope cells the rate of cargo cleavage was reduced, probably reflecting reduced cargo transport from the ER, and POMC glycosylation and sulfation in the Golgi were not affected. The p24gamma(3)-transgenic cells displayed features of both the p24alpha(3)-transgenics (reduced cargo cleavage, normal POMC sulfation) and the p24delta(2)-transgenics (affected POMC glycosylation). CONCLUSIONS Our results show that the four upregulated proteins p24alpha(3), beta(1), gamma(3) and delta(2) have non-redundant roles in the early secretory pathway, and suggest that each p24 subfamily member provides a proper ER/Golgi subcompartmental microenvironment, together allowing correct secretory protein transport and processing.
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Strating JRPM, Bouw G, Hafmans TGM, Martens GJM. Disparate effects of p24alpha and p24delta on secretory protein transport and processing. PLoS One 2007; 2:e704. [PMID: 17684551 PMCID: PMC1933603 DOI: 10.1371/journal.pone.0000704] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Accepted: 07/02/2007] [Indexed: 11/20/2022] Open
Abstract
Background The p24 family is thought to be somehow involved in endoplasmic reticulum (ER)-to-Golgi protein transport. A subset of the p24 proteins (p24α3, -β1, -γ3 and -δ2) is upregulated when Xenopus laevis intermediate pituitary melanotrope cells are physiologically activated to produce vast amounts of their major secretory cargo, the prohormone proopiomelanocortin (POMC). Methodology/Principal Findings Here we find that transgene expression of p24α3 or p24δ2 specifically in the Xenopus melanotrope cells in both cases causes an effective displacement of the endogenous p24 proteins, resulting in severely distorted p24 systems and disparate melanotrope cell phenotypes. Transgene expression of p24α3 greatly reduces POMC transport and leads to accumulation of the prohormone in large, ER-localized electron-dense structures, whereas p24δ2-transgenesis does not influence the overall ultrastructure of the cells nor POMC transport and cleavage, but affects the Golgi-based processes of POMC glycomaturation and sulfation. Conclusions/Significance Transgenic expression of two distinct p24 family members has disparate effects on secretory pathway functioning, illustrating the specificity and non-redundancy of our transgenic approach. We conclude that members of the p24 family furnish subcompartments of the secretory pathway with specific sets of machinery cargo to provide the proper microenvironments for efficient and correct secretory protein transport and processing.
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Affiliation(s)
- Jeroen R. P. M. Strating
- Department of Molecular Animal Physiology, Nijmegen Centre for Molecular Life Sciences, Institute for Neuroscience, Faculty of Science, Radboud University, Nijmegen, The Netherlands
| | - Gerrit Bouw
- Department of Molecular Animal Physiology, Nijmegen Centre for Molecular Life Sciences, Institute for Neuroscience, Faculty of Science, Radboud University, Nijmegen, The Netherlands
| | - Theo G. M. Hafmans
- Department of Molecular Animal Physiology, Nijmegen Centre for Molecular Life Sciences, Institute for Neuroscience, Faculty of Science, Radboud University, Nijmegen, The Netherlands
| | - Gerard J. M. Martens
- Department of Molecular Animal Physiology, Nijmegen Centre for Molecular Life Sciences, Institute for Neuroscience, Faculty of Science, Radboud University, Nijmegen, The Netherlands
- * To whom correspondence should be addressed. E-mail:
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Menéndez-González M, Pérez-Pinera P, Martínez-Rivera M, Calatayud MT, Blázquez Menes B. APP processing and the APP-KPI domain involvement in the amyloid cascade. NEURODEGENER DIS 2006; 2:277-83. [PMID: 16909010 DOI: 10.1159/000092315] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2005] [Accepted: 12/08/2005] [Indexed: 12/21/2022] Open
Abstract
Alternative APP mRNA splicing can generate isoforms of APP containing a Kunitz protease inhibitor (KPI) domain. KPI is one of the main serine protease inhibitors. Protein and mRNA KPI(+)APP levels are elevated in Alzheimer's disease (AD) brain and are associated with increased amyloid beta deposition. In the last years increasing evidence on multiple points in the amyloid cascade where KPI(+)APP is involved has been accumulated, admitting an outstanding position in the pathogenesis of AD to the KPI domain. This review focuses on the APP processing, the molecular activity of KPI and its physiological and pathological roles and the KPI involvement in the amyloid cascade through the nerve growth factor, the lipoprotein receptor-related protein, the tumor necrosis factor-alpha converting enzyme and the Notch1 protein.
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Affiliation(s)
- M Menéndez-González
- Neurology Department, Hospital Universitario Central de Asturias, Oviedo, Spain.
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Collin RWJ, Martens GJM. The coding sequence of amyloid-beta precursor protein APP contains a neural-specific promoter element. Brain Res 2006; 1087:41-51. [PMID: 16626649 DOI: 10.1016/j.brainres.2006.02.101] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2005] [Revised: 01/23/2006] [Accepted: 02/26/2006] [Indexed: 10/24/2022]
Abstract
The amyloid-beta precursor protein APP is generally accepted to be involved in the pathology of Alzheimer's disease. Since its physiological role is still unclear, we decided to study the function of APP via stable transgenesis in the amphibian Xenopus laevis. However, the application of constructs encoding (mutant) APP fused to the C-terminus of the green fluorescent protein GFP (GFP-APP), and harboring a tissue-specific or an inducible gene promoter did not result in transgene expression of APP in neuronal and neuroendocrine cells. Surprisingly, a construct encoding either Xenopus or human APP fused to the N-terminus of GFP (APP-GFP) gave fluorescence throughout the whole brain of the tadpole, despite the fact that a proopiomelanocortin gene promoter was used to target transgene expression specifically to the intermediate pituitary cells. Detailed analysis with deletion mutants revealed the presence of a neural-specific, transcriptionally active DNA element within the 3'-end of the APP-coding sequence that gave rise to an aberrant transcript and protein in the APP-GFP transgenic animals. The DNA element appears to prevent proper APP transgene expression in Xenopus neuronal and neuroendocrine cells. Thus, the coding sequences of Xenopus and human APP contain a neural-specific promoter element, the physiological significance of which is at present unclear.
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Affiliation(s)
- Rob W J Collin
- Department of Molecular Animal Physiology, Nijmegen Center for Molecular Life Sciences, NCMLS, and Institute for Neuroscience, Radboud University Nijmegen, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands
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van Rosmalen JWG, Born JM, Martens GJM. Prion protein mRNA expression in Xenopus laevis: No induction during melanotrope cell activation. Brain Res 2006; 1075:20-5. [PMID: 16466702 DOI: 10.1016/j.brainres.2005.12.105] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2005] [Revised: 12/12/2005] [Accepted: 12/15/2005] [Indexed: 11/16/2022]
Abstract
In mammals, the prion protein (PrP) is expressed in most tissues, but predominantly in neuronal tissues. Here, we investigated the temporal and spatial mRNA expression of PrP in the non-mammalian South African claw-toed frog Xenopus laevis. PrP transcripts were maternally expressed and detected throughout embryonic development, most strongly from neurulation onwards and including the tadpole stage. Microinjection of PrP mRNA into fertilized Xenopus eggs did not affect early embryonic development. In adult frogs, PrP mRNA expression was observed in all tissues examined, with high expression in brain, pituitary and testis. In Xenopus, the intermediate pituitary melanotrope cells are involved in background adaptation of the animal and produce high levels of the prohormone proopiomelanocortin (POMC) when the melanotrope cells are active (i.e. when the animal is black-adapted). Remarkably and in contrast to most secretory pathway components, PrP was not upregulated in the melanotropes of black-adapted animals, arguing against a direct role of this protein in POMC biosynthesis.
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Affiliation(s)
- Jos W G van Rosmalen
- Department of Molecular Animal Physiology, Nijmegen Center for Molecular Life Sciences (NCMLS) and Institute for Neuroscience, Radboud University Nijmegen, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands
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Collin RWJ, Martens GJM. The amyloid-β precursor-like protein APLP2 and its relative APP are differentially regulated during neuroendocrine cell activation. Mol Cell Neurosci 2005; 30:429-36. [PMID: 16154762 DOI: 10.1016/j.mcn.2005.08.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2005] [Revised: 08/03/2005] [Accepted: 08/16/2005] [Indexed: 10/25/2022] Open
Abstract
The amyloid-beta precursor-like protein APLP2 is structurally and functionally related to the amyloid-beta precursor protein APP, the protein generally accepted to be involved in Alzheimer's disease. Since we previously observed that the levels of APP mRNA and protein were up-regulated threefold in the active intermediate pituitary melanotrope cells of black-adapted Xenopus laevis, we now decided to study the regulation of APLP2 in these physiologically inducible neuroendocrine cells. Interestingly, both the mRNA and protein levels of Xenopus APLP2 were similar in the melanotrope cells of black and white frogs. Newly synthesized APLP2 became glycosylated and sulfated, chondroitin sulfate glycosaminoglycan chains were added, and eventually the protein was proteolytically cleaved. Unlike for APP, no phosphorylated APLP2 was observed. Our results show that, although APP and APLP2 are thought to be functionally related, their responses to neuroendocrine cell activation differ, suggesting distinct roles for these proteins.
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Affiliation(s)
- Rob W J Collin
- Department of Molecular Animal Physiology, Nijmegen Center for Molecular Life Sciences (NCMLS) and Institute for Neuroscience, Radboud University Nijmegen, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands
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