Are alpha-synuclein fragments novel substrates of glutaminyl cyclase?
Final Report Abstract
The aim of the project was to investigate whether fragments of α-synuclein represent new substrates for the enzyme glutaminyl cyclase (QC) and its isoenzyme (isoQC). Using enzymatic activity assays and peptide substrates, we demonstrated that both QC and isoQC are capable of converting the α-synuclein-79 fragment with high catalytic efficiency into the pGlu-modified variant. The α-synuclein-99 fragment, however, was converted with high catalytic efficiency only by QC but with poor catalytic efficiency by isoQC into the pGlu variant. Moreover, α-synuclein was shown to be forced to aggregation by Abeta peptides, in particular by pGlu-Abeta peptides. We developed and characterized novel rabbit polyclonal antibodies which specifically detect the pGlu-α-synuclein-79 and pGlu-α-synuclein-99 fragments in mouse and human brain tissue. The pGlu-α-synuclein-79 antibody labelled the cytoplasm of pyramidal neurons and Abeta plaque-associated dystrophic neurites and activated astrocytes in brains of transgenic mice with amyloid pathology and in human AD brain tissue. In contrast, the pGlu-α-synuclein-99 antiserum resulted in a more nuclear labelling of neurons and in additional labelling of glial cells. This is supportive for a putative role of this fragment in transcriptional regulation. These data provide the basis for future detailed studies on the temporal and spatial appearance of pGlu-modified α-synuclein peptides, their neurotoxicity and pathogenic potential for the development of protein aggregation disorders such as Alzheimer’s disease and Parkinson’s disease. It is planned to develop mouse monoclonal antibodies against the pGlu-α-synuclein-79 and pGlu-αsynuclein-99 epitopes to have unlimited antibody amounts for our own ongoing and future studies and to supply collaborators. We were particularly surprised – and impressed – by the detection of pGlu-α-synuclein-79 in dystrophic neurites and in reactive astrocytes in proximity to Abeta plaques in brains of Alzheimer’s disease patients and in a transgenic mouse model developing Abeta plaques. We will continue to investigate the generation, propagation in brain and disease-related effects of this peptide. There was news coverage at www.alzforum.org on the publication Höfling et al. (2016) about the development of new research tools that were used in the project (http://www.alzforum.org/news/research-news/new-app-antibodies-expose-variation-mouse-modelsad).
Publications
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(2014) Mouse strain and brain region-specific expression of the glutaminyl cyclases QC and isoQC. Int. J. Devl. Neurosci. 36, 64-73
C. Höfling, H. Indrischek, T. Höpcke, A. Waniek, H. Cynis, B. Koch, S. Schilling, H.U. Demuth, M. Morawski, S. Roßner, M. Hartlage-Rübsamen
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(2015) Identification of thyrotropin-releasing hormone as hippocampal glutaminyl cyclase substrate in neurons and reactive astrocytes. Biochim. Biophys. Acta Molec. Basis Dis. 1852, 146-155
A. Waniek, M. Hartlage-Rübsamen, C. Höfling, A. Kehlen, S. Schilling, H.U. Demuth, S. Roßner
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(2015) Isoglutaminyl cyclase contributes to CCL2-driven neuroinflammation in Alzheimer’s disease. Acta Neuropathol. 129, 565-583
M. Hartlage-Rübsamen, A. Waniek, J. Meißner, M. Morawski, S. Schilling, C. Jäger, M. Kleinschmidt, H. Cynis, A. Kehlen, T. Arendt, H.U. Demuth, S. Roßner
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(2016) Differential transgene expression patterns in Alzheimer mouse models revealed by novel human APP-specific antibodies. Aging Cell 15, 953-963
C. Höfling, M. Morawski, U. Zeitschel, K. Moschke, F. Canneva, S. von Hörsten, C. Jäger, E. Kremmer, S. Roßner, S. Lichtenthaler, P.H. Kuhn
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(2016) Early changes in hippocampal neurogenesis in transgenic mouse models for Alzheimer's disease. Mol. Neurobiol. 53, 5796-5806
M.S. Unger, J. Marschallinger, J. Kaindl, C. Höfling, S. Roßner, M.T. Heneka, A. van der Linden, L. Aigner
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(2016) Early pathologic amyloid induces hypersynchrony of BOLD resting-state networks in transgenic mice and provides an early therapeutic window before amyloid plaque deposition. Alzheimer’s & Dementia 12, 964-976
D. Shah, J. Praet, A. Latif Hernandez, C. Höfling, C. Anckaerts, F. Bard, M. Morawski, J. Detrez, E. Prinsen, A. Villa, W. de Vos, A. Maggi, R. D’Hooge, D. Balschun, S. Roßner, M. Verhoye, A. Van der Linden
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A glutaminyl cyclase-catalyzed α-synuclein modification identified in human synucleinopathies. Acta Neuropathologica, 2021, online first.
Hartlage-Rübsamen, M., Bluhm, A., Moceri, S. et al.
