The Nuclear Inclusion a (NIa) Protease of Turnip Mosaic Virus (TuMV) Cleaves Amyloid-β

Abstract

BackgroundThe nuclear inclusion a (NIa) protease of turnip mosaic virus (TuMV) is responsible for the processing of the viral polyprotein into functional proteins. NIa was previously shown to possess a relatively strict substrate specificity with a preference for Val-Xaa-His-Gln↓, with the scissile bond located after Gln. The presence of the same consensus sequence, Val12-His-His-Gln15, near the presumptive α-secretase cleavage site of the amyloid-β (Aβ) peptide led us to hypothesize that NIa could possess activity against Aβ.Methodology/Principal FindingsWestern blotting results showed that oligomeric as well as monomeric forms of Aβ can be degraded by NIa in vitro. The specific cleavage of Aβ was further confirmed by mass spectrometry analysis. NIa was shown to exist predominantly in the cytoplasm as observed by immunofluorescence microscopy. The overexpression of NIa in B103 neuroblastoma cells resulted in a significant reduction in cell death caused by both intracellularly generated and exogenously added Aβ. Moreover, lentiviral-mediated expression of NIa in APPsw/PS1 transgenic mice significantly reduced the levels of Aβ and plaques in the brain.Conclusions/SignificanceThese results indicate that the degradation of Aβ in the cytoplasm could be a novel strategy to control the levels of Aβ, plaque formation, and the associated cell death.

Disruption of Ethylene Responses by Turnip mosaic virus Mediates Suppression of Plant Defense against the Green Peach Aphid Vector

“…NIa-Pro possesses relatively strict substrate specificity, cleaving after Gln at Val-Xaa-HisGln (Kang et al, 2001). A previous study demonstrated that the same consensus sequence site, Val-Xaa-HisGln, exists in an amyloid-b peptide from animals and that NIa-Pro has activity against this site (Han et al, 2010). It is possible that NIa-Pro also cleaves a plant protein that possesses the NIa-Pro cleavage substrate.…”

Sharka: The Past, The Present and The Future

“…In addition, NIa proteinase possesses structural motifs shared with cellular serine proteases with the substitution of serine by a cysteine as the active site nucleophile. The specificity of enzyme and control its activity is discussed in some recently published papers [72,73,74], which are focused on the investigation of recombinant viruses and their host interactions. Mutation in the Lys(27) of NIa-Pro has established the role of this enzyme in the determination of host specificity.…”

Impairment of adenylyl cyclase 2 function and expression in hypoxanthine phosphoribosyltransferase-deficient rat B103 neuroblastoma cells as model for Lesch–Nyhan disease: BODIPY–forskolin as pharmacological tool

“…B103 cells possess neuron-like properties, and upon exposure to cAMP-increasing compounds, cell morphology changes in terms of rounding of the cell body and neurite extension, indicative for differentiation (Schubert et al 1974;Ishii et al 1990). Major advantages of B103 cells are that they are well characterized and broadly used in the neurosciences since the 1970s until now for topics encompassing addiction, cellular ultrastructure, differentiation, tumor cell biology, neurodegeneration, neurotoxicity, receptor function, and signal transduction, and that they grow rapidly and reproducibly (Schubert et al 1974;Cabral et al 1987;Kokoz et al 1999;Kawanabe et al 2001;Han et al 2002;Tanura et al 2006;Crespo-López et al 2007;Han et al 2010;Kato et al 2012). A HPRT-deficient clone of B103 cells was generated by selection of 6-thioguanine-resistant cells (Zoref-Shani et al 1993).…”