http://hdl.handle.net/10027/7213 Wed, 19 Jun 2013 04:29:01 GMT 2013-06-19T04:29:01Z http://hdl.handle.net/10027/8715 Intraneuronal Aβ detection in 5xFAD mice by a new Aβ-specific antibody Youmans, Katherine L.; Tai, Leon M.; Kanekiyo, Takahisa; Stine Jr, W Blaine; Michon, Sara-Claude; Nwabuisi-Heath, Evelyn; Manelli, Arlene M.; Fu, Yifan; Riordan, Sean; Eimer, William A; Binder, Lester; Bu, Guojun; Yu, Chunjiang; Hartley, Dean M.; LaDu, Mary Jo Background: The form(s) of amyloid-b peptide (Ab) associated with the pathology characteristic of Alzheimer’s disease (AD) remains unclear. In particular, the neurotoxicity of intraneuronal Ab accumulation is an issue of considerable controversy; even the existence of Ab deposits within neurons has recently been challenged by Winton and co-workers. These authors purport that it is actually intraneuronal APP that is being detected by antibodies thought to be specific for Ab. To further address this issue, an anti-Ab antibody was developed (MOAB- 2) that specifically detects Ab, but not APP. This antibody allows for the further evaluation of the early accumulation of intraneuronal Ab in transgenic mice with increased levels of human Ab in 5xFAD and 3xTg mice. Results: MOAB-2 (mouse IgG2b) is a pan-specific, high-titer antibody to Ab residues 1-4 as demonstrated by biochemical and immunohistochemical analyses (IHC), particularly compared to 6E10 (a commonly used commercial antibody to Ab residues 3-8). MOAB-2 did not detect APP or APP-CTFs in cell culture media/lysates (HEK-APPSwe or HEK-APPSwe/BACE1) or in brain homogenates from transgenic mice expressing 5 familial AD (FAD) mutation (5xFAD mice). Using IHC on 5xFAD brain tissue, MOAB-2 immunoreactivity co-localized with C-terminal antibodies specific for Ab40 and Ab42. MOAB-2 did not co-localize with either N- or C-terminal antibodies to APP. In addition, no MOAB-2-immunreactivity was observed in the brains of 5xFAD/BACE-/- mice, although significant amounts of APP were detected by N- and C-terminal antibodies to APP, as well as by 6E10. In both 5xFAD and 3xTg mouse brain tissue, MOAB-2 co-localized with cathepsin-D, a marker for acidic organelles, further evidence for intraneuronal Ab, distinct from Ab associated with the cell membrane. MOAB-2 demonstrated strong intraneuronal and extra-cellular immunoreactivity in 5xFAD and 3xTg mouse brain tissues. Conclusions: Both intraneuronal Ab accumulation and extracellular Ab deposition was demonstrated in 5xFAD mice and 3xTg mice with MOAB-2, an antibody that will help differentiate intracellular Ab from APP. However, further investigation is required to determine whether a molecular mechanism links the presence of intraneuronal Ab with neurotoxicity. As well, understanding the relevance of these observations to human AD patients is critical. © 2012 Youmans et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Sun, 01 Jan 2012 06:00:00 GMT http://hdl.handle.net/10027/8715 2012-01-01T06:00:00Z http://hdl.handle.net/10027/8592 Introducing Human APOE into Aβ Transgenic Mouse Models Tai, Leon M.; Youmans, Katherine L.; Jungbauer, Lisa; Yu, Chunjiang; LaDu, Mary Jo Apolipoprotein E (apoE) and apoE/amyloid-β (Aβ) transgenic (Tg) mouse models are critical to understanding apoE-isoform effects on Alzheimer’s disease risk. Compared to wild type, apoE−/− mice exhibit neuronal deficits, similar to apoE4-Tg compared to apoE3-Tg mice, providing a model for Aβ-independent apoE effects on neurodegeneration. To determine the effects of apoE on Aβ-induced neuropathology, apoE−/− mice were crossed with Aβ-Tg mice, resulting in a significant delay in plaque deposition. Surprisingly, crossing human-apoE-Tg mice with apoE−/−/Aβ-Tg mice further delayed plaque deposition, which eventually developed in apoE4/Aβ-Tg mice prior to apoE3/Aβ-Tg. One approach to address hAPOE-induced temporal delay in Aβ pathology is an additional insult, like head injury. Another is crossing human-apoE-Tg mice with Aβ-Tg mice that have rapid-onset Aβ pathology. For example, because 5xFAD mice develop plaques by 2 months, the prediction is that human-apoE/5xFAD-Tg mice develop plaques around 6 months and 12 months before other human-apoE/Aβ-Tg mice. Thus, tractable models for human-apoE/Aβ-Tg mice continue to evolve. Copyright © 2011 Leon M. Tai et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. doi:10.4061/2011/810981 Sat, 01 Jan 2011 06:00:00 GMT http://hdl.handle.net/10027/8592 2011-01-01T06:00:00Z http://hdl.handle.net/10027/8577 Pathogenic Forms of Tau Inhibit Kinesin-Dependent Axonal Transport Through a Tau-Dependent Mechanism Involving Activation of Axonal Phosphotransferases Morfini, Gerardo; Kanaan, Nicholas; LaPointe, Nichole; Pigino, Gustavo; Patterson, Kristina R.; Song, Yuyu; Andreadis, Athena Aggregated filamentous forms of hyperphosphorylated tau (a microtubule-associated protein) represent pathological hallmarks of Alzheimer’s disease (AD) and other tauopathies. While axonal transport dysfunction is thought to represent a primary pathogenic factor in AD and other neurodegenerative diseases, the direct molecular link between pathogenic forms of tau and deficits in axonal transport remain unclear. Recently, we demonstrated that filamentous, but not soluble, forms of wild-type tau inhibit anterograde, kinesin-based fast axonal transport (FAT) by activating axonal protein phosphatase 1 (PP1) and glycogen synthase kinase 3 (GSK3), independent of microtubule binding. Here, we demonstrate that amino acids 2-18 of tau, comprising a phosphatase-activating domain (PAD), are necessary and sufficient for activation of this pathway in axoplasms isolated from squid giant axons. Various pathogenic forms of tau displaying increased exposure of PAD inhibited anterograde FAT in squid axoplasm. Importantly, immunohistochemical studies using a novel PAD-specific monoclonal antibody in human postmortem tissue indicated that increased PAD exposure represents an early pathogenic event in AD that closely associates in time with AT8 immunoreactivity, an early marker of pathological tau. We propose a model of pathogenesis in which disease-associated changes in tau conformation lead to increased exposure of PAD, activation of PP1-GSK3 and inhibition of FAT. Results from these studies reveal a novel role for tau in modulating axonal phosphotransferases and provide a molecular basis for a toxic gain-of-function associated with pathogenic forms of tau. © 2011 by Society for Neuroscience, Journal of Neuroscience DOI: 10.1523/JNEUROSCI.0560-11.2011 Fri, 01 Jul 2011 05:00:00 GMT http://hdl.handle.net/10027/8577 2011-07-01T05:00:00Z http://hdl.handle.net/10027/8476 Oligodendrocyte Progenitor Cells Proliferate And Survive In An Immature State Following Treatment With An Axolemma-Enriched Fraction. Becker-Catania, Sara G.; Nelson, Julie K.; Olivares, Shantel; Chen, Shu-Jen; DeVries, George H. The ability of an axolemma-enriched fraction (AEF) to influence the proliferation, survival, and differentiation of oligodendrocyte progenitor cells (OPC) was evaluated. Following addition of AEF to cultured OPC, the AEF associated with the outer surface of OPC so that subsequent metabolic events were likely mediated by direct AEF-OPC contact. Addition of AEF to the cultured OPC resulted in a dose- and time-dependent increase in proliferation which was partially dependent on Akt and MAP kinase activation. The major mitogen in a soluble 2.0 M NaCl extract of the AEF was identified as aFGF and accounted for 50% of the mitogenicity. The remaining 50% of the mitogenicity had properties consistent with bFGF but was not unequivocally identified. Under conditions that limit the survival of OPC in culture, AEF treatment prolonged the survival of the OPC. Antigenic and morphological examination of the AEF-treated OPC indicated that the AEF treatment helped the OPC survive in a more immature state. The potential downstream metabolic pathways potentially activated in OPC by AEF and the consequences of these activated pathways are discussed. The results of these studies are consistent with the view that direct contact of axons with OPC stimulates their proliferation and survival while preventing their differentiation. The final version of record is available at http://www.asnneuro.org/an/003/an003e053.htm DOI: 10.1042/AN20100035 Sat, 01 Jan 2011 06:00:00 GMT http://hdl.handle.net/10027/8476 2011-01-01T06:00:00Z