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King MR, Anderson NJ, Deciu M, Guernsey LS, Cundiff M, Hajizadeh S, Jolivalt CG. Insulin deficiency, but not resistance, exaggerates cognitive deficits in transgenic mice expressing human amyloid and tau proteins. Reversal by Exendin-4 treatment. J Neurosci Res 2020; 98:2357-2369. [PMID: 32737929 DOI: 10.1002/jnr.24706] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 06/29/2020] [Accepted: 07/12/2020] [Indexed: 12/24/2022]
Abstract
Epidemiological studies have pointed at diabetes as a risk factor for Alzheimer's disease (AD) and this has been supported by several studies in animal models of both type 1 and type 2 diabetes. However, side-by-side comparison of the two types of diabetes is limited. We investigated the role of insulin deficiency and insulin resistance in the development of memory impairments and the effect of Exendin-4 (Ex4) treatment in a mouse model of AD. Three-4-month-old female wild type (WT) mice and mice overexpressing human tau and amyloid precursor protein (TAPP) were injected with streptozotocin (STZ) or fed a high-fat diet (HFD). A second study was performed in TAPP-STZ mice treated with Ex4, a long-lasting analog of GLP-1. Plasma and brain were collected at study termination for ELISA, Western blot, and immunohistochemistry analysis. Learning and memory deficits were impaired in TAPP transgenic mice compared with WT mice at the end of the study. Deficits were exaggerated by insulin deficiency in TAPP mice but 12 weeks of insulin resistance did not affect memory performances in either WT or TAPP mice. Levels of phosphorylated tau were increased in the brain of WT-STZ and TAPP-STZ mice but not in the brain of WT or TAPP mice on HFD. In the TAPP-STZ mice, treatment with Ex4 initiated after established cognitive deficits ameliorated learning, but not memory, impairments. This was accompanied by the reduction of amyloid β and phosphorylated tau expression. Theses studies support the role of Ex4 in AD, independently from its actions on diabetes.
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Affiliation(s)
- Matthew R King
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Nicholas J Anderson
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Mihaela Deciu
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Lucie S Guernsey
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Morgan Cundiff
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Shohreh Hajizadeh
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Corinne G Jolivalt
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
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Kubo A, Misonou H, Matsuyama M, Nomori A, Wada-Kakuda S, Takashima A, Kawata M, Murayama S, Ihara Y, Miyasaka T. Distribution of endogenous normal tau in the mouse brain. J Comp Neurol 2018; 527:985-998. [PMID: 30408165 PMCID: PMC6587864 DOI: 10.1002/cne.24577] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Revised: 10/26/2018] [Accepted: 10/29/2018] [Indexed: 01/09/2023]
Abstract
Tau is a microtubule‐associated protein (MAP) that is localized to the axon. In Alzheimer's disease (AD), the distribution of tau undergoes a remarkable alteration, leading to the formation of tau inclusions in the somatodendritic compartment. While the abnormal aggregated tau has been extensively studied in human patient tissues and animal models of AD, how normal tau localizes to the axon, which would be the foundation to understand how the mis‐localization occurs, has not been well studied due to the poor detectability of normal unaggregated tau in vivo. Therefore, we developed immunohistochemical techniques that can detect normal mouse and human tau in brain tissues with high sensitivity. Using these techniques, we demonstrate the global distribution of tau in the mouse brain and confirmed that normal tau is exclusively localized to the axonal compartment in vivo. Interestingly, tau antibodies strongly labeled nonmyelinated axons such as hippocampal mossy fibers, while white matters generally exhibited low levels of immunoreactivity. Furthermore, mouse tau is highly expressed not only in neurons but also in oligodendrocytes. With super resolution imaging using the stimulated‐depletion microscopy, axonal tau appeared punctate rather than fibrous, indicating that tau decorates microtubules sparsely. Co‐labeling with presynaptic and postsynaptic markers revealed that normal tau is not localized to synapses but sparsely distributes in the axon. Taken together, this study reports novel antibodies to investigate the localization and mis‐localization of tau in vivo and novel findings of normal tau localization in the mouse brain.
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Affiliation(s)
- Atsuko Kubo
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, Japan
| | - Hiroaki Misonou
- Laboratory of Ion Channel Pathophysiology, Graduate School of Brain Science, Doshisha University, Kyoto, Japan.,Center for Research in Neurodegenerative Diseases, Doshisha University, Kyoto, Japan
| | - Makoto Matsuyama
- Division of Molecular Genetics, Shigei Medical Research Institute, Okayama, Japan
| | - Akane Nomori
- Division of Molecular Genetics, Shigei Medical Research Institute, Okayama, Japan
| | - Satoko Wada-Kakuda
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, Japan
| | - Akihiko Takashima
- Laboratory for Alzheimer's Disease, Department of Life Science, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, 171-8588, Tokyo, Japan.,Center for Research in Neurodegenerative Diseases, Doshisha University, Kyoto, Japan
| | - Mitsuhiro Kawata
- Department of Physical Therapy, School of Health Sciences, Bukkyo University, Nakagyo-ku, Kyoto, 604-8418, Japan
| | - Shigeo Murayama
- Neuropathology, The Brain Bank for Aging Research, Tokyo Metropolitan Geriatric Hospital, Tokyo, Japan
| | - Yasuo Ihara
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, Japan.,Laboratory of Cognition and Aging, Graduate School of Brain Science, Doshisha University, Kyoto, Japan
| | - Tomohiro Miyasaka
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, Japan.,Center for Research in Neurodegenerative Diseases, Doshisha University, Kyoto, Japan
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