Co-reporter:Kenichi Nagata;Sumiko Kiryu-Seo;Hiromi Tamada;Fumi Okuyama-Uchimura;Hiroshi Kiyama;Takaomi C. Saido
Acta Neuropathologica 2016 Volume 132( Issue 1) pp:111-126
Publication Date(Web):2016/07/01
DOI:10.1007/s00401-016-1554-0
The membrane-bound metalloprotease endothelin-converting enzyme-like 1 (ECEL1) has been newly identified as a causal gene of a specific type of distal arthrogryposis (DA). In contrast to most causal genes of DA, ECEL1 is predominantly expressed in neuronal cells, suggesting a unique neurogenic pathogenesis in a subset of DA patients with ECEL1 mutation. The present study analyzed developmental motor innervation and neuromuscular junction formation in limbs of the rodent homologue damage-induced neuronal endopeptidase (DINE)-deficient mouse. Whole-mount immunostaining was performed in DINE-deficient limbs expressing motoneuron-specific GFP to visualize motor innervation throughout the limb. Although DINE-deficient motor nerves displayed normal trajectory patterns from the spinal cord to skeletal muscles, they indicated impaired axonal arborization in skeletal muscles in the forelimbs and hindlimbs. Systematic examination of motor innervation in over 10 different hindlimb muscles provided evidence that DINE gene disruption leads to insufficient arborization of motor nerves after arriving at the skeletal muscle. Interestingly, the axonal arborization defect in foot muscles appeared more severe than in other hindlimb muscles, which was partially consistent with the proximal–distal phenotypic discordance observed in DA patients. Additionally, the number of innervated neuromuscular junction was significantly reduced in the severely affected DINE-deficient muscle. Furthermore, we generated a DINE knock-in (KI) mouse model with a pathogenic mutation, which was recently identified in DA patients. Axonal arborization defects were clearly detected in motor nerves of the DINE KI limb, which was identical to the DINE-deficient limb. Given that the encoded sequences, as well as ECEL1 and DINE expression profiles, are highly conserved between mouse and human, abnormal arborization of motor axons and subsequent failure of NMJ formation could be a primary cause of DA with ECEL1 mutation.
Co-reporter:Per Nilsson, Takashi Saito, and Takaomi C Saido
ACS Chemical Neuroscience 2014 Volume 5(Issue 7) pp:499
Publication Date(Web):May 22, 2014
DOI:10.1021/cn500105p
Amyloid β-peptide (Aβ) accumulation is a key characteristic of Alzheimer’s disease (AD); therefore, mouse models of AD exhibiting Aβ pathology are valuable tools for unraveling disease mechanisms. However, the overexpression of Aβ precursor protein (APP) used in previous mouse models may cause Aβ-independent artifacts that influence data interpretation. To circumvent these problems, we used an APP knock-in (KI) strategy to introduce mutations to the mouse APP gene to develop a new generation of AD mouse models. These new models, termed APPNL-F and APPNL-G-F, have endogenous APP levels and develop robust Aβ amyloidosis, which induce synaptic degeneration and memory impairments. Thus, we suggest that these novel APP KI mice will serve as important tools to elucidate molecular mechanisms of AD.Keywords: Alzheimer’s disease; APP knock-in; Aβ; mouse models
Co-reporter:Per Nilsson;Nobuhisa Iwata;Shin-ichi Muramatsu;Lars O. Tjernberg;Bengt Winblad;Takaomi C. Saido
Journal of Cellular and Molecular Medicine 2010 Volume 14( Issue 4) pp:741-757
Publication Date(Web):
DOI:10.1111/j.1582-4934.2010.01038.x
Abstract
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Introduction
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Targets and ongoing research
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NGF
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Neurotrophic function of NGF
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Levels of NGF in AD
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Role of NGF in AD
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NGF as a therapeutic agent
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Development of NGF gene therapy
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In vivo gene delivery of NGF
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BDNF
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Neprilysin
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Potential gene therapy target candidates
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Down-regulation of AD-associated proteins by siRNA
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Concluding remarks
Alzheimer’s disease (AD) is the major cause of dementia in the elderly, leading to memory loss and cognitive decline. The mechanism underlying onset of the disease has not been fully elucidated. However, characteristic pathological manifestations include extracellular accumulation and aggregation of the amyloid β-peptide (Aβ) into plaques and intracellular accumulation and aggregation of hyperphosphorylated tau, forming neurofibrillary tangles. Despite extensive research worldwide, no disease modifying treatment is yet available. In this review, we focus on gene therapy as a potential treatment for AD, and summarize recent work in the field, ranging from proof-of-concept studies in animal models to clinical trials. The multifactorial causes of AD offer a variety of possible targets for gene therapy, including two neurotrophic growth factors, nerve growth factor and brain-derived neurotrophic factor, Aβ-degrading enzymes, such as neprilysin, endothelin-converting enzyme and cathepsin B, and AD associated apolipoprotein E. This review also discusses advantages and drawbacks of various rapidly developing virus-mediated gene delivery techniques for gene therapy. Finally, approaches aiming at down-regulating amyloid precursor protein (APP) and β-site APP cleaving enzyme 1 levels by means of siRNA-mediated knockdown are briefly summarized. Overall, the prospects appear hopeful that gene therapy has the potential to be a disease modifying treatment for AD.
Co-reporter:Ryuichi Nakajima;Keizo Takao;Shu-Ming Huang;Jiro Takano
Molecular Brain 2008 Volume 1( Issue 1) pp:
Publication Date(Web):2008 December
DOI:10.1186/1756-6606-1-7
Calpastatin is an endogenous inhibitor of calpain, intracellular calcium-activated protease. It has been suggested to be involved in molecular mechanisms of long-term plasticity and excitotoxic pathways. However, functions of calpastatin in vivo are still largely unknown. To examine the physiological roles of calpastatin, we subjected calpastatin-knockout mice to a comprehensive behavioral test battery.Calpastatin-knockout mice showed decreased locomotor activity under stressful environments, and decreased acoustic startle response, but we observed no significant change in hippocampus-dependent memory function.These results suggest that calpastatin is likely to be more closely associated with affective rather than cognitive aspects of brain function.
Co-reporter:Akira Masuda, Yuki Kobayashi, Naomi Kogo, Takashi Saito, Takaomi C. Saido, Shigeyoshi Itohara
Neurobiology of Learning and Memory (November 2016) Volume 135() pp:73-82
Publication Date(Web):1 November 2016
DOI:10.1016/j.nlm.2016.07.001
•App-KI mice carrying NL-G-F mutations showed deficits in broad cognitive domains.•App-KI mice carrying NL-F mutations showed moderate abnormalities.•Gender effects were detected histopathologically in NL-G-F mice.•App-KI mice are useful as animal models for AD.Transgenic mouse models of Alzheimer’s disease (AD) with nonphysiologic overexpression of amyloid precursor protein (APP) exhibit various unnatural symptoms/dysfunctions. To overcome this issue, mice with single humanized App knock-in (KI) carrying Swedish (NL), Beyreuther/Iberian (F), and Arctic (G) mutations in different combinations were recently developed. The validity of these mouse models of AD from a behavioral viewpoint, however, has not been extensively evaluated. Thus, using an automated behavior monitoring system, we analyzed various behavioral domains, including executive function, and learning and memory. The App-KI mice carrying NL-G-F mutations showed clear deficits in spatial memory and flexible learning, enhanced compulsive behavior, and reduced attention performance. Mice carrying NL-F mutations exhibited modest abnormalities. The NL-G-F mice had a greater and more rapid accumulation of Aβ deposits and glial responses. These findings reveal that single pathologic App-KI is sufficient to produce deficits in broad cognitive domains and that App-KI mouse lines with different levels of pathophysiology are useful models of AD.Download high-res image (124KB)Download full-size image
