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Tohru Yamamoto

Publications and source records attributed to Tohru Yamamoto.

8 recordsLinked to original sources
PubMed2006

MDGA1, an IgSF molecule containing a MAM domain, heterophilically associates with axon- and muscle-associated binding partners through distinct structural domains.

Molecules belonging to the immunoglobulin superfamily (IgSF) are reported to be involved in intercellular communication in the developing nervous system. We have identified a novel GPI-anchored IgSF molecule containing a MAM (meprin, A5 protein, PTPmu) domain, named MDGA1, by screening for genes that are expressed by subpopulations of cells in the embryonic chick spinal cord. MDGA1 is selectively expressed by brachial LMCm motor neurons, some populations of DRG neurons, and interneurons. We found that MDGA1 interacts heterophilically with axon-rich regions, mainly through its MAM domain. Interestingly, MDGA1 also interacts with differentiating muscle through its N-terminal region, which contains Ig domains. These results suggest that MDGA1 functions in MDGA1-expressing nerves en route to and at their target site.

Animals↗
PubMed2006

Trafficking of Alzheimer's disease-related membrane proteins and its participation in disease pathogenesis.

Alzheimer's disease (AD) is a common neurodegenerative disorder that causes senile dementia. The pathological characteristics are the appearance of neurofibrillary tangles comprising abnormally phosphorylated tau and senile plaques composed of amyloid beta-protein depositions. Amyloid beta-protein precursor (APP) and presenilin (PS) are known to be causative genes of familial AD. Recent analyses have documented that APP functions in the axonal transport of vesicles and PS regulates intracellular protein trafficking. Dystrophic neurites, in which APP and Alcadein accumulate in swollen axons, are also observed in AD brain. These pathological characteristics and the features of AD-related proteins suggest that AD is a disease of the vesicular transport system. Here we review recent progress of research on AD pathogenesis from the viewpoint of membrane trafficking.

Alzheimer Disease↗
PubMed2004

Langmuir and Langmuir-Blodgett films of amphiphilic bistable rotaxanes.

A series of amphiphilic bistable [2]rotaxanes--in which a ring-shaped component, the tetracationic cyclophane, cyclobis(paraquat-p-phenylene), has been assembled around two recognition sites, a tetrathia-fulvalene (TTF) unit and a 1,5-dioxynaphthalene (DNP) ring system, situated apart at different strategic locations within the central polyether section of an amphiphilic dumbbell component that is terminated by a hydrophobic tetraarylmethane-based stopper (near the TTF unit) at one end and by a hydrophilic tetraarylmethane-based stopper (near the DNP ring system) at the other end--has been designed and synthesized. The effects of systematic changes in the constitutions of the three ethylene glycol tails (diethylene or tetraethylene glycol) and end groups (hydroxyl or methoxyl functions) attached to the hydrophilic stoppers on Langmuir film balance and surface rheology experiments at 20 degreesC were examined to determine the monolayer stabilities and co-conformations of the [2] rotaxanes and their free dumbbell counterparts. These experiments allow us to propose a model for the rotaxane's structures at different surface pressures. All the [2]rotaxanes form stable Langmuir films. These films typically pass from a liquid-expanded region to a liquid-condensed region. The transition between the two regions was either directly observed or ascertained using film stability experiments. Film balance and surface rheology experiments showed that the addition of the tetracationic cyclophane component and hydroxyl end groups markedly increased the stabilities and viscoelasticity of the films.

Membranes, Artificial↗
PubMed2004

Coordinated metabolism of Alcadein and amyloid beta-protein precursor regulates FE65-dependent gene transactivation.

The Alcadeins (Alcs)/calsyntenins and the amyloid beta-protein precursor (APP) associate with each other in the brain by binding via their cytoplasmic domains to X11L (the X11-like protein). We previously reported that the formation of this APP-X11L-Alc tripartite complex suppresses the metabolic cleavages of APP. We show here that the metabolism of the Alcs markedly resembles that of APP. The Alcs are subjected to a primary cleavage event that releases their extracellular domain. Alcs then undergo a secondary presenilin-dependent gamma-cleavage that leads to the secretion of the amyloid beta-protein-like peptide and the liberation of an intracellular domain fragment (AlcICD). However, when Alc is in the tripartite complex, it escapes from these cleavages, as does APP. We also found that AlcICD suppressed the FE65-dependent gene transactivation activity of the APP intracellular domain fragment, probably because AlcICD competes with the APP intracellular domain fragment for binding to FE65. We propose that the Alcs and APP are coordinately metabolized in neurons and that their cleaved cytoplasmic fragments are reciprocally involved in the regulation of FE65-dependent gene transactivation. Any imbalance in the metabolism of Alcs and APP may influence the FE65-dependent gene transactivation, which together with increased secretion of amyloid beta-protein may contribute to neural disorders.

Amyloid Precursor Protein Secretases↗
PubMed2002

Two-dimensional molecular electronics circuits.

Addressing an array of bistable [2]rotaxanes through a two-dimensional crossbar arrangement provides the device element of a current-driven molecular electronic circuit. The development of the [2]rotaxane switches through an iterative, evolutionary process is described. The arrangement reported here allows both memory and logic functions to use the same elements.

Journal Article↗