Masami Hayashi

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Gaining an understanding of the structural and functional roles of cholesterol in membrane lipid rafts is a critical issue in studies on cellular signaling and because of the possible involvement of lipid rafts in various diseases. We have focused on the potential of perfringolysin O (theta-toxin), a cholesterol-binding cytolysin produced by Clostridium(More)
To explore whether any co-stimulatory receptor(s) for TCR signaling is involved in the age-associated decline in T-cell function, we analyzed changes in these receptors in freshly isolated mouse CD4(+) T cells during aging. Both the mRNA and protein expression levels of CTLA-4 and PD-1, negative co-stimulatory receptors, increase with aging. No such changes(More)
Cholesterol is one of the major constituents of mammalian cell membranes. It plays an indispensable role in regulating the structure and function of cell membranes and affects the pathology of various diseases. In recent decades much attention has been paid to the existence of membrane microdomains, generally termed lipid "rafts", and cholesterol, along(More)
PURPOSE It is well known that m-calpain, a ubiquitous calpain, is involved in cataract formation in rodent lens. Involvement of Lp82, a lens-specific calpain, in the cataract formation is also suggested. However, the exact relationship between Lp82-mediated proteolysis and lens opacification has not yet been established. We therefore compared Lp82- and(More)
We isolated a cholesterol-enriched membrane subpopulation from the so-called lipid raft fractions of Jurkat T-cells by taking advantage of its selective binding to a cholesterol-binding probe, BCtheta. The BCtheta-bound membrane subpopulation has a much higher cholesterol/phospholipid (C/P) molar ratio (approximately 1.0) than the BCtheta-unbound population(More)
To examine the involvement of lipid rafts in an age-associated decline in T cell function, we analyzed the effect of aging on the constituents of lipid rafts in resting mouse CD4(+) T cells. We found a pronounced, age-dependent reduction in PAG/Cbp, which is involved in the regulation of Src family kinases (SFKs) by recruiting Csk (a negative regulator of(More)
The plasma membrane of eukaryotic cells participates in signal transduction and many other cellular events to maintain the physiological state of cells. In recent decades, much attention has been paid to membrane microdomains, called lipid rafts or membrane rafts, as signaling platforms in the plasma membrane. Lipid rafts are lateral lipid clusters enriched(More)
The C-terminal domain (D4) of perfringolysin O binds selectively to cholesterol in cholesterol-rich microdomains. To address the issue of whether cholesterol-rich microdomains exist in the inner leaflet of the plasma membrane, we expressed D4 as a fusion protein with EGFP in MEF cells. More than half of the EGFP-D4 expressed in stable cell clones was bound(More)
There is increasing evidence that calpain contributes to the reorganization of the cytoskeleton in the integrin-mediated signaling pathway. Osteoclastic bone resorption requires cell-matrix contact, an event mediated by integrin alphavbeta3, and subsequent cytoskeletal reorganization to form characteristic membrane domains such as the sealing zone and(More)
We characterized the effects of in vitro cellular aging on constituents of lipid rafts in human diploid fibroblasts, TIG-1. Cholesterol recovery from lipid rafts of senescent cells was decreased by the detaching treatment, while the decrease was far less obvious in young cells. A probe that binds selectively to cholesterol in lipid rafts revealed that the(More)
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