N Sakamoto

Publications (3)6.39 Total impact

• Article: Cyclophilin A and nuclear factor of activated T cells are essential in cyclosporine-mediated suppression of polyomavirus BK replication.

  Y J Li, H H Wu, C H Weng, Y C Chen, C C Hung, C W Yang, R Y L Wang, N Sakamoto, Y C Tian
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  ABSTRACT: Immunosuppressants have impacts on the development of polyomavirus-associated nephropathy. We previously demonstrated that cyclosporin A (CsA) suppressed polyomavirus BK (BKV) replication. The role of cyclophilin A (CypA) and nuclear factor of activated T cells (NFAT) in CsA-imposed suppression of BKV replication was determined in this study. Results demonstrated that knockdown of CypA but not CypB significantly reduced BKV large T antigen (TAg) expression and BKV titer. Overexpression of CypA reversed CypA siRNA-induced inhibition in BKV TAg expression. In addition, CypA overexpression attenuated the suppressive effect of CsA on TAg expression, suggesting CypA implicated in CsA-mediated anti-BKV effect. Knockdown of NFATc3 abrogated TAg expression, while overexpression of NFATc3 promoted TAg expression and augmented BKV promoter activity. NFATc3 binding to the BKV promoter was verified by chromatin immunoprecipitation assay and electrophoretic mobility shift assay. Renal histology also displayed an increase in NFATc3 expression in tubulointerstitium of BKV-associated nephropathy. Furthermore, overexpression of NFATc3 rescued CsA-mediated inhibition of BKV load and TAg expression. A CsA analog, NIM811, which cannot block NFAT functionality, failed to suppress TAg expression. In conclusion, CypA and NFAT are indispensable in BKV replication. CsA inhibits BKV replication through CypA and NFAT, which may be potential targets of anti-BKV treatment.
  American Journal of Transplantation 05/2012; 12(9):2348-62. · 6.39 Impact Factor
• Article: Observation of Slow Dynamics on a Liquid Surface by Time-Resolved Ripplon Light-Scattering Spectroscopy

  D. Mizuno, K. Hattori, N. Sakamoto, K. Sakai, K. Takagi
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  ABSTRACT: We developed a nonperturbative and noncontact method of time-resolved ripplon light scattering for investigating slow dynamics on a liquid surface over a frequency range of 10-3 Hz to 1 Hz. Surface area of the liquid under study was periodically changed by a movable barrier and the following change in the surface pressure was observed from the ripplon spectrum. This technique was applied for the aqueous solutions of decyl alcohol and a relaxation phenomenon associated with the adsorption and desorption of surfactant molecules was found. The result was successfully interpreted in terms of a relaxation model in which both the potential barrier formed just under the surface and the molecular diffusion in the solution take comparable contributions to the sorption kinetics. The obtained relaxation parameters were discussed in correlation with the Frumkin's adsorption model.
  11/1999;
• Article: [A trial in instruction on self-examination of breast cancer--1. Problems observed in the analysis of the results of questionnaires].

  H Utsunomiya, N Sakamoto, T Sato, K Shono, K Takagi
  Kurinikaru sutadī = Clinical study 10/1981; 2(9):1130-6.