Heat shock cognate protein 70 is a cell fusion-enhancing factor but not an entry factor for human T-cell lymphotropic virus type I

Deyu Fang, Yuji Haraguchi, Atsushi Jinno, Yasushi Soda, Nobuaki Shimizu, Hiroo Hoshino*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

Heat shock cognate protein 70 (HSC70) has been shown to bind to the peptide corresponding to amino acids 197 to 216 of human T-cell lymphotropic virus type I (HTLV-I) envelope protein, gp46, and an anti-HSC70 monoclonal antibody (mAb) inhibits HTLV-I-induced syncytium formation. These findings suggest that HSC70 is necessary for the entry of HTLV-I into its target cells. Here we showed that HSC70 directly binds to gp46 by co-immunoprecipitation of HSC70 and gp46 from HTLV-I-producing human T-cell lysate. However, transduction of human HSC70 cDNA into BaF3 cells, which were found to be highly resistant to HTLV-I infection, did not support the HTLV-I entry, and HSC70 expressed in NIH3T3 cells, which were found to be almost resistant to syncytium formation upon cocultivation with HTLV-I-producing cells but sensitive to infection with cell-free HTLV-I, enhanced cell fusion induced by HTLV-I-producing cells, but did not enhance the entry of cell-free HTLV-I into these cells. The mAb against HSC70 inhibited syncytium formation in NIH3T3 cells expressing HSC70, but showed little effect on infection of these cells with cell-free HTLV-I. These findings indicate that HSC70 markedly enhances syncytium formation induced by HTLV-I but does not facilitate HTLV-I entry into target cells.

Original languageEnglish (US)
Pages (from-to)357-363
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume261
Issue number2
DOIs
StatePublished - Aug 2 1999

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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