Heat shock cognate protein 70 is a cell fusion-enhancing factor but not an entry factor for human T-cell lymphotropic virus type I.
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.
Fang
D
D
Department of Virology and Preventive Medicine, Gunma University School of Medicine, Showa-machi, Maebashi, Gunma, 371-8511, Japan.
Haraguchi
Y
Y
Jinno
A
A
Soda
Y
Y
Shimizu
N
N
Hoshino
H
H
D016475:3T3 Cells; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D002415:Cats; D002459:Cell Fusion / Q000502:physiology*; D002460:Cell Line; D017931:DNA Primers / Q000235:genetics; D015686:Gene Products, env / Q000235:genetics / Q000502:physiology; D015726:Giant Cells / Q000473:pathology / Q000502:physiology; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D015368:Human T-lymphotropic virus 1 / Q000235:genetics / Q000472:pathogenicity*; D006801:Humans; D051379:Mice; D051381:Rats; D015682:Retroviridae Proteins, Oncogenic / Q000235:genetics / Q000502:physiology; D014161:Transduction, Genetic
D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D017931:DNA Primers; D015686:Gene Products, env; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; C494371:HSPA8 protein, human; C494372:Hspa8 protein, mouse; C494373:Hspa8 protein, rat; D015682:Retroviridae Proteins, Oncogenic; C055266:gp46 protein, Human T-cell leukemia virus type I