title: Human T-cell leukemia virus type 2 (HTLV-2) Tax protein transforms a rat fibroblast cell line but less efficiently than HTLV-1 Tax.
abstract: Human T-cell leukemia virus type 1 (HTLV-1) and HTLV-2 are retroviruses with similar biological properties. Whereas HTLV-1 is the causative agent of an aggressive T-cell leukemia, HTLV-2 has been associated with only a few cases of lymphoproliferative disorders. Tax1 and Tax2 are the transcriptional activators of HTLV-1 and HTLV-2, respectively. Here we show that Tax2 transformed a Rat-1 fibroblast cell line to form colonies in soft agar, but the size and number of the colonies were lower than those of Tax1. Use of a chimeric Tax protein showed that the C-terminal amino acids 300 to 353 were responsible for the high transforming activity of Tax1. Activation of cellular genes by Tax1 through transcription factor NF-kappa B is reportedly essential for the transformation of Rat-1 cells. Tax2 also activated the transcription through NF-kappa B in Rat-1 cells, and such activity was equivalent to that induced by Tax1. Thus, the high transforming activity of Tax1 is mediated by mechanisms other than NF-kappa B activation. Our results showed that Tax2 has a lower transforming activity than Tax1 and suggest that the high transforming activity of Tax1 is involved in the leukemogenic property of HTLV-1.
authors.affiliation: Division of Virology, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-Dori, Niigata 951-8510, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Endo
authors.forename: Akira
authors.initials: A
authors.lastname: Hirata
authors.forename: Kousuke
authors.initials: K
authors.lastname: Iwai
authors.forename: Mamoru
authors.initials: M
authors.lastname: Sakurai
authors.forename: Masaya
authors.initials: M
authors.lastname: Fukushi
authors.forename: Masayasu
authors.initials: M
authors.lastname: Oie
authors.forename: Masaya
authors.initials: M
authors.lastname: Higuchi
authors.forename: William W
authors.initials: WW
authors.lastname: Hall
authors.forename: Fumitake
authors.initials: F
authors.lastname: Gejyo
authors.forename: Masahiro
authors.initials: M
authors.lastname: Fujii
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002472:Cell Transformation, Viral; D005347:Fibroblasts; D016356:Gene Products, tax / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D015367:Human T-lymphotropic virus 2 / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D051381:Rats; D014162:Transfection
chemical_list: D016356:Gene Products, tax