Kazuhiko Uchida

POLY(ADP-RIBOSE) POLYMERASE INTERACTS WITH NOVEL DROSOPHILA RIBOSOMAL PROTEINS, L22 AND L23A, WITH UNIQUE HISTONE-LIKE AMINO-TERMINAL EXTENSIONS

Poly(ADP-ribose) polymerase (PARP) is a nuclear enzyme that recognizes and binds to the nicks and ends of DNA, and catalyses successive ADP-ribosylation reactions. To clarify the function of PARP at the molecular level, we searched proteins which interact with PARP. In the auto-modification domain of PARP in Drosophila, there is a putative leucine-zipper motif which can interact with other protein molecules. To find interacting proteins we examined the auto-modification domain of Drosophila PARP, using the Far-Western screening method. From six independent cDNA clones isolated, we characterized two clones, PBP-3 and PBP-12. The predicted amino acid sequences from 109 to 269 of PBP-3 and from 184 to 312 of PBP-12 had more than 62% identities to mammalian L23a (rpl23a) and L22 (rpl22), the ribosomal proteins of the large subunit. This indicated that PBP-3 and PBP-12 are Drosophila homologues of L23a and L22, respectively. These Drosophila ribosomal protein L22 and L23a have additional Ala-, Lys- and Pro-rich sequences at the amino terminus, which have a resemblance to the carboxy-terminal portion of histone H1. Thus, Drosophila L22 and L23a might have two functions, namely the role of DNA-binding similar to histone H1 and the role of organizing the ribosome.

Age-dependent paraparesis in WKA rats: evaluation of MHC k-haplotype and HTLV-1 infection.

Human T-cell leukemia virus type 1 (HTLV-1) infection is shown to be closely associated with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Although the occurrence of HAM/TSP was reported to be associated with MHC class II, the mechanism is still unclear. The WKA(RT1k) strain of rats was reported to develop HAM/TSP-like paraparesis after HTLV-1 infection, and was suggested to be an animal model of HAM/TSP. We asked whether MHC k-haplotype is specifically involved in the pathogenesis of paraparesis of WKA(RT1k) rats. We injected the HTLV-1 producing human T cells (MT-2 cells) intravenously into WKA(RT1k) rats and MHC congenic WKA.1L(RT1l) rats which have MHC l-haplotype of LEW rats on the WKA background. Positive antibody response to HTLV-1 antigens and presence of provirus in peripheral blood mononuclear cells confirmed that MT-2 cell-injected rats were infected with HTLV-1. Two of 13 MT-2 cell-injected WKA(RT1k) rats and five of 13 MT-2 cell-injected WKA.1L(RT1l) rats developed HAM/TSP-like hindlimb paraparesis between 16 and 26 months old. Interestingly, three of 14 MT-2 cell-uninjected WKA(RT1k) rats and four of 13 MT-2 cell-uninjected WKA.1L(RT1l) rats showed similar paraparesis between 15 and 26 months old. MHC k-haplotype is not specific to the development of paraparesis in WKA(RT1k) rats. The role of aging, genetic background, HTLV-1 infection and other factors on the development of HAM/TSP-like paraparesis in rats are discussed.

Human T-cell Leukemia Virus Type 1 Can Infect a Wide Variety of Cells in Mice

Analysis of human T‐cell leukemia virus type 1 (HTLV‐1)‐infected cell types and the interplay of these infected cells in vivo should provide valuable information to elucidate the pathogenesis of HTLV‐1‐associated diseases in humans and in animal models. In this study, HTLV‐1‐infected cell types were identified in HTLV‐1‐infected C3H/HeJ mice. Pan T, CD+4, CD8+8, granulocyte and pan B cell fractions in the splenocytes of MT‐2 cell‐inoculated mice were sorted by use of their cell surface high‐density expression of CD3e, CD4, CD8, Gr‐1 and B220 antigens, respectively, with a fluorescence‐activated cell sorter. the pX sequence of HTLV‐1 provirus in the lysate of each fraction was amplified by polymerase chain reaction and detected by Southern hybridization. Interestingly, in addition to the CD+4 cell fraction, the pX sequence was also found in CD8+ cell, B cell and granulocyte fractions. The broad cell spectrum of HTLV‐1 infection in mice is consistent with the situation in humans. Our findings indicate that HTLV‐1 receptor or coreceptor is widely distributed among different cell types in mice.