Poster Session

International Symposium on Tumor Biology in Kanazawa & Symposium on Drug Discoverry in Academics 2014 [DATE]: January 23(Thu)-24(Fri),2014, [Place]:Kanazawa Excel Hotel Tpkyu, Kanazawa, Japan, [Organizers]:Kanazawa Association of Tumor Biologists / Cancer Research Institute, Kanazawa Universit

Susceptibility of muridae cell lines to ecotropic murine leukemia virus and the cationic amino acid transporter 1 viral receptor sequences: implications for evolution of the viral receptor

Ecotropic murine leukemia viruses (Eco-MLVs) infect mouse and rat, but not other mammalian cells, and gain access for infection through binding the cationic amino acid transporter 1 (CAT1). Glycosylation of the rat and hamster CAT1s inhibits Eco-MLV infection, and treatment of rat and hamster cells with a glycosylation inhibitor, tunicamycin, enhances Eco-MLV infection. Although the mouse CAT1 is also glycosylated, it does not inhibit Eco-MLV infection. Comparison of amino acid sequences between the rat and mouse CAT1s shows amino acid insertions in the rat protein near the Eco-MLV-binding motif. In addition to the insertion present in the rat CAT1, the hamster CAT1 has additional amino acid insertions. In contrast, tunicamycin treatment of mink and human cells does not elevate the infection, because their CAT1s do not have the Eco-MLV-binding motif. To define the evolutionary pathway of the Eco-MLV receptor, we analyzed CAT1 sequences and susceptibility to Eco-MLV infection of other several murinae animals, including the southern vole (Microtus rossiaemeridionalis), large Japanese field mouse (Apodemus speciosus), and Eurasian harvest mouse ( Micromys minutus). Eco-MLV infection was enhanced by tunicamycin in these cells, and their CAT1 sequences have the insertions like the hamster CAT1. Phylogenetic analysis of mammalian CAT1s suggested that the ancestral CAT1 does not have the Eco-MLV-binding motif, like the human CAT1, and the mouse CAT1 is thought to be generated by the amino acid deletions in the third extracellular loop of CAT1

Multigenic System Controlling Viral Systemic Infection Determined by the Interactions Between Cucumber mosaic virus Genes and Quantitative Trait Loci of Soybean Cultivars

Soybean 'Harosoy' is resistant to Cucumber mosaic virus soybean strain C (CMV-SC) and susceptible to CMV-S strain D (CMV-SD). Using enzyme-linked immunosorbent assay and Northern hybridization, we characterized the Harosoy resistance and found that CMV-SC did not spread systemically but was restricted to the inoculated leaves in Harosoy. Harosoy resistance was not controlled by either a dominant or recessive single gene. To dissect this system controlling long-distance movement of CMV in soybean, we constructed infectious cDNA clones of CMV-SC and CMV-SD. Using these constructs and the chimeric RNAs, we demonstrated that two viral components were required for systemic infection by the virus. The region including the entire 2b gene and the 5' region of RNA3 (mainly the 5' untranslated region) together were required. By quantitative trait locus (QTL) analysis using an F2 population and the F3 families derived from Harosoy and susceptible 'Nemashirazu', we also showed that at least three QTLs affected systemic infection of CMV in soybean. Our study on Harosoy resistance to CMV-SC revealed an interesting mechanism, in which multiple host and viral genes coordinately controlled viral systemic infection

Genetic mapping of the compatibility between a lily isolate of Cucumber mosaic virus and a satellite RNA

Five isolates of Cucumber mosaic virus (CMV) from Lilium sp. (lily), which were isolated from specimens in Japan, Korea and Taiwan, were unable to support satellite RNA (satRNA) accumulation. In order to map the CMV sequences that are involved in satRNA support, HL-CMV (Japanese lily isolate), Y-CMV (ordinary strain) and Y-satellite RNA (Y-sat) were used as the source material. The pseudorecombinants between Y-CMV and HL-CMV revealed that RNA1 was essential for satRNA replication in lily. The results of chimeric constructs and various mutations showed that two amino acid residues (at positions 876 and 891) in the 1a protein were the determinants for the inability of HL-CMV to support a satRNA. Specifically, Thr at position 876 had a more pronounced effect than Met at position 891. Specific changes in RNA sequence were also detected in the 3' terminus of Y-sat and these particular alterations allowed it to be supported by HL-CMV. It is believed that, through evolution, the adaptation of CMV to lily resulted in the introduction of amino acid changes in the 1a protein, changes that coincidentally affected the ability of lily CMV to support satRNAs

Phloem-Localizing Sulfate Transporter, Sultr1;3, Mediates Re-Distribution of Sulfur from Source to Sink Organs in Arabidopsis

For the effective recycling of nutrients, vascular plants transport pooled inorganic ions and metabolites through the sieve tube. A novel sulfate transporter gene, Sultr1;3, was identified as an essential member contributing to this process for redistribution of sulfur source in Arabidopsis. Sultr1;3 belonged to the family of high-affinity sulfate transporters, and was able to complement the yeast sulfate transporter mutant. The fusion protein of Sultr1;3 and green fluorescent protein was expressed by the Sultr1;3 promoter in transgenic plants, which revealed phloem-specific expression of Sultr1;3 in Arabidopsis. Sultr1;3-green fluorescent protein was found in the sieve element-companion cell complexes of the phloem in cotyledons and roots. Limitation of external sulfate caused accumulation of Sultr1;3 mRNA both in leaves and roots. Movement of (35)S-labeled sulfate from cotyledons to the sink organs was restricted in the T-DNA insertion mutant of Sultr1;3. These results provide evidence that Sultr1;3 transporter plays an important role in loading of sulfate to the sieve tube, initiating the source-to-sink translocation of sulfur nutrient in Arabidopsis

Posttranscriptional Regulation of High-Affinity Sulfate Transporters in Arabidopsis by Sulfur Nutrition1[OA]

High-affinity sulfate transporters SULTR1;1 and SULTR1;2 are expressed at epidermis and cortex of Arabidopsis (Arabidopsis thaliana) roots during sulfur limitation. Here, we report that SULTR1;1 and SULTR1;2 are two essential components of the sulfate uptake system in roots and are regulated at posttranscriptional levels together with the previously reported transcriptional control. Double knockout of SULTR1;1 and SULTR1;2 by T-DNA insertion gene disruption resulted in complete lack of sulfate uptake capacity and severely affected plant growth under low-sulfur conditions. Expression of epitope-tagged proteins SULTR1;1mycHis and SULTR1;2mycHis, under the control of the cauliflower mosaic virus 35S promoter, rescued the uptake of sulfate and the growth of the sultr1;1 sultr1;2 double knockout mutant. The recovery of the double knockout phenotypes was attributable to the posttranscriptional accumulation of sulfate transporter proteins that derive from the epitope-tagged transgenic constructs. Both SULTR1;1mycHis and SUTLR1;2mycHis mRNAs were predominantly found in roots and slightly induced by long-term sulfur limitation. SULTR1;1mycHis and SULTR1;2mycHis proteins were found exclusively in roots, and significantly accumulated by sulfur limitation, correlating with the induction of sulfate uptake activities. In the time course of short-term sulfate starvation treatment, SULTR1;1mycHis and SULTR1;2mycHis proteins were significantly accumulated during the 8- to 72-h period, causing substantial induction of sulfate uptake activities, while their corresponding mRNAs were expressed constantly around the initial levels, except for the transient induction in the first 2 h. This study suggested the importance of root-specific and sulfur deficiency-inducible accumulation of SULTR1;1 and SULTR1;2 sulfate transporter proteins for the acquisition of sulfate from low-sulfur environment