| Budget Amount *help |
¥15,440,000 (Direct Cost: ¥14,600,000、Indirect Cost: ¥840,000)
Fiscal Year 2007: ¥3,640,000 (Direct Cost: ¥2,800,000、Indirect Cost: ¥840,000)
Fiscal Year 2006: ¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 2005: ¥9,000,000 (Direct Cost: ¥9,000,000)
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| Research Abstract |
Since telomerase activity is barely detectable in primary cells but clearly detected in cancerous cells, telomerase has been considered to be a strong candidate of the targets to cancer treatment In the fiscal year, we concentrated in several experiments including purification and characterization of recombinant human telomerase complex, and biological function of the specific interaction of nucleolin and hTERT recovered from a HeLa cell line stably expressing FLAG-hTERT (Murakami), analyses of human primary cells immortalized by hTERT (Honda), and the tyrosine kinases of receptor type which play critical odes in cell proliferation and differentiation (Yoshioka). The followings are the main conclusions of the experiments.
1) The partially purified active telomerase complexes comprise two different complexities, complex I (around 680 kDa), and complex II (around 400 kDa), that are quite alike to those that can be recovered firm the insect cells co-expressing FLAG-hTERT and hTERC. The com
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plex I does not contain Hsp90 and is resistant to Hsp90 inhibitors, whereas complex II contains Hsp90 and is sensitive to Hsp90 inhibitors. Human TEAT in the complex II is rather unstable during incubation in vim and in ring. Such unstable property was not observed with the complex I. Since MG132, a specific proteasome inhibitor, but not MG133, a negative control, stabilized hTERT in the complex Z strongly suggesting that hTERT in the complex If is under degradation pathway under the control of proteasome. The two different complexities of human telomerase seem to imply two different entities of active telomerase in different subcellular localization or its different functions. 2) We have established a cell line of the human primary fibroblasts(BJ cells) stably expressing hTERT, and we compared expression profiles of RI cells and the KJ cells immortalized by MERE Some genes involving in cell cycle progression and cell proliferation were evidently expressed higher in the immortalized 131-hTERT than these in in the primary cells. 3) Nucleolin, one of the specific interacting partners of hTERT can bind to Hepatitis C Virus (HCV) NS5B, RNA-dependent RNA replication of HCV. We evaluated the role of the specific interaction of nucleolin and NS5B in HCV replication. The HCV subreplicon system has been applied for the address We found that the HCV subreplicons harboring alanine substitution mutations or mutation at the residue(s) either one of two critical sequences within NS5B both of which are necessary for the nucleolin-binding could not replicate at all in a transient HCV replication system in HepG2 ml/s., although the wild replicon could support efficient HCV. By introducing transiently RNAi of nucleolin, that down regulated expression of nucleolin by half to one third, reduced HCV evidently reduced HCV replication using the HCV subreplicon system. Taken together, the specific interaction of nucleolin and NS5B is critical for HCV replication. Less
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