A Possible mRNA Splicing Mechanism for Regulation of Telomerase Activity in Rice (Oryza sativa L.)

摘要

The mechanism of telomerase regulation is far better understood in mammalian systems than it is in plant systems. In this study, we investigated the possibility that regulation of telomerase activity occurs at the post-transcriptional level in rice plants (Oryza sativa). Specifically, we used RT-PCR with primers based on the rice telomerase reverse tran-scriptase (OsTERT) cDNA sequence to detect alternative mRNA splicing products. Five types of DNA product that were shorter than predicted by the cDNAsequence were observed for all the tested cells and tissues. Sequencing of these products indicated that they were alternatively spliced OsTERT fragments lacking some portions of the full-length sequence. These results suggest that regulation of telomerase activity occurs at the post-transcriptional level in rice cells and tissues. The relative amounts of full-length OsTERT mRNA and the shorter, alternatively spliced mRNAs were estimated by quantitative RT-Southern analysis. No correlation was found between levels of telomerase activity and accumulation of full-length OsTERT mRNA in the various cell and tissue types, indicating that splicing of OsTERT mRNAs may be important in telomerase regulation in rice. Further studies are necessary to determine whether the spliced OsTERT mRNAs are translated into proteins and if these putative proteins affect telomerase activity.