| PRR11 (proline rich 11) is a novel gene located in 17q22, and its character is still unknown. It is found from 50 cancer-related new genes by semi-quantitative PCR screening in our previous studies. We have found that the mRNA expression level of PRR11 is significantly decreased after DNA damage, which suggesting that this gene may be a tumor-related gene regulated by p53. Bioinformatics analysis showed that: (1) Chromosomal location region of PRR11 is an area of high incidence of gene amplification in lung cancer and other tumors; (2) A number of cDNA microarray data also suggested that PRR11 is up-regulated in tumor tissues. However, there is no any report about this gene right now. In the present study, we have systematically investigated the identification of PRR11 and its role in cell cycle and proliferation. The results are summarized as follows.(1) Full-length cDNA cloning and sequence analysis of PRR11. At first, the 5 'and 3' end cDNA sequences have been identified by 5 ' -RACE and 3' -RACE. Results showed that there are seven fragments have been cloned in 5 ' end, and four of them are more evident。The length are 200bp, 300bp, 400bp and 700bp,respectively. Among them, the 400bp band is the most evident one, and that means it is the main transcript. There are two fragments have been cloned in 3 ' end and the length are 1.5kb and 2kb,respectively. Sequencing results showed that, in 5 ' end fragments, the sequences of 200bp, 300bp, 400bp are conformity with the published mRNA sequence of PRR11.However, the transcription start sites of these three fragments are different. The 700bp sequence is 284bp extended in 5 '-UTR. Compare with the published mRNA sequence of PRR11, the two fragments cloned in 3 ' end are 172bp and 778bp extended in 3 '-UTR. Splicing the 400bp fragment in 5 ' end with the two fragments in 3 ' end, two major transcripts of the full-length of PRR11 are obtained, whose length are 1520bp and 2091bp. However, the amino acid sequences encoded by these two transcripts are the same, which contain 360 amino acids. To investigate the homology of different spaces, alignment was performed among human and other species using ClustalW online software. The result showed that the PRR11 proteins of other species were highly homologous with human PRR11. This high evolutionary conservation implies that PRR11 may have an important biological role. Phosphorylation analysis showed that PRR11 contains MAPK and cdc2 phosphorylation sites. These results suggest that PRR11 might play an important role in the growth and proliferation in eukaryotic cells.(2) The expression analysis in tissue and cell cycle of PRR11. In different normal human tissues, PRR11 is abundantly expressed in the thyroid, cervix, placenta and other active tissues but weakly expressed in heart and brain. The expression level of PRR11 is higher in tumor than normal tissues, and its expression increases along with the malignant stage elevates. Analysis of PRR11 expression profile during cell cycle indicated that PRR11 is a novel G2/M phase gene like Plk1 and which shows a higher expression level during G2/M phase and lower expression level during G1/S phase. These results indicated that PRR11 may involve in cell growth and proliferation, and relates with tumor occurrence and progression.(3)The role of PRR11 in cell growth and proliferation.The siRNA-mediated PRR11 knockdown caused a significant morphogenesis changes and growth inhibition in HeLa cells. In addition, PRR11 depletion also induced the S phase arrest during cell cycle. Furthermore, results suggested that PRR11 can be regulated by transcription factor E2F family and MYB, and this might be the mechanism that PRR11 involve in cell proliferation and cell cycle.Taken together, those results indicated that PRR11 plays an important role in in cell growth, cell proliferation and cell cycle, and it may be used as an attractive target to develop novel therapeutic chemosensitizers and gene therapeutic drugs against cancer. |
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