Objective: Previous studies proved that somatic mutations of mitochondrial DNA(mtDNA) are strongly associated with tumorigenesis and tumor progression.However,conventional sequencing methods are not able to detect mtDNA mutations with high-throughput and high accuracy.In this study,we established a new approach for detecting mutations in mtDNA based on next-generation sequencing technology.Methods: mtDNA were amplified by PCR using genome DNA samples obtained from tumor tissue,paired normal tissue or peripheral blood.The PCR products went through blunt end ligation,sticky end ligation,or amino-modification before sequencing library preparation.The mtDNA libraries were sequenced utilizing Illumina HiSeq 2000 platform.The sequences were then compared with human mtDNA referencing sequences,and further analysis using bioinformatical methods.Results: After assessing the genomic DNA samples with different qualities,we found that using three pairs of PCR primers is applicable to most mtDNA enrichment reactions.We also found the amino-modified PCR primers could significantly improve the coverage uniformity,and reduce the sequencing costs.Conclusion: A method to optimize mtDNA enching and the coverage uniformity has been built up in this study based on next-generation sequencing technology.Further a sensitive mtDNA mutation detecting system with high specificity and high-throughput was aslo established.This system may provide a new method for research in mtDNA mutation detection and disease association studies.

Objective:Domain is considered an evolutionary unit of proteins.The aim of our research is to quantitative analysis on the domains within the drug-target proteins that could useful to predicting novel drug-targets.Methods:Based on the information about protein-protein interactions,protein domains and drug-targets,we analyzed that whether the characteristic of domains within the drug-targets or within the non-drug-targets is different.Results:There is significantly different in the number of domains that within the drug-targets and that within the non-drug-targets(P=1.03×10 -6 ).Drug-target proteins tend to have two domains.Moreover,the classification of domains in the drug-targets is mainly Alpha or Alpha Beta.Conclusion:Our results showed that the characteristic of domains within the drug-targets or that within the non-drug-targets is different,which could help to discovering new drug-target proteins.

The investigation of topological properties of proteins in protein-protein interaction network (PPIN) has great potentials to identify basic protein functions and mechanisms of action. Based on human PPIN, previous study has shown that the topological properties of drug targets are significantly distinguished from those of proteins that are not targeted by drugs (non-drug-targets). MicroRNAs (miRNAs) are known to regulate gene expression at the post-transcriptional level. To determine whether the differences in topological properties between drug targets and non-drug-targets are dominated by the proteins that are regulated by miRNA, we divided the drug targets into two sets: those are regulated by miRNA (mir-drug-targets) and those are not regulated by miRNA (non-mir-drug-targets). We compared the probability of interactions and five topological properties among the three types of proteins in human PPIN. Our results demonstrated that mir-drug-targets preferentially interact with other mir-drug-targets and tend to be hub-bottlenecks. However, there was no bias on topological properties between non-mir-drug-targets and non-drug-targets. The same topological features are observed among non-drug targets. These findings indicate that miRNA regulation has an important role in human PPIN, and may be useful in the development of novel drugs.