Messenger RNA polyadenylation is one of the critical steps in eukaryotic gene expression. The poly(A) tail of a mature mRNA is essential for its function, including mRNA translatability, stability and translocation to cytoplasm. The process also affects pre-mRNA splicing and transcription termination. Recent studies have linked mRNA polyadenylation to other cellular processes, e.g. pathogen invasion and cancer development. In plants, it has been shown that the polyadenylation process, and the alternative polyadenylation of mRNA, can lead to gene expression regulation. In particular, alternative polyadenylation of certain genes plays an important role in many biological processes like flower development, self-incompatibility, stress responses, etc.
I am interested to elucidate plant mRNA polyadenylation mechanisms at genetic, biochemical, and molecular levels. We have used bioinformatics and molecular biology approaches to identify and clone plant (Arabidopsis) polyadenylation related genes. Funded by US National Science Foundation's Arabidopsis 2010 Project, we use functional genomic tools to study the functions of this set of genes. Currently funded by US National Science Foundation and US National Instate of Health, we are studying the biochemical, genetic and molecular functions of some polyadenylation factors, and their role in plant gene expression regulations in gametophyte development and stress responses.
It has been demonstrated in recent years that alternative polyadenylation, a process that generates a few poly(A) sites on different transcripts of a gene, is a widely used post-transcriptional molecular mechanism in gene expression regulation, including cancer development, embryo development and stress responses. Since the poly(A) site marks the end of a transcript, different placements of a poly(A) site may include or exclude coding sequences, regulatory cis-elements (micro RNA targets, stability elements, etc). Thus, regulated placements of poly(A) sites can be a strategy for gene expression regulation. We are performing large-scale analyses of alternative polyadenylation to discover the full landscape of polyadenylation in plants. The emergent theme is that over 50% genes use alternative polyadenylation to regulate their expression.
The cis-elements which direct the plant mRNA polyadenylation process are not well understood yet. We are using bioinformatics tools to search and analyze such polyadenylation signals in the plant genomes, and building models and algorithms to predict poly(A) sites. This exercise has two major applications: genome annotation by predicting the end of a transcript and transcription termination, and prediction of unwanted poly(A) sites for candidate genes to be transformed to plants. The latter can be used to guide gene modification to ensure desired expression in plants.
Selected Publications (Career Total 50; *corresponding author)
Hongwei Zhao, Jun Zheng, Q. Quinn Li*. 2011. A novel plant in vitro assay system for pre-mRNA cleavage and polyadenylation. Plant Physiology, 157:1546-1554. Download paper
Yingjia Shen, R. C. Venu, Kan Nobuta, Xiaohui Wu, Varun Notibula, Caghan Demirci, Blake C Meyers, Guo-Liang Wang, Guoli Ji, Q. Quinn Li*. 2011. Transcriptome Dynamics Through Alternative Polyadenylation in Developmental and Environmental Responses in Plants Revealed by Deep Sequencing. Genome Research, 21:1478-1486. Download paper
Xiaohui Wu, Man Liu, Bruce Downie, Chun Liang, Guoli Ji, Q. Quinn Li*, Arthur Hunt*. 2011. The genome-wide landscape of polyadenylation in Arabidopsis provides evidence for extensive alternative polyadenylation. Proc. Nat. Acad. Sci. USA, 108:12533-12538. doi/10.1073/pnas.1019732108 Download paper
Jianti Zheng, Denghui Xing, Xiaohui Wu, Diana Kroll, Yingjia Shen, Guoli Ji*, Q. Quinn Li*. 2011. Ratio-based analysis of differential mRNA processing and expression of a polyadenylation factor mutant pcfs4 using Arabidopsis tiling microarray. PLoS One, 6:e14719. Download paper
David A. Francko*, Kenneth G. Wilson, Q. Quinn Li and Alejandra Equiza. 2011. A topical spray to enhance plant resistance to cold injury and mortality. HortTechnology, 21(1):109-118. Abstract
Denghui Xing, Q. Quinn Li*. 2010. Alternative polyadenylation and gene expression regulation in plants. WIREs (Willey Interdisciplinary Reviews) RNA, 2:445-458. (Invited review) Download paper
Ji*, Xiaohui Wu, Yingjia Shen, Jiangyin Huang, Zhoujing Wang and Q. Quinn Li.
2010. Classification-Based Prediction Models of Messenger RNA Polyadenylation
Sites. Journal of Theoretical Biology, 265:287-296.
Guoli Ji*, Xiaohui Wu, Jiangyin Huang, Q. Quinn Li. 2010. Implementation of a
Classification-Based Prediction Model for Plant mRNA Poly(A) Sites. Journal
of Computational and Theoretical Nanoscience, 7(5):927-932. Abstract
Hongwei Zhao, Denghui Xing, Q.
Quinn Li*. 2009. Unique features of plant cleavage and polyadenylation specificity
factor revealed by proteomic studies. Plant Physiology,
151:1546-1556 (DOI: 10.1104/pp.109.142729).Download
Denghui Xing, Shuisong Ni, Michael
A. Kennedy, Q. Quinn Li*. 2009. Identification of a plant-specific Zn-sensitive
ribonuclease activity. Planta, 230:819-825. Download
Denghui Xing and Q. Quinn Li*. 2009.
Alternative polyadenylation: a mechanism maximizing transcriptome diversity
in higher eukaryotes. Plant Signaling and Behavior,
Denghui Xing, Hongwei Zhao and Q. Quinn Li *. 2008. Arabidopsis CLPS3, an ortholog of human polyadenylation factor CLP1, functions in gametophyte, embryo and post-embryonic development. Plant Physiology, 148:2059-2069. (DOI: 10.1104/pp.108.129817). Download paper
Denghui Xing, Hongwei Zhao, Ruqiang Xu and Q. Quinn Li* . 2008 . Arabidopsis PCFS4, a homologue of yeast polyadenylation factor Pcf11p, regulates FCA alternative processing and promotes flowering time. Plant Journal, 54:899-910. Download paper
Chun Liang*, Yuansheng Liu, Lin Liu, Adam C. Davis, Yingjia Shen, and Q. Quinn Li . 2008 ESTs with cDNA termini - previously overlooked resources for gene annotation and transcriptome exploration in Chlamydomonas reinhardtii. Genetics, 179:83-93 (doi: 10.1534/genetics.107.085605). Download paper
Yingjia Shen, Guoli Ji, Brian J. Haas, Xiaohui Wu, Jianti Zheng, Greg J. Reese, and Q. Quinn Li* . 2008 Genome level analysis of rice mRNA 3'-end processing signals and alternative polyadenylation. Nucleic Acids Research, 36:3150-3161 (doi:10.1093/nar/gkn158). Download paper
Yingjia Shen, Yuansheng Liu, Lin Liu, Chun Liang, and Q. Quinn Li *. 2008 Unique features of nuclear mRNA poly(A) signals and alternative polyadenylation in Chlamydomonas reinhardtii. Genetics, 179:167-176 (doi: 10.1534/genetics.108.088971). Download paper
Arthur G. Hunt*, Ruqiang Xu, Balasubrahmanyam Addepalli, Suryadevara Rao, Kevin P. Forbes, Lisa R. Meeks, Denghui Xing, Min Mo, Hongwei Zhao, Amrita Bandyopadhyay , Lavanya Dampanaboina, Amanda Marion, Carol Von Lanken, and Q. Quinn Li *. 2008 Arabidopsis mRNA polyadenylation machinery: comprehensive analysis of protein-protein interactions and gene expression profiling. BMC Genomics, 9:220. Download paper
Ruqiang Xu and Q. Quinn Li*. 2008. Streamline cloning of genes into binary vectors in Agrobacterium via the Gateway® TOPO vector system. Plant Methods, 4:4. Download paper
Jingxian Zhang, Kil-Young Yun , Ruqiang Xu, Arthur G. Hunt, Irina Artiushin, Kim Delaney, Q. Quinn Li and Deane L. Falcone*. 2008. Differential RNA processing implicated in responses of Arabidopsis thaliana to oxidative stress: a stress-tolerant mutant is deficient in a calmodulin-regulated RNA-binding protein. PLoS One , 3:e2410. Download paper
Guoli Ji, Xiaohui Wu, Jianti Zheng, Yingjia Shen and Q. Quinn Li*. 2007. Modeling Plant mRNA Poly(A) sites: Software Design and Implementation. J. Computational Theoretical Nanoscience, 4:1365-1368.
Guoli Ji, Jianti Zheng, Yingjia Shen, Xiaohui Wu, Ronghan Jiang, Yun Lin, Johnny C. Loke, Kimberly M. Davis, Greg J. Reese and Q. Quinn Li*. 2007. Predictive modeling of plant messenger RNA polyadenylation sites. BMC Bioinformatics, 8:43 (doi:10.1186/1471-2105-8-43). Download paper
Kim Delaney, Ruqiang Xu, Jingxian Zhang, Q. Quinn Li, Kil-Young Yun, Deane L. Falcone and Arthur G. Hunt*. 2006. Calmodulin interacts with and regulates the RNA-binding activity of an Arabidopsis polyadenylation factor subunit. Plant Physiology , 140:1507-1521.
Addepalli Balasubrahmanyam, Ruqiang Xu, Tomal Dattaroy, Baochun Li, W. Troy Bass, Q. Quinn Li and Arthur G. Hunt*. 2006. Disease resistance in plants that carry a feedback-regulated yeast poly(A) binding protein gene. Plant Molecular Biology, 61:383 - 397.
Ruqiang Xu, Hongwei Zhao, Randy Dinkins, Xiaowen Cheng, George Carberry and Q. Quinn Li*. 2006. The 73 kD subunit of the cleavage and polyadenylation specificity factor (CPSF) complex affects reproductive development in Arabidopsis. Plant Molecular Biology, 61:799-815.
Hongyan Xing, Orlando Chambers, Chris B. Lawrence, H. Maelor Davies, Nicholas P. Everett and Q. Quinn Li *. 2006. Increased pathogen resistance and yield in transgenic plants expressing combinations of the modified antimicrobial peptides based on indolicidin and magainin. Planta , 223:1024-1032.
Johnny C . Loke, Eric Stahlberg, Dave Strenski, Brian J. Haas, P. Chris Wood and Q. Quinn Li. 2005. Compilation of mRNA Polyadenylation Signals in Arabidopsis Revealed a New Signal Element and Potential Secondary Structures . Plant Physiology , 138: 1457-1468.
Ruqiang Xu, Xinfu Ye, Q. Quinn Li. 2004. AtCPSF73-II gene encoding an Arabidopsis homolog of CPSF 73 kDa subunit is critical for early embryo development. Gene , 324: 35-45.
Gail J. Pruss, Christopher B. Lawrence, Troy Bass, Q. Quinn Li, Lewis H. Bowman and Vicki Vance. 2004. The viral suppressor of RNA silencing confers enhanced resistance to multiple pathogens. Virology , 320:107-120. (Cover image)
Ruqiang Xu and Q. Quinn Li. 2003. A RING-H2 zinc finger protein gene RIE1 is essential for seed development in Arabidopsis . Plant Molecular Biology , 53:37-50. (Cover image)
Q. Quinn Li, Christopher B. Lawrence, H. Maelor Davies and Nicholas P. Everett. 2002. A tridecapeptide possesses both antimicrobial and protease-inhibitory activities. Peptides 23: 1-6
Urvee A. Desai, Gargi Sur, Sylvia Daunert, Ruth A. Babbitt, and Q. Quinn Li. 2002. Expression and affinity purification of recombinant proteins from plants. Protein Expression and Purification , 25: 195-202.
Q. Quinn Li, Chris B. Lawrence, Hongyan Xing, Ruth A. Babbitt, W. Troy Bass Indu B. Maiti and Nicholas P. Everett. 2001. Enhanced disease resistance conferred by expression of an antimicrobial peptide magainin analogue in transgenic tobacco. Planta , 212: 635-639
Q. Quinn Li, Carol von Lanken, Jianjun Yang, Chris B. Lawrence and Arthur G. Hunt. 2000. The yeast polyadenylate binding protein ( PAB1 ) gene acts as a disease lesion mimic gene when expressed in plants. Plant Molecular Biology , 42:335-344.
Songhai Shen, Q. Quinn Li , Shengyang He, Debao Li, Kenneth Barker and Arthur G. Hunt. 2000. Conversion of compatible plant-pathogen interactions into incompatible interactions by expression of the Pseudomonas syringae pv. syringae 61 hrmA gene in transgenic tobacco plants. Plant Journal , 23:205-213.
Jaydip Dasgupta, Q. Quinn Li and Arthur G. Hunt. 1998. Identification and characterization of two distinctive RNA-binding activities in pea nuclear extracts . Journal of Plant Biochemistry and Biotechnology, 7: 1-5.
Jaydip Dasgupta, Q. Quinn Li, A. Brian Thomson and Arthur G. Hunt. 1998. Characterization of cDNAs encoding a novel plant poly(A) polymerase. Plant Molecular Biology, 37: 729-734.
Q. Quinn Li, Jaydip Dasgupta and Arthur G. Hunt. 1998. Polynucleotide phosphorylase is a component of a novel plant poly(A) polymerase. Journal of Biological Chemistry , 273: 17539-17543.
Q. Quinn Li and Arthur G. Hunt. 1997. The Polyadenylation of RNA in Plants. Plant Physiology, 115: 321-326.
Q. Quinn Li, Jaydip Dasgupta and Arthur G. Hunt. 1996. A plant poly(A ) polymerase requires a novel RNA binding protein for activity. Journal of Biological Chemistry , 271:19831-35
Jaydip Dasgupta, Q. Quinn Li, A. Brian Thomson and Arthur G. Hunt, 1995. Characterization of a poly(A) polymerase from plants. Plant Science , 110: 215-226.
Q. Quinn Li and Arthur G. Hunt. 1995. A near upstream element in a plant polyadenylation signal consists of more than six bases. Plant Molecular Biology , 28: 927-934.
Nicholas P. Everett, Q. Quinn Li , Christopher Lawrence, H. Maelor Davies. 2007. Peptides with enhanced stability to protease degradation. US Patent #7,214,766.
Q. Quinn Li, Songhai Shen, Arthur G. Hunt and Shengyang He. 2002. Use of hrmA proteins and their genes for broad range protection of plants against bacterial, viral and fungal pathogens. US Patent #6342654
Arthur G. Hunt, Glen B. Collins, Q. Quinn Li, Christopher B. Lawrence and Santanu Dasgupta. 2002. Use of bacterial acetate kinase and their genes for protection of plants against different pathogens. US Patent # 6476293
Arthur G. Hunt, Q. Quinn Li, Jianjun Yang and Carol von Lanken. 2000. Use of yeast poly(A) binding proteins and their genes for broad range protection of plants against bacterial, fungal and viral pathogens. US Patent #6018106.
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