1;Preface;6 2;Contents;8 3;Contributors;9 4;Understanding How miRNAs Post- Transcriptionally Regulate Gene Expression;11 4.1;1.1 Introduction;12 4.2;1.2 miRNA Biogenesis;15 4.3;1.3 miRNA-Mediated Regulation of Eukaryotic Gene Expression;17 4.4;1.4 Summary;25 4.5;References;25 5;Translational Control of Endogenous MicroRNA Target Genes in C. elegans;31 5.1;2.1 Introduction;32 5.2;2.2 lin-4 and let-7 miRNAs in C. elegans Development;32 5.3;2.3 Polysome Profiling as an Assay to Assess the Translational State of mRNAs;34 5.4;2.4 MicroRNA-Mediated Gene Regulation in C. elegans: The Early View;35 5.5;2.5 MicroRNA Mediated Gene Regulation in Other Model Organisms;36 5.6;2.6 The let-7 miRNA Extensively Interacts with Translation Factors;40 5.7;2.7 Polysome Profiling Confirms Translational Repression at the Initiation Step in C. elegans;41 5.8;2.8 Inhibition of Translation Initiation and Transcript Degradation Both Depend on the GW182 Proteins AIN-1 and AIN- 2;44 5.9;2.9 Conclusions and Future Perspectives;46 5.10;References;47 6;Translational Inhibition by MicroRNAs in Plants;51 6.1;3.1 Introduction;52 6.2;3.2 miRNA and siRNA Biogenesis;52 6.3;3.3 ARGONAUTE Proteins;54 6.4;3.4 Translational Inhibition by Small RNAs is Common in Plants;55 6.5;3.5 Roles of miRNA-Mediated Translational Inhibition in Plants;58 6.6;3.6 Conclusion;62 6.7;References;63 7;Regulation of p27kip1 mRNA Expression by MicroRNAs;68 7.1;4.1 Introduction;68 7.2;4.2 miRNAs in Cancer;69 7.3;4.3 Role of p27 in Tumor Progression;71 7.4;4.4 Regulation of p27 Expression: Role of miRNAs;72 7.5;4.5 Conclusions;75 7.6;References;75 8;The Inhibitory Effect of Apolipoprotein B mRNA- Editing Enzyme Catalytic Polypeptide- Like 3G ( APOBEC3G) and Its Family Members on the Activity of Cellular MicroRNAs;80 8.1;5.1 The Antiviral Activity of APOBEC3G;81 8.2;5.2 The Translational Suppression Function of MicroRNA;82 8.3;5.3 The Role of P-bodies in Regulating the Function of MicroRNAs;84 8.4;5.4 APOBEC3G Counteracts miRNA-Mediated Repression of Protein Translation;85 8.5;5.5 Conclusion Remarks;87 8.6;References;88 9;MicroRNA-Mediated mRNA Deadenylation and Repression of Protein Synthesis in a Mammalian Cell- Free System;93 9.1;6.1 Introduction;94 9.2;6.2 Cell-Free Systems that Recapitulate RNA Silencing;95 9.3;6.3 Cell Extract Preparation Methodology;95 9.4;6.4 Processing of Pre-miRNA;96 9.5;6.5 In Vitro Translation Assay;97 9.6;6.6 Let-7-Mediated mRNA Deadenylation;100 9.7;6.7 Poly(A) tail and miRNA-Mediated Repression;102 9.8;6.8 Poly(A) tail and Post-Transcriptional Regulation;103 9.9;6.9 Concluding Remarks;103 9.10;References;104 10;miRNA Effects on mRNA Closed-Loop Formation During Translation Initiation;106 10.1;7.1 Introduction;106 10.2;7.2 Analysing Translational Repression by an miRNA;109 10.3;7.3 Towards a Model for miRNA-Mediated Translational Control;114 10.4;7.4 Concluding Remarks;116 10.5;Note Added in Proof;116 10.6;References;116 11;Index;120