microRNAs
MicroRNAs are ~22 nucleotide RNAs processed from RNA hairpin structures. MicroRNAs are much too short to code for protein and instead play important roles in regulating gene expression. In humans, they regulate most protein-coding genes, including genes important in cancer and other diseases.
Introduction to microRNAs: Bartel explains how microRNAs are made, how they have evolved, how they recognize and bind to target mRNA sequences, how this binding leads to the repression of the target mRNAs, and how this repression can be important for normal development and disease.
Regulatory Effects of Mammalian microRNAs: Bartel recounts experiments measuring the effect of microRNAs on mRNA levels, protein levels and protein synthesis in mammalian cells. The results showed that almost all of the changes in protein levels and synthesis are due to changes in the amount of mRNA.
Interestingly, experiments in zebrafish embryos describe a somewhat different situation. In the early embryo, initial decreases in protein synthesis are due to shortening of the mRNA polyA tail, which is followed later by a decrease in the amount of RNA.
What is a microRNA?: Bartel asks how a cell knows which hairpin RNA molecules are pre-microRNAs, and should be processed into microRNAs, and which should be ignored. He leads us through the experiments that identified some of the key conserved features of human pre-microRNAs.
David Bartel is a Professor of Biology at the Massachusetts Institute of Technology, a Member of the Whitehead Institute and an Investigator of the Howard Hughes Medical Institute.
(from ibiology.org)
1. Introduction to microRNAs
Bartel explains how microRNAs are made, how they have evolved, how they recognize and bind to target mRNA sequences, how this binding leads to the repression of the target mRNAs, and how this repression can be important for normal development and disease.
2. Regulatory Effects of Mammalian microRNAs
Bartel recounts experiments measuring the effect of microRNAs on mRNA levels, protein levels and protein synthesis in mammalian cells.
3. What is a microRNA?
Bartel asks how a cell knows which hairpin RNA molecules are pre-microRNAs, and should be processed into microRNAs, and which should be ignored.
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| The Life of Eukaryotic mRNA The control of mRNA production and function is a key aspect of the regulation of gene expression. |
| RNA Structure, Function and Recognition Anna Marie Pyle explains that many RNA molecules have elaborate structures that are essential for their functions. |
| RNA Processing Melissa Moore explains that eukaryotic pre-mRNA contains long stretches of non-protein coding sequences interspersed with protein coding regions. |
| Protein Synthesis Green provides a detailed look at protein synthesis, or translation. Translation is the process by which nucleotides, the "language" of DNA and RNA, are translated into amino acids, the "language" of proteins. |