In the right place at the right time : understanding basic microrna biology through the control of developmental timing by lin-4 and let-7 in caenorhabditis elegans
Abstract/Contents
- Abstract
- MicroRNAs are an important class of short RNA molecules that regulate gene expression in diverse organisms. Despite their short history, extensive research on microRNAs has revealed how microRNAs are made, their regulatory mechanisms and functions in different biological processes. In addition, novel experimental techniques and computational algorithms have been developed to study microRNAs. Our knowledge of microRNAs is constantly evolving as newer studies turn up exceptions to canonical models established by early studies. This highlights how our understanding of microRNAs is far from complete and much work is still needed to investigate unexplored aspects of the microRNA world. The founding microRNAs, C. elegans lin-4 and let-7, have well-characterized heterochronic defects in mutant animals and their target genes have been genetically validated. Combined with powerful experimental tools available in C. elegans, the microRNA function of lin-4 and let-7 in developmental timing of C. elegans is an ideal in vivo model system for testing microRNA-related hypotheses. Using functional assays to evaluate lin-4 and let-7 rescue activities in transgenic animals, we have investigated several poorly understood aspects of microRNAs, from biogenesis to functional mechanism. In this work, we first demonstrated the cell autonomous nature of lin-4 in C. elegans temporal development. Through tissue/cell-specific expression of lin-4 and the use of tissue/cell-specific reporters and microRNA sponges, we have shown that lin-4 rescue activities were limited to sites of lin-4 expression, despite its broad endogenous expression and function in many tissues. Next, we showed that intron-containing microRNAs ("inc-miRs") are functional in C. elegans, raising the possibility that mature microRNAs need not be encoded as contiguous units in the genome. This result also highlights a blindspot in our current novel microRNA discovery methods that assume inc-miRs do not exist. Lastly, we investigated the partnership between microRNA "seed" and "non-seed" sequences in providing microRNA function during C. elegans temporal development. By assessing microRNA function in transgenic mutant animals expressing lin-4 or let-7 mutant microRNA, we found contrasting results between lin-4 and let-7. While the results suggest a functional requirement for lin-4 seed sequence, mutations in either let-7 seed or non-seed sequences provided similar levels of functional activities. Using C. elegans lin-4 and let-7 as an experimental model, this work has furthered our understanding on microRNA autonomy, microRNA biogenesis and functional partnership between microRNA seed and non-seed sequence.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2012 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Zhang, Huibin |
|---|---|
| Associated with | Stanford University, Department of Genetics |
| Primary advisor | Fire, Andrew Zachary |
| Thesis advisor | Fire, Andrew Zachary |
| Thesis advisor | Brunet, Anne, 1972- |
| Thesis advisor | Li, Jin |
| Thesis advisor | Villeneuve, Anne, 1959- |
| Advisor | Brunet, Anne, 1972- |
| Advisor | Li, Jin |
| Advisor | Villeneuve, Anne, 1959- |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Huibin Zhang. |
|---|---|
| Note | Submitted to the Department of Genetics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2012. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2012 by Huibin Zhang
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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