Caenorhabditis elegans ALG-1 antimorphic mutations uncover functions for Argonaute in microRNA guide strand selection and passenger strand disposal
Authors
Zinovyeva, Anna Y.Veksler-Lublinsky, Isana
Vashisht, Ajay A.
Wohlschlegel, James A.
Ambros, Victor R.
Document Type
Journal ArticlePublication Date
2015-09-22Keywords
Caenorhabditis elegansMicroRNAs
ALG-1
Argonaute
microRNA
microRNA*
passenger
Developmental Biology
Genetics and Genomics
Molecular Biology
Molecular Genetics
Metadata
Show full item recordAbstract
MicroRNAs are regulators of gene expression whose functions are critical for normal development and physiology. We have previously characterized mutations in a Caenorhabditis elegans microRNA-specific Argonaute ALG-1 (Argonaute-like gene) that are antimorphic [alg-1(anti)]. alg-1(anti) mutants have dramatically stronger microRNA-related phenotypes than animals with a complete loss of ALG-1. ALG-1(anti) miRISC (microRNA induced silencing complex) fails to undergo a functional transition from microRNA processing to target repression. To better understand this transition, we characterized the small RNA and protein populations associated with ALG-1(anti) complexes in vivo. We extensively characterized proteins associated with wild-type and mutant ALG-1 and found that the mutant ALG-1(anti) protein fails to interact with numerous miRISC cofactors, including proteins known to be necessary for target repression. In addition, alg-1(anti) mutants dramatically overaccumulated microRNA* (passenger) strands, and immunoprecipitated ALG-1(anti) complexes contained nonstoichiometric yields of mature microRNA and microRNA* strands, with some microRNA* strands present in the ALG-1(anti) Argonaute far in excess of the corresponding mature microRNAs. We show complex and microRNA-specific defects in microRNA strand selection and microRNA* strand disposal. For certain microRNAs (for example mir-58), microRNA guide strand selection by ALG-1(anti) appeared normal, but microRNA* strand release was inefficient. For other microRNAs (such as mir-2), both the microRNA and microRNA* strands were selected as guide by ALG-1(anti), indicating a defect in normal specificity of the strand choice. Our results suggest that wild-type ALG-1 complexes recognize structural features of particular microRNAs in the context of conducting the strand selection and microRNA* ejection steps of miRISC maturation.Source
Proc Natl Acad Sci U S A. 2015 Sep 22;112(38):E5271-80. doi: 10.1073/pnas.1506576112. Epub 2015 Sep 8. Link to article on publisher's site
DOI
10.1073/pnas.1506576112Permanent Link to this Item
http://hdl.handle.net/20.500.14038/44447PubMed ID
26351692Related Resources
Link to Article in PubMedRights
Publisher PDF posted as allowed by the publisher's author rights policy at http://www.pnas.org/site/aboutpnas/authorfaq.xhtml.
ae974a485f413a2113503eed53cd6c53
10.1073/pnas.1506576112