Albany 2015:Book of Abstracts
June 9-13 2015
©Adenine Press (2012)
Focus on a clear message: Conserved RNA binding proteins function in mRNA control in eye lens development and their deficiency causes cataract
We study the molecular mechanisms that are essential for development and maintenance of transparency in the eye lens. Toward this goal, we have applied the bioinformatics-based gene discovery tool iSyTE (integrated Systems Tool for Eye gene discovery, http://bioinformatics.udel.edu/Research/iSyTE) to identify a new regulatory function for the conserved RNA binding protein Celf1 (CUGBP, Elav-like family member 1; also known as Cugbp1) in vertebrate lens development. Celf1 has three RNA Recognition Motifs that directly interact with target RNAs to control mRNA decay, alternative splicing or translation into protein. We find that Celf1 deficiency in mouse (Mus musculus), frog (Xenopus) or fish (Zebrafish) causes severe lens defects including cataracts, which indicates that it has a conserved function in vertebrate lens development. Gene expression microarrays and RNA-Sequencing experiments identify over 100 transcripts that are significantly mis-regulated in Celf1 mouse mutant lens and RNA-immunoprecipitation (RIP) and Cross-linked immunoprecipitation (CLIP) assays demonstrate that Celf1 complexes are enriched for mRNAs (e.g. p27Kip1, Dnase2b) that critically function in lens differentiation. Celf1 protein associates with the cyclin-dependent kinase inhibitor p27Kip1 mRNA to inhibit its translation in differentiating lens fiber cells. These data represents the first example of a novel RNA binding protein-mediated mechanism for controlling cell cycle regulators in mammalian eye development and moreover, has broader significance given that the human genome encodes several hundred RNA binding proteins but to date less than twenty have been directly associated with mammalian developmental defects or disease. Finally, the findings on Celf1, taken in context of our recent discovery on the conserved function of a Tudor protein Tdrd7 in human, mouse and chicken eye development (Lachke et al. 2011) suggest that conserved post-transcriptional regulatory circuitries have evolved to control eye development in vertebrates.
This research has been supported by NIH R01 EY021505 and The Pew Charitable Trust Scholars Program in Biomedical Sciences.
Lachke, S.A., Alkuraya, F.S., et al. (2011). Mutations in the RNA granule component TDRD7 causes cataract and glaucoma. Science, 331, 1571-1576.
Archana D. Siddam1
1 Department of Biological Sciences