Integration of 3′UTR regulatory signals in the worm germline

Abstract

Translational regulation of maternal mRNAs drives embryogenesis prior to zygotic transcription. Maternal mRNAs are transcribed during oogenesis and translationally silenced until fertilization. It is not clear how specific mRNAs are selected for translational regulation. C. elegans Notch receptor GLP‐1 serves as a model for studying this process. At least ten RNA‐binding proteins are required to restrict GLP‐1 expression via its 3′UTR. These proteins bind RNA with limited specificity, recognizing short partially degenerate sequence motifs. We have detected a cluster of eight highly conserved motifs within a 100 nucleotide element required for spatial patterning of GLP‐1 expresison. We are dissecting the contribution of each protein and each motif to binding and repression. Our results suggest that competition for binding to key regulatory sequences, driven by the context of overlapping binding motifs, is critical for appropriate expression patterning in the embryo. We have identified similar clusters in ~60 additional maternal transcripts, suggesting antagonism between multiple factors may be a general mechanism to coordinate regulation of mRNAs encoding critical cell fate determinants in the embryo.