RRM
2012 Rustbelt RNA Meeting
RRM
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Talk abstracts
Abstract:
PUFs are unique RNA-binding proteins with incredible specificity and high affinity for their mRNA targets. PUFs limit gene expression through induction of mRNA decay and translational inhibition. PUF proteins are present across eukaryotes, and are involved in a myriad of important biological processes including stem cell maintenance, learning and memory, and embryonic development. I study the founding PUF family member, Pumilio (Pum), which binds to UGUANAUA sequences in the Drosophila transcriptome. Binding to this element in the Hunchback (Hb) mRNA 3 UTR, Pum creates an anterior-posterior gradient of Hb protein which confers correct abdominal segmentation in the developing Drosophila embryo. I have developed an assay which measures Pum repression in a Drosophila cell line. Using this assay, I have shown that Pum employs multiple strategies to block expression of its targets. The Zn finger protein Nanos was originally thought to be required for Pum repression, but I have discovered that Nanos merely serves to robustly activate repression through Pums RNA-binding domain (RBD). By itself, the RBD bears very minimal activity without Nanos, and is weaker than the full length protein even when stimulated. Consequently, I have also identified multiple autonomous repressor domains in the Pum N-terminus that inhibit translation in a manner independent of Nanos and other known corepressors. These regions are auto-regulated by conserved motifs within Pums N-terminus. This work is an important step in understanding how PUFs can fine-tune mRNA expression by utilizing multiple mechanisms that act in concert via repression domains appended to its highly conserved RBD.
Keywords: PUF, translation inhibition, mRNA repression
