Poster abstracts
Poster number 37 submitted by Swetha Rajasekaran
Post-transcriptional regulation and DICER1 syndrome
Swetha Rajasekaran (Department of Molecular Genetics, OSU), Wayne Miles (Department of Molecular Genetics, OSU)
Abstract:
DICER1 is an endoribonuclease involved in the processing of mature miRNAs. Mutations in the active domain of DICER1 causes DICER1 syndrome – an inherited disorder that increases the risk of generally uncommon cancerous and benign tumors. The most common tumors observed have been in the lungs, kidneys, ovaries and thyroid. However, these active site mutations do not account for all the DICER1 syndrome patients and around 30% of these patients do not have a mapped mutation in Dicer1 coding sequence. By analyzing sequences from a large cohort of patients with DICER1 syndrome, we identified a mutation in the 3’UTR of DICER1 that disrupts the binding site of the Pumilio (PUM) RNA-binding protein (RBP). The PUM family of proteins binds to a set PUMILIO Regulatory Element within the 3’UTR of the mRNA to affect the level of protein translation and mRNA turnover of the substrate. When we deplete the PUM proteins using shRNA or CRISPR, we observed a decrease in DICER1 protein levels suggesting that PUM-mediated regulation might have a functional role in regulating DICER1 levels. Consistent with these results, we have also observed that these changes PUM protein levels affects the maturation of DICER1-dependent miRNAs. To test if PUM-mediated DICER1 regulation can modify cancer phenotype, we made CRISPR-mediated knock-in lines in MDA-MB231 (triple negative breast cancer cell line) with a mutated PRE in the DICER1 3’UTR. These cells will be used to perform functional assays to observe cell growth, invasion and migration rates compared to control. DICER1 expression is a double-edged sword in cancer and it is important for the cells to maintain the right amount of DICER1 making it hard to develop therapeutic strategies directly targeting DICER1. Understanding PUM-mediated post-transcriptional regulation of DICER1 and its role in promoting DICER1 protein production may provide opportunities to target DICER1 activity in tumors.
Keywords: Pumilio, Post-transcriptional Regulation, Dicer1