RRP1B, a novel metastasis suppressor, regulates alternative mRNA splicing

Wednesday, October 10, 2012 — Poster Session II
Noon – 2:00 p.m	Natcher Conference Center, Building 45	NHGRI	CANCER-19

* FARE Award Winner

Authors

• M. Lee
• A.M. Dworkin
• D. Gildea
• N.S. Trivedi
• T.G. Wolfsberg
• N.P. Crawford

Abstract

RRP1B (ribosomal RNA processing 1 homolog B) was first identified as a metastasis susceptibility gene in breast cancer by its association with the expression of extracellular matrix genes, which are common factors in metastasis predictive gene expression signatures. Many RRP1B binding candidates are involved in alternative mRNA splicing, including SRSF1 (SF2/ASF), a splicing regulator that also functions as an oncogene. We hypothesized that RRP1B regulates alternative splicing through its interaction with SRSF1. Interaction between RRP1B and SRSF1 was verified by co-immunoprecipitation and co-immunofluorescence. Earlier studies demonstrated that splicing and transcription occur concurrently and are coupled processes. Treatment of cells with transcriptional inhibitors significantly increased the interaction between RRP1B and SRSF1, demonstrating that the association of these two proteins is transcriptionally regulated. RNA-seq demonstrated that Rrp1b knockdown induced a significant change in isoform expression in over 600 genes compared to control cell lines. Pathway enrichment analyses identified cell cycle and checkpoint regulation pathways to be those most affected by Rrp1b knockdown. Minigene splicing assays confirmed the role of Rrp1b in alternative splicing. These data suggest that the metastasis modifier RRP1B may mediate metastatic progression by regulating alternatively spliced isoform preference through its interaction with splicing regulators such as SRSF1.

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