Abstract 362: Genomewide Assessment of Posttranscriptional Events Orchestrated by Quaking that Determine Monocyte Fate
The post-transcriptional events that enable monocytes to home to sites of vascular injury, and subsequently differentiate into macrophages within atherosclerotic lesions are poorly understood. We discovered that the mRNA and protein levels of the RNA-binding protein Quaking (QKI) are augmented in CD14+ myeloid cells extracted from advanced human atherosclerotic plaques (4.2-fold upregulated vs. early lesions; p<0.01). This prompted us to investigate how the RNA-binding properties of QKI could influence monocyte fate.
Our approach was to examine, at a genome-wide level, how altering the expression levels of QKI could impact pre-mRNA splicing, expression, and localization upon differentiation of human monocytes into Mf. For this, we employed both array-based gene expression analyses as well as next-generation sequencing techniques (RNA-seq) of THP-1 monocytic cells as well as CD14+ monocytes derived from the peripheral blood of a unique, QKI haploinsufficient subject (with sibling control). Despite low expression levels of QKI in monocytes, the abrogation of QKI in these cells perturbed cellular adhesion and the ensuing establishment of the cytoskeletal architecture. Interestingly, our investigation of post-transcriptional events that are associated with the conversion of the monocyte to a macrophage, uncovered: 1) 536 alternative splicing events (p<0.05) that are directly mediated by binding of QKI proximal to the splice site (QBS)(Fig. 1A); and 2) 1214 differentially expressed genes (minimally +/- 1.5-fold; p<0.05) that indicate that QKI modulates monocyte activation and differentiation by regulating inflammation, cell growth and survival, RNA editing and lipid metabolism via activation of the LXR/RXR pathway (Fig. 1B).
Collectively, our data illustrate the post-transcriptional events that drive monocyte to macrophage differentiation, and identify the RNA-binding protein QKI as an orchestrator of this inflammatory response.
Author Disclosures: E.P. van der Veer: None.
- © 2014 by American Heart Association, Inc.