Abstract-Alternative splicing enables the generation of different proteins from a single gene, greatly increasing the use of genetic information. The resultant protein isoforms often have different biological properties effecting the phenotype of the cell in which it is expressed. Dysregulation of alternative splicing is a common occurrence in cancer and may lead to the formation of truncated or degraded proteins through the introduction of immature stop codons or nonsense mediated decay. Increasing evidence indicates that cancerassociated splicing variants play an important role in tumor initiation and progression. In this review, we summarize the evidence supporting the relevance of alternative splicing in glioblastoma multiforme (GBM). Specifically, we focus on the role of alternative splicing in GBM pathogenesis with an emphasis on the effect of aberrant alternative splicing of FGFR, GLI-1, and EGFR. The significance of exploiting alternatively spliced isoforms as potential biomarkers which may contribute to the development of diagnostic and prognostic methods, in addition to serving as molecular targets in GBM, will be discussed.
Keywords-glioblastoma; alternative splicing
Medical Research Archives
2015Issue 1 Copyright © 2015, Knowledge Enterprises Incorporated. All rights reserved. 2 INTRODUCTION Alternative splicing is a key regulator of gene expression and enables the generation of numerous transcripts from a single gene, thereby increasing the coding potential of the genome. During mRNA processing, approximately 90% of premRNA is removed as introns, with the remaining 10% joined together as exonic sequences (Tazi, Bakkour, and Stamm 2009). Thus the process has been considered a key driver in the evolution of phenotypic complexity. Splicing is the process by which introns are removed from a precursor mRNA (pre2mRNA) and exons are ligated to form a mature mRNA. Considered one of the most complicated RNA-protein complexes within the eukaryotic cell (Nilsen 2003), pre-mRNA splicing is catalyzed by the spliceosome, a large complex composed of five small nuclear ribonucleoprotein (RNP) subunits each composed of a single uridine rich small nuclear RNA (snRNA) in addition to as many as 150 proteins that assemble in an ordered stepwise manner on each intron to be spliced [reviewed in (Kim, Goren, and Ast 2008, Smith, Query, and Konarska 2008, Wahl, Will, and Luhrmann 2009. The spliceosome performs the two primary functions of splicing: recognition of the intron/exon boundaries and catalysis of the cut and paste reactions that remove introns and join exons. It is responsible for directing both constitutive and alternative splicing (Faustino and Cooper 2003).Definition of the exon/intron boundary is maintained through cis-regulatory RNA elements which serve as splicing enhancers or silencers, essentially determining the splice site. Splicing regulatory elements (SREs) fall into four different categories: exonic splicing enhancers (ESEs), intronic splicing enhancers (ISEs), exonic splicing silencers (ESSs), and in...