Crossregulation and Functional Redundancy between the Splicing Regulator PTB and Its Paralogs nPTB and ROD1

• Published in: Molecular cell Vol. 27; no. 3; pp. 420 - 434
• Main Authors: Spellman, Rachel, Llorian, Miriam, Smith, Christopher W.J.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 03-08-2007; Cell Press
• Subjects: Alternative Splicing - genetics; Cells, Cultured; Electrophoresis, Gel, Two-Dimensional; Exons; Gene Expression Regulation; HeLa Cells; Humans; Myocytes, Smooth Muscle - metabolism; Neurons - metabolism; Polypyrimidine Tract-Binding Protein - genetics; Polypyrimidine Tract-Binding Protein - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA; RNA Processing, Post-Transcriptional; RNA, Messenger - chemistry; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; RNA
• ISSN: 1097-2765; 1097-4164
• DOI: 10.1016/j.molcel.2007.06.016

Among the targets of the repressive splicing regulator, polypyrimidine tract binding protein (PTB) is its own pre-mRNA, where PTB-induced exon 11 skipping produces an RNA substrate for nonsense-mediated decay (NMD). To identify additional PTB-regulated alternative splicing events, we used quantitative proteomic analysis of HeLa cells after knockdown of PTB. Apart from loss of PTB, the only change was upregulation of the neuronally restricted nPTB, resulting from decreased skipping of nPTB exon 10, a splicing event that leads to NMD of nPTB mRNA. Compared with knockdown of PTB alone, simultaneous knockdown of PTB and nPTB led to larger changes in alternative splicing of known and newly identified PTB-regulated splicing events. Strikingly, the hematopoietic PTB paralog ROD1 also switched from a nonproductive splicing pathway upon PTB/nPTB knockdown. Our data indicate crossregulation between PTB and its paralogs via nonproductive alternative splicing and a large degree of functional overlap between PTB and nPTB.