Repression of prespliceosome complex formation at two distinct steps by Fox-1/Fox-2 proteins.
Precise and robust regulation of alternative splicing provides cells with an essential means of gene expression control. However, the mechanisms that ensure the tight control of tissue-specific alternative splicing are not well understood. It has been demonstrated that robust regulation often results from the contributions of multiple factors to one particular splicing pathway. We report here a novel strategy used by a single splicing regulator that blocks the formation of two distinct prespliceosome complexes to achieve efficient regulation. Fox-1/Fox-2 proteins, potent regulators of alternative splicing in the heart, skeletal muscle, and brain, repress calcitonin-specific splicing of the calcitonin/CGRP pre-mRNA. Using biochemical analysis, we found that Fox-1/Fox-2 proteins block prespliceosome complex formation at two distinct steps through binding to two functionally important UGCAUG elements. First, Fox-1/Fox-2 proteins bind to the intronic site to inhibit SF1-dependent E' complex formation. Second, these proteins bind to the exonic site to block the transition of E' complex that escaped the control of the intronic site to E complex. These studies provide evidence for the first example of regulated E' complex formation. The two-step repression of presplicing complexes by a single regulator provides a powerful and accurate regulatory strategy.
Zhou
Hua-Lin
HL
Department of Genetics, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106, USA.
Lou
Hua
H
D001483:Base Sequence; D002116:Calcitonin / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D004742:Enhancer Elements, Genetic / Q000235:genetics; D005091:Exons / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D051916:Membrane Cofactor Protein / Q000378:metabolism; D008954:Models, Biological; D009687:Nuclear Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding; D022821:RNA Splice Sites; D012326:RNA Splicing / Q000235:genetics; D000072260:RNA Splicing Factors; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000378:metabolism; D000068103:Serine-Arginine Splicing Factors; D037941:Silencer Elements, Transcriptional; D017381:Spliceosomes / Q000378:metabolism*; D000072668:Splicing Factor U2AF; D014157:Transcription Factors / Q000378:metabolism
C497857:CD46 protein, human; D004268:DNA-Binding Proteins; D051916:Membrane Cofactor Protein; D009687:Nuclear Proteins; D010750:Phosphoproteins; C455479:RBFOX1 protein, human; C454924:RBFOX2 protein, human; D022821:RNA Splice Sites; D000072260:RNA Splicing Factors; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D012261:Ribonucleoproteins; C107467:SF1 protein, human; C489470:SRSF6 protein, human; D000072668:Splicing Factor U2AF; D014157:Transcription Factors; C000607494:U2AF2 protein, human; D000068103:Serine-Arginine Splicing Factors; D002116:Calcitonin