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Signaling-Dependent and Coordinated Regulation of Transcription, Splicing, and Translation Resides in a Single Coregulator, PCBP1
Qingchang Meng, Suresh K. Rayala, Anupama E. Gururaj, Amjad H. Talukder, Bert W. O'Malley and Rakesh Kumar
Proceedings of the National Academy of Sciences of the United States of America
Vol. 104, No. 14 (Apr. 3, 2007), pp. 5866-5871
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/25427293
Page Count: 6
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Transcription, splicing, and translation are potentially coordinately regulatable in a temporospatial-dependent manner, although supporting experimental evidence for this notion is scarce. Yeast two-hybrid screening of a mammary gland cDNA library with human p21-activated kinase 1 (Pak1) as bait identified polyC-RNAbinding protein 1 (PCBP1), which controls translation from mRNAs containing the DICE (differentiation control element). Mitogenic stimulation of human cells phosphorylated PCBP1 on threonines 60 and 127 in a Pak1-sensitive manner. Pak1-dependent phosphorylation of PCBP1 released its binding and translational inhibition from a DICE-minigene. Overexpression of PCBP1 also inhibited the translation of the endogenous L1 cell adhesion molecule mRNA, which contains two DICE motifs in the 3' untranslated region. We also found that Pak1 activation led to an increased nuclear retention of PCBP1, recruitment to the eukaryotic translation initiation factor 4E (eIF4E) promoter, and stimulation of eIF4E expression in a Pak1-sensitive manner. Moreover, mitogenic stimulation promoted Pak1- and PCBP1-dependent alternative splicing and exon inclusion from a CD44 minigene. The alternative splicing functions of PCBP1 were in turn mediated by its intrinsic interaction with Caper α, a U2 snRNP auxiliary factor-related protein previously implicated in RNA splicing. These findings establish the principle that a single coregulator can function as a signal-dependent and coordinated regulator of transcription, splicing, and translation.
Proceedings of the National Academy of Sciences of the United States of America © 2007 National Academy of Sciences