Antagonistic regulation of α-actinin alternative splicing by CELF proteins and polypyrimidine tract binding protein

Gromak, Natalia; Matlin, Arianne J.; Cooper, Thomas A.; Smith, Christopher W.J.

doi:10.1261/rna.2191903

Cited by 100 publications

(122 citation statements)

References 52 publications

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“…Finally, it was also shown that PTB binding sites can overlap with enhancer elements. In this case, PTB can compete the binding of activator factors, preventing the formation of an activator complex (46,47). In accord with this model, we identified a complex intronic enhancer element that overlaps with the repressor region.…”

Section: Discussionsupporting

confidence: 55%

Polypyrimidine Tract-binding Protein Is Involved in Vivo in Repression of a Composite Internal/3′ -Terminal Exon of the Xenopus α-Tropomyosin Pre-mRNA

Hamon

Sommer

Méreau

et al. 2004

Journal of Biological Chemistry

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The Xenopus ␣ fast -tropomyosin gene contains, at its 3 -end, a composite internal/3 -terminal exon (exon 9A9 ), which is subjected to three different patterns of splicing according to the cell type. Exon 9A9 is included as a terminal exon in the myotome and as an internal exon in adult striated muscles, whereas it is skipped in nonmuscle cells. We have developed an in vivo model based on transient expression of minigenes encompassing the regulated exon 9A9 in Xenopus oocytes and embryos. We first show that the different ␣-tropomyosin minigenes recapitulate the splicing pattern of the endogenous gene and constitute valuable tools to seek regulatory sequences involved in exon 9A9 usage. A mutational analysis led to the identification of an intronic element that is involved in the repression of exon 9A9 in nonmuscle cells. This element harbors four polypyrimidine track-binding protein (PTB) binding sites that are essential for the repression of exon 9A9 . We show using UV cross-linking and immunoprecipitation experiments that Xenopus PTB (XPTB) interacts with these PTB binding sites. Finally, we show that depletion of endogenous XPTB in Xenopus embryos using a morpholinobased translational inhibition strategy resulted in exon 9A9 inclusion in embryonic epidermal cells. These results demonstrate that XPTB is required in vivo to repress the terminal exon 9A9 and suggest that PTB could be a major actor in the repression of regulated 3 -terminal exon.Alternative splicing is a widespread mechanism in metazoans, by which multiple mRNAs can be produced from a single gene. This process is often subjected to tissue or developmental control and allows the production of protein isoforms differing in specific domains.Over the last few years, some general topics have emerged from the intensive studies undertaken to elucidate the mechanism of alternative splicing. It is thus established that regulated exons are generally flanked by suboptimal splice sites whose recognition is modulated by cis-acting regulatory sequences present within exons or introns. In most cases, alternative exons are subject to positive and negative regulation which insures a tight control on their usage (reviewed in Ref.1). Numerous trans-acting factors that modulate alternative splicing have also been characterized. These regulatory factors belong to two broad families of RNA-binding proteins, designated hnRNP proteins and RS-domain proteins. The latter includes the SR protein subfamily (2, 3) that is involved in constitutive or alternative exon recognition through exonic sequence called exonic enhancer (4).Despite this significant breakthrough, the basis of tissue regulation of alternative splicing is still poorly understood in vertebrates. Indeed, contrary to the paradigm described in Drosophila, where many splicing events are controlled by tissue-specific factors (5), to date the implication of such factors appears limited in vertebrates.To overcome this lack of tissue specific factors it was proposed that ubiquitously expressed splicing factors could...

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Section: Discussionsupporting

confidence: 55%

Polypyrimidine Tract-binding Protein Is Involved in Vivo in Repression of a Composite Internal/3′ -Terminal Exon of the Xenopus α-Tropomyosin Pre-mRNA

Hamon

Sommer

Méreau

et al. 2004

Journal of Biological Chemistry

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“…Therefore, it will be meaningful to examine its functional role, as well as its structure, in more detail and look for differences between the splice variants. Beside U2AF, the repressive role of PTB has been antagonized by many different RNA binding proteins, namely the CELF [13,25] proteins ETR3 and CUG-BP, RBM4 [33], TIA-1 [27,34], Nova [40] and Fox-1 [102]. It will be valuable to gain a better understanding of the molecular mechanisms behind these antagonisms.…”

Section: Discussionmentioning

confidence: 99%

“…Polypyrimidine tract binding protein (PTB) is a ubiquitous regulator of alternative splicing that influences different types of alternative-splicing events (a) PTB represses the N1 "cassette-exon" in the c-src pre-mRNA [7,9,10,103]. (b) PTB represses the "mutually exclusive" SM exon of the a-actinin mRNA [12,13]. (c) PTB regulates the choice of the 3'-terminal exon of the calcitonin/CGRP mRNA [104].…”

Section: The Many Functions Of Polypyrimidine Tract Binding Proteinmentioning

confidence: 99%

Structure-function relationships of the polypyrimidine tract binding protein

Auweter

Allain

2007

Cell. Mol. Life Sci.

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Abstract. The polypyrimidine tract binding protein (PTB) is a 58-kDa RNA binding protein involved in multiple aspects of mRNA metabolism including splicing regulation, polyadenylation, 3'end formation, internal ribosomal entry site-mediated translation, RNA localization and stability. PTB contains four RNA recognition motifs (RRMs) separated by three linkers. In this review we summarize structural information on PTB in solution that has been gathered during the past 7 years using NMR spectroscopy and small-angle X-ray scattering. The structures of all RRMs of PTB in their free state and in complex with short pyrimidine tracts, as well as a structural model of PTB RRM2 in complex with a peptide, revealed unusual structural features that provided new insights into the mechanisms of action of PTB in the different processes of RNA metabolism and in particular splicing regulation.

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“…In the nucleus, CELF proteins regulate pre-mRNA alternative splicing of a subset of transcripts by binding to intronic U/G-rich sequences and communicating with the basal splicing machinery through some as-yet-unknown mechanism (Ladd et al, 2001(Ladd et al, , 2005Charlet-B. et al, 2002a;Suzuki et al, 2002;Zhang et al, 2002;Gromak et al, 2003). In the cytoplasm, CELF proteins can regulate both transcript stability and translation by interacting with A/U-rich sequences in the 3Ј untranslated regions of target mRNAs (Timchenko et al, 2001;Mukhopadhyay et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Cloning and embryonic expression patterns of the chicken CELF family

Brimacombe

Ladd

2007

Developmental Dynamics

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The CUG-BP and ETR-3-like factor (CELF) protein family has been implicated in the regulation of premRNA alternative splicing, mRNA stability, and translation. Here we discuss the evolution and radiation of the CELF protein subfamilies, and report the cloning of the chicken CELF family members. In this study, we examined the embryonic expression patterns of the CELF family in the chick by in situ hybridization. We found that the tissue specificity reported for CELF proteins in the adult is established early during embryogenesis. Members of one subfamily, CUG-BP1 and ETR-3, are broadly expressed in the early embryo, while members of the second subfamily, CELF4-6, are restricted primarily to the nervous system. Expression patterns of individual CELF genes in several tissues, including the heart, liver, eye, and neural tube, exhibit distinct, yet overlapping, expression patterns. This suggests that different members of the CELF family play distinct functional roles during embryogenesis. Developmental Dynamics 236:2216 -2224, 2007.

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Antagonistic regulation of α-actinin alternative splicing by CELF proteins and polypyrimidine tract binding protein

Cited by 100 publications

References 52 publications

Polypyrimidine Tract-binding Protein Is Involved in Vivo in Repression of a Composite Internal/3′ -Terminal Exon of the Xenopus α-Tropomyosin Pre-mRNA

Polypyrimidine Tract-binding Protein Is Involved in Vivo in Repression of a Composite Internal/3′ -Terminal Exon of the Xenopus α-Tropomyosin Pre-mRNA

Structure-function relationships of the polypyrimidine tract binding protein

Cloning and embryonic expression patterns of the chicken CELF family

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