The CD44 Alternative v9 Exon Contains a Splicing Enhancer Responsive to the SR Proteins 9G8, ASF/SF2, and SRp20

Galiana-Arnoux, Delphine; Lejeune, Fabrice; Gesnel, Marie-Claude; Stévenin, James; Breathnach, Richard; Gatto–Konczak, Fabienne Del

doi:10.1074/jbc.m301090200

Cited by 69 publications

(40 citation statements)

References 43 publications

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“…Galiana-Arnoux et al 22 have, however, recently demonstrated the presence within CD44 exon v9 of a splicing enhancer of approximately 30 nucleotides that binds the SR proteins 9G8, ASF/SF2 and SRp20, promoting inclusion of this particular exon. Similar splice enhancer elements have also been identified within several other alternatively spliced CD44 exons, most notably exon v5.…”

Section: Discussionmentioning

confidence: 99%

Molecular mechanisms regulating the tumor-targeting potential of splice-activated gene expression

Hayes

Dougherty

Davis³

et al. 2004

Cancer Gene Ther

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Previous studies have suggested that differences in the ability of normal and malignant cells to process certain alternatively spliced pre-mRNA transcripts can be exploited as a potentially powerful means of targeting the expression of therapeutic genes to tumor cells in vivo and in vitro. Specifically, it was shown that efficient processing of minigene constructs containing the alternatively spliced CD44 exons v9 and v10 only occurs in tumor cells that express CD44 isoforms that incorporate these exons (e.g. CD44R1). In the present study, efforts were made to define the molecular mechanisms that underlie the apparent specificity of this process. RT-PCR analysis and DNA sequencing were used to characterize the various splicing events that occur between CD44 exons v8, v9 and v10 following transfection of minigene constructs containing these various exons into CD44R1-positive (PC3) and CD44R1-negative (T24) cell lines. The results obtained confirm that although the v8-v9 intron is efficiently removed in both CD44R1-positive and CD44R1-negative cells, the corresponding v9-v10 intron is accurately spliced and the exons appropriately joined only in lines that express v10-containing CD44 isoforms (e.g. PC3). In CD44R1-negative cell lines (e.g. T24) alternative 5 0 and 3 0 splice sites located within the v9-v10 intron are preferentially used, resulting in various portions of the intron being retained within the final processed mRNA product. It is proposed that identification of these functionally important intronic sequence elements will facilitate the development of second generation ''splice activated gene expression'' vectors that may prove useful in various cancer gene therapy applications.

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Section: Discussionmentioning

confidence: 99%

Molecular mechanisms regulating the tumor-targeting potential of splice-activated gene expression

Hayes

Dougherty

Davis³

et al. 2004

Cancer Gene Ther

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“…In other alternative splicing systems in which its action has been examined, 9G8 usually acts as a splicing activator (Cramer et al, 1999;Galiana-Arnoux et al, 2003;Li et al, 2000) and the sites it influences are also regulated by ASF/SF2 and/or SRp20. In our study, 9G8 acts as a strong splicing inhibitor and binds to an element which behaves as an intronic splicing silencer.…”

Section: G8 As a Regulator Of Other Alternatively Spliced Exonsmentioning

confidence: 99%

SR protein 9G8 modulates splicing of tau exon 10 via its proximal downstream intron, a clustering region for frontotemporal dementia mutations

Gao

Wang

et al. 2007

Molecular and Cellular Neuroscience

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The microtubule-associated protein tau is important to normal neuronal function in the mammalian nervous system. Aggregated tau is the major component of neurofibrillary tangles (NFTs), present in several neurodegenerative diseases, including Alzheimer's and frontotemporal dementia with Parkinsonism (FTDP). Splicing misregulation of adult-specific exon 10 results in expression of abnormal ratios of tau isoforms, leading to FTDP. Positions +3 to +16 of the intron downstream of exon 10 define a clustering region for point mutations that are found in FTDP. The serine/argininerich (SR) factor 9G8 strongly inhibits inclusion of tau exon 10. In this study, we established that 9G8 binds directly to this clustering region, requires a wild-type residue at position +14 to inhibit exon inclusion, and RNAi constructs against 9G8 increase exon 10 inclusion. These results indicate that 9G8 plays a key role in regulation of exon 10 splicing and imply a pathogenic role in neurodegenerative diseases.

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“…Therefore, these small SR proteins may have a role in CD44 splicing and metastasis, and they were also found to be up-regulated in a mouse mammary tumorigenesis model (55). 9G8 is one of the 30-kDa SR proteins, and a 9G8-responsive exonic splicing enhancer sequence was found in the v9 exon (56).…”

Section: Alternative Splicing Of Transmembrane Proteinsmentioning

confidence: 99%

Aberrant and Alternative Splicing in Cancer

2004

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Pre-mRNA splicing is a sophisticated and ubiquitous nuclear process, which is a natural source of cancer-causing errors in gene expression. Intronic splice site mutations of tumor suppressor genes often cause exon-skipping events that truncate proteins just like classical nonsense mutations. Also, many studies over the last 20 years have reported cancerspecific alternative splicing in the absence of genomic mutations. Affected proteins include transcription factors, cell signal transducers, and components of the extracellular matrix. Antibodies against alternatively spliced products on cancer cells are currently in clinical trials, and competitive reverse transcription-PCR across regions of alternative splicing is being used as a simple diagnostic test. As well as being associated with cancer, the nature of the alternative gene products is usually consistent with an active role in cancer; therefore, the alternative splicing process itself is a potential target for gene therapy. Splice Site Mutations Can Cause Aberrant Splicing and CancerDefects in mRNA splicing are an important cause of disease (1-3). The most common form of splicing defects are genomic splice site point mutations, and a recent survey found 29 different p53 splice site mutations in Ͼ12 different types of cancer (4). Ninety-nine percent of all exons are flanked by the intronic dinucleotides GT and AG at the 5Ј and 3Ј splice sites respectively, and mutation of these sites usually causes exclusion of the adjacent exon (Fig. 1A), although sometimes splice site mutations have even more drastic consequences, e.g., double exon skipping in MLH1 in hereditary nonpolyposis colorectal cancer (5). More than half of all exon deletions lead to truncation of the encoded protein and as such, mutations in tumor suppressor genes at the invariant intronic dinucleotide can act much as classical nonsense mutations. For example a GT to AT 5Ј splice site mutation in hSNF5 causes deletion of exon 7, a frame shift, and a truncated reading frame, and this causes infant brain tumors when a "second hit" is provided at the wild-type allele by a deletion (6). Similarly a 3Ј splice site AG to AT mutation caused constitutive loss of exon 4 of the APC gene in colorectal to liver metastases, where the wild-type allele was deleted (ref. 7; Fig. 1A).Mutations in the less conserved splice site consensus away from the invariant dinucleotides tend to lead to partial aberrant splicing, often with a relatively mild phenotype. For example, the most common pathogenic mutation of the ATM gene is linked to breast cancer but is incompletely penetrant and is thought to have originated in Palaeolithic times. This is a mutation at the sixth position of an intron that causes a proportion of transcripts to skip an exon and to be frame shifted leading to a truncated protein (8). The polypyrimidine tract signal associated with the 3Ј splice site is another hot spot for mutation (Fig. 1A). An intronic mutation 11 nucleotides upstream of a 3Ј splice site in MLH1 knocks out an exon, and this ...

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The CD44 Alternative v9 Exon Contains a Splicing Enhancer Responsive to the SR Proteins 9G8, ASF/SF2, and SRp20

Cited by 69 publications

References 43 publications

Molecular mechanisms regulating the tumor-targeting potential of splice-activated gene expression

Molecular mechanisms regulating the tumor-targeting potential of splice-activated gene expression

SR protein 9G8 modulates splicing of tau exon 10 via its proximal downstream intron, a clustering region for frontotemporal dementia mutations

Aberrant and Alternative Splicing in Cancer

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