Analysis of CCM1 expression uncovers novel minor-form exons and variable splicing patterns
Cerebral cavernous malformations (CCM) are vascular lesions, which occur sporadically or following an autosomal dominant inheritance pattern with variable expression and incomplete penetrance. Three genes have been associated with the disease (CCM1, CCM2 and CCM3). CCM1 has been reported to express atypical transcripts in addition to alternative splicing of non-coding exons. Here, we report the identification of novel alternative splicing events in the CCM1 gene. 5′RACE analysis revealed several transcription start sites, novel exons located in introns 2 and 7, and a larger exon 13. The 5′UTR CCM1 region showed at least eight splicing variants which were differentially transcribed. The results shown here expand our knowledge of CCM1 gene expression, which seems to be more complex than previously reported. The novel minor-form exons herein described should be considered in molecular diagnosis of CCM. These findings support new functional transcript sequences that could be considered in the pathogenesis and variable clinical penetrance of Krit1-linked CCMs.
KeywordsCerebral cavernous malformations (CCMs) CCM1 Atypical splicing 5′UTR exons Transcription start site (TSS) Minor-form exons
This work has been supported by grants CP10/00526 (Instituto de Salud Carlos III, Spain) and P07-CVI-02790 (Junta de Andalucía, Spain). RM received a grant for Rio Hortega specialised healthcare post-training contract (Instituto de Salud Carlos III). MD received a fellowship of Asociación Neuroinvest. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This research adhered to the tenets of the Declaration of Helsinki. A written consent was obtained from each of the adult individuals tested. This study was approved by the ‘‘Committee of Ethics and Clinical Investigation’’ from Hospital Universitario Virgen Macarena.
- Cave-Riant F, Denier C, Labauge P, Cécillon M, Maciazek J, Joutel A, Laberge-Le Couteulx S, Tournier-Lasserve E (2002) Spectrum and expression analysis of KRIT1 mutations in 121 consecutive and unrelated patients with cerebral cavernous malformations. Eur J Hum Genet 10:733–740CrossRefPubMedGoogle Scholar
- Chateauvieux S, Morceau F, Dicato M (2010) Diederich M (2010). Molecular and therapeutic potential and toxicity of valproic acid, J Biomed BiotechnolGoogle Scholar
- Craig HD, Gunel M, Cepeda O, Johnson EW, Ptacek L, Steinberg GK, Ogilvy CS, Berg MJ, Crawford SC, Scott RM et al (1998) Multilocus linkage identifies two new loci for a mendelian form of stroke, cerebral cavernous malformation, at 7p15-13 and 3q25.2-27. Hum Mol Genet 7:1851–1858CrossRefPubMedGoogle Scholar
- Kimura K, Wakamatsu A, Suzuki Y, Ota T, Nishikawa T, Yamashita R, Yamamoto J, Sekine M, Tsuritani K, Wakaguri H et al (2006) Diversification of transcriptional modulation: large-scale identification and characterization of putative alternative promoters of human genes. Genome Res 16:55–65CrossRefPubMedPubMedCentralGoogle Scholar
- Liquori CL, Berg MJ, Siegel AM, Huang E, Zawistowski JS, Stoffer T, Verlaan D, Balogun F, Hughes L, Leedom TP et al (2003) Mutations in a gene encoding a novel protein containing a phosphotyrosine-binding domain cause type 2 cerebral cavernous malformations. Am J Hum Genet 73:1459–1464CrossRefPubMedPubMedCentralGoogle Scholar
- Liu Y, Ren S, Castellanos-Martin A, Perez-Losada J, Kwon YW, Huang Y, Wang Z, Abad M, Cruz-Hernandez JJ, Rodriguez CA et al (2012) Multiple novel alternative splicing forms of FBXW7α have a translational modulatory function and show specific alteration in human cancer. PLoS One 7:e49453CrossRefPubMedPubMedCentralGoogle Scholar
- Regadas I, Matos MR, Monteiro FA, Gómez-Skarmeta JL, Lima D, Bessa J, Casares F, Reguenga C (2013) Several cis-regulatory elements control mRNA stability, translation efficiency, and expression pattern of Prrxl1 (paired related homeobox protein-like 1). J Biol Chem 288:36285–36301CrossRefPubMedPubMedCentralGoogle Scholar