Atlas of Genetics and Cytogenetics

in Oncology and Haematology

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Gene Section Review

CELF2 (CUGBP, Elav-like family member 2) Satish Ramalingam, Shrikant Anant Department of Molecular and Integrative Physiology, Kansas University Medical Center, Kansas City, KS, USA (SR, SA)

Published in Atlas Database: May 2014 Online updated version : http://AtlasGeneticsOncology.org/Genes/CELF2ID52815ch10p14.html DOI: 10.4267/2042/56292 This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 2.0 France Licence. © 2015 Atlas of Genetics and Cytogenetics in Oncology and Haematology

Abstract Location: 10p14 Note: Size: 331416 bases. Orientation: plus strand. CELF2 belongs to the family of RNA binding This is encoded by a gene located on implicated in mRNA splicing, editing, 10p13-p14 between Généthon stability and translation. markers D10S547 and D10S223 (Li et al., 2001). This gene is encoded in a single large gene spanning over 159 kilo bases located on DNA/RNA p13-p14 (between D10S547 and D10S223). Description This gene has 14 transcripts (splice variants) and The human CELF2 gene contains 14 exons the 3 major splice variants have distinct exon 1. spanning over approximately 159 kb of the This is an evolutionarily conserved ubiquitously genomic DNA. expressed . The members of the CELF protein family contain two N-terminal RNA Transcription recognition motif (RRM) domains and one C- Alternative promoters usage of CELF2 gene results terminal RRM domain, and a divergent segment of in three transcript variants, where the variants 2 and 160-230 amino acids between second and third 3 proteins have distinct exon 1 resulting in different RRM domains. This divergent domain is unique to 5' untranslated region (UTR) and have extended N- CELF2 proteins and has been shown to contain one terminal sequences (Ramalingam et al., 2008). or more activation molecules required for splicing There are totally 14 transcripts (splice variants) activity. CELF2 has been shown to bind to the reported so far. CUG and Au-rich element (ARE) in the target mRNA and shown to be implicated in muscular Protein dystrophy and cancer. Keywords Description RNA binding protein, mRNA stability, splicing, This is an evolutionarily conserved protein. The apoptosis, translation inhibition, muscular members of the CELF protein family contain two dystrophy, cancer N-terminal RNA recognition motif (RRM) domains and one C-terminal RRM domain, and a divergent Identity segment of 160-230 amino acids between second and third RRM domains. This divergent domain is Other names: BRUNOL3, CUGBP2, ETR-3, unique to CELF2 proteins and has been shown to ETR3, NAPOR contain one or more activation molecules required HGNC (Hugo): CELF2 for splicing activity (figure 1).

Atlas Genet Cytogenet Oncol Haematol. 2015; 19(2) 93 CELF2 (CUGBP, Elav-like family member 2) Ramalingam S, Anant S

Figure 1. RRM position of CELF2 protein variants.

Expression untranslated region (3' UTR) of the target mRNAs. Upon binding to the AU-rich sequences in CELF2 is a ubiquitously expressed protein. cyclooxygenase-2 (COX-2) 3' UTR, CELF2 According to the NCBI GEO profiles the enhances the stability of COX-2 mRNA. However, CELF2 is expressed in brain, heart, thymus, spleen, CUGBP2 binding also results in the inhibition of its bone, tongue, stomach, intestine, pancreas, liver, translation (Murmu et al., 2004). In our earlier breast, lung, kidney, testis, ovary, prostate, placenta studies we have demonstrated that CELF2 can and skin. In addition, according to expression atlas interact with HuR, a key inducer of RNA stability brain, bone marrow, heart, spleen, lymph node, and translation, and competitively inhibit HuR ovary and adipose tissue has more expression of function (Sureban et al., 2007). Recently, platelet CELF2. derived growth factor was shown to enhance Localisation CELF2 binding to COX-2 mRNA through CELF2 variant 1 is predominantly nuclear, while increased phosphorylation of a tyrosine residue at variants 2 and 3 are predominantly cytoplasmic position 39 in the protein (Xu et al., 2007). These (Ramalingam et al., 2008). CELF2 variant 1 data suggest that posttranscriptional control accumulates in the cytoplasm following radiation mechanisms are in place to modulate the CELF2 exposure (Mukhopadhyay et al., 2003a). The C function as a regulator of stability and translation of terminus of CELF2 transcript variant 1 is rich in AU-rich transcripts. arginine and lysine residues 13 amino acids Homology (KRLKVQLKRSKND) 467 - 480, which is common for NLS elements recognized by importin According to GeneCards, the CELF2 has orthologs proteins. Ladd and Cooper, has reported that the C- in 72 species including much lower organisms such terminus of CELF2 contains a strong nuclear as Danio rerio, Drosophila melanogaster, localization signal overlapping the third RRM Caenorhabditis elegans, Xenopus tropicalis and (Ladd and Cooper, 2004). However, our Oryza sativa. Furthermore, in humans it has 6 unpublished data suggests that nuclear localization paralogs from CELF1 to CELF6. signal extends to the RNA recognition motif 1 and 2 domains. Finally, CELF2 has several leucine-rich Mutations motifs that resembles nuclear export signals Note recognized by the export protein CRM1. According to GeneCards, there is 7518 single Function nucleotide polymorphism. However, Ensembl CELF2 is an RNA-binding protein implicated in the reports that CELF2 has 7768 SNPs. In addition, the regulation of several post-transcriptional events. It Database of Genomic Variants shows that CELF2 has been shown to regulate pre-mRNA splicing has 18 structural variations. (Faustino and Cooper, 2005), mRNA editing (Anant et al., 2001), mRNA translation and Implicated in stability. CELF2 has been shown to be involved in of muscle specific Colon cancer including exon 5 of cardiac troponin T (Ladd et al., Note 2001), exon 11 of insulin receptor, intron 2 of Putative tumor suppressor CELF2 expression is chloride channel 1, exons 5 and 21 of NMDAR-1, consistently reduced during neoplastic and the muscle-specific exon of α-actinin (Gromak transformation suggesting that it might play a et al., 2003). Another function for CELF2 relates to crucial role in tumor initiation and progression of its ability to bind to AU-rich sequences in 3' colon cancer. In addition, CELF2 has been shown

Atlas Genet Cytogenet Oncol Haematol. 2015; 19(2) 94 CELF2 (CUGBP, Elav-like family member 2) Ramalingam S, Anant S

to induce mitotic catastrophic cell death in colon muscular atrophy (Anderson et al., 2004). Spinal cancer (Ramalingam et al., 2012). and bulbar muscular atrophy (SBMA) is an Pancreatic cancer inherited neurodegenerative disorder caused by the expansion of the polyglutamine (polyQ) tract of the Note androgen receptor (AR-polyQ). It has been shown Curcumin inhibits the pancreatic cancer growth by that miR-196a enhanced the decay of the AR inducing the expression of CELF2 thereby mRNA by silencing CUGBP, Elav-like family regulating the levels of cyclooxygenase 2 and member 2 (CELF2). CELF2 shown to directly act vascular endothelial growth factor expression on AR mRNA and enhance the stability of AR (Subramaniam et al., 2011). mRNA (Miyazaki et al., 2012). Myotonic Breast cancer dystrophy (DM) is a neuromuscular disorder associated with CTG triplet repeat expansion in the Note myotonin protein kinase gene (DMPK). It has been Breast cancer cells underwent apoptotic cell death suggested that the expanded CUG repeats sequester in response to radiation injury and this was reversed specific RNA-binding proteins and that such a by knockdown of CELF2 using specific siRNA sequestration results in abnormal RNA processing (Mukhopadhyay et al., 2003b). of several RNAs containing CUG repeats in Neuroblastoma multiple tissues affected in patients with DM. One Note of the members of the CUG-binding proteins, Colchicine treatment of neuroblastoma cells CUG-BP, has been identified previously (Lu et al., resulted in apoptotic cell death and CELF2 has been 1999). shown to be involved in the process of cell death Development (Li et al., 2001). Note Alzheimer's disease Overexpression of CELF2 by RNA microinjection Note resulted in severe defects in nervous system and It has been shown that variants in CUGBP2 on gastrulation, suggesting the need for tight control of chromosome 10p, are associated with AD in those napor gene regulation during embryo development highest-risk APOE e4 homozygotes. This (Choi et al., 2003). CELF2 appears to be an interaction observation is replicated in independent important factor for thymus development and is samples. CELF2 has one isoform that is expressed therefore a candidate gene for the thymus predominantly in neurons, and identification of hypoplasia/aplasia seen in partial monosomy 10p such a new risk is important because of the patients (Lichtner et al., 2002). severity of AD (Wijsman et al., 2011). References Heart disease Lu X, Timchenko NA, Timchenko LT. Cardiac elav-type Note RNA-binding protein (ETR-3) binds to RNA CUG repeats Arrhythmogenic right ventricular dysplasia is the expanded in myotonic dystrophy. Hum Mol Genet. 1999 most common cause of sudden cardiac death in the Jan;8(1):53-60 young in Italy and the second most common cause Anant S, Henderson JO, Mukhopadhyay D, Navaratnam in the United States. One of the genes that was N, Kennedy S, Min J, Davidson NO. Novel role for RNA- mapped to this is in the vicinity of chromosome binding protein CUGBP2 in mammalian RNA editing. CUGBP2 modulates C to U editing of 10p12-p14 and it is CELF2 (Li et al., 2001). mRNA by interacting with apobec-1 and ACF, the apobec- Ischemia 1 complementation factor. J Biol Chem. 2001 Dec 14;276(50):47338-51 Note Ladd AN, Charlet N, Cooper TA. The CELF family of RNA The transient global ischemia induces the binding proteins is implicated in cell-specific and translational inhibition of genes with increased developmentally regulated alternative splicing. Mol Cell expression in normothermic mice. The author's Biol. 2001 Feb;21(4):1285-96 correlate the translational inhibition with CELF2 Li D, Bachinski LL, Roberts R. Genomic organization and expression and this might play an important role in isoform-specific tissue expression of human NAPOR the progress of neuronal injury after transient global (CUGBP2) as a candidate gene for familial arrhythmogenic right ventricular dysplasia. Genomics. 2001 Jun ischemia (Otsuka et al., 2009). 15;74(3):396-401 Atrophy Lichtner P, Attié-Bitach T, Schuffenhauer S, Henwood J, Note Bouvagnet P, Scambler PJ, Meitinger T, Vekemans M. Expression and mutation analysis of BRUNOL3, a The differential expression of CELF2 has been candidate gene for heart and thymus developmental confirmed with real-time RT-PCR in spinal cord defects associated with partial monosomy 10p. J Mol Med and muscle of three different models of spinal (Berl). 2002 Jul;80(7):431-42

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Choi DK, Yoo KW, Hong SK, Rhee M, Sakaki Y, Kim CH. growth factor-induced stabilization of cyclooxygenase 2 Isolation and expression of Napor/CUG-BP2 in embryo mRNA in rat smooth muscle cells requires the c-Src family development. Biochem Biophys Res Commun. 2003 Jun of protein-tyrosine kinases. J Biol Chem. 2007 Nov 6;305(3):448-54 9;282(45):32699-709 Gromak N, Matlin AJ, Cooper TA, Smith CW. Antagonistic Ramalingam S, Natarajan G, Schafer C, Subramaniam D, regulation of alpha-actinin alternative splicing by CELF May R, Ramachandran I, Queimado L, Houchen CW, proteins and polypyrimidine tract binding protein. RNA. Anant S. Novel intestinal splice variants of RNA-binding 2003 Apr;9(4):443-56 protein CUGBP2: isoform-specific effects on mitotic catastrophe. Am J Physiol Gastrointest Liver Physiol. 2008 Mukhopadhyay D, Houchen CW, Kennedy S, Dieckgraefe Apr;294(4):G971-81 BK, Anant S. Coupled mRNA stabilization and translational silencing of cyclooxygenase-2 by a novel RNA binding Otsuka N, Tsuritani K, Sakurai T, Kato K, Matoba R, Itoh J, protein, CUGBP2. Mol Cell. 2003a Jan;11(1):113-26 Okuyama S, Yamada K, Yoneda Y. Transcriptional induction and translational inhibition of Arc and Cugbp2 in Mukhopadhyay D, Jung J, Murmu N, Houchen CW, mice hippocampus after transient global ischemia under Dieckgraefe BK, Anant S. CUGBP2 plays a critical role in normothermic condition. Brain Res. 2009 Sep 1;1287:136- apoptosis of breast cancer cells in response to genotoxic 45 injury. Ann N Y Acad Sci. 2003b Dec;1010:504-9 Subramaniam D, Ramalingam S, Linehan DC, Dieckgraefe Anderson KN, Baban D, Oliver PL, Potter A, Davies KE. BK, Postier RG, Houchen CW, Jensen RA, Anant S. RNA Expression profiling in spinal muscular atrophy reveals an binding protein CUGBP2/CELF2 mediates curcumin- RNA binding protein deficit. Neuromuscul Disord. 2004 induced mitotic catastrophe of pancreatic cancer cells. Nov;14(11):711-22 PLoS One. 2011 Feb 11;6(2):e16958 Ladd AN, Cooper TA. Multiple domains control the Wijsman EM, Pankratz ND, Choi Y, Rothstein JH, Faber subcellular localization and activity of ETR-3, a regulator of KM, Cheng R, Lee JH, Bird TD, Bennett DA, Diaz-Arrastia nuclear and cytoplasmic RNA processing events. J Cell R, Goate AM, Farlow M, Ghetti B, Sweet RA, Foroud TM, Sci. 2004 Jul 15;117(Pt 16):3519-29 Mayeux R. Genome-wide association of familial late-onset Murmu N, Jung J, Mukhopadhyay D, Houchen CW, Riehl Alzheimer's disease replicates BIN1 and CLU and TE, Stenson WF, Morrison AR, Arumugam T, Dieckgraefe nominates CUGBP2 in interaction with APOE. PLoS BK, Anant S. Dynamic antagonism between RNA-binding Genet. 2011 Feb;7(2):e1001308 protein CUGBP2 and cyclooxygenase-2-mediated Miyazaki Y, Adachi H, Katsuno M, Minamiyama M, Jiang prostaglandin E2 in radiation damage. Proc Natl Acad Sci YM, Huang Z, Doi H, Matsumoto S, Kondo N, Iida M, U S A. 2004 Sep 21;101(38):13873-8 Tohnai G, Tanaka F, Muramatsu S, Sobue G. Viral Faustino NA, Cooper TA. Identification of putative new delivery of miR-196a ameliorates the SBMA phenotype via splicing targets for ETR-3 using sequences identified by the silencing of CELF2. Nat Med. 2012 Jul;18(7):1136-41 systematic evolution of ligands by exponential enrichment. Ramalingam S, Ramamoorthy P, Subramaniam D, Anant Mol Cell Biol. 2005 Feb;25(3):879-87 S. Reduced Expression of RNA Binding Protein CELF2, a Sureban SM, Murmu N, Rodriguez P, May R, Maheshwari Putative Tumor Suppressor Gene in Colon Cancer. R, Dieckgraefe BK, Houchen CW, Anant S. Functional Immunogastroenterology. 2012;1(1):27-33 antagonism between RNA binding proteins HuR and CUGBP2 determines the fate of COX-2 mRNA translation. This article should be referenced as such: Gastroenterology. 2007 Mar;132(3):1055-65 Ramalingam S, Anant S. CELF2 (CUGBP, Elav-like family Xu K, Kitchen CM, Shu HK, Murphy TJ. Platelet-derived member 2). Atlas Genet Cytogenet Oncol Haematol. 2015; 19(2):93-96.

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