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Aran V. K-RAS4A: Lead or Supporting Role in Cancer Biology? Front Mol Biosci 2021; 8:729830. [PMID: 34604308 PMCID: PMC8479197 DOI: 10.3389/fmolb.2021.729830] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 09/01/2021] [Indexed: 11/19/2022] Open
Abstract
The RAS oncogene is one of the most frequently mutated genes in human cancer, with K-RAS having a leading role in tumorigenesis. K-RAS undergoes alternative splicing, and as a result its transcript generates two gene products K-RAS4A and K-RAS4B, which are affected by the same oncogenic mutations, are highly homologous, and are expressed in a variety of human tissues at different levels. In addition, both isoforms localise to the plasma membrane by distinct targeting motifs. While some evidence suggests nonredundant functions for both splice variants, most work to date has focused on K-RAS4B, or even just K-RAS (i.e., without differentiating between the splice variants). This review aims to address the most relevant evidence published regarding K-RAS4A and to discuss if this “minor” isoform could also play a leading role in cancer, concluding that a significant body of evidence supports a leading role rather than a supporting (or secondary) role for K-RAS4A in cancer biology.
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Affiliation(s)
- Veronica Aran
- Laboratorio de Biomedicina Do Cérebro, Instituto Estadual Do Cérebro Paulo Niemeyer, Rio de Janeiro, Brazil
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2
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Cruse G, Kaur D, Leyland M, Bradding P. A novel FcεRIβ-chain truncation regulates human mast cell proliferation and survival. FASEB J 2010; 24:4047-57. [PMID: 20554927 PMCID: PMC2996906 DOI: 10.1096/fj.10-158378] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Accepted: 06/03/2010] [Indexed: 12/26/2022]
Abstract
Mast cells contribute to allergy through IgE-dependent activation via the high-affinity IgE receptor FcεRI. The role of the FcεRIβ chain (MS4A2) in mast cell function is not understood fully, although it serves to amplify FcεRI-dependent signaling. We demonstrate the expression of a novel MS4A2 truncation lacking exon 3 in human mast cells termed MS4A2(trunc). MS4A2(trunc) gene expression was regulated negatively by the mast cell growth factor stem cell factor (SCF), and its expression was not detected in the SCF receptor gain-of-function human mast cell line HMC-1. Unlike MS4A2, MS4A2(trunc) did not traffic to the cytoplasmic membrane but instead was associated with the nuclear membrane. Overexpression of MS4A2(trunc) induced human lung mast cell death and profoundly inhibited HMC-1 cell proliferation by inducing G(2)-phase cell cycle arrest and apoptosis. Thus, we have identified a novel splice variant of MS4A2 that might be important in the regulation of human mast cell proliferation and survival. This finding demonstrates that the MS4A2 gene has multiple roles, extending beyond the regulation of acute allergic responses. By understanding the mechanisms regulating its function, it might be possible to induce its expression in mast cells in vivo, which could lead to better treatments for diseases such as mastocytosis and asthma.
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Affiliation(s)
- Glenn Cruse
- Department of Infection, Immunity and Inflammation, Institute for Lung Health, Glenfield Hospital, University of Leicester, Leicester, UK.
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3
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Chiu PL, Ng BH, Chang GW, Gordon S, Lin HH. Putative alternative trans-splicing of leukocyte adhesion-GPCR pre-mRNAs generates functional chimeric receptors. FEBS Lett 2008; 582:792-8. [PMID: 18267122 DOI: 10.1016/j.febslet.2008.02.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Revised: 01/07/2008] [Accepted: 02/01/2008] [Indexed: 10/22/2022]
Abstract
The EGF-TM7 receptors, a subfamily of adhesion-GPCRs mostly restricted to leukocytes, are known to express multiple functional protein isoforms through extensive alternative cis-splicing. Here, we demonstrate that EGF-TM7 pre-mRNAs also undergo the rare trans-splicing, leading to the generation of functional chimeric receptors. RT-PCR and in silico analyses of EMR2 transcripts identified unique fragments containing the EGF-like motif 3 of a closely related EGF-TM7 gene, CD97, in addition to the alternative cis-spliced products. The sequence swapping is restricted to the EGF-3 exon, generating unique EMR2(1-2-3*-5) and EMR2(1-2-3*-4-5) molecules, which are functional in ligand-binding as the wild-type EMR2(1-2-3-4-5) and CD97(1-2-3-4-5) receptors. Our results suggest that human leukocytes employ trans-splicing as well as cis-splicing to increase the repertoire of functional adhesion-GPCRs.
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Affiliation(s)
- Pei-Ling Chiu
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan
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4
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Guimarães GS, Latini FRM, Camacho CP, Maciel RMB, Dias-Neto E, Cerutti JM. Identification of candidates for tumor-specific alternative splicing in the thyroid. Genes Chromosomes Cancer 2006; 45:540-53. [PMID: 16493598 DOI: 10.1002/gcc.20316] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Alternative splicing is the differential processing of exon junctions to produce a new transcript variant from one gene. Some aberrant splicing, however, has been shown to be cancer specific. Identification of these specific splice variations will provide important insight into the molecular mechanism of normal cellular physiology as well as the disease processes. To gain knowledge about whether alternative splicing is linked to thyroid tumorigenesis, we used our prediction database to select targets for analysis. Fifteen putatively new alternative splicing isoforms were selected on the basis of their expression in thyroid libraries and/or their origin in genes previously associated with carcinogenesis. Using a set of 66 normal, benign, and malignant thyroid tissue samples, new splicing events were confirmed by RT-PCR for 13 of 15 genes (a validation rate of 87%). In addition, new alternative splicing isoforms not predicted by the system and not previously described in public databases were identified. Five genes (PTPN18, ABI3BP, PFDN5, SULF2, and ST5) presented new and/or additional unpredicted isoforms differentially expressed between malignant and benign or normal thyroid tissues, confirmed by sequencing. PTPN18, ABI3BP, and PFDN5 revealed a statistically significant differential splicing profile. In addition, real-time PCR analysis revealed that expression of an alternative PFDN5 variant was higher in malignant lesions than in benign lesions or normal tissues.
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Affiliation(s)
- Gustavo S Guimarães
- Laboratory of Molecular Endocrinology, Department of Medicine, Federal University of São Paulo, Brazil
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5
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Ravichandran LV, Dean NM, Marcusson EG. Use of antisense oligonucleotides in functional genomics and target validation. Oligonucleotides 2004; 14:49-64. [PMID: 15104896 DOI: 10.1089/154545704322988058] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
With the completion of sequencing of the human genome, a great deal of interest has been shifted toward functional genomics-based research for identification of novel drug targets for treatment of various diseases. The major challenge facing the pharmaceutical industry is to identify disease-causing genes and elucidate additional roles for genes of known functions. Gene functionalization and target validation are probably the most important steps involved in identifying novel potential drug targets. This review focuses on recent advances in antisense technology and its use for rapid identification and validation of new drug targets. The significance and applicability of this technology as a beginning of the drug discovery process are underscored by relevant cell culture-based assays and positive correlation in specific animal disease models. Some of the antisense inhibitors used to validate gene targets are themselves being developed as drugs. The current clinical trials based on such leads that were identified in a very short time further substantiate the importance of antisense technology-based functional genomics as an integral part of target validation and drug target identification.
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6
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Allen M, Pratscher B, Roka F, Krepler C, Wacheck V, Schöfer C, Pehamberger H, Müller M, Lucas T. Loss of novel mda-7 splice variant (mda-7s) expression is associated with metastatic melanoma. J Invest Dermatol 2004; 123:583-8. [PMID: 15304100 DOI: 10.1111/j.0022-202x.2004.23321.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Expression of melanoma differentiation associated gene-7 (mda-7) also known as interleukin 24 (IL-24) decreases during melanoma cell differentiation and induces apoptosis in melanoma cells but not in melanocytes. Here we identify a novel splice variant of the cancer growth suppressor gene mda-7/IL-24 (mda-7s) that is differentially expressed in RNA preparations from normal human melanocytes, transformed melanocytes, nevi, subcutaneous metastasis, lymph node metastasis, and melanoma cell lines. The 450 bp mda-7s mRNA encodes a protein of 63 residues with a molecular weight of 12 kDa. mda-7s lacks exons 3 and 5 of the full-length transcript and contains only 14 amino acids of homology to MDA-7 located within the signal peptide region of the wild-type sequence. Despite minimal homology, MDA-7S coprecipitates full length MDA-7 and reduces secretion of cotransfected MDA-7. mda-7 and mda-7s are coexpressed in all RNA preparations other than subcutaneous and lymph node metastasis where mda-7s expression is lacking. mda-7s expression is therefore linked to a non-metastatic phenotype.
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Affiliation(s)
- Matthew Allen
- Department of Clinical Pharmacology, Section of Experimental Oncology/Molecular Pharmacology, University of Vienna, Vienna General Hospital, Waehringer Guertel 18-20, A-1090 Vienna, Austria
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7
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Inoue R, Moghaddam KA, Ranasinghe M, Saeki Y, Chiocca EA, Wade-Martins R. Infectious delivery of the 132 kb CDKN2A/CDKN2B genomic DNA region results in correctly spliced gene expression and growth suppression in glioma cells. Gene Ther 2004; 11:1195-204. [PMID: 15164098 DOI: 10.1038/sj.gt.3302284] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The expression of genes from genomic loci can be relatively complex, utilizing exonic, intronic and flanking sequences to regulate tissue and developmental specificity. Infectious bacterial artificial chromosomes (iBACs) have been shown to deliver and express large genomic loci (up to 135 kb) into primary cells for functional analyses. The delivery of large genomic DNA inserts allows the expression of complex loci and of multiple splice variants. Herein, we demonstrate for the first time that an iBAC will deliver and correctly express in human glioma cells the entire CDKN2A/CDKN2B genomic region, which encodes for at least three important cell-cycle regulatory proteins (p16(INK4a), p14(ARF) and p15(INK4b)). Two of these proteins are expressed from overlapping genes, utilizing alternative splicing and promoter usage. The delivered locus expresses each gene at physiological levels and cellular responses (apoptosis versus growth arrest) occur dependent on cellular p53 status, as expected. The work further demonstrates the potential of the iBAC system for the delivery of genomic loci whose expression is mediated by complex splicing and promoter usage both for gene therapy applications and functional genomics studies.
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Affiliation(s)
- R Inoue
- Molecular Neuro-Oncology Laboratories, Neurosurgery Service, Massachusetts General Hospital-East and Harvard Medical School, Charlestown, MA 02129, USA
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8
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Kraft S, Rana S, Jouvin MH, Kinet JP. The role of the FcepsilonRI beta-chain in allergic diseases. Int Arch Allergy Immunol 2004; 135:62-72. [PMID: 15316148 DOI: 10.1159/000080231] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The high affinity receptor for IgE, FcepsilonRI, is a multimeric surface receptor that is expressed exclusively as a tetramer on rodent cells, but exists as a tetramer or trimer on human cells. The tetrameric form is expressed on effector cells of allergic responses such as mast cells and basophils and is composed of an IgE-binding alpha-subunit, a beta-subunit and a gamma-subunit dimer. Complexes lacking the beta-subunit are found on human antigen-presenting cells. On mast cells and basophils, FcepsilonRI is essential for IgE-mediated acute allergic reactions. Crosslinking of FcepsilonRI by IgE and multivalent antigen induces a signaling cascade that culminates in the release of preformed mediators and the synthesis of lipid mediators and cytokines. The beta-subunit functions as an amplifier of FcepsilonRI expression and signaling. As a consequence, strongly enhanced mast cell effector functions and in vivo allergic reactions can be observed in the presence of FcepsilonRIbeta. In contrast, a truncated beta-isoform (betaT) that is produced by alternative splicing acts as an inhibitor of FcepsilonRI surface expression. Thus, by producing two proteins with antagonistic functions, the FcepsilonRIbeta gene could serve as a potent regulator of allergic responses. In addition, the genomic region encompassing the beta-chain has been linked to atopy and a number of polymorphisms within the FcepsilonRIbeta gene are associated with various atopic diseases. It remains to be elucidated how these polymorphisms might affect the allergic phenotype. These functions of the beta-chain together with the described genetic linkages to atopy make it a candidate for a role in the pathophysiology of allergic diseases.
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Affiliation(s)
- Stefan Kraft
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA
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9
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Roesser JR. Both U2 snRNA and U12 snRNA are required for accurate splicing of exon 5 of the rat calcitonin/CGRP gene. RNA (NEW YORK, N.Y.) 2004; 10:1243-50. [PMID: 15272120 PMCID: PMC1370614 DOI: 10.1261/rna.5210404] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2003] [Accepted: 05/10/2004] [Indexed: 05/24/2023]
Abstract
Two classes of spliceosome are present in eukaryotic cells. Most introns in nuclear pre-mRNAs are removed by a spliceosome that requires U1, U2, U4, U5, and U6 small nuclear ribonucleoprotein particles (snRNPs). A minor class of introns are removed by a spliceosome containing U11, U12, U5, U4atac, and U6 atac snRNPs. We describe experiments that demonstrate that splicing of exon 5 of the rat calcitonin/CGRP gene requires both U2 snRNA and U12 snRNA. In vitro, splicing to calcitonin/ CGRP exon 5 RNA was dependent on U2 snRNA, as preincubation of nuclear extract with an oligonucleotide complementary to U2 snRNA abolished exon 5 splicing. Addition of an oligonucleotide complementary to U12 snRNA increased splicing at a cryptic splice site in exon 5 from <5% to 50% of total spliced RNA. Point mutations in a candidate U12 branch sequence in calcitonin/CGRP intron 4, predicted to decrease U12-pre-mRNA base-pairing, also significantly increased cryptic splicing in vitro. Calcitonin/CGRP genes containing base changes disrupting the U12 branch sequence expressed significantly decreased CGRP mRNA levels when expressed in cultured cells. Coexpression of U12 snRNAs containing base changes predicted to restore U12-pre-mRNA base pairing increased CGRP mRNA synthesis to the level of the wild-type gene. These observations indicate that accurate, efficient splicing of calcitonin/CGRP exon 5 is dependent upon both U2 and U12 snRNAs.
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Affiliation(s)
- James R Roesser
- Department of Biochemistry, Virginia Commonwealth University, 40l College Street, Richmond 23298, USA.
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10
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Sun L, Vitolo MI, Qiao M, Anglin IE, Passaniti A. Regulation of TGFβ1-mediated growth inhibition and apoptosis by RUNX2 isoforms in endothelial cells. Oncogene 2004; 23:4722-34. [PMID: 15107836 DOI: 10.1038/sj.onc.1207589] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Runx transcription factors regulate viral growth, hematopoiesis, bone formation, angiogenesis, and gastric epithelial development through specific DNA-binding motifs on target gene promoters. Vascular endothelial cells (ECs) express RUNX genes that are activated by angiogenic factors. The RUNX2 gene also activates the vascular endothelial growth factor promoter. Alternatively spliced forms of RUNX genes have been described, but their functions in angiogenesis have not been elucidated. In this study, expression of a novel alternatively spliced variant of RUNX2 (RUNX2Delta8), lacking the region encoded by exon 8, was detected in aortic tissue undergoing angiogenesis in vitro and in ECs. Expression of RUNX2 and RUNX2Delta8 increased in vascular sprouts concomitant with expression of cellular proteases and cytokines known to mediate angiogenesis. RUNX2 DNA-binding activity was expressed in proliferating but not quiescent ECs. Ectopic expression of RUNX2 in ECs increased cell sprouting, cell proliferation, DNA synthesis, and phosphorylation of phosphorylated retinoblastoma relative to control transfectants while RUNX2, but not RUNX2Delta8 transfectants, acquired resistance to growth inhibition by transforming growth factor (TGFbeta1). Furthermore, RUNX2Delta8-transfected cells were more sensitive to TGFbeta1-induced apoptosis than RUNX2 transfectants. Consistent with these data, the RUNX2 gene was a strong repressor of the promoter of the cyclin-dependent kinase inhibitor, p21(CIP1), while RUNX2Delta8 was a competitive inhibitor of RUNX2 and exhibited weak repression activity. These results support the hypothesis that ECs regulate growth and apoptosis, in part, by alternative splicing events in the RUNX2 transcription factor to affect the TGFbeta1 signaling pathway. The exon 8 domain of RUNX2 may contribute to the strong repression activity of RUNX2 for some target gene promoters.
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Affiliation(s)
- Lixin Sun
- Greenebaum Cancer Center, University of Maryland School of Medicine, 655 W. Baltimore Street, Baltimore, MD 21201, USA
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11
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Jin P, Fu GK, Wilson AD, Yang J, Chien D, Hawkins PR, Au-Young J, Stuve LL. PCR isolation and cloning of novel splice variant mRNAs from known drug target genes. Genomics 2004; 83:566-71. [PMID: 15028279 DOI: 10.1016/j.ygeno.2003.09.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2003] [Accepted: 09/25/2003] [Indexed: 11/25/2022]
Abstract
Alternative splicing of pre-mRNAs is an important mechanism for the generation of vertebrate protein diversity. Unfortunately, the contribution of alternative splicing to protein diversity is currently not well understood because many full-length mRNA sequences have yet to be identified. In this report, we describe the use of RT-PCR to identify and clone 279 novel alternatively spliced mRNAs from 114 well-known drug target genes. Our findings demonstrate the existence of many novel alternatively spliced mRNA transcripts and suggest that many more genes undergo functionally significant alternative splicing than previously thought.
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Affiliation(s)
- Pei Jin
- Incyte Corporation, 3160 Porter Drive, Palo Alto, CA 94304, USA
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12
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Donnadieu E, Jouvin MH, Rana S, Moffatt MF, Mockford EH, Cookson WO, Kinet JP. Competing functions encoded in the allergy-associated F(c)epsilonRIbeta gene. Immunity 2003; 18:665-74. [PMID: 12753743 DOI: 10.1016/s1074-7613(03)00115-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Allergic reactions are triggered via crosslinking of the high-affinity receptor for immunoglobulin E, F(c)epsilonRI. In humans, F(c)epsilonRI is expressed as a tetramer (alphabetagamma(2)) and a trimer (alphagamma(2)). The beta subunit is an amplifier of F(c)epsilonRI surface expression and signaling. Here, we show that as a consequence of alternative splicing, the F(c)epsilonRIbeta gene encodes two proteins with opposing and competing functions. One isoform is the full-length classical beta, the other a novel truncated form, beta(T). In contrast to beta, beta(T) prevents F(c)epsilonRI surface expression by inhibiting alpha chain maturation. Moreover, beta(T) competes with beta to control F(c)epsilonRI surface expression in vitro. We propose that the relative abundance of the products of the beta gene may control the level of F(c)epsilonRI surface expression and thereby influence susceptibility to allergic diseases.
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Affiliation(s)
- Emmanuel Donnadieu
- Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
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13
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Workman P. The impact of genomic and proteomic technologies on the development of new cancer drugs. Ann Oncol 2003; 13 Suppl 4:115-24. [PMID: 12401677 DOI: 10.1093/annonc/mdf648] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- P Workman
- Cancer Research UK, Centre for Cancer Therapeutics, Institute of Cancer Research, Sutton, UK
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14
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Xie H, Zhu WY, Wasserman A, Grebinskiy V, Olson A, Mintz L. Computational analysis of alternative splicing using EST tissue information. Genomics 2002; 80:326-30. [PMID: 12213203 DOI: 10.1006/geno.2002.6841] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Expressed sequence tags (ESTs) from normal and tumor tissues have been deposited in public databases. These ESTs and all mRNA sequences were aligned with the human genome sequence using LEADS, Compugen's alternative splicing modeling platform. We developed a novel computational approach to analyze tissue information of aligned ESTs in order to identify cancer-specific alternative splicing and gene segments highly expressed in particular cancers. Several genes, including one encoding a possible pre-mRNA splicing factor, displayed cancer-specific alternative splicing. In addition, multiple candidate gene segments highly expressed in colon cancers were identified.
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Affiliation(s)
- Hanqing Xie
- Compugen Inc. 7 Centre Drive, Jamesburg, New Jersey 08831, USA.
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15
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Abstract
The protein coding sequences of most eukaryotic messenger RNA precursors (pre-mRNAs) are interrupted by non-coding sequences called introns. Pre-mRNA splicing is the process by which introns are removed and the protein coding elements assembled into mature mRNAs. Alternative pre-mRNA splicing selectively joins different protein coding elements to form mRNAs that encode proteins with distinct functions, and is therefore an important source of protein diversity. The elaboration of this mechanism may have had a significant role in the expansion of metazoan proteomes during evolution.
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Affiliation(s)
- Tom Maniatis
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA
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16
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Dean NM. Functional genomics and target validation approaches using antisense oligonucleotide technology. Curr Opin Biotechnol 2001; 12:622-5. [PMID: 11849945 DOI: 10.1016/s0958-1669(01)00270-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The recent increase in the amount and rate of accumulation of genomic information has created new challenges for the pharmaceutical industry. These include how best to rapidly and efficiently identify key genes responsible for complex disease phenotypes and how to use this information to develop new and specific classes of drugs. Antisense technology offers a powerful approach to identify novel cellular networks and signaling "cassettes" and provides a method to validate genes in vivo as attractive drug targets.
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Affiliation(s)
- N M Dean
- Department of Functional Genomics, GeneTrove (a division of Isis Pharmaceuticals), 2292 Faraday Avenue, Carlsbad, CA 92008, USA.
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Pisarchik A, Slominski AT. Alternative splicing of CRH-R1 receptors in human and mouse skin: identification of new variants and their differential expression. FASEB J 2001; 15:2754-6. [PMID: 11606483 DOI: 10.1096/fj.01-0487fje] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We identified four new isoforms of human CRH-R1 (e-h) and three of mouse (mCRH-R1c, e, and f). In all new forms exon 6 was missing. Human CRH-R1e was characterized by the deletion of exons 3 and 4; exon 12 from CRH-R1f; exon 11, 27 base pairs (bp) of exon 10 and 28 bp of exon 12 from CRH-R1g and CRH-R1h by the addition of a cryptic exon. In mouse CRH-R1c exon 3 was spliced out; in mCRH-R1e exons 3 and 4 and in mCRH-R1f exon 11 were spliced from mRNA. CRH-R1 was expressed in all skin specimens in patterns dependent on the cell type, physiological status, and presence of pathology. CRH-R1a, the most prevalent form, was detected in almost all samples. Ultraviolet radiation (UV) changed the splicing pattern and induced or increased expression of CRH-R1a in cultured skin cells. Continuing UV treatment of succeeding generations of cells resulted in a progressive increase in the number of CRH-R1 isoforms, which suggests that receptor heterogeneity might favor cell survival. TPA (phorbol 12-myristate 13-acetate), forskolin, dbcAMP (N6, 2'-O-dibutyryladenosine 3':5'-cyclic monophospate sodium), and IBMX (3-isobutyl-1-methylxanthine) also changed the splicing pattern. We suggest that a polymorphism of CRH-R1 expression is related to anatomic location, skin physiological or pathologic status, specific cell type, and external stress (UV), and that cAMP-dependent pathways and TPA may regulate CRH-R1.
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Affiliation(s)
- A Pisarchik
- Department of Pathology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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18
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Marden JH, Fitzhugh GH, Girgenrath M, Wolf MR, Girgenrath S. Alternative splicing, muscle contraction and intraspecific variation: associations between troponin T transcripts, Ca2+ sensitivity and the force and power output of dragonfly flight muscles during oscillatory contraction. J Exp Biol 2001; 204:3457-70. [PMID: 11707496 DOI: 10.1242/jeb.204.20.3457] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYThe flight muscles of Libellula pulchella dragonflies contain a mixture of six alternatively spliced transcripts of a single troponin T (TnT) gene. Here, we examine how intraspecific variation in the relative abundance of different TnT transcripts affects the Ca2+ sensitivity of skinned muscle fibers and the performance of intact muscles during work-loop contraction regimes that approximate in vivo conditions during flight. The relative abundance of one TnT transcript, or the pooled relative abundance of two TnT transcripts, showed a positive correlation with a 10-fold range of variation in Ca2+ sensitivity of skinned fibers (r2=0.77, P<0.0001) and a threefold range in peak specific force (r2=0.74, P<0.0001), specific work per cycle (r2=0.54; P<0.0001) and maximum specific power output (r2=0.48, P=0.0005) of intact muscle. Using these results to reanalyze previously published data for wing kinematics during free flight, we show that the relative abundances of these particular transcripts are also positively correlated with wingbeat frequency and amplitude. TnT variation alone may be responsible for these effects, or TnT variation may be a marker for changes in a suite of co-regulated molecules. Dragonflies from two ponds separated by 16 km differed significantly in both TnT transcript composition and muscle contractile performance, and within each population there are two distinct morphs that showed different maturational trajectories of TnT transcript composition and muscle contractility. Thus, there is broad intraspecific variability and a high degree of population structure for contractile performance phenotypes, TnT ribotypes and ontogenetic patterns involving these traits that affect locomotor performance.
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Affiliation(s)
- J H Marden
- 208 Mueller Laboratory, Department of Biology, Pennsylvania State University, University Park, PA 16802, USA.
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