Atlas of Genetics and Cytogenetics in Oncology and Haematology
ACTB (Actin, beta)
| Identity |
| Other names | Beta cytoskeletal actin |
| Beta actin | |
| HGNC | ACTB |
| Location | 7p22 |
| Note | Six actin isoforms are known: two sarcomeric (a-skeletal and a-cardiac), two smooth muscle actins (a and g), and two non-muscle, cytoskeletal actins (b and g). |
| DNA/RNA |
 | |
| Genomic organization of the ACTB gene. | |
| Description | Six exons, spans approximately 3.4 kb of genomic DNA in the centromere-to-telomere orientation. The translation initiation codon ATG is located in exon 2, and the stop codon in exon 6. |
| Transcription | mRNA of approximately 1.8 kb. |
| Pseudogene | At least 19 processed, non-expressed, pseudogenes are dispersed throughout the genome. |
| Protein |
| Description | The open reading frame encodes a 374 amino acid protein, with an estimated molecular weight of approximately 41.7 kDa. |
| Expression | Abundantly expressed in all mammalian and avian non-muscle cells. |
| Localisation | Cytoplasm |
| Function | Component (together with cytoplasmic g actin) of the cytoskeletal microfilaments. Involved in the transport of chromosomes and organelles as well as in cell motility. |
| Homology | The ACTB proteins are evolutionary conserved. Mammalian cytoplasmic actins (actin g and b) are remarkably similar to each other, but differ in at least 25 residues from the muscle actins. |
| Mutations |
| Somatic | ACTB is interrupted by the t(7;12)(p22;q13) detected in pericytoma with t(7;12). |
| Implicated in |
| Disease | Pericytoma with t(7;12) |
| Prognosis | Benign or low-malignant |
| Cytogenetics | t(7;12)(p22;q13) |
 | |
| Representative G-banded partial karyotype of the t(7;12)(p22;q13). | |
| Hybrid/Mutated Gene | ACTB-GLI1 fusion gene. The breakpoints reported so far have been located to introns 1, 2 or 3 within the ACTB gene, and to introns 5 or 6 or to exon 7 within the GLI1 gene. Reciprocal GLI1-ACTB gene fusions have also been detected. The breakpoints have been located to introns 5 or 7 within the GLI1 gene, and to intron 3 of the ACTB gene. |
| Abnormal Protein | The ACTB-GLI1 fusion protein contains the N-terminal of ACTB and the C-terminal of GLI1, including the DNA-binding zink finger motifs (encoded by exons 7-10) and transactivating motifs (exon 12). |
| Oncogenesis | It is suggested that the strong ACTB promoter causes an overexpression of GLI1 sequences important for transcriptional activation of downstream target genes, akin to the oncogenic mechanisms of the COL1A1-PDGFB fusion gene detected in dermatofibrosarcoma protuberans. |
| External links |
| Bibliography |
| Mammalian cytoplasmic actins are the products of at least two genes and differ in primary structure in at least 25 identified positions from skeletal muscle actins. |
| Vandekerckhove J, Weber K |
| Proceedings of the National Academy of Sciences of the United States of America. 1978 ; 75 (3) : 1106-1110. |
| PMID 274701 |
| The human beta-actin multigene family. |
| Kedes L, Ng SY, Lin CS, Gunning P, Eddy R, Shows T, Leavitt J |
| Transactions of the Association of American Physicians. 1985 ; 98 : 42-46. |
| PMID 3842206 |
| Molecular structure of the human cytoplasmic beta-actin gene: interspecies homology of sequences in the introns. |
| Nakajima-Iijima S, Hamada H, Reddy P, Kakunaga T |
| Proceedings of the National Academy of Sciences of the United States of America. 1985 ; 82 (18) : 6133-6137. |
| PMID 2994062 |
| Evolution of the functional human beta-actin gene and its multi-pseudogene family: conservation of noncoding regions and chromosomal dispersion of pseudogenes. |
| Ng SY, Gunning P, Eddy R, Ponte P, Leavitt J, Shows T, Kedes L |
| Molecular and cellular biology. 1985 ; 5 (10) : 2720-2732. |
| PMID 3837182 |
| FISH localization of human cytoplasmic actin genes ACTB to 7p22 and ACTG1 to 17q25 and characterization of related pseudogenes. |
| Ueyama H, Inazawa J, Nishino H, Ohkubo I, Miwa T |
| Cytogenetics and cell genetics. 1996 ; 74 (3) : 221-224. |
| PMID 8941379 |
| Deregulation of the platelet-derived growth factor B-chain gene via fusion with collagen gene COL1A1 in dermatofibrosarcoma protuberans and giant-cell fibroblastoma. |
| Simon MP, Pedeutour F, Sirvent N, Grosgeorge J, Minoletti F, Coindre JM, Terrier-Lacombe MJ, Mandahl N, Craver RD, Blin N, Sozzi G, Turc-Carel C, O'Brien KP, Kedra D, Fransson I, Guilbaud C, Dumanski JP |
| Nature genetics. 1997 ; 15 (1) : 95-98. |
| PMID 8988177 |
| Activation of the GLI oncogene through fusion with the beta-actin gene (ACTB) in a group of distinctive pericytic neoplasms: pericytoma with t(7;12). |
| Dahlˆ©n A, Fletcher CD, Mertens F, Fletcher JA, Perez-Atayde AR, Hicks MJ, Debiec-Rychter M, Sciot R, Wejde J, Wedin R, Mandahl N, Panagopoulos I |
| The American journal of pathology. 2004 ; 164 (5) : 1645-1653. |
| PMID 15111311 |
| Molecular genetic characterization of the genomic ACTB-GLI fusion in pericytoma with t(7;12). |
| Dahlˆ©n A, Mertens F, Mandahl N, Panagopoulos I |
| Biochemical and biophysical research communications. 2004 ; 325 (4) : 1318-1323. |
| PMID 15555571 |
| REVIEW articles | automatic search in PubMed |
| Last year publications | automatic search in PubMed |
| Contributor(s) |
| Written | 03-2005 | Anna Dahlén, Fredrik Mertens, Nils Mandahl, Ioannis Panagopoulos |
| Citation |
| This paper should be referenced as such : |
| Dahlén A, Mertens F, Mandahl N, Panagopoulos I . ACTB (Actin, beta). Atlas Genet Cytogenet Oncol Haematol. March 2005 . URL : http://AtlasGeneticsOncology.org/Genes/ACTBID42959ch7p22.html |
| © Atlas of Genetics and Cytogenetics in Oncology and Haematology | indexed on : Mon Aug 11 21:11:42 2008 |
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