{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,12]],"date-time":"2026-04-12T08:56:38Z","timestamp":1775984198584,"version":"3.50.1"},"reference-count":43,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2019,11,1]],"date-time":"2019-11-01T00:00:00Z","timestamp":1572566400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000054","name":"National Cancer Institute","doi-asserted-by":"publisher","award":["R21CA178117"],"award-info":[{"award-number":["R21CA178117"]}],"id":[{"id":"10.13039\/100000054","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cells"],"abstract":"<jats:p>Rad6B, a principal component of the translesion synthesis pathway, and activator of canonical Wnt signaling, plays an essential role in cutaneous melanoma development and progression. As Rad6 is encoded by two genes, namely, UBE2A (RAD6A) and UBE2B (RAD6B), in humans, we compared their expressions in melanomas and normal melanocytes. While both genes are weakly expressed in normal melanocytes, Rad6B is more robustly expressed in melanoma lines and patient-derived metastatic melanomas than RAD6A. The characterization of RAD6B transcripts revealed coexpression of various splice variants representing truncated or modified functional versions of wild-type RAD6B in melanomas, but not in normal melanocytes. Notably, two RAD6B isoforms with intact catalytic domains, RAD6B\u0394exon4 and RAD6Bintron5ins, were identified. We confirmed that RAD6B\u0394exon4 and RAD6Bintron5ins variants are expressed as 14 and 15 kDa proteins, respectively, with functional in vivo ubiquitin conjugating activity. Whole exome sequence analysis of 30 patient-derived melanomas showed RAD6B variants coexpressed with wild-type RAD6B in all samples analyzed, and RAD6Bintron5ins variants were found in half the cases. These variants constitute the majority of the RAD6B transcriptome in contrast to RAD6A, which was predominantly wild-type. The expression of functional RAD6B variants only in melanomas reveals RAD6B\u2019s molecular heterogeneity and its association with melanoma pathogenesis.<\/jats:p>","DOI":"10.3390\/cells8111375","type":"journal-article","created":{"date-parts":[[2019,11,1]],"date-time":"2019-11-01T12:30:50Z","timestamp":1572611450000},"page":"1375","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Alternative Splicing of RAD6B and Not RAD6A Is Selectively Increased in Melanoma: Identification and Functional Characterization"],"prefix":"10.3390","volume":"8","author":[{"given":"Ambikai","family":"Gajan","sequence":"first","affiliation":[{"name":"Karmanos Cancer Institute, Detroit, MI 48201, USA"},{"name":"Department of Oncology, Wayne State University School of Medicine, Detroit, MI 48201, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Carly E.","family":"Martin","sequence":"additional","affiliation":[{"name":"Karmanos Cancer Institute, Detroit, MI 48201, USA"},{"name":"Department of Oncology, Wayne State University School of Medicine, Detroit, MI 48201, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Seongho","family":"Kim","sequence":"additional","affiliation":[{"name":"Karmanos Cancer Institute, Detroit, MI 48201, USA"},{"name":"Department of Oncology, Wayne State University School of Medicine, Detroit, MI 48201, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Milap","family":"Joshi","sequence":"additional","affiliation":[{"name":"Karmanos Cancer Institute, Detroit, MI 48201, USA"},{"name":"Department of Oncology, Wayne State University School of Medicine, Detroit, MI 48201, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sharon K.","family":"Michelhaugh","sequence":"additional","affiliation":[{"name":"Karmanos Cancer Institute, Detroit, MI 48201, USA"},{"name":"Department of Oncology, Wayne State University School of Medicine, Detroit, MI 48201, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ido","family":"Sloma","sequence":"additional","affiliation":[{"name":"Champions Oncology, Rockville, MD 20850, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sandeep","family":"Mittal","sequence":"additional","affiliation":[{"name":"Karmanos Cancer Institute, Detroit, MI 48201, USA"},{"name":"Department of Oncology, Wayne State University School of Medicine, Detroit, MI 48201, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Steven","family":"Firestine","sequence":"additional","affiliation":[{"name":"Pharmaceutical Sciences, Wayne State University, Detroit, MI 48201, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Malathy P. V.","family":"Shekhar","sequence":"additional","affiliation":[{"name":"Karmanos Cancer Institute, Detroit, MI 48201, USA"},{"name":"Department of Oncology, Wayne State University School of Medicine, Detroit, MI 48201, USA"},{"name":"Department of Pathology, Wayne State University School of Medicine, Detroit, MI 48201, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,11,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1079","DOI":"10.3892\/or.2014.2977","article-title":"Analysis of the B-RafV600E mutation in cutaneous melanoma patients with occupational sun exposure","volume":"31","author":"Candido","year":"2014","journal-title":"Oncol. Rep."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2135","DOI":"10.1056\/NEJMoa050092","article-title":"Distinct sets of genetic alterations in melanoma","volume":"353","author":"Curtin","year":"2005","journal-title":"N. Engl. J. Med."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1341","DOI":"10.1056\/NEJM199904293401707","article-title":"The pathogenesis of melanoma induced by ultraviolet radiation","volume":"340","author":"Gilchrest","year":"1999","journal-title":"N. Engl. J. Med."},{"key":"ref_4","first-page":"291","article-title":"Association of surface ultraviolet B radiation levels with melanoma and nonmelanoma skin cancer in United States blacks","volume":"9","author":"Pennello","year":"2000","journal-title":"Cancer Epidemiol. Biomarkers Prev."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"207","DOI":"10.1146\/annurev-biophys-060414-033841","article-title":"Regulation of Rad6\/Rad18 activity during DNA damage tolerance","volume":"44","author":"Hedglin","year":"2015","journal-title":"Annu. Rev. Biophys."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1038\/nature00991","article-title":"RAD6-dependent DNA repair is linked to modification of PCNA by ubiquitin and SUMO","volume":"419","author":"Hoege","year":"2002","journal-title":"Nature"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"96","DOI":"10.1038\/nrc2998","article-title":"DNA polymerases and cancer","volume":"11","author":"Lange","year":"2011","journal-title":"Nat. Rev. Cancer"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"873","DOI":"10.1016\/j.febslet.2004.11.029","article-title":"Replication of damaged DNA by translesion synthesis in human cells","volume":"579","author":"Lehmann","year":"2005","journal-title":"FEBS Lett."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"317","DOI":"10.1146\/annurev.biochem.74.082803.133250","article-title":"Eukaryotic translesion synthesis DNA polymerases: specificity of structure and function","volume":"74","author":"Prakash","year":"2005","journal-title":"Annu. Rev. Biochem."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1038\/nrm3289","article-title":"Y-family DNA polymerases and their role in tolerance of cellular DNA damage","volume":"13","author":"Sale","year":"2012","journal-title":"Nat. Rev. Mol. Cell Biol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"491","DOI":"10.1016\/S1097-2765(04)00259-X","article-title":"Interaction of human DNA polymerase eta with monoubiquitinated PCNA: a possible mechanism for the polymerase switch in response to DNA damage","volume":"14","author":"Kannouche","year":"2004","journal-title":"Mol. Cell"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"8865","DOI":"10.1073\/pnas.88.20.8865","article-title":"Structural and functional conservation of two human homologs of the yeast DNA repair gene RAD6","volume":"88","author":"Koken","year":"1991","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"447","DOI":"10.1016\/0888-7543(92)90433-S","article-title":"Localization of two human homologs, HHR6A and HHR6B, of the yeast DNA repair gene RAD6 to chromosomes Xq24-q25 and 5q23-q31","volume":"12","author":"Koken","year":"1992","journal-title":"Genomics"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"131","DOI":"10.1038\/329131a0","article-title":"The yeast DNA repair gene RAD6 encodes a ubiquitin-conjugating enzyme","volume":"329","author":"Jentsch","year":"1987","journal-title":"Nature"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"384","DOI":"10.1016\/j.tranon.2014.04.009","article-title":"Rad6 is a Potential Early Marker of Melanoma Development","volume":"7","author":"Rosner","year":"2014","journal-title":"Transl. Oncol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"439205","DOI":"10.1155\/2014\/439205","article-title":"Melanoma development and progression are associated with Rad6 upregulation and beta-catenin relocation to the cell membrane","volume":"2014","author":"Rosner","year":"2014","journal-title":"J. Skin Cancer"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Sarma, A.P.S., Liu, F., Nangia-Makker, P., Mao, G., and Shekhar, M. (2017). Targeting Rad6B suppresses melanomagenesis. Cancer Res., 77.","DOI":"10.1158\/1538-7445.AM2017-1149"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"729","DOI":"10.1158\/1541-7786.MCR-06-0136","article-title":"Essential role of T-cell factor\/beta-catenin in regulation of Rad6B: a potential mechanism for Rad6B overexpression in breast cancer cells","volume":"4","author":"Shekhar","year":"2006","journal-title":"Mol. Cancer Res."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1741","DOI":"10.1158\/0008-5472.CAN-07-2111","article-title":"Rad6B is a positive regulator of beta-catenin stabilization","volume":"68","author":"Shekhar","year":"2008","journal-title":"Cancer Res."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2107","DOI":"10.1242\/dev.073064","article-title":"Temporal control of neural crest lineage generation by Wnt\/beta-catenin signaling","volume":"139","author":"Hari","year":"2012","journal-title":"Development"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"962038","DOI":"10.1155\/2013\/962038","article-title":"Oncogenic alternative splicing switches: role in cancer progression and prospects for therapy","volume":"2013","author":"Bonomi","year":"2013","journal-title":"Int. J. Cell Biol"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"870","DOI":"10.1042\/BST20120026","article-title":"Role of splice variants in the metastatic progression of prostate cancer","volume":"40","author":"Hagen","year":"2012","journal-title":"Biochem. Soc. Trans."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"5311","DOI":"10.1038\/onc.2013.533","article-title":"Hallmarks of alternative splicing in cancer","volume":"33","author":"Oltean","year":"2014","journal-title":"Oncogene"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"2595","DOI":"10.1093\/annonc\/mdx416","article-title":"Patient-derived xenografts effectively capture responses to oncology therapy in a heterogeneous cohort of patients with solid tumors","volume":"28","author":"Izumchenko","year":"2017","journal-title":"Ann. Oncol."},{"key":"ref_25","first-page":"2115","article-title":"Rad6 overexpression induces multinucleation, centrosome amplification, abnormal mitosis, aneuploidy, and transformation","volume":"62","author":"Shekhar","year":"2002","journal-title":"Cancer Res."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"10347","DOI":"10.1074\/jbc.M117.792192","article-title":"Pharmacological targeting of RAD6 enzyme-mediated translesion synthesis overcomes resistance to platinum-based drugs","volume":"292","author":"Sanders","year":"2017","journal-title":"J. Biol. Chem."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1681","DOI":"10.1016\/j.cell.2015.05.044","article-title":"Genomic classification of cutaneous melanoma","volume":"161","author":"Akbani","year":"2015","journal-title":"Cell"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"459","DOI":"10.1016\/j.cell.2009.02.027","article-title":"RAD6-Mediated transcription-coupled H2B ubiquitylation directly stimulates H3K4 methylation in human cells","volume":"137","author":"Kim","year":"2009","journal-title":"Cell"},{"key":"ref_29","first-page":"31","article-title":"Two different stages of epidermal growth factor (EGF) receptor endocytosis are sensitive to free ubiquitin depletion produced by proteasome inhibitor MG132","volume":"30","author":"Melikova","year":"2006","journal-title":"Cell Biol. Int."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"4536","DOI":"10.1128\/MCB.17.8.4536","article-title":"Domains required for dimerization of yeast Rad6 ubiquitin-conjugating enzyme and Rad18 DNA binding protein","volume":"17","author":"Bailly","year":"1997","journal-title":"Mol. Cell Biol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"107","DOI":"10.1038\/nsmb.1550","article-title":"Nonsense-mediated mRNA decay (NMD) mechanisms","volume":"16","author":"Brogna","year":"2009","journal-title":"Nat. Struct. Biol."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"388","DOI":"10.1093\/molehr\/gat008","article-title":"UBE2B mRNA alterations are associated with severe oligozoospermia in infertile men","volume":"19","author":"Yatsenko","year":"2013","journal-title":"Mol. Hum. Reprod."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"342","DOI":"10.1002\/gcc.20156","article-title":"Alterations of pre-mRNA splicing in cancer","volume":"42","author":"Kalnina","year":"2005","journal-title":"Genes Chromosomes Cancer"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"191","DOI":"10.1136\/mp.56.4.191","article-title":"Emerging roles of BRCA1 alternative splicing","volume":"56","author":"Orban","year":"2003","journal-title":"Mol. Pathol"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1083\/jcb.124.1.71","article-title":"Expression and modulation of CD44 variant isoforms in humans","volume":"124","author":"Mackay","year":"1994","journal-title":"J. Cell Biol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"247","DOI":"10.1007\/978-94-017-9211-0_14","article-title":"Splice variants of MDM2 in oncogenesis","volume":"85","author":"Rosso","year":"2014","journal-title":"Subcell. Biochem."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"799","DOI":"10.1016\/S0092-8674(00)80154-3","article-title":"Inactivation of the HR6B ubiquitin-conjugating DNA repair enzyme in mice causes male sterility associated with chromatin modification","volume":"86","author":"Roest","year":"1996","journal-title":"Cell"},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Mulugeta Achame, E., Wassenaar, E., Hoogerbrugge, J.W., Sleddens-Linkels, E., Ooms, M., Sun, Z.W., van, I.W.F., Grootegoed, J.A., and Baarends, W.M. (2010). The ubiquitin-conjugating enzyme HR6B is required for maintenance of X chromosome silencing in mouse spermatocytes and spermatids. BMC Genomics, 11.","DOI":"10.1186\/1471-2164-11-367"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"472","DOI":"10.1016\/j.molmed.2012.06.006","article-title":"Pre-mRNA splicing in disease and therapeutics","volume":"18","author":"Singh","year":"2012","journal-title":"Trends Mol. Med."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"777","DOI":"10.1007\/s00294-017-0802-8","article-title":"Intron specificity in pre-mRNA splicing","volume":"64","author":"Mishra","year":"2018","journal-title":"Curr. Genet."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"332","DOI":"10.1097\/CMR.0000000000000071","article-title":"Rare SF3B1 R625 mutations in cutaneous melanoma","volume":"24","author":"Kong","year":"2014","journal-title":"Melanoma Res."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"189","DOI":"10.1097\/CMR.0000000000000345","article-title":"Whole-exome sequencing identifies recurrent SF3B1 R625 mutation and comutation of NF1 and KIT in mucosal melanoma","volume":"27","author":"Hintzsche","year":"2017","journal-title":"Melanoma Res."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"203","DOI":"10.1101\/gr.225615.117","article-title":"Transcription rate strongly affects splicing fidelity and cotranscriptionality in budding yeast","volume":"28","author":"Aslanzadeh","year":"2018","journal-title":"Genome Res."}],"container-title":["Cells"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4409\/8\/11\/1375\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T13:31:18Z","timestamp":1760189478000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4409\/8\/11\/1375"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,11,1]]},"references-count":43,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2019,11]]}},"alternative-id":["cells8111375"],"URL":"https:\/\/doi.org\/10.3390\/cells8111375","relation":{},"ISSN":["2073-4409"],"issn-type":[{"value":"2073-4409","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,11,1]]}}}