Alternative Splicing of RAD6B and Not RAD6A is Selectively Increased in Melanoma: Identification and Functional Characterization
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, <i>UBE2A</i> (<i>RAD</i><i>6A</i>) and...
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MDPI AG
2019-11-01
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| Series: | Cells |
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| Online Access: | https://www.mdpi.com/2073-4409/8/11/1375 |
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| author | Ambikai Gajan Carly E. Martin Seongho Kim Milap Joshi Sharon K. Michelhaugh Ido Sloma Sandeep Mittal Steven Firestine Malathy P. V. Shekhar |
| author_facet | Ambikai Gajan Carly E. Martin Seongho Kim Milap Joshi Sharon K. Michelhaugh Ido Sloma Sandeep Mittal Steven Firestine Malathy P. V. Shekhar |
| author_sort | Ambikai Gajan |
| collection | DOAJ |
| description | 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, <i>UBE2A</i> (<i>RAD</i><i>6A</i>) and <i>UBE2B</i> (<i>R</i><i>AD</i><i>6B</i>), 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, RAD6BΔexon4 and RAD6Bintron5ins, were identified. We confirmed that RAD6BΔexon4 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’s molecular heterogeneity and its association with melanoma pathogenesis. |
| first_indexed | 2024-03-12T06:07:15Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 2073-4409 |
| language | English |
| last_indexed | 2024-03-12T06:07:15Z |
| publishDate | 2019-11-01 |
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| record_format | Article |
| series | Cells |
| spelling | doaj.art-f94f9d3ec0ce41acac0a76d5dc7d19a02023-09-03T03:35:35ZengMDPI AGCells2073-44092019-11-01811137510.3390/cells8111375cells8111375Alternative Splicing of RAD6B and Not RAD6A is Selectively Increased in Melanoma: Identification and Functional CharacterizationAmbikai Gajan0Carly E. Martin1Seongho Kim2Milap Joshi3Sharon K. Michelhaugh4Ido Sloma5Sandeep Mittal6Steven Firestine7Malathy P. V. Shekhar8Karmanos Cancer Institute, Detroit, MI 48201, USAKarmanos Cancer Institute, Detroit, MI 48201, USAKarmanos Cancer Institute, Detroit, MI 48201, USAKarmanos Cancer Institute, Detroit, MI 48201, USAKarmanos Cancer Institute, Detroit, MI 48201, USAChampions Oncology, Rockville, MD 20850, USAKarmanos Cancer Institute, Detroit, MI 48201, USAPharmaceutical Sciences, Wayne State University, Detroit, MI 48201, USAKarmanos Cancer Institute, Detroit, MI 48201, USARad6B, 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, <i>UBE2A</i> (<i>RAD</i><i>6A</i>) and <i>UBE2B</i> (<i>R</i><i>AD</i><i>6B</i>), 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, RAD6BΔexon4 and RAD6Bintron5ins, were identified. We confirmed that RAD6BΔexon4 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’s molecular heterogeneity and its association with melanoma pathogenesis.https://www.mdpi.com/2073-4409/8/11/1375melanomahistone ubiquitinationalternative splicingexon skippingwhole exome sequencing |
| spellingShingle | Ambikai Gajan Carly E. Martin Seongho Kim Milap Joshi Sharon K. Michelhaugh Ido Sloma Sandeep Mittal Steven Firestine Malathy P. V. Shekhar Alternative Splicing of RAD6B and Not RAD6A is Selectively Increased in Melanoma: Identification and Functional Characterization Cells melanoma histone ubiquitination alternative splicing exon skipping whole exome sequencing |
| title | Alternative Splicing of RAD6B and Not RAD6A is Selectively Increased in Melanoma: Identification and Functional Characterization |
| title_full | Alternative Splicing of RAD6B and Not RAD6A is Selectively Increased in Melanoma: Identification and Functional Characterization |
| title_fullStr | Alternative Splicing of RAD6B and Not RAD6A is Selectively Increased in Melanoma: Identification and Functional Characterization |
| title_full_unstemmed | Alternative Splicing of RAD6B and Not RAD6A is Selectively Increased in Melanoma: Identification and Functional Characterization |
| title_short | Alternative Splicing of RAD6B and Not RAD6A is Selectively Increased in Melanoma: Identification and Functional Characterization |
| title_sort | alternative splicing of rad6b and not rad6a is selectively increased in melanoma identification and functional characterization |
| topic | melanoma histone ubiquitination alternative splicing exon skipping whole exome sequencing |
| url | https://www.mdpi.com/2073-4409/8/11/1375 |
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