1
|
Goyal S, Vanita V. A missense mutation in TTC8/BBS8 affecting mRNA splicing in patients with non-syndromic retinitis pigmentosa. Mol Genet Genomics 2022; 297:1439-1449. [PMID: 35939099 DOI: 10.1007/s00438-022-01933-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 07/19/2022] [Indexed: 11/27/2022]
Abstract
Splicing disruption is one type of mutation mechanism for disease-predisposing alleles. To date, less than 30 mutations in TTC8/BBS8 have been reported; however, mutations affecting the splice site are rare. Generally missense mutations are assumed to alter protein function; however, reports have shown that mutations in protein coding exons can disrupt splicing by altering exonic splicing silencer or enhancer motifs. Hence, a missense mutation c.1347G > C (p.Q449H) involving final base of the exon 13 in the TTC8, previously identified by us to be linked with non-syndromic autosomal recessive retinitis pigmentosa (arRP), in an Indian family, that might deleteriously affect splicing has been functionally characterized. RNA was isolated, cDNA prepared and amplified using region-specific primers. PCR products were purified and sequenced bi-directionally by Sanger sequencing. Effect of mutation (c.1347G > C) on mRNA splicing has been predicted using bioinformatics tools. We reported that missense mutation (c.1347G > C) at the last base of exon 13 of TTC8 disrupted the canonical donor splice-site resulting in aberrant RNA splicing. A cryptic donor splice-site got activated 77 bases downstream of the authentic splice donor site in intron 13, resulting in the retention of 77 bases of intron 13, and a frameshift leading to pre-mature termination codon in exon 14 at codon 486. Further, duplication of exon 15 and fusion of its duplicated copy occurred with exon 13. The binding site for SC35 protein, normally involved in splicing, also got disrupted (as predicted by SpliceAid2 software), hence, leading to alternative splicing. Our findings strongly suggest that a missense mutation c.1347G > C in TTC8 disrupted the splice donor site causing retention of 77 bases of intron 13, resulting in a frameshift and subsequently introduced a pre-mature termination codon into exon 14, hence creating an altered mRNA transcript. These findings emphasize the significance of examining missense mutations especially in TTC8, to determine their pathogenic role through alternative splicing. Present findings also reiterate the notion that mutations in the TTC8/BBS8 cause phenotypic heterogeneity and does not always follow Mendelian genetics in this ciliopathy.
Collapse
Affiliation(s)
- Shiwali Goyal
- Department of Human Genetics, Guru Nanak Dev University, Amritsar, Punjab, 143005, India
| | - Vanita Vanita
- Department of Human Genetics, Guru Nanak Dev University, Amritsar, Punjab, 143005, India.
| |
Collapse
|
2
|
MiR-137 Targets the 3' Untranslated Region of MSH2: Potential Implications in Lynch Syndrome-Related Colorectal Cancer. Cancers (Basel) 2021; 13:cancers13184662. [PMID: 34572889 PMCID: PMC8470766 DOI: 10.3390/cancers13184662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 09/13/2021] [Accepted: 09/15/2021] [Indexed: 11/17/2022] Open
Abstract
Mismatch Repair (MMR) gene dysregulation plays a fundamental role in Lynch Syndrome (LS) pathogenesis, a form of hereditary colorectal cancer. Loss or overexpression of key MMR genes leads to genome instability and tumorigenesis; however, the mechanisms controlling MMR gene expression are unknown. One such gene, MSH2, exerts an important role, not only in MMR, but also in cell proliferation, apoptosis, and cell cycle control. In this study, we explored the functions and underlying molecular mechanisms of increased MSH2 expression related to a c.*226A>G variant in the 3'untranslated (UTR) region of MSH2 that had been previously identified in a subject clinically suspected of LS. Bioinformatics identified a putative binding site for miR-137 in this region. To verify miRNA targeting specificity, we performed luciferase gene reporter assays using a MSH2 3'UTR psiCHECK-2 vector in human SW480 cells over-expressing miR-137, which showed a drastic reduction in luciferase activity (p > 0.0001). This effect was abolished by site-directed mutagenesis of the putative miR-137 seed site. Moreover, in these cells we observed that miR-137 levels were inversely correlated with MSH2 expression levels. These results were confirmed by results in normal and tumoral tissues from the patient carrying the 3'UTR c.*226A>G variant in MSH2. Finally, miR-137 overexpression in SW480 cells significantly suppressed cell proliferation in a time- and dose-dependent manner (p < 0.0001), supporting a role for MSH2 in apoptosis and cell proliferation processes. Our findings suggest miR-137 helps control MSH2 expression via its 3'UTR and that dysregulation of this mechanism appears to promote tumorigenesis in colon cells.
Collapse
|
3
|
Alternative splicing of mRNA in colorectal cancer: new strategies for tumor diagnosis and treatment. Cell Death Dis 2021; 12:752. [PMID: 34330892 PMCID: PMC8324868 DOI: 10.1038/s41419-021-04031-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 07/12/2021] [Accepted: 07/12/2021] [Indexed: 02/07/2023]
Abstract
Alternative splicing (AS) is an important event that contributes to posttranscriptional gene regulation. This process leads to several mature transcript variants with diverse physiological functions. Indeed, disruption of various aspects of this multistep process, such as cis- or trans- factor alteration, promotes the progression of colorectal cancer. Therefore, targeting some specific processes of AS may be an effective therapeutic strategy for treating cancer. Here, we provide an overview of the AS events related to colorectal cancer based on research done in the past 5 years. We focus on the mechanisms and functions of variant products of AS that are relevant to malignant hallmarks, with an emphasis on variants with clinical significance. In addition, novel strategies for exploiting the therapeutic value of AS events are discussed.
Collapse
|
4
|
Shao WH, Wang CY, Wang LY, Xiao F, Xiao DS, Yang H, Long XY, Zhang L, Luo HG, Yin JY, Wu W. A Hereditable Mutation of MSH2 Gene Associated with Lynch Syndrome in a Five Generation Chinese Family. Cancer Manag Res 2020; 12:1469-1482. [PMID: 32161499 PMCID: PMC7051253 DOI: 10.2147/cmar.s222572] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 12/24/2019] [Indexed: 12/12/2022] Open
Abstract
Purpose In order to clarify which variants of the MMR gene could provide current "healthy" members in affected families a more accurate risk assessment or predictive testing. Patients and Methods One family, which meets the criteria according to both Amsterdam I/II and Bethesda guidelines, is reported in this study. The proband and some relatives of the patient have been investigated for whole genome sequencing, microsatellite instability, immunohistochemical MMR protein staining and verified by Sanger sequencing. Results A heterozygous insertion of uncertain significance (c.420dup, p.Met141Tyrfs) in MSH2 gene was found in proband (III-16) and part of His relatives. The variant was associated with a lack of expression of MSH2 protein (MMR deficient) and high microsatellite instability analysis (MSI) status in tumor tissues of LS patients. In addition, we found that the variant could affect the expression of MSH2 and the response to chemotherapy drugs in vitro. Conclusion We identified an insertion mutation (rs1114167810, c.420dup, p.Met141Tyrfs) in MSH2 in LS using whole genome-wide sequencing (WGS). We further confirmed that this mutation plays an important role in LS patients of this pedigree based on in vivo and vitro study.
Collapse
Affiliation(s)
- Wei-Hua Shao
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410078, People's Republic of China.,Institute of Clinical Pharmacology, Central South University; Hunan Key Laboratory of Pharmacogenetics, Changsha 410078, People's Republic of China.,Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, Changsha 410078, People's Republic of China.,Department of Geratic Surgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, People's Republic of China
| | - Cheng-Yu Wang
- Department of Geratic Surgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, People's Republic of China.,National Clinical Research Center for Geriatric Disorders, Changsha, Hunan 410008, People's Republic of China
| | - Lei-Yun Wang
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410078, People's Republic of China.,Institute of Clinical Pharmacology, Central South University; Hunan Key Laboratory of Pharmacogenetics, Changsha 410078, People's Republic of China.,Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, Changsha 410078, People's Republic of China.,Department of Geratic Surgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, People's Republic of China
| | - Fan Xiao
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410078, People's Republic of China.,Institute of Clinical Pharmacology, Central South University; Hunan Key Laboratory of Pharmacogenetics, Changsha 410078, People's Republic of China.,Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, Changsha 410078, People's Republic of China.,Department of Geratic Surgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, People's Republic of China
| | - De-Sheng Xiao
- Department of Pathology, Xiangya Hospital/School of Basic Medicine, Central South University, Changsha 410078, Hunan, People's Republic of China
| | - Hao Yang
- Department of Geratic Surgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, People's Republic of China.,National Clinical Research Center for Geriatric Disorders, Changsha, Hunan 410008, People's Republic of China
| | - Xue-Ying Long
- Department of Radiology, Xiangya Hospital, Central South University, Changsha 410008, People's Republic of China
| | - Le Zhang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, People's Republic of China
| | - Heng-Gui Luo
- Department of General Surgery, The Central Hospital of Xiangtan City, Xiangtan, Hunan, People's Republic of China
| | - Ji-Ye Yin
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410078, People's Republic of China.,Institute of Clinical Pharmacology, Central South University; Hunan Key Laboratory of Pharmacogenetics, Changsha 410078, People's Republic of China.,Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, Changsha 410078, People's Republic of China.,Department of Geratic Surgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, People's Republic of China
| | - Wei Wu
- Department of Geratic Surgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, People's Republic of China.,National Clinical Research Center for Geriatric Disorders, Changsha, Hunan 410008, People's Republic of China
| |
Collapse
|
5
|
Liu Q, Tan YQ. Advances in Identification of Susceptibility Gene Defects of Hereditary Colorectal Cancer. J Cancer 2019; 10:643-653. [PMID: 30719162 PMCID: PMC6360424 DOI: 10.7150/jca.28542] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Accepted: 12/08/2018] [Indexed: 12/17/2022] Open
Abstract
Colorectal cancer (CRC) is a common malignant tumor of the digestive system worldwide, associated with hereditary genetic features. CRC with a Mendelian genetic predisposition accounts for approximately 5-10% of total CRC cases, mainly caused by a single germline mutation of a CRC susceptibility gene. The main subtypes of hereditary CRC are hereditary non-polyposis colorectal cancer (HNPCC) and familial adenomatous polyposis (FAP). With the rapid development of genetic testing methods, especially next-generation sequencing technology, multiple genes have now been confirmed to be pathogenic, including DNA repair or DNA mismatch repair genes such as APC, MLH1, and MSH2. Since familial CRC patients have poor clinical outcomes, timely clinical diagnosis and mutation screening of susceptibility genes will aid clinicians in establishing appropriate risk assessment and treatment interventions at a personal level. Here, we systematically summarize the susceptibility genes identified to date and the potential pathogenic mechanism of HNPCC and FAP development. Moreover, clinical recommendations for susceptibility gene screening, diagnosis, and treatment of HNPCC and FAP are discussed.
Collapse
Affiliation(s)
- Qiang Liu
- Hunan Key Laboratory of Translational Radiation Oncology, Hunan cancer Hospital and The Affiliated Cancer of Xiangya School of Medicine, Central South University, Changsha, China.,Institute of Reproductive and Stem Cell Engineering, School of Basic Medical Science, Central South University, Changsha, China.,Reproductive and Genetic Hospital of CITIC-Xiangya, Changsha, China
| | - Yue-Qiu Tan
- Institute of Reproductive and Stem Cell Engineering, School of Basic Medical Science, Central South University, Changsha, China.,Reproductive and Genetic Hospital of CITIC-Xiangya, Changsha, China
| |
Collapse
|