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A novel TSC1 frameshift mutation c.1550_1551del causes tuberous sclerosis complex by aberrant splicing and nonsense-mediated mRNA degradation (NMD) simultaneously in a Chinese family.

ABSTRACT: BACKGROUND:Tuberous sclerosis complex (TSC), belongs to autosomal dominant genetic disorder, which affects multiple organ systems in the body, including the skin, brain, lungs, kidneys, liver, and eyes. Mutations in TSC1 or TSC2 was proved to be associated with these conditions. METHODS:Gene-panel Sequence of NGS was used to detect the mutation in a Chinese family. The research further investigates whether aberrant splicing and nonsense-mediated mRNA degradation (NMD) could serve as a mechanism cause by TSC1 mutation. MINI-Gene assay apply by pcMINI-TSC1wt/mut plasmids delivered in HeLa and 293T cell lines. Recombinant plasmids expressing wild-type and mutant-type EGFP-TSC1 were constructed and transiently transfected into human embryonic kidney cells 293T by lipofectamine. Real-time PCR and Western Blot were performed to analyze the expression of mRNAs and proteins of EGFP-TSC1 and NMD factor UPF1. RESULTS:The gene test verified a novel heterozygous TSC1 frameshift mutation (TSC1 c.1550_1551del) in the proband and her mother. From MINI-Gene assay, the agarose gel showed that both the mutant and wild-type mRNA possess two main bands, indicating two splicing modes, named band A and B, respectively. The mutation c.1550_1551del has not produced new splicing site, but there is a selective splicing in varying degree significantly after mutation. On the contrary, function validation assay showed that cells transfected with the mutant TSC1 plasmids expressed significantly lower TSC1 in mRNAs and proteins levels, compared with the wild-type TSC1 plasmid transfection. A translation inhibitor cycloheximide and small interfering RNA of UPF1 (siRNA-UPF1) increased mRNA or protein expression of TSC1 significantly in cells transfected with the mutant plasmids. CONCLUSION:Our study demonstrated that the novel TSC1 frameshift mutation (TSC1 c.1550_1551del) trigger aberrant splicing and NMD simultaneously, causing decrease of hamartin, then, leading to tuberous sclerosis complex formation.

SUBMITTER: Qiu C

PROVIDER: S-EPMC7549554 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

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A novel TSC1 frameshift mutation c.1550_1551del causes tuberous sclerosis complex by aberrant splicing and nonsense-mediated mRNA degradation (NMD) simultaneously in a Chinese family.

Qiu Cong C Li Chengyan C Tong Xiaoyun X Dai Luoyang L Liu Wenda W Xie Yulie Y Zhang Qimei Q Yang Guohua G Li Tao T

Molecular genetics & genomic medicine 20200731 10

<h4>Background</h4>Tuberous sclerosis complex (TSC), belongs to autosomal dominant genetic disorder, which affects multiple organ systems in the body, including the skin, brain, lungs, kidneys, liver, and eyes. Mutations in TSC1 or TSC2 was proved to be associated with these conditions.<h4>Methods</h4>Gene-panel Sequence of NGS was used to detect the mutation in a Chinese family. The research further investigates whether aberrant splicing and nonsense-mediated mRNA degradation (NMD) could serve ...[more]

PMID: 32735081

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Project description:Tuberous sclerosis complex (TSC) is an autosomal dominant disorder that is associated with neurological symptoms, including autism spectrum disorder. Tuberous sclerosis complex is caused by pathogenic germline mutations of either the TSC1 or TSC2 gene, but somatic mutations were identified in both genes, and the combined effects of TSC1 and TSC2 mutations have been unknown. The present study investigated social behaviors by the social interaction test and three-chambered sociability tests, effects of rapamycin treatment, and gene expression profiles with a gene expression microarray in Tsc1 and Tsc2 double heterozygous mutant (TscD+/-) mice. TscD+/- mice exhibited impairments in social behaviors, and the severity of impairments was similar to Tsc2+/- mice rather than Tsc1+/- mice. Impairments in social behaviors were rescued by rapamycin treatment in all mutant mice. Gene expression profiles in the brain were greatly altered in TscD+/- mice more than in Tsc1+/- and Tsc2+/- mice. The gene expression changes compared with wild type (WT) mice were similar between TscD+/- and Tsc2+/- mice, and the overlapping genes whose expression was altered in mutant mice compared with WT mice were enriched in the neoplasm- and inflammation-related canonical pathways. The "signal transducer and activator of transcription 3, interferon regulatory factor 1, interferon regulatory factor 4, interleukin-2R α chain, and interferon-γ" signaling pathway, which is initiated from signal transducer and activator of transcription 4 and PDZ and LIM domain protein 2, was associated with impairments in social behaviors in all mutant mice. It is unclear whether the signaling pathway also plays a critical role in autism spectrum disorders not caused by Tsc1 and Tsc2 mutations. These findings suggest that TSC1 and TSC2 double mutations cause autistic behaviors similarly to TSC2 mutations, although significant changes in gene expression were attributable to the double mutations. These findings contribute to the knowledge of genotype-phenotype correlations in TSC and suggest that mutations in both the TSC1 and TSC2 genes act in concert to cause neurological symptoms, including autism spectrum disorder.

Dataset Information

A novel TSC1 frameshift mutation c.1550_1551del causes tuberous sclerosis complex by aberrant splicing and nonsense-mediated mRNA degradation (NMD) simultaneously in a Chinese family.

Publications

A novel TSC1 frameshift mutation c.1550_1551del causes tuberous sclerosis complex by aberrant splicing and nonsense-mediated mRNA degradation (NMD) simultaneously in a Chinese family.

Similar Datasets

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