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01.12.2018 | Research | Ausgabe 1/2018 Open Access

Journal of Translational Medicine 1/2018

A loss-of-function mutation p.T52S in RIPPLY3 is a potential predisposing genetic risk factor for Chinese Han conotruncal heart defect patients without the 22q11.2 deletion/duplication

Zeitschrift:
Journal of Translational Medicine > Ausgabe 1/2018
Autoren:
Nanchao Hong, Erge Zhang, Qingjie Wang, Xiaoqing Zhang, Fen Li, Qihua Fu, Rang Xu, Yu Yu, Sun Chen, Yuejuan Xu, Kun Sun
Wichtige Hinweise

Electronic supplementary material

The online version of this article (https://​doi.​org/​10.​1186/​s12967-018-1633-1) contains supplementary material, which is available to authorized users.
Nanchao Hong and Erge Zhang contributed equally to this work

Abstract

Background

Conotruncal heart defect (CTD) is a complex congenital heart disease with a complex and poorly understood etiology. The transcriptional corepressor RIPPLY3 plays a pivotal role in heart development as a negative regulator of the key cardiac transcription factor TBX1. A previous study showed that RIPPLY3 contribute to cardiac outflow tract development in mice, however, the relationship between RIPPLY3 and human cardiac malformation has not been reported.

Methods

615 unrelated CTD Chinese Han patients were enrolled, we excluded the 22q11.2 deletion/duplication using a modified multiplex ligation-dependent probe amplification method—CNVplex®, and investigated the variants of RIPPLY3 in 577 patients without the 22q11.2 deletion/duplication by target sequencing. Functional assays were performed to testify the potential pathogenicity of nonsynonymous variants found in these CTD patients.

Results

Four rare heterozygous nonsynonymous variants (p.P30L, p.T52S, p.D113N and p.V179D) were identified in four CTD patients, the variant NM_018962.2:c.155C>G (p.T52S) is referred as rs745539198, and the variant NM_018962.2:c.337G>A (p.D113N) is referred as rs747419773. However, variants p.P30L and p.V179D were not found in multiple online human gene variation databases. Western blot analysis and immunofluorescence showed that there were no significant difference between wild type RIPPLY3 and these four variants. Luciferase assays revealed that the p.T52S variant altered the inhibition of TBX1 transcriptional activity in vitro, and co-immunoprecipitation assays showed that the p.T52S variant reduced the physical interaction of RIPPLY3 with TBX1. In addition to the results from pathogenicity prediction tools and evolutionary protein conservation, the p.T52S variant was thought to be a potentially deleterious variant.

Conclusion

Our results provide evidence that deleterious variants in RIPPLY3 are potential molecular mechanisms involved in the pathogenesis of human CTD.
Zusatzmaterial
Additional file 1: Table S1. Primer pairs used to amplify the coding regions contain candidate variants. Table S2. Primer pairs used to amplify the TBX1C variants identified in patients harboring RIPPLY3 variants. Figure S1. Subcellular localization of wild-type TBX1 protein in transiently transfected HEK293T cells. The wild-type TBX1 localized exclusively to the nuclei with normal nuclear distribution.
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