Functional characterization of a novel mutation in NKX2-5 associated with congenital heart disease and adult-onset cardiomyopathy

Mauro Da Costa, Guanglan Guo, Orit Wolstein, Molly Vale, Maria Leticia Castro, Libin Wang, Robyn Otway, Peter Riek, Natalie Cochrane, Milena Bastos Furtado, Christopher Semsarian, Robert Weintraub, Thomas Yeoh, Christopher S Hayward, Anne Keogh, Peter Macdonald, Michael P Feneley, Robert M Graham, Jonathan G Seidman, Christine E SeidmanNadia Alicia Rosenthal, Diane Fatkin, Richard P Harvey

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The transcription factor NKX2-5 is crucial for heart development, and mutations in this gene have been implicated in diverse congenital heart diseases and conduction defects in mouse models and humans. Whether NKX2-5 mutations have a role in adult-onset heart disease is unknown. Methods and Results- Mutation screening was performed in 220 probands with adult-onset dilated cardiomyopathy. Six NKX2-5 coding sequence variants were identified, including 3 nonsynonymous variants. A novel heterozygous mutation, I184M, located within the NKX2-5 homeodomain, was identified in 1 family. A subset of family members had congenital heart disease, but there was an unexpectedly high prevalence of dilated cardiomyopathy. Functional analysis of I184M in vitro demonstrated a striking increase in protein expression when transfected into COS-7 cells or HL-1 cardiomyocytes because of reduced degradation by the Ubiquitin-proteasome system. In functional assays, DNA-binding activity of I184M was reduced, resulting in impaired activation of target genes despite increased expression levels of mutant protein. Conclusions- Certain NKX2-5 homeodomain mutations show abnormal protein degradation via the Ubiquitin-proteasome system and partially impaired transcriptional activity. We propose that this class of mutation can impair heart development and mature heart function and contribute to NKX2-5-related cardiomyopathies with graded severity.
Original languageEnglish
Pages (from-to)238 - 247
Number of pages10
JournalCirculation: Cardiovascular Genetics
Issue number3
Publication statusPublished - 2013

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