Identification of a novel ZIC3 isoform and mutation screening in patients with heterotaxy and congenital heart disease

James E J Bedard, Allison M. Haaning, Stephanie Ware

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Patients with heterotaxy have characteristic cardiovascular malformations, abnormal arrangement of their visceral organs, and midline patterning defects that result from abnormal left-right patterning during embryogenesis. Loss of function of the transcription factor ZIC3 causes X-linked heterotaxy and isolated congenital heart malformations and represents one of the few known monogenic causes of congenital heart disease. The birth incidence of heterotaxy-spectrum malformations is significantly higher in males, but our previous work indicated that mutations within ZIC3 did not account for the male over-representation. Therefore, cross species comparative sequence alignment was used to identify a putative novel fourth exon, and the existence of a novel alternatively spliced transcript was confirmed by amplification from murine embryonic RNA and subsequent sequencing. This transcript, termed Zic3-B, encompasses exons 1, 2, and 4 whereas Zic3-A encompasses exons 1, 2, and 3. The resulting protein isoforms are 466 and 456 amino acid residues respectively, sharing the first 407 residues. Importantly, the last two amino acids in the fifth zinc finger DNA binding domain are altered in the Zic3-B isoform, indicating a potential functional difference that was further evaluated by expression, subcellular localization, and transactivation analyses. The temporo-spatial expression pattern of Zic3-B overlaps with Zic3-A in vivo, and both isoforms are localized to the nucleus in vitro. Both isoforms can transcriptionally activate a Gli binding site reporter, but only ZIC3-A synergistically activates upon co-transfection with Gli3, suggesting that the isoforms are functionally distinct. Screening 109 familial and sporadic male heterotaxy cases did not identify pathogenic mutations in the newly identified fourth exon and larger studies are necessary to establish the importance of the novel isoform in human disease.

Original languageEnglish (US)
Article numbere23755
JournalPLoS One
Volume6
Issue number8
DOIs
StatePublished - 2011
Externally publishedYes

Fingerprint

heart diseases
exons
Heart Diseases
Screening
Protein Isoforms
screening
mutation
Mutation
Exons
protein isoforms
amino acids
zinc finger motif
alternative splicing
sequence alignment
transcriptional activation
transfection
human diseases
RNA Sequence Analysis
Amino Acids
binding sites

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Identification of a novel ZIC3 isoform and mutation screening in patients with heterotaxy and congenital heart disease. / Bedard, James E J; Haaning, Allison M.; Ware, Stephanie.

In: PLoS One, Vol. 6, No. 8, e23755, 2011.

Research output: Contribution to journalArticle

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