Faculty Collaboration Database

Analysis of RNA splicing defects in PITX2 mutants supports a gene dosage model of Axenfeld-Rieger syndrome. BMC Med Genet 2006 Jul 11;7:59

Date

07/13/2006

Pubmed ID

16834779

Pubmed Central ID

PMC1553432

DOI

10.1186/1471-2350-7-59

Scopus ID

2-s2.0-33748048489 (requires institutional sign-in at Scopus site)   22 Citations

Abstract

BACKGROUND: Axenfeld-Rieger syndrome (ARS) is associated with mutations in the PITX2 gene that encodes a homeobox transcription factor. Several intronic PITX2 mutations have been reported in Axenfeld-Rieger patients but their effects on gene expression have not been tested.

METHODS: We present two new families with recurrent PITX2 intronic mutations and use PITX2c minigenes and transfected cells to address the hypothesis that intronic mutations effect RNA splicing. Three PITX2 mutations have been analyzed: a G>T mutation within the AG 3' splice site (ss) junction associated with exon 4 (IVS4-1G>T), a G>C mutation at position +5 of the 5' (ss) of exon 4 (IVS4+5G>C), and a previously reported A>G substitution at position -11 of 3'ss of exon 5 (IVS5-11A>G).

RESULTS: Mutation IVS4+5G>C showed 71% retention of the intron between exons 4 and 5, and poorly expressed protein. Wild-type protein levels were proportionally expressed from correctly spliced mRNA. The G>T mutation within the exon 4 AG 3'ss junction shifted splicing exclusively to a new AG and resulted in a severely truncated, poorly expressed protein. Finally, the A>G substitution at position -11 of the 3'ss of exon 5 shifted splicing exclusively to a newly created upstream AG and resulted in generation of a protein with a truncated homeodomain.

CONCLUSION: This is the first direct evidence to support aberrant RNA splicing as the mechanism underlying the disorder in some patients and suggests that the magnitude of the splicing defect may contribute to the variability of ARS phenotypes, in support of a gene dosage model of Axenfeld-Rieger syndrome.

Author List

Maciolek NL, Alward WL, Murray JC, Semina EV, McNally MT

Authors

Mark T. McNally PhD Associate Professor in the Microbiology and Immunology department at Medical College of Wisconsin
Elena V. Semina PhD Chief, Professor in the Ophthalmology and Visual Sciences department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Abnormalities, Multiple
Cell Line
Eye Abnormalities
Female
Gene Dosage
Homeodomain Proteins
Humans
Introns
Male
Models, Genetic
Mutation
Pedigree
RNA Splice Sites
RNA Splicing
Syndrome
Transcription Factors