Abstract 18669: A Novel Association Between GATA4 and Left Ventricular Noncompaction
Background: Left ventricular noncompaction (LVNC) is characterized by a heavily trabeculated left ventricle and often systolic dysfunction. In contrast to other inherited cardiomyopathies, only in a minority of cases of LVNC can a definitive genetic cause be identified, highlighting the need for new gene discovery.
Methods and Results: A 48 year old male proband and his 19 year old son were diagnosed with LVNC and mild left ventricular systolic dysfunction. Clinical genetic testing with a dilated cardiomyopathy 27-gene panel was negative. Whole exome sequencing revealed a novel mutation in GATA4, Arg260Trp, which was present in both affected individuals. GATA4 is an important transcriptional regulator of cardiogenesis. Mutations in GATA4 have been linked to congenital heart defects and dilated cardiomyopathy (DCM), but not previously to LVNC. Arg260Trp is absent in large population databases, affects a conserved site, and in silico analysis predicts it is probably damaging. We hypothesized that the Arg260Trp mutation impairs transcriptional activity of GATA4. A GATA4 mutation, Cys271Ser, associated with DCM was used as a positive control in functional assays. Wild type (WT) human GATA4 cDNA was obtained from Harvard PlasmID and mutant constructs were generated by site-directed mutagenesis. GATA4 transcriptional activity was evaluated by a luciferase reporter assay using a firefly luciferase under control of the atrial natriuretic factor (ANF) promoter. HEK293 cells were transfected with equal DNA quantities of WT or mutant GATA4, ANF-luciferase, and Renilla luciferase plasmids. Luciferase activity was significantly reduced in both the Arg260Trp and Cys271Ser mutations compared to WT (1.64±0.11 and 1.41±0.13 vs. 3.56±0.26 [fold increase in activity compared with empty vector], n=9, p<0.0001). Immunofluorescence showed that both mutant GATA4 proteins correctly localized to the nucleus in a pattern similar to the WT protein.
Conclusions: The Arg260Trp mutation leads to reduced GATA4 transcriptional activity despite correct nuclear localization, implying that this mutation may result in reduced DNA binding affinity. These functional data provide support for disease causality and a novel link between GATA4 and LVNC.
Author Disclosures: V.T. Tang: None. P. Arscott: None. A.S. Helms: None. S.M. Day: None.
- © 2016 by American Heart Association, Inc.