584 - The Role of GATA4 in Lung Hypoplasia and Pulmonary Hypertension Associated with Congenital Diaphragmatic Hernia

Poster Number: 584
Publication Number: 584.1668

Background: Congenital diaphragmatic hernia (CDH) is a common and severe malformation affecting 1/3,000 births with a high mortality rate (10-50%) due to lung hypoplasia (LH) and pulmonary hypertension (PHN). The long-standing model has been that lung and pulmonary vascular (PV) defects in CDH are due to mechanical compression by herniated abdominal organs. However, data from fetal patients and animal models suggest that there may be primary defects in lung and PV development that occur independent of mechanical compression. Our central hypothesis is that pathogenic genome variants in CDH patients play a direct role in lung and PV development. The Diaphragmatic Hernia Research and Exploration; Advancing Molecular Science study found that GATA4 is one of the most common genes (5%) implicated in CDH patients. Patients with pathogenic GATA4 loss-of-function (LOF) variants had severe phenotypes with 67% mortality and survivors required oxygen and pulmonary vasodilating medications at discharge.

Objective: GATA4 is required for diaphragm development but has an unclear role in lung and PV development. Our hypothesis is that GATA4 directs lung and PV development and that GATA4 LOF causes LH and PHN independent of its role in the diaphragm.

Design/Methods: We inactivated Gata4 expression in developing murine lung mesenchyme using an inducible, tissue-specific gene deletion approach. Gata4 conditional deletion (Gata4 CKO) and control mice were analyzed at embryonic and postnatal stages. We performed histology, immunofluorescence staining, qRT-PCR, and physiology testing (echocardiography and pulmonary function testing) for phenotype analysis.

Results: Gata4 is expressed in the lung mesothelium with peak expression at E12. Counter to related work and our hypothesis, Gata4 deletion did not impact lung branching morphogenesis, alveologenesis, or PV development. Lung cell lineages (mesenchyme, mesothelium, endothelium, and epithelium) were not affected by loss of Gata4 expression. Physiological testing showed no PHN and unchanged pulmonary function in Gata4 CKO mice.

Conclusion(s): While a severe phenotype is seen in CDH patients with GATA4 LOF variants, our work demonstrates that GATA4 does not have a direct role in lung or PV development. These data are significant because they suggest that lung and PV defects in patients with GATA4 LOF variants are due to mechanical compression during development. Our data suggest that genomic analysis in patients and functional studies in mouse models could be used to identify patients who are more likely to benefit from high-risk fetal procedures that address mechanical compression.