Impaired mesenchymal cell function in Gata4 mutant mice leads to diaphragmatic hernias and primary lung defects

Abstract

Congenital diaphragmatic hernia (CDH) is an often fatal birth defect that is commonly associated with pulmonary hypoplasia and cardiac malformations. Some investigators hypothesize that this constellation of defects results from genetic or environmental triggers that disrupt mesenchymal cell function in not only the primordial diaphragm but also the thoracic organs. The alternative hypothesis is that the displacement of the abdominal viscera in the chest secondarily perturbs the development of the heart and lungs. Recently, loss-of-function mutations in the gene encoding FOG-2, a transcriptional co-regulator, have been linked to CDH and pulmonary hypoplasia in humans and mice. Here we show that mutagenesis of the gene for GATA-4, a transcription factor known to functionally interact with FOG-2, predisposes inbred mice to a similar set of birth defects. Analysis of wild-type mouse embryos demonstrated co-expression of Gata4 and Fog2 in mesenchymal cells of the developing diaphragm, lungs, and heart. A significant fraction of C57Bl/6 mice heterozygous for a Gata4 deletion mutation died within 1 day of birth. Developmental defects in the heterozygotes included midline diaphragmatic hernias, dilated distal airways, and cardiac malformations. Heterozygotes had any combination of these defects or none. In chimeric mice, Gata4(-/-) cells retained the capacity to contribute to cells in the diaphragmatic central tendon and lung mesenchyme, indicating that GATA-4 is not required for differentiation of these lineages. We conclude that GATA-4, like its co-regulator FOG-2, is required for proper mesenchymal cell function in the developing diaphragm, lungs, and heart.

The Transcription Factor Atonal homolog 8 Regulates Gata4 and Friend of Gata-2 during Vertebrate Development

“…Although the cause of death was not identified in these studies, a higher incidence of cardiovascular defects (27,53) was identified in Gata4 ϩ/Ϫ animals compared with wild-type littermates. To determine whether Gata4…”

“…ϩ/Ϫ heterozygotes have been reported to exhibit partial postnatal lethality when backcrossed onto a C57/BL6 background (27,53). Although the cause of death was not identified in these studies, a higher incidence of cardiovascular defects (27,53) was identified in Gata4 ϩ/Ϫ animals compared with wild-type littermates.…”

“…7D) at E18.5, suggesting that both type I and type II cells are present at normal numbers. Although we could not identify morphologic defects in lung development, we next examined the expression of molecular factors involved in mesenchymal-toepithelial signaling in Gata4 ϩ/Ϫ Atoh8 GFP/GFP animals because Gata4 expression in the lung is limited to the mesenchyme (53,56). Mesenchymal expression of Wnt2, Fgf10, and Tbx4 has previously been shown to be required for proper lung development (57)(58)(59).…”

“…Another explanation for this difference may lie in the expression and function of GATA and FOG in the mouse versus the zebrafish. Previous studies using either hypomorphic Gata4 alleles or Gata4 ϩ/Ϫ animals have revealed that partial loss of GATA4 is sufficient to confer a lethal phenotype (27,53,64). In contrast, lethality in Fog2 heterozygotes has not been reported, suggesting that larger reductions in FOG2 levels may be necessary to confer phenotypes in the mouse.…”

Candidate genes for congenital diaphragmatic hernia from animal models: sequencing of FOG2 and PDGFRα reveals rare variants in diaphragmatic hernia patients

“…FOG2 was shown to be an important regulator of Gata-4 in the developing heart, and both genes are co-expressed during cardiac embryogenesis. 28 Interestingly, C57Bl/6 mice that were heterozygous for a deletion mutation of the Gata-4 gene have midline diaphragmatic defects, 29 suggesting that abnormal regulation of Gata-4 by FOG2 might also be important for diaphragm development. FOG2 also binds to the ligandbinding domain of chicken ovalbumin upstream promoter transcription factor II (COUP-TFII; also known as NR2F2).…”