BMP4 and LGL1 are Down Regulated in an Ovine Model of Congenital Diaphragmatic Hernia

Abstract

Background/Purpose: The molecular pathophysiology of lung hypoplasia in congenital diaphragmatic hernia (CDH) remains poorly understood. The Wnt signaling pathway and downstream targets, such as bone morphogenetic proteins (BMP) 4 and other factors such as late gestation lung protein 1 (LGL1), are essential to normal lung development. Nitrofen-induced hypoplastic CDH rodent lungs demonstrate down regulation of the Wnt pathway including BMP4 and reduced LGL1 expression. The aim of the current study was to examine the molecular pathophysiology associated with a surgically induced CDH in an ovine model.Methods: Left thoracotomy was performed at 80 days in 14 fetal sheep; CDH was created in seven experimental animals. Lungs were harvested at 136 days (term = 145 days). Lung weight (LW) and mean terminal bronchiole density (MTBD) were measured to determine the degree of pulmonary hypoplasia. Quantitative real time PCR was undertaken to analyze Wnt2, Wnt7b, BMP4, and LGL1 mRNA expression.Results: Total LW was decreased while MTBD was increased in the CDH group (p < 0.05), confirming pulmonary hypoplasia. BMP4 and LGL1 mRNA was significantly reduced in CDH lungs (p < 0.05). Wnt2 mRNA was decreased, although not significantly (p < 0.06).Conclusion: For the first time, down regulation of BMP4 and LGL1 are reported in an ovine CDH model. In contrast to other animal models, these changes are persistent to near term. These findings suggest that mechanical compression from herniated viscera may play a more important role in causing pulmonary hypoplasia in CDH, rather than a primary defect in lung organogenesis.

Genetic profile of isolated congenital diaphragmatic hernia revealed by targeted next‐generation sequencing

“…The identified TBX1 :p.(Gly310Ser) variant has been shown to prevent TBX1‐SMAD1 interaction with a subsequent BMP4 pathway dysregulation . BMP4 knockdown in chicken leads to CDH and lung hypoplasia . Similarly, BMP4 loss of function leads to syndromic CDH in humans .…”

“…16 BMP4 knockdown in chicken leads to CDH and lung hypoplasia. 23 Similarly, BMP4 loss of function leads to syndromic CDH in humans. 24,25 Therefore, TBX1 could control diaphragm development through BMP pathway regulation.…”

Pathogenic variants in E3 ubiquitin ligase RLIM/RNF12 lead to a syndromic X-linked intellectual disability and behavior disorder

“…For example, BMP4 is involved in lung development, plays an essential role in atrioventricular septation of the heart, is important for complete development of the urethra during embryonic development, forms the precursor germ cell formation to seminal vesicle development and is involved in the generation of preadipocytes from mesenchymal stem cells followed by differentiation into adipocytes [77]. Knockdown of BMP4 in chicken leads to lethal CDH and LH [78]. Four RLIM-affected males presented with CHD resembling CHD types described in the 22q11-deletion syndrome.…”

The effects of tracheal occlusion on Wnt signaling in a rabbit model of congenital diaphragmatic hernia

“…Nitrofen inhibits retinal dehydrogenase of the RA signaling pathway and downregulates Lgl1 expression in CDH fetuses. Lgl1 was found to downregulated in the sheep model of CDH [42]. In the nitrofen-induced CDH rat model, Lgl1 was found to be upregulated in CDH fetal rat lungs following RA prenatal therapy [45].…”

“…Messenger RNA (mRNA) levels of Wnt7b and Wnt2 were significantly decreased during early lung development in the nitrofen-induced congenital diaphragmatic hernia rat model [37]. Bone morphogenetic protein 4 (BMP4), a downstream target of Wnt2 was downregulated in the ovine model of CDH [42]. Furthermore, in a large pulmonary transcriptome analysis of fetal rabbits, Wnt inhibitor factor 1 (WIF1) was upregulated in CDH and downregulated following TO, while marker of proliferation Ki-67 (MKI67) was upregulated in CDH+TO fetuses [43].…”