Gene network and familial analyses uncover a gene network involving Tbx5/Osr1/Pcsk6 interaction in the second heart field for atrial septation

Abstract

Atrial septal defects (ASDs) are a common human congenital heart disease (CHD) that can be induced by genetic abnormalities. Our previous studies have demonstrated a genetic interaction between Tbx5 and Osr1 in the second heart field (SHF) for atrial septation. We hypothesized that Osr1 and Tbx5 share a common signaling networking and downstream targets for atrial septation. To identify this molecular networks, we acquired the RNA-Seq transcriptome data from the posterior SHF of wild-type, Tbx5(+/) (-), Osr1(+/-), Osr1(-/-) and Tbx5(+/-)/Osr1(+/-) mutant embryos. Gene set analysis was used to identify the Kyoto Encyclopedia of Genes and Genomes pathways that were affected by the doses of Tbx5 and Osr1. A gene network module involving Tbx5 and Osr1 was identified using a non-parametric distance metric, distance correlation. A subset of 10 core genes and gene-gene interactions in the network module were validated by gene expression alterations in posterior second heart field (pSHF) of Tbx5 and Osr1 transgenic mouse embryos, a time-course gene expression change during P19CL6 cell differentiation. Pcsk6 was one of the network module genes that were linked to Tbx5. We validated the direct regulation of Tbx5 on Pcsk6 using immunohistochemical staining of pSHF, ChIP-quantitative polymerase chain reaction and luciferase reporter assay. Importantly, we identified Pcsk6 as a novel gene associated with ASD via a human genotyping study of an ASD family. In summary, our study implicated a gene network involving Tbx5, Osr1 and Pcsk6 interaction in SHF for atrial septation, providing a molecular framework for understanding the role of Tbx5 in CHD ontogeny.

Osr1 functions downstream of Hedgehog pathway to regulate foregut development

“…So far OSR1 has been associated with congenital kidney and heart defects in both animal models (Wang et al 2005) and in human patients (Zhang et al 2016). Our results suggest Osr1 is a potential gene associated with human respiratory and digestive diseases as well, serving as another screening candidate and potential treatment target in humans with congenital respiratory and digestive defects.…”

Development and evolution of the metazoan heart

“…Failure to differentiate may lead to AVSDs . Molecular mechanisms controlling atrium and DMP development include PDGF signaling, BMP, Tbx5, Osr1, and FoxF1 . Tissue‐specific deletion of Smoothened resulted in compromised DMP formation, AVDs, reduced proliferation, and diminished Wnt/β‐catenin signaling .…”

“…73,219 Molecular mechanisms controlling atrium and DMP development include PDGF signaling, 171,218 BMP, Tbx5, Osr1, and FoxF1. 220,221 Tissue-specific deletion of Smoothened resulted in compromised DMP formation, AVDs, reduced proliferation, and diminished Wnt/β-catenin signaling. 216 In humans, ASDs account for about 9% of more 9700 patients, which is far less than the 69% of children with OFT malformations.…”

Gata4 potentiates second heart field proliferation and Hedgehog signaling for cardiac septation

“…For example, genetic inducible fate mapping (GIFM) has shown that the entire atrial septum, including the DMP, derives from the SHF (32). Furthermore, the molecular requirement for the Hedgehog (Hh) and BMP signaling pathways and the Tbx5 cardiogenic transcription factor for AV septation reside in the SHF (32)(33)(34)(35)(36)(37)(38). These observations lay the groundwork for investigating the molecular pathways required for atrial septum formation in SHF cardiac progenitor cells.…”