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ABSTRACT Many developmental processes rely on the localized activation of receptor tyrosine kinases and their canonical downstream effectors Erk and Akt, yet the specific roles played by each of these signals is still poorly understood. Gastruloids, 3D cell culture models of mammalian gastrulation and axial elongation, enable quantitative dissection of signaling patterns and cell responses in a simplified, experimentally accessible context. We find that mouse gastruloids contain posterior-to-anterior gradients of Erk and Akt phosphorylation induced by distinct receptor tyrosine kinases, with features of the Erk pattern and expression of its downstream target Snail exhibiting hallmarks of size-invariant scaling. Both Erk and Akt signaling contribute to cell proliferation, whereas Erk activation is also sufficient to induce Snail expression and precipitate profound tissue shape changes. We further uncover that Erk signaling is sufficient to convert the entire gastruloid to one of two mesodermal fates depending on position along the anteroposterior axis. In all, these data demonstrate functional roles for two core signaling gradients in mammalian development and suggest how these modules might be harnessed to engineer user-defined tissues with predictable shapes and cell fates.
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DNA Methylation Dynamics During Esophageal Epithelial Regeneration Following Repair with Acellular Silk Fibroin Grafts in Rat
Abstract Esophageal pathologies such as atresia and benign strictures often require surgical reconstruction with autologous tissues to restore organ continuity. Complications such as donor site morbidity and limited tissue availability have spurred the development of acellular grafts for esophageal tissue replacement. Acellular biomaterials for esophageal repair rely on the activation of intrinsic regenerative mechanisms to mediate de novo tissue formation at implantation sites. Previous research has identified signaling cascades involved in neoepithelial formation in a rat model of onlay esophagoplasty with acellular silk fibroin grafts, including phosphoinositide 3‐kinase (PI3K), and protein kinase B (Akt) signaling. However, it is currently unknown how these mechanisms are governed by DNA methylation (DNAme) during esophageal wound healing processes. Reduced‐representation bisulfite sequencing is performed to characterize temporal DNAme dynamics in host and regenerated tissues up to 1 week postimplantation. Overall, global hypermethylation is observed at postreconstruction timepoints and an inverse correlation between promoter DNAme and the expression levels of differentially expressed proteins during regeneration. Site‐specific hypomethylation targets genes associated with immune activation, while hypermethylation occurs within gene bodies encoding PI3K‐Akt signaling components during the tissue remodeling period. The data provide insight into the epigenetic mechanisms during esophageal regeneration following surgical repair with acellular grafts.
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- Award ID(s):
- 1763272
- PAR ID:
- 10392111
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Biology
- Volume:
- 7
- Issue:
- 5
- ISSN:
- 2701-0198
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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