GATA6 Cooperates with EOMES/SMAD2/3 to Deploy the Gene Regulatory Network Governing Human Definitive Endoderm and Pancreas Formation.

Heterozygous de novo mutations in GATA6 are the most frequent cause of pancreatic agenesis in humans. In mice, however, a similar phenotype requires the biallelic loss of Gata6 and its paralog Gata4. To elaborate the human-specific requirements for GATA6, we chose to model GATA6 loss in vitro by combining both gene-edited and patient-derived pluripotent stem cells (hPSC) and directed differentiation toward beta-like cells. We find that GATA6 heterozygous hPSC show a modest reduction in definitive endoderm (DE) formation, while GATA6 null hPSC fail to enter the DE lineage. Consistent with these results, genome-wide studies show that GATA6 binds and cooperates with EOMES/SMAD2/3 to regulate the expression of cardinal endoderm genes. The early deficit in DE is accompanied by a significant reduction in PDX1+ pancreatic progenitors and C-PEPTIDE+ beta-like cells. Taken together, our data position GATA6 as a gatekeeper to early human, but not murine, pancreatic ontogeny.We thank the NIHR Cambridge BRC hiPSC core facility for the derivation of GATA6 hiPSC lines, Dr. Norihiro Tsuneyoshi for advice and guidance on gene editing using TALENs, and Dr. Bruno Reversade for insightful discussions. This work was funded by an EDB Singapore Childhood Undiagnosed Diseases Program grant and an A*STAR Strategic Positioning Fund (SPF) Genetic Orphan Diseases Adopted: Fostering Innovation Therapy (GODAFIT) grant and by an ERC starting grant Relieve IMDs and core grant funding from the Wellcome Trust and Medical Research Council (PSAG028) (LV and PM). A.T.H. is a Wellcome Trust Senior Investigato