Browsing by Subject "single-cell RNA-sequencing"

Rare mutations in the primate specific ZNF808 gene are a novel cause of pancreatic agenesis, a congenital developmental disorder that leads to neonatal diabetes. ZNF808 loss-of-function has been shown to lead to aberrant activation of regulatory MER11 elements, followed by upregulation of genes in proximity to these elements and increased expression of hepatic lineage markers. These findings suggest ZNF808 to play a key role in balancing the differentiation of endoderm progenitor cells between pancreatic and liver lineages during early human development. This thesis work aimed to study the gene regulatory mechanisms of ZNF808 in the differentiating endoderm progenitor cells to understand its function in controlling pancreatic lineage specification. This was achieved by comparing the lineage specification processes in wild-type (H1) and ZNF808 knockout (H1-ZNF808-KO) human embryonic stem cells (hESCs) during pancreatic differentiation. Further characterization of cellular heterogeneity and gene expression profiles upon ZNF808 loss was done using single-cell RNA sequencing (scRNA-seq). To validate the role of ZNF808 as the mediator of the observed lineage specification bias, the phenotype rescue was examined in a ZNF808 knockout overexpression cell line (H1-ZNF808-KO-OX). The results of this study demonstrate a clear lineage specification bias in the ZNF808 knockout, seen as divergence of the multipotent endoderm progenitors towards alternate hepatic and biliary fates at the posterior foregut stage. By modifying the pancreatic differentiation protocol, we were able to observe phenotype manifestation and cellular heterogeneity suppressed in the standard differentiation conditions. The scRNA-seq data analysis revealed the emergence of a biliary cell population showing upregulation of several hepatic markers, suggesting an alternative lineage specification process governed by ZNF808. Additionally, preliminary results from ZNF808 overexpression showed rescue of the ZNF808 knockout phenotype, further supporting its critical role in the normal pancreatic lineage development. In conclusion, these findings demonstrate the important role of ZNF808 in early human pancreatic development and warrant further studies on the detailed gene regulatory network guiding pancreatic lineage specification.