Guiggey, D. | Search bioRxiv

bioRxiv2022

Dynamic changes in the niche and transcription trigger early murine and human pluripotent stem cell-derived liver organogenesis

The shift from collective migration to differentiation is a crucial process in epithelial biology but recreating this intricate transition has thus far proved elusive. We provide experimental, mechanistic, in vivo, and bioinformatic data supporting an undoubtable link between human pluripotent stem cell (hPSC)- derived collectively migrating hepatoblasts (MHB), and transcriptionally mature, functional hPSC- hepatocytes (HEPs), which incorporates two unrecognized steps. The protocol induces FOXA-dependent induction of HBs, leading to TBX3-positive, YAP-TEAD active MHBs which provide a transcriptional match with murine liver E9.5 MHBs. Simple cultivation changes trigger MHBs to rapidly form functional day 18 HEPs, predicted by a deep-learning designed gene circuit, resulting in a [~]236% fold- increase in maturation (PACNet), on par with the highest score, but with enhanced global transcriptional shaping. Overall, incorporating the MHB to HEP transition establishes a new, unrecognized, and highly efficient mechanism for differentiation that can be cumulatively integrated with existing methods to overcome barriers to maturation.

bioengineering↗

bioRxiv2020

Foxa1/2 downregulates liver differentiation markers and the endoderm and liver gene regulatory network in human stem cells and in a human stable liver cell line

FOXA factors are critical members of the developmental gene regulatory network (GRN) composed of master transcription factors (TF) which regulate murine cell fate and metabolism in the gut and liver. How FOXA dictates human liver cell fate, differentiation, and simultaneously regulate metabolic pathways is poorly understood. Here, we aimed to determine the role of FOXA2 (and FOXA1 which is believed to compensate for FOXA2) in hepatic differentiation and cell metabolism in a human hepatic cell line (HepG2). siRNA targeting of FOXA1 and FOXA2 in human hepatic (HepG2) cells and during hepatic differentiation significantly downregulated albumin (p < 0.05) and GRN TF gene expression (HNF4A, HEX, HNF1B, TBX3) (p < 0.05) and significantly upregulated endoderm/gut/hepatic endoderm markers (goosecoid (GSC), FOXA3, and GATA4), gut TF (CDX2), pluripotent TF (NANOG), and neuroectodermal TF (PAX6) (p < 0.05), all consistent with a partial/transient cell reprogramming. shFOXA1/2 targeting resulted in similar findings and demonstrated evidence of reversibility. RNA-seq followed by bioinformatic analysis of shFOXA1/2 knockdown HepG2 cells demonstrated 235 significant downregulated genes and 448 upregulated genes, including upregulation of markers for alternate germ layers lineages (cardiac, endothelial, muscle) and neurectoderm (eye, neural). We found widespread downregulation of glycolysis, citric acid cycle, mitochondrial genes, and alterations in lipid metabolism, pentose phosphate pathway, and ketogenesis. Functional metabolic analysis agreed with these findings, demonstrating significantly diminished glycolysis and mitochondrial respiration, and accumulation of lipid droplets. We hypothesized that FOXA1/2 inhibit the initiation of human liver differentiation in vitro. During hPSC-hepatic differentiation, siRNA knockdown demonstrated de-differentiation and unexpectedly, activation of pluripotency factors and neuroectoderm. shRNA knockdown demonstrated similar results and activation of SOX9 (hepatobiliary). These results demonstrate complex effects of FOXA1/2 on hepatic GRN effecting de-differentiation and metabolism with applications in studies of cancer, differentiation, and organogenesis.

bioengineering↗