The GLI-code controls HNF1A levels during in-vitro foregut differentiation
Ontology highlight
ABSTRACT: Differentiation of human induced pluripotent stem cells towards pancreatic islet endocrine cells is a complex process, involving the stepwise modulation of key developmental pathways, such as the Hedgehog signaling inhibition during early differentiation stages. In tandem with this active inhibition, key transcription factors for the islet endocrine cell fate, such as HNF1A, show specific changes in their expression patterns. Here we designed a forthright pilot study aimed at investigating the potential interconnection between HH-signaling inhibition and the increase in the HNF1A expression during early regeneration, by inducing changes in the GLI code. This unveiled a link between the two, where GLI3-R mediated Hedgehog target genes inhibition is apparently required for HNF1A efficient expression.
Project description:The Hedgehog signaling pathway is essential for the maintenance and response of several types of stem cells. To study the transcriptional response of stem cells to HH signaling, we searched for proteins binding to GLI proteins, the transcriptional effectors of the HH pathway in mouse embryonic stem (ES) cells. We purified GLI protein complex from an ES cell line that contained a tamoxifen-inducible 3XFLAG-tagged GLI3 repressor allele by anti-FLAG immunoprecipitation and several novel GLI co-factors were identified in the complex by subsequent mass spectrometry analysis.
Project description:Mutations in HNF1A cause Maturity Onset Diabetes of the Young type 3, the second most frequent form of diabetes caused by single gene mutation. We generated human pancreatic stem cell-derived endocrine cells with mutations in HNF1A and show that HNF1A deficiency impairs scβ-cell fate, insulin granule maturation and the secretion of insulin in a glucose responsive manner. Single-cell RNA sequencing reveals that HNF1A orchestrates a network of genes involved in glucose metabolism, zinc transport, calcium ion binding and hormone exocytosis. Furthermore, in both patients and stem cell-derived β-cells, HNF1A deficiency altered the stoichiometry of secreted c-peptide to insulin. Sulfonylurea, used in the treatment of these patients, restored both insulin secretion and stoichiometry. Significantly, uncoupling of c-peptide and insulin secretion as described here questions the common practice in using c-peptide as a proxy to evaluate β-cell function. We also demonstrate that correction of the HNF1A locus restores function, providing a path to cell therapy.
Project description:Purpose: Most Hedgehog responsive gene expression is mediated through GLI de-repression. Additionally GLI -repression is proposed to play roles in limb pre-patterning before HH pathway activation. This study evaluates if GLI repression is established prior to HH pathway activation. Methods: To determine if GLI-repression is established prior to pathway activation, we used genomic approaches to study GLI-mediated repression using the mouse developing limb as a model. We identified pre-HH (E9.25, 21-23S) and post-HH (E10.5, 32-25S) GLI3 binding regions using CUT&RUN for endogenous FLAG-tagged GLI3 proteins. Using a combination of ChIP-seq, CUT&RUN, CUT&Tag, ATAC-seq and RNA-seq, we tested whether loss of Gli3 prior to HH signaling was able to de-repress genes and enhancers, as it does after HH signaling. Results: Prior to HH signaling, GLI3 binds to poised, accessible regions with histone deacetylase (HDAC) proteins, similar to post-HH signaling. Despite GLI3 binding to most regions as it does in the post-HH limb, loss of Gli3 is unable to prematurely active target genes or enhancers. Furthermore, we find that GLI3-dependent chromatin compaction does not occur until roughly 10 hours after HH signaling would have normally been induced. Collectively, these results support that GLI repressor proteins are inert prior to HH pathway activation.
Project description:Despite significant progress in therapy, melanoma is still the most lethal form of skin cancer, with a rising incidence worldwide. Little is known about the impact of deregulated Hedgehog-GLI (HH-GLI) signalling pathway in the progression of this disease. Based on previous research, we hypothesized that in melanoma activation of HH-GLI signaling pathway is non- canonical due to its crosstalk with MAPK signaling pathway, which is the most deregulated pathway in melanoma. In order to investigate the link between the two pathways and to find novel GLI transcriptional targets that could be considered for potential combination therapy, we performed RNA sequencing on three melanoma cell lines with overexpressed GLI1, GLI2 and GLI3 and combined them with results of ChIP sequencing on endogenous GLI1, GLI2 and GLI3 proteins on the same cell lines. RNA-seq revealed a total of 808 DEGs for GLI1, 941 DEGs for GLI2 and 58 DEGs for GLI3. ChIP-seq identified 527 genes that contained GLI1 binding sites in their promoters, 1103 for GLI2 and 553 for GLI3. After combining these results, 21 targets were selected for validation by qPCR. Fifteen of these targets were validated in the tested cell lines, 6 of which were detected by both RNA-seq and ChIP-seq.
Project description:Mutations in HNF1A cause Maturity Onset Diabetes of the Young type 3, the second most frequent form of diabetes caused by single gene mutation. We generated human pancreatic stem cell-derived endocrine cells with mutations in HNF1A and show that HNF1A deficiency impairs scβ-cell fate, insulin granule maturation and the secretion of insulin in a glucose responsive manner. Single-cell RNA sequencing reveals that HNF1A orchestrates a network of genes involved in glucose metabolism, zinc transport, calcium ion binding and hormone exocytosis. Furthermore, in both patients and stem cell-derived β-cells, HNF1A deficiency altered the stoichiometry of secreted c-peptide to insulin. Sulfonylurea, used in the treatment of these patients, restored both insulin secretion and stoichiometry. Significantly, uncoupling of c-peptide and insulin secretion as described here questions the common practice in using c-peptide as a proxy to evaluate β-cell function. We also demonstrate that correction of the HNF1A locus restores function, providing a path to cell therapy.
Project description:The biological properties of pancreatic cancer stem cells (PCSCs) remain incompletely defined and the central regulators are unknown. By bioinformatic analysis of a PCSC-enriched gene signature, we identified the transcription factor HNF1A as a putative central regulator of PCSC function. Levels of HNF1A and its target genes were found to be elevated in PCSCs and tumorspheres, and depletion of HNF1A resulted in growth inhibition, apoptosis, impaired tumorsphere formation, PCSC depletion, and downregulation of OCT4 expression. Conversely, HNF1A overexpression increased PCSC numbers and tumorsphere formation in pancreatic cancer cells and drove PDA cell growth. Importantly, depletion of HNF1A in primary tumor xenografts impaired tumor growth and depleted PCSCs in vivo. Finally, we established an HNF1A-dependent gene signature in PDA cells that significantly correlated with reduced survivability in patients. These findings identify HNF1A as a central transcriptional regulator of the PCSC state and novel oncogene in pancreatic ductal adenocarcinoma.
Project description:The biological properties of pancreatic cancer stem cells (PCSCs) remain incompletely defined and the central regulators are unknown. By bioinformatic analysis of a PCSC-enriched gene signature, we identified the transcription factor HNF1A as a putative central regulator of PCSC function. Levels of HNF1A and its target genes were found to be elevated in PCSCs and tumorspheres, and depletion of HNF1A resulted in growth inhibition, apoptosis, impaired tumorsphere formation, PCSC depletion, and downregulation of OCT4 expression. Conversely, HNF1A overexpression increased PCSC numbers and tumorsphere formation in pancreatic cancer cells and drove PDA cell growth. Importantly, depletion of HNF1A in primary tumor xenografts impaired tumor growth and depleted PCSCs in vivo. Finally, we established an HNF1A-dependent gene signature in PDA cells that significantly correlated with reduced survivability in patients. These findings identify HNF1A as a central transcriptional regulator of the PCSC state and novel oncogene in pancreatic ductal adenocarcinoma.
Project description:Generating insulin-producing β-cells from human induced pluripotent stem cells is a promising cell replacement therapy aimed at improving or curing certain forms of diabetes. Nevertheless, despite important recent advances, the efficient production of functionally mature β-cells is yet to be achieved, with most current differentiation protocols generating a heterogeneous population comprising of subpopulation of cells expressing different islet hormones, including hybrid polyhormonal entities. A solution to this issue is transplanting end-stages differentiating cells into living hosts, which was demonstrated to majorly improve β-cell maturation. Yet, to date, the cellular and molecular mechanisms underlying the transplanted cells response to the in vivo environment exposure was not yet properly characterized. Here we use global proteomics and large-scale imaging techniques aimed at demultiplexing and filtering cellular processes and molecular signatures modulated by the immediate in vivo effect. We show that in vivo exposure swiftly confines in vitro generated human pancreatic progenitors to single hormone expression. The global proteome landscape of the transplanted cells was closer to the one presented by native human islets, especially in regard to energy metabolism and redox balance. Moreover our study indicates a possible link between these processed and certain epigenetic regulators involved in maintenance and propagation of the islet cells identity. Pathway analysis predicted HNF1A and HNF4A as key regulators controlling the in vivo islet-promoting response, with experimental evidence confirming their involvement in confining islet cell identity. To our knowledge this is the first study demultiplexing the immediate response of the transplanted pancreatic progenitors to in vivo exposure.
Project description:Purpose: This study seeks to determine whether GLI3 is required to recruit the SMARCC1 complex to GLI enhancers in the limb. Methods: To determine if Gli3 is required to recruit SMARCC1 to its anhancers, we performed differential chromatin binding to compare SMARCC1 binding in control and Gli3 mutants. We performed Cut&Run for SMARCC1 binding on individually genotyped E11.5 (40-43s) anterior forelimb pairs from control (Gli3+/+; 3 replicates) and Gli3 mutant (Gli3-/-; 4 replicates) embryos. Results: We found that there is no major difference in SMARCC1 binding in Gli3-mutants compared to controls.