Project description:NEUROD1 is a transcription factor that helps maintain a mature phenotype of pancreatic β cells. Disruption of Neurod1 during pancreatic development causes severe neonatal diabetes; however, the exact role of NEUROD1 in the differentiation programs of endocrine cells is unknown. Here, we report a crucial role of the NEUROD1 regulatory network in endocrine lineage commitment and differentiation. Mechanistically, transcriptome and chromatin landscape analyses demonstrate that Neurod1 inactivation triggers a downregulation of endocrine differentiation transcription factors and upregulation of non-endocrine genes within the Neurod1-deficient endocrine cell population, disturbing endocrine identity acquisition. Neurod1 deficiency altered the H3K27me3 histone modification pattern in promoter regions of differentially expressed genes, which resulted in gene regulatory network changes in the differentiation pathway of endocrine cells, compromising endocrine cell potential, differentiation, and functional properties.
Project description:While diabetes incidence is gradually rising worldwide, novel therapeutical approaches are required in the search for a replacement of dysfunctional endocrine tissue, especially beta-cells. A promising potential lies in direct cellular reprogramming of similar cell types sharing common multipotent progenitors. With the knowledge of molecular mechanisms determining the endocrine cell fate commitment and endocrine lineage differentiation, other endocrine cells contained within the islets of Langerhans or closely related cells could be trans- or dedifferentiated either in situ or in vitro with their subsequent transplantation into the patient. NEUROD1 is a transcription factor situated on the base of the gene regulatory network of the developing endocrine precursors, directly downstream of endocrine lineage master regulator NEUROG3. While NEUROG3 initiates a rapid cascade of chromatin reorganization in numerous bivalent promoters resulting in spatiotemporal gene expression leading to differentiation of all endocrine cell subtypes from pancreatic multipotent progenitors, the role of NEUROD1 has yet to be clarified. Notably, NEUROD1 can induce neuronal program through pioneering and chromatin remodelling in other cell types. In this study, we performed advanced molecular and phenotypic analyses in early endocrine-specific Neurod1-deficient mouse model, including RNA and CUT&Tag sequencing and lightsheet microscopy, to gain insight into the NEUROD1-regulated transcription network driving endocrine lineage cell fate commitment. Besides a postnatal diabetic phenotype, disrupted endocrine differentiation and associated altered islet architecture, we observed an apparent elevation in the non-endocrine gene expression pattern and uncovered alterations in the epigenetic landscape of characteristic genes, specifically in the H3K4me3 and H3K27me3 distribution. Therefore, we provide evidence that NEUROD1 is critical player responsible for the establishment of the endocrine cell identity, which further affects endocrine development and may serve as a potent proendocrine reprogramming driver.
Project description:While diabetes incidence is gradually rising worldwide, novel therapeutical approaches are required in the search for a replacement of dysfunctional endocrine tissue, especially beta-cells. A promising potential lies in direct cellular reprogramming of similar cell types sharing common multipotent progenitors. With the knowledge of molecular mechanisms determining the endocrine cell fate commitment and endocrine lineage differentiation, other endocrine cells contained within the islets of Langerhans or closely related cells could be trans- or dedifferentiated either in situ or in vitro with their subsequent transplantation into the patient. NEUROD1 is a transcription factor situated on the base of the gene regulatory network of the developing endocrine precursors, directly downstream of endocrine lineage master regulator NEUROG3. While NEUROG3 initiates a rapid cascade of chromatin reorganization in numerous bivalent promoters resulting in spatiotemporal gene expression leading to differentiation of all endocrine cell subtypes from pancreatic multipotent progenitors, the role of NEUROD1 has yet to be clarified. Notably, NEUROD1 can induce neuronal program through pioneering and chromatin remodelling in other cell types. In this study, we performed advanced molecular and phenotypic analyses in early endocrine-specific Neurod1-deficient mouse model, including RNA and CUT&Tag sequencing and lightsheet microscopy, to gain insight into the NEUROD1-regulated transcription network driving endocrine lineage cell fate commitment. Besides a postnatal diabetic phenotype, disrupted endocrine differentiation and associated altered islet architecture, we observed an apparent elevation in the non-endocrine gene expression pattern and uncovered alterations in the epigenetic landscape of characteristic genes, specifically in the H3K4me3 and H3K27me3 distribution. Therefore, we provide evidence that NEUROD1 is critical player responsible for the establishment of the endocrine cell identity, which further affects endocrine development and may serve as a potent proendocrine reprogramming driver.
Project description:Geminin is a small nucleoprotein that neuralizes ectoderm in the Xenopus embryo. Geminin promotes neural fate acquisition of mouse embryonic stem cells: Geminin knockdown during neural fate acquisition decreased expression of neural precursor cell markers (Pax6, Sox1), while increasing expression of Pitx2, Lefty1 and Cited2, genes involved in formation of the mouse node. Here we differentiated mouse embryonic stem cells into embryoid bodies to study Geminin's ability to repress primitive streak mesendoderm fate acquisition. We used microarrays to define the sets of genes that are regulated by Geminin during cell fate acquisition in embryoid bodies, using Dox-inducible Geminin knockdown or overexpression mouse embryonic stem cell lines. ES cell lines for Geminin over-expression (GemOE) were treated without or with Dox from day 3 to day 5 of EB differentiation and were collected on days 4 or 5 for microarray analysis. Gem knockdown (KD) ES cell lines were treated without or with Dox from day 0 to day 4 of EB differentiation and were collected on day 4 for microarray analysis.
Project description:Cell fate specification relies on the action of critical transcription factors that become available at distinct stages of embryonic development. One such factor is NeuroD1, which is essential for eliciting the neuronal development program and possesses the ability to reprogram other cell types into neurons. Given this capacity, it is important to understand its targets and the mechanism underlying neuronal specification. Here, we show that NeuroD1 directly binds regulatory elements of neuronal genes that are developmentally silenced by epigenetic mechanisms. This targeting is sufficient to initiate events that confer transcriptional competence, including reprogramming of transcription factor landscape, conversion of heterochromatin to euchromatin and increased chromatin accessibility, indicating potential pioneer factor ability of NeuroD1. The transcriptional induction of neuronal fate genes is maintained via epigenetic memory despite a transient NeuroD1 induction during neurogenesis. Our study not only reveals the NeuroD1-dependent gene regulatory program driving neurogenesis but also increases our understanding of how cell-fate specification during development involves a concerted action of transcription factors and epigenetic mechanisms. 1. Ectopic NeuroD1 was induced for 48 hours (+Dox) in ES cells for checking initiation of neuronal transcriptional program in comparison to uninduced condition (-Dox) 2. ChIP-seq was performed after 24 hours of NeuroD1 induction in ES cells.