During embryogenesis, the pancreas develops from separate dorsal and ventral buds, which fuse to form the mature pancreas. Little is known about the functional differences between these two buds or the relative contribution of cells derived from each portion to the pancreas after fusion. To follow the fate of dorsal or ventral bud derived cells in the pancreas after fusion, we produced chimeric Elas-GFP transgenic/wild type embryos in which either dorsal or ventral pancreatic bud cells expressed GFP. We found that ventral pancreatic cells migrate extensively into the dorsal pancreas after fusion, whereas the converse does not occur. Moreover, we found that annular pancreatic tissue is composed exclusively of ventral pancreas derived cells. To identify ventral pancreas specific genes that may play a role in pancreatic bud fusion, we isolated individual dorsal and ventral pancreatic buds, prior to fusion, from stage 38/39 Xenopus laevis tadpoles and compared their gene expression profiles. Morpholino-mediated knockdown of one of these ventral specific genes, transmembrane 4 superfamily member 3 (tm4sf3), inhibited dorsal-ventral pancreatic bud fusion as well as acinar cell differentiation. Conversely, overexpression of tm4sf3 promoted the development of annular pancreas. Our results are the first to define molecular and behavioral differences between the dorsal and ventral pancreas, and suggest an unexpected role for the ventral pancreas in pancreatic bud fusion.
The tetraspanin Tm4sf3 is localized to the ventral pancreas and regulates fusion of the dorsal and ventral pancreatic buds.
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View SamplesNgn3 is a master regulator of pancreatic endocrine development. It is necessary for the creation of all endocrine cells in mice. Little is known about the genes that act downstream of the transcription factor Ngn3 in pancreas endocrine development to specify each of the endocrine lineages. As a consequence, little is known about the genes involved in early development and the specification of the beta cell. We used microarrays to identify Ngn3 downstream genes that are involved in early and ectopic beta cell development in Xenopus laevis. We overexpressed Ngn3 in the Xenopus early endoderm and analyzed the genes that are upregulated four hours after.
Transient expression of Ngn3 in Xenopus endoderm promotes early and ectopic development of pancreatic beta and delta cells.
Specimen part, Treatment
View SamplesRecently a new neonatal diabetes syndrome, Mitchell-Riley syndrome, was discovered. To identify the genetic cause of the syndrome homozygosity mapping was used, several chromosomal regions were linked to Mitchell-Riley syndrome. In situ hybridization of genes from one such region using model organism Xenopus laevis identified RFX6 as a potential candidate gene; mutant forms of RFX6 were subsequently found in Mitchell-Riley patients. Analysis of the expression pattern of RFX6 in Xenopus development shows it is expressed broadly in the endoderm early in development, and later RFX6 becomes restricted to the endocrine cells of the gut and pancreas. Morpholino knockdown of RFX6 in Xenopus caused a loss of pancreas marker gene expression. Injection of exogenous wild type RFX6 rescued the morpholino phenotype in Xenopus tadpoles. Attempts to rescue the loss-of-function phenotype using mutant forms of RFX6 found in Mitchell-Riley patients were unsuccessful suggesting the changes lead to loss-of-function and could be the cause of Mitchell-Riley syndrome. Microarray analysis of gene expression in knockdown tissue suggested a downregulation in marker genes for lung, stomach and heart, ambiguous results for the liver, and an upregulation in kidney marker gene expression. RT-PCR and in situ hybridization confirms a loss of lung, stomach and heart gene expression, no change in liver marker hex and an upregulation in kidney marker KcnJ1. The fact that the morpholino phenotype affects multiple organs suggests that RFX6 has a broad role early in endoderm development.
Functional analysis of Rfx6 and mutant variants associated with neonatal diabetes.
Specimen part, Treatment
View SamplesTo gain insight in the kinetics and interplay of the predominant transcriptional responses of DNA damage signalling pathways in undifferentiated cells, mouse embryonic stem cells were exposed to cisplatin at four different time points (2, 4, 8 and 24 hr) and concentrations (1, 2, 5 and 10 uM). RNA was isolated and subjected to genome-wide expression profiling.
A portrait of cisplatin-induced transcriptional changes in mouse embryonic stem cells reveals a dominant p53-like response.
Specimen part, Compound, Time
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Altering TET dioxygenase levels within physiological range affects DNA methylation dynamics of HEK293 cells.
Specimen part, Cell line, Treatment
View SamplesOur study in zebrafish is the first to use an animal model to understand the biology of the developmental disorder Roberts Syndrome (RBS). RBS is caused by mutations in the ESCO2 gene.
A zebrafish model of Roberts syndrome reveals that Esco2 depletion interferes with development by disrupting the cell cycle.
Age, Specimen part
View SamplesTo further understand the differences occurring in MCF10A cells as they polarize and differentiate in the Transwell model, we performed gene expression profiling with Affymetrix Human Genome U133 Plus 2.0 Arrays. Four experimental time points, were sampled: conventional cultures of MCF10A cells grown on plastic (Monolayer) and MCF10A cells plated on Transwells sampled at three TEER values, 200-300 cm2 (Base), 1400-1600 cm2 (Midpoint), and 3000-3200 cm2 (Plateau).
In vitro multipotent differentiation and barrier function of a human mammary epithelium.
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View SamplesWe compared TET1 and TET3 overexpressing cells to uninduced cells with endogenous levels of the respective transcript to determine global gene expression changes.
Altering TET dioxygenase levels within physiological range affects DNA methylation dynamics of HEK293 cells.
Specimen part, Treatment
View SamplesWe initiated a study to investigate the transcriptional profiles associated with cell states of the stomatal lineage. A stem-cell like precursor of stomata, a meristemoid. reiterates asymmetric divisions and renews itself before differentiating into guard cells. The transient and asynchronous nature of the meristemoid has made it difficult to study its molecular characteristics. Through combinatorial use of genetic resources that either arrest or constitutively drive stomatal cell-state progressions due to loss- or gain-of-function mutations in the key transcription factor genes, SPEECHLESS, MUTE, and SCRM, we obtained seedlings highly enriched in pavement cells, meristemoids, or stomata. Here we present transcriptome and genome-wide trends in gene regulation associated with each cell state and identify molecular signatures associated with meristemoids.
Molecular profiling of stomatal meristemoids reveals new component of asymmetric cell division and commonalities among stem cell populations in Arabidopsis.
Age, Specimen part
View SamplesWe report that increased nutrient availability increases breeding success and egg production. RNA-seq analysis revealed that parental diet altered the expression of metabolic genes in the unfertilized eggs. Offspring from the differentially fed parents showed altered survival and energy expenditure as adults. Overall design: RNA from unfertilized eggs after two parental diets.
Dietary Intake Influences Adult Fertility and Offspring Fitness in Zebrafish.
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