Hepatocyte differentiation initiates during endodermal-mesenchymal interactions prior to liver formation

Development ◽  
1991 ◽  
Vol 113 (1) ◽  
pp. 217-225 ◽  
Author(s):  
S. Cascio ◽  
K.S. Zaret
Keyword(s):  
General Pattern ◽  
Cell Aggregation ◽  
Cell Types ◽  
Specific Gene ◽  
Mrna Levels ◽  
Cellular Interactions ◽  
Hepatocyte Differentiation ◽  
Endodermal Cells ◽  
Tissue Matrix ◽  
Albumin Mrna

Previous studies with embryonic tissue explants showed that cellular interactions with mesenchyme are required for endodermal cells to differentiate into hepatocytes. However, these studies assayed hepatocyte characteristics that were evident after days of culture, leaving open the question of whether the primary inductive interactions initiated hepatocyte differentiation, or whether subsequent steps, such as may occur during cell aggregation to form the liver, were necessary. Using the technique of in situ hybridization, we find that serum albumin mRNA, a liver-specific gene product, is first detected in hepatic precursor cells of the endoderm as early as 9.5 days of mouse embryo development, a full day prior to cell aggregation and liver formation. The endodermal cells express albumin mRNA upon migration into strands of connective tissue matrix within mesenchyme. Thus, the onset of differentiation of the endoderm is coincident with its interaction with mesenchyme. Early albumin transcripts are initiated at the same site of the albumin promoter as in adult hepatocytes, suggesting that at least a subset of the transcription factors that control albumin transcription in the adult may be involved in executing the early steps of hepatic determination. We also observe a sharp increase in albumin mRNA levels shortly after the definitive formation of the liver, apparently reflecting cell interactions that enhance hepatocyte differentiation. Hepatocyte differentiation is therefore similar in several respects to pancreatic exocrine cell development, and may represent a general pattern for gut-derived tissues. For both cell types, early interactions with mesenchyme are coincident with the initial expression of differentiated gene products at a low level in proliferating endoderm, and the initial pattern of expression is amplified upon organ formation.

scholarly journals Temperature-sensitive mRNA degradation is an early event in hepatocyte de-differentiation

1997 ◽  
Vol 328 (3) ◽  
pp. 937-944 ◽  
Author(s):  
Xiu-Jun WANG ◽  
P. Conrad HODGKINSON ◽  
C. Matthew WRIGHT ◽  
J. Alan PAINE
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Transcriptional Silencing ◽  
Rnase Activity ◽  
Early Event ◽  
Specific Gene ◽  
Temperature Sensitive ◽  
Mrna Levels ◽  
Cultured Hepatocytes ◽  
Albumin Mrna

The isolation and culture of metabolically active hepatocytes by proteolytic digestion of the extracellular matrix of the liver results in the transcriptional silencing of liver-specific genes encoding cytochromes P-450 (CYP) and albumin together with an induction of cellular RNase activity. The levels of albumin mRNA are maintained in cultured hepatocytes at similar levels to that present in the intact liver for at least 24 h, whereas the major constitutively expressed CYP2C11 mRNA is rapidly degraded. Hepatocytes heat-shocked at 40 °C during the isolation procedure (which results in an induction of heat-shock protein mRNA species) blocks the increase in RNase activity and abrogates the loss of CYP2C11 mRNA for at least 4 h. Cycloheximide-dependent inhibition of protein synthesis blocks the temperature-dependent induction of heat-shock proteins without affecting the protection afforded to CYP2C11 mRNA, indicating that CYP2C11 mRNA levels are not directly dependent on heat-shock protein induction and suggesting that the induction of RNase activity might be responsible for the specific loss of CYP2C11 mRNA in hepatocytes isolated at 37 °C. Differential rates of degradation of CYP2C11 transcribed in vitro and of albumin mRNA are observed in the presence of cellular extracts from cultured hepatocytes isolated at 37 °C (which have maximally induced levels of cellular RNase activity) but not in comparable extracts from cultured hepatocytes isolated at 40 °C, supporting the hypothesis that an RNase activity is induced in culture that specifically degrades CYP2C11 mRNA but not albumin mRNA. These results suggest that an early event in hepatocyte de-differentiation involves the induction of RNase activity in addition to transcriptional silencing of liver-specific genes and that the induced RNase activity demonstrates specificity within liver-specific gene products.

scholarly journals ModelingIn VitroCellular Responses to Silver Nanoparticles

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Dwaipayan Mukherjee ◽  
Steven G. Royce ◽  
Srijata Sarkar ◽  
Andrew Thorley ◽  
Stephan Schwander ◽  
...  
Keyword(s):  
High Throughput Screening ◽  
Cell Types ◽  
Engineered Nanoparticles ◽  
Mrna Levels ◽  
Cellular Interactions ◽  
Cellular Mechanisms ◽  
Nanoparticle Transport ◽  
Cell Culture Systems

Engineered nanoparticles (NPs) have been widely demonstrated to induce toxic effects to various cell types.In vitrocell exposure systems have high potential for reliable, high throughput screening of nanoparticle toxicity, allowing focusing on particular pathways while excluding unwanted effects due to other cells or tissue dosimetry. The work presented here involves a detailed biologically based computational model of cellular interactions with NPs; it utilizes measurements performed in human cell culture systemsin vitro, to develop a mechanistic mathematical model that can support analysis and prediction ofin vivoeffects of NPs. The model considers basic cellular mechanisms including proliferation, apoptosis, and production of cytokines in response to NPs. This new model is implemented for macrophages and parameterized usingin vitromeasurements of changes in cellular viability and mRNA levels of cytokines: TNF, IL-1b, IL-6, IL-8, and IL-10. The model includesin vitrocellular dosimetry due to nanoparticle transport and transformation. Furthermore, the model developed here optimizes the essential cellular parameters based onin vitromeasurements, and provides a “stepping stone” for the development of more advancedin vivomodels that will incorporate additional cellular and NP interactions.

scholarly journals Metabolism-Based Gene Differences in Neurons Expressing Hyperphosphorylated AT8− Positive (AT8+) Tau in Alzheimer’s Disease

ASN NEURO ◽  
2021 ◽  
Vol 13 ◽  
pp. 175909142110194
Author(s):  
Audra York ◽  
Angela Everhart ◽  
Michael P. Vitek ◽  
Kirby W. Gottschalk ◽  
Carol A. Colton
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Metabolic Pathways ◽  
Cell Types ◽  
Specific Protein ◽  
Specific Gene ◽  
Specific Cell ◽  
Mrna Levels ◽  
Double Labeling ◽  
Expression Levels

Metabolic adaptations in the brain are critical to the establishment and maintenance of normal cellular functions and to the pathological responses to disease processes. Here, we have focused on specific metabolic pathways that are involved in immune-mediated neuronal processes in brain using isolated neurons derived from human autopsy brain sections of normal individuals and individuals diagnosed as Alzheimer’s disease (AD). Laser capture microscopy was used to select specific cell types in immune-stained thin brain sections followed by NanoString technology to identify and quantify differences in mRNA levels between age-matched control and AD neuronal samples. Comparisons were also made between neurons isolated from AD brain sections expressing pathogenic hyperphosphorylated AT8- positive (AT8+) tau and non-AT8+ AD neurons using double labeling techniques. The mRNA expression data showed unique patterns of metabolic pathway expression between the subtypes of captured neurons that involved membrane based solute transporters, redox factors, and arginine and methionine metabolic pathways. We also identified the expression levels of a novel metabolic gene, Radical-S-Adenosyl Domain1 ( RSAD1) and its corresponding protein, Rsad1, that impact methionine usage and radical based reactions. Immunohistochemistry was used to identify specific protein expression levels and their cellular location in NeuN+ and AT8+ neurons. APOE4 vs APOE3 genotype-specific and sex-specific gene expression differences in these metabolic pathways were also observed when comparing neurons from individuals with AD to age-matched individuals.

Epithelial Organotypic Cultures: A Viable Model to Address Mechanisms of Carcinogenesis by Epitheliotropic Viruses

2018 ◽  
Vol 18 (4) ◽  
pp. 246-255 ◽  
Author(s):  
Lara Termini ◽  
Enrique Boccardo
Keyword(s):  
Three Dimensional ◽  
Cell Types ◽  
Experimental Models ◽  
Biological Research ◽  
Specific Gene ◽  
Specific Cell ◽  
Organotypic Cultures ◽  
Skin Physiology

In vitro culture of primary or established cell lines is one of the leading techniques in many areas of basic biological research. The use of pure or highly enriched cultures of specific cell types obtained from different tissues and genetics backgrounds has greatly contributed to our current understanding of normal and pathological cellular processes. Cells in culture are easily propagated generating an almost endless source of material for experimentation. Besides, they can be manipulated to achieve gene silencing, gene overexpression and genome editing turning possible the dissection of specific gene functions and signaling pathways. However, monolayer and suspension cultures of cells do not reproduce the cell type diversity, cell-cell contacts, cell-matrix interactions and differentiation pathways typical of the three-dimensional environment of tissues and organs from where they were originated. Therefore, different experimental animal models have been developed and applied to address these and other complex issues in vivo. However, these systems are costly and time consuming. Most importantly the use of animals in scientific research poses moral and ethical concerns facing a steadily increasing opposition from different sectors of the society. Therefore, there is an urgent need for the development of alternative in vitro experimental models that accurately reproduce the events observed in vivo to reduce the use of animals. Organotypic cultures combine the flexibility of traditional culture systems with the possibility of culturing different cell types in a 3D environment that reproduces both the structure and the physiology of the parental organ. Here we present a summarized description of the use of epithelial organotypic for the study of skin physiology, human papillomavirus biology and associated tumorigenesis.

scholarly journals Analysis of the transcriptome of bovine endometrial cells isolated by laser micro-dissection (1): specific signatures of stromal, glandular and luminal epithelial cells

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Wiruntita Chankeaw ◽  
Sandra Lignier ◽  
Christophe Richard ◽  
Theodoros Ntallaris ◽  
Mariam Raliou ◽  
...  
Keyword(s):  
Gene Expression ◽  
Protein Localization ◽  
Expression Profiles ◽  
Cell Types ◽  
Molecular Signature ◽  
Receptor Protein ◽  
Specific Gene ◽  
Specific Cell ◽  
Biological Processes ◽  
Endometrial Cells

Abstract Background A number of studies have examined mRNA expression profiles of bovine endometrium at estrus and around the peri-implantation period of pregnancy. However, to date, these studies have been performed on the whole endometrium which is a complex tissue. Consequently, the knowledge of cell-specific gene expression, when analysis performed with whole endometrium, is still weak and obviously limits the relevance of the results of gene expression studies. Thus, the aim of this study was to characterize specific transcriptome of the three main cell-types of the bovine endometrium at day-15 of the estrus cycle. Results In the RNA-Seq analysis, the number of expressed genes detected over 10 transcripts per million was 6622, 7814 and 8242 for LE, GE and ST respectively. ST expressed exclusively 1236 genes while only 551 transcripts were specific to the GE and 330 specific to LE. For ST, over-represented biological processes included many regulation processes and response to stimulus, cell communication and cell adhesion, extracellular matrix organization as well as developmental process. For GE, cilium organization, cilium movement, protein localization to cilium and microtubule-based process were the only four main biological processes enriched. For LE, over-represented biological processes were enzyme linked receptor protein signaling pathway, cell-substrate adhesion and circulatory system process. Conclusion The data show that each endometrial cell-type has a distinct molecular signature and provide a significantly improved overview on the biological process supported by specific cell-types. The most interesting result is that stromal cells express more genes than the two epithelial types and are associated with a greater number of pathways and ontology terms.

scholarly journals Characterization and Regulation of Type A Endothelin Receptor Gene Expression in Bovine Luteal Cell Types

Endocrinology ◽  
1999 ◽  
Vol 140 (5) ◽  
pp. 2110-2116 ◽  
Author(s):  
Roni Mamluk ◽  
Nitzan Levy ◽  
Bo Rueda ◽  
John S. Davis ◽  
Rina Meidan
Keyword(s):  
Gene Expression ◽  
Receptor Gene ◽  
Cell Types ◽  
Cell Populations ◽  
Mrna Levels ◽  
Factor I ◽  
Receptor Mrna ◽  
Progesterone Production ◽  
Eta Receptor ◽  
Receptor Gene Expression

Abstract Our previous studies demonstrated that endothelin-1 (ET-1), a 21-amino acid vasoconstrictor peptide, has a paracrine regulatory role in bovine corpus luteum (CL). The peptide is produced within the gland where it inhibits progesterone production by acting via the selective type A endothelin (ETA) receptors. The present study was designed to characterize ETA receptor gene expression in different ovarian cell types and its hormonal regulation. ETA receptor messenger RNA (mRNA) levels were high in follicular cells as well as in CL during luteal regression. At this latter stage, high ETA receptor expression concurred with low prostaglandin F2α receptor mRNA. The ETA receptor gene was expressed by all three major cell populations of the bovine CL; i.e. small and large luteal cells, as well as in luteal endothelial cells. Among these various cell populations, the highest ETA receptor mRNA levels were found in endothelial cells. cAMP elevating agents, forskolin and LH, suppressed ETA receptor mRNA expression in luteinized theca cells (LTC). This inhibition was dose dependent and was evident already after 24 h of incubation. In luteinized granulosa cells (LGC), 10 and 100 ng/ml of insulin-like growth factor I and insulin (only at a concentration of 2000 ng/ml) markedly decreased ETA receptor mRNA levels. In both LGC and LTC there was an inverse relationship between ETA receptor gene expression and progesterone production; insulin (in LGC) and forskolin (in LTC) enhanced progesterone production while inhibiting ETA receptor mRNA levels. Our findings may therefore suggest that, during early stages of luteinization when peak levels of both LH and insulin-like growth factor I exist, the expression of ETA receptors in the gland are suppressed. This study demonstrates physiologically relevant regulatory mechanisms controlling ETA receptor gene expression and further supports the inhibitory role of ET-1 in CL function.

scholarly journals An analytical method for the identification of cell type-specific disease gene modules

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Jinting Guan ◽  
Yiping Lin ◽  
Yang Wang ◽  
Junchao Gao ◽  
Guoli Ji
Keyword(s):  
Disease Gene ◽  
Gene Interaction ◽  
Cell Types ◽  
Autism Spectrum ◽  
Specific Gene ◽  
Cell Type ◽  
Specific Disease ◽  
Cell Type Specific ◽  
Gene Modules ◽  
Disease Associated Genes

Abstract Background Genome-wide association studies have identified genetic variants associated with the risk of brain-related diseases, such as neurological and psychiatric disorders, while the causal variants and the specific vulnerable cell types are often needed to be studied. Many disease-associated genes are expressed in multiple cell types of human brains, while the pathologic variants affect primarily specific cell types. We hypothesize a model in which what determines the manifestation of a disease in a cell type is the presence of disease module comprised of disease-associated genes, instead of individual genes. Therefore, it is essential to identify the presence/absence of disease gene modules in cells. Methods To characterize the cell type-specificity of brain-related diseases, we construct human brain cell type-specific gene interaction networks integrating human brain nucleus gene expression data with a referenced tissue-specific gene interaction network. Then from the cell type-specific gene interaction networks, we identify significant cell type-specific disease gene modules by performing statistical tests. Results Between neurons and glia cells, the constructed cell type-specific gene networks and their gene functions are distinct. Then we identify cell type-specific disease gene modules associated with autism spectrum disorder and find that different gene modules are formed and distinct gene functions may be dysregulated in different cells. We also study the similarity and dissimilarity in cell type-specific disease gene modules among autism spectrum disorder, schizophrenia and bipolar disorder. The functions of neurons-specific disease gene modules are associated with synapse for all three diseases, while those in glia cells are different. To facilitate the use of our method, we develop an R package, CtsDGM, for the identification of cell type-specific disease gene modules. Conclusions The results support our hypothesis that a disease manifests itself in a cell type through forming a statistically significant disease gene module. The identification of cell type-specific disease gene modules can promote the development of more targeted biomarkers and treatments for the disease. Our method can be applied for depicting the cell type heterogeneity of a given disease, and also for studying the similarity and dissimilarity between different disorders, providing new insights into the molecular mechanisms underlying the pathogenesis and progression of diseases.

Analysis of a tissue-specific enhancer: ARF6 regulates adipogenic gene expression

1992 ◽  
Vol 12 (3) ◽  
pp. 1202-1208
Author(s):  
R A Graves ◽  
P Tontonoz ◽  
B M Spiegelman
Keyword(s):  
Gene Expression ◽  
Cultured Cells ◽  
Mutational Analysis ◽  
Cell Types ◽  
Specific Gene ◽  
Enhancer Activity ◽  
Cis Acting ◽  
Specific Gene Expression ◽  
Nuclear Extracts ◽  
Adipogenic Gene

The molecular basis of adipocyte-specific gene expression is not well understood. We have previously identified a 518-bp enhancer from the adipocyte P2 gene that stimulates adipose-specific gene expression in both cultured cells and transgenic mice. In this analysis of the enhancer, we have defined and characterized a 122-bp DNA fragment that directs differentiation-dependent gene expression in cultured preadipocytes and adipocytes. Several cis-acting elements have been identified and shown by mutational analysis to be important for full enhancer activity. One pair of sequences, ARE2 and ARE4, binds a nuclear factor (ARF2) present in extracts derived from many cell types. Multiple copies of these elements stimulate gene expression from a minimal promoter in preadipocytes, adipocytes, and several other cultured cell lines. A second pair of elements, ARE6 and ARE7, binds a separate factor (ARF6) that is detected only in nuclear extracts derived from adipocytes. The ability of multimers of ARE6 or ARE7 to stimulate promoter activity is strictly adipocyte specific. Mutations in the ARE6 sequence greatly reduce the activity of the 518-bp enhancer. These data demonstrate that several cis- and trans-acting components contribute to the activity of the adipocyte P2 enhancer and suggest that ARF6, a novel differentiation-dependent factor, may be a key regulator of adipogenic gene expression.

Expression of the Brachyury gene during mesoderm development in differentiating embryonal carcinoma cell cultures

Development ◽  
1994 ◽  
Vol 120 (1) ◽  
pp. 115-122 ◽  
Author(s):  
G. Vidricaire ◽  
K. Jardine ◽  
M.W. McBurney
Keyword(s):  
Bone Morphogenetic Proteins ◽  
Embryonal Carcinoma ◽  
Carcinoma Cell ◽  
Cell Aggregation ◽  
Cell Types ◽  
Carcinoma Cells ◽  
Embryonal Carcinoma Cell ◽  
P19 Cells ◽  
Mesoderm Development ◽  
P19 Embryonal Carcinoma Cells

When aggregated and treated with dimethyl sulfoxide (DMSO), P19 embryonal carcinoma cells differentiate into cell types normally derived from the mesoderm and endoderm including epithelium and cardiac and skeletal muscle. The Brachyury gene is expressed transiently in these differentiating cultures several days before the appearance of markers of the differentiated cell types. The expression of Brachyury is not affected by DMSO but is induced by cell aggregation, which requires extracellular calcium. Expression of Brachyury is also induced by various members of the TGF beta family such as activin and bone morphogenetic proteins. D3 is a mutant clone of P19 cells selected for its failure to differentiate when aggregated in DMSO. Aggregated D3 cells express Brachyury mRNA suggesting that the mutation(s) responsible for the phenotype of D3 cells is downstream of the chain of events initiated by Brachyury expression.

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