scholarly journals Redundant and additive functions of the four Lef/Tcf transcription factors in lung epithelial progenitors

2020 ◽  
Vol 117 (22) ◽  
pp. 12182-12191 ◽  
Author(s):  
Kamryn N. Gerner-Mauro ◽  
Haruhiko Akiyama ◽  
Jichao Chen
Keyword(s):  
Transcription Factors ◽  
Purifying Selection ◽  
Mouse Lung ◽  
Cell Type ◽  
Genetic Redundancy ◽  
Specific Expression ◽  
Complex Genetics ◽  
Lung Epithelial ◽  
And Function

In multicellular organisms, paralogs from gene duplication survive purifying selection by evolving tissue-specific expression and function. Whether this genetic redundancy is also selected for within a single cell type is unclear for multimember paralogs, as exemplified by the four obligatory Lef/Tcf transcription factors of canonical Wnt signaling, mainly due to the complex genetics involved. Using the developing mouse lung as a model system, we generate two quadruple conditional knockouts, four triple mutants, and various combinations of double mutants, showing that the four Lef/Tcf genes function redundantly in the presence of at least two Lef/Tcf paralogs, but additively upon losing additional paralogs to specify and maintain lung epithelial progenitors. Prelung-specification, pan-epithelial double knockouts have no lung phenotype; triple knockouts have varying phenotypes, including defective branching and tracheoesophageal fistulas; and the quadruple knockout barely forms a lung, resembling theCtnnb1mutant. Postlung-specification deletion of all four Lef/Tcf genes leads to branching defects, down-regulation of progenitor genes, premature alveolar differentiation, and derepression of gastrointestinal genes, again phenocopying the correspondingCtnnb1mutant. Our study supports a monotonic, positive signaling relationship between CTNNB1 and Lef/Tcf in lung epithelial progenitors as opposed to reported repressor functions of Lef/Tcf, and represents a thorough in vivo analysis of cell-type-specific genetic redundancy among the four Lef/Tcf paralogs.

scholarly journals Redundant and additive functions of the four Lef/Tcf transcription factors in lung epithelial progenitors

2020 ◽  
Author(s):  
Kamryn N. Gerner-Mauro ◽  
Haruhiko Akiyama ◽  
Jichao Chen
Keyword(s):  
Transcription Factors ◽  
Purifying Selection ◽  
Cell Type ◽  
Genetic Redundancy ◽  
Specific Expression ◽  
Lung Epithelial ◽  
Single Cell Type ◽  
Canonical Wnt ◽  
Multicellular Organisms

ABSTRACTIn multicellular organisms, paralogs from gene duplication survive purifying selection by evolving tissue-specific expression and function. Whether this genetic redundancy is also selected for within a single cell type is unclear for multi-member paralogs, as exemplified by the 4 obligatory Lef/Tcf transcription factors of canonical Wnt signaling, mainly due to the dauntingly complex genetics involved. Using the developing mouse lung as a model system, we generate 2 quadruple conditional knockouts and myriad triple and double combinations, and show that the 4 Lef/Tcf genes function redundantly in the presence of at least 2 Lef/Tcf paralogs, but additively upon losing additional paralogs to specify and maintain lung epithelial progenitors. Pre-lung-specification, pan-epithelial double knockouts have no lung phenotype, triple knockouts have varying phenotypes, including defective branching and tracheoesophageal fistulas, and the quadruple knockout barely forms a lung, resembling the Ctnnb1 mutant. Post-lung-specification deletion of all 4 Lef/Tcf genes leads to branching defects, downregulation of progenitor genes, premature alveolar differentiation, and derepression of gastrointestinal genes, again phenocopying the corresponding Ctnnb1 mutant. Our study supports a monotonic, positive signaling relationship between CTNNB1 and Lef/Tcf in lung epithelial progenitors and represents, to our knowledge, the first in vivo analysis of cell-type-specific genetic redundancy among the 4 Lef/Tcf paralogs.SIGNIFICANCE STATEMENTParalogs represent genetic redundancy and survive purifying selection by evolving overlapping and distinct functions. In multicellular organisms, such functional diversification can manifest as tissue and cell type specific expression, which masks possible selective pressure for genetic redundancy within a single cell type. Using in vivo genetic and genomic analyses, we show that although the 4 mammalian Lef/Tcf transcription factors have evolved organ-specific functions, they function additively and redundantly, depending on gene dosage, to promote lung epithelial progenitors and do so in a monotonic, positive manner with beta-Catenin in the canonical Wnt signaling pathway.

scholarly journals Cell type- and stage-specific expression of Otx2 is regulated by multiple transcription factors and cis-regulatory modules in the retina

Development ◽  
2020 ◽  
Vol 147 (14) ◽  
pp. dev187922 ◽  
Author(s):  
Candace S. Y. Chan ◽  
Nicolas Lonfat ◽  
Rong Zhao ◽  
Alexander E. Davis ◽  
Liang Li ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Expression Patterns ◽  
Cell Types ◽  
Retinal Cell ◽  
Mouse Retina ◽  
Cell Type ◽  
Specific Expression ◽  
Regulatory Modules ◽  
A Cell

ABSTRACTTranscription factors (TFs) are often used repeatedly during development and homeostasis to control distinct processes in the same and/or different cellular contexts. Considering the limited number of TFs in the genome and the tremendous number of events that need to be regulated, re-use of TFs is necessary. We analyzed how the expression of the homeobox TF, orthodenticle homeobox 2 (Otx2), is regulated in a cell type- and stage-specific manner during development in the mouse retina. We identified seven Otx2 cis-regulatory modules (CRMs), among which the O5, O7 and O9 CRMs mark three distinct cellular contexts of Otx2 expression. We discovered that Otx2, Crx and Sox2, which are well-known TFs regulating retinal development, bind to and activate the O5, O7 or O9 CRMs, respectively. The chromatin status of these three CRMs was found to be distinct in vivo in different retinal cell types and at different stages. We conclude that retinal cells use a cohort of TFs with different expression patterns and multiple CRMs with different chromatin configurations to regulate the expression of Otx2 precisely.

scholarly journals Cell type- and stage-specific expression of Otx2 is coordinated by a cohort of transcription factors and multiple cis-regulatory modules in the retina

2019 ◽  
Author(s):  
Candace Chan ◽  
Nicolas Lonfat ◽  
Rong Zhao ◽  
Alexander Davis ◽  
Liang Li ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Expression Patterns ◽  
Cell Types ◽  
Retinal Cell ◽  
Cell Type ◽  
Specific Expression ◽  
Regulatory Modules ◽  
Specific Manner ◽  
A Cell

AbstractTranscription factors (TFs) are often used repeatedly during development and homeostasis to control distinct processes in the same and/or different cellular contexts. Considering the limited number of TFs in the genome and the tremendous number of events that need to be regulated, re-use of TFs is an advantageous strategy. However, the mechanisms that control the activation of TFs in different cell types and at different stages of development remain unclear. The neural retina serves as a model of the development of a complex tissue. We used this system to analyze how expression of the homeobox TF, Orthodenticle homeobox 2 (Otx2), is regulated in a cell type- and stage-specific manner during retinogenesis. We identified seven Otx2 cis-regulatory modules (CRMs), among which the O5, O7 and O9 CRMs mark three distinct cellular contexts of Otx2 expression. These include mature bipolar interneurons, photoreceptors, and retinal progenitor/precursor cells. We discovered that Otx2, Crx and Sox2, which are well-known TFs regulating retinal development, bind to and activate the O5, O7 or O9 CRMs respectively. The chromatin status of these three CRMs was found to be distinct in vivo in different retinal cell types and at different stages, as revealed by ATAC-seq and DNase-seq analyses. We conclude that retinal cells utilize a cohort of TFs with different expression patterns, and multiple CRMs with different chromatin configurations, to precisely regulate the expression of Otx2 in a cell type- and stage-specific manner in the retina.

scholarly journals Profound functional and molecular diversity of mitochondria revealed by cell type-specific profiling in vivo

2018 ◽  
Author(s):  
Caroline Fecher ◽  
Laura Trovò ◽  
Stephan A. Müller ◽  
Nicolas Snaidero ◽  
Jennifer Wettmarshausen ◽  
...  
Keyword(s):  
Molecular Diversity ◽  
Molecular Level ◽  
Cell Types ◽  
Long Chain Fatty Acids ◽  
Cell Type ◽  
Mitochondrial Proteome ◽  
Novel Approach ◽  
Cell Type Specific ◽  
And Function

AbstractMitochondria vary in morphology and function in different tissues, however little is known about their molecular diversity among cell types. To investigate mitochondrial diversity in vivo, we developed an efficient protocol to isolate cell type-specific mitochondria based on a new MitoTag mouse. We profiled the mitochondrial proteome of three major neural cell types in cerebellum and identified a substantial number of differential mitochondrial markers for these cell types in mice and humans. Based on predictions from these proteomes, we demonstrate that astrocytic mitochondria metabolize long-chain fatty acids more efficiently than neurons. Moreover, we identified Rmdn3 as a major determinant of ER-mitochondria proximity in Purkinje cells. Our novel approach enables exploring mitochondrial diversity on the functional and molecular level in many in vivo contexts.

Isoform-specific expression and function of neuregulin

Development ◽  
1997 ◽  
Vol 124 (18) ◽  
pp. 3575-3586 ◽  
Author(s):  
D. Meyer ◽  
T. Yamaai ◽  
A. Garratt ◽  
E. Riethmacher-Sonnenberg ◽  
D. Kane ◽  
...  
Keyword(s):  
Biological Effects ◽  
Type I ◽  
Mouse Development ◽  
Specific Expression ◽  
Independent Functions ◽  
Cell Growth And Differentiation ◽  
Cranial Ganglia ◽  
And Function

Neuregulin (also known as NDF, heregulin, ARIA, GGF or SMDF), induces cell growth and differentiation. Biological effects of neuregulin are mediated by members of the erbB family of tyrosine kinase receptors. Three major neuregulin isoforms are produced from the gene, which differ substantially in sequence and in overall structure. Here we use in situ hybridization with isoform-specific probes to illustrate the spatially distinct patterns of expression of the isoforms during mouse development. Ablation of the neuregulin gene in the mouse has demonstrated multiple and independent functions of this factor in development of both the nervous system and the heart. We show here that targeted mutations that affect different isoforms result in distinct phenotypes, demonstrating that isoforms can take over specific functions in vivo. Type I neuregulin is required for generation of neural crest-derived neurons in cranial ganglia and for trabeculation of the heart ventricle, whereas type III neuregulin plays an important role in the early development of Schwann cells. The complexity of neuregulin functions in development is therefore due to independent roles played by distinct isoforms.

Glucose-induced transcription of the insulin gene is mediated by factors required for beta-cell-type-specific expression

1994 ◽  
Vol 14 (2) ◽  
pp. 871-879
Author(s):  
A Sharma ◽  
R Stein
Keyword(s):  
Beta Cell ◽  
Insulin Gene ◽  
Control Element ◽  
Cell Type ◽  
Specific Expression ◽  
Cis Acting ◽  
Cell Extracts ◽  
Cell Type Specific Expression ◽  
Cell Type Specific

The insulin gene is expressed exclusively in pancreatic islet beta cells. The principal regulator of insulin gene transcription in the islet is the concentration of circulating glucose. Previous studies have demonstrated that transcription is regulated by the binding of trans-acting factors to specific cis-acting sequences within the 5'-flanking region of the insulin gene. To identify the cis-acting control elements within the rat insulin II gene that are responsible for regulating glucose-stimulated expression in the beta cell, we analyzed the effect of glucose on the in vivo expression of a series of transfected 5'-flanking deletion mutant constructs. We demonstrate that glucose-induced transcription of the rat insulin II gene is mediated by sequences located between -126 and -91 bp relative to the transcription start site. This region contains two cis-acting elements that are essential for directing pancreatic beta-cell-type-specific expression of the rat insulin II gene, the insulin control element (ICE; -100 to -91 bp) and RIPE3b1 (-115 to -107 bp). The gel mobility shift assay was used to determine whether the formation of the ICE- and RIPE3b1-specific factor-DNA element complexes were affected in glucose-treated beta-cell extracts. We found that RIPE3b1 binding activity was selectively induced by about eightfold. In contrast, binding to other insulin cis-acting element sequences like the ICE and RIPE3a2 (-108 to -99 bp) were unaffected by these conditions. The RIPE3b1 binding complex was shown to be distinct from the glucose-inducible factor that binds to an element located between -227 to -206 bp of the human and rat insulin I genes (D. Melloul, Y. Ben-Neriah, and E. Cerasi, Proc. Natl. Acad. Sci. USA 90:3865-3869, 1993). We have also shown that mannose, a sugar that can be metabolized by the beta cell, mimics the effects of glucose in the in vivo transfection assays and the in vitro RIPE3b1 binding assays. These results suggested that the RIPE3b1 transcription factor is a primary regulator of glucose-mediated transcription of the insulin gene. However, we found that mutations in either the ICE or the RIPE3b1 element reduced glucose-responsive expression from transfected 5'-flanking rat insulin II gene constructs. We therefore conclude that glucose-regulated transcription of the insulin gene is mediated by cis-acting elements required for beta-cell-type-specific expression.

Orchestrated biomechanical, structural, and biochemical stimuli for engineering anisotropic meniscus

2019 ◽  
Vol 11 (487) ◽  
pp. eaao0750 ◽  
Author(s):  
Zheng-Zheng Zhang ◽  
You-Rong Chen ◽  
Shao-Jie Wang ◽  
Feng Zhao ◽  
Xiao-Gang Wang ◽  
...  
Keyword(s):  
Rabbit Model ◽  
Proper Function ◽  
Type I ◽  
Specific Expression ◽  
Tissue Organization ◽  
Meniscus Tissue ◽  
Biomimetic Scaffold ◽  
And Function

Reconstruction of the anisotropic structure and proper function of the knee meniscus remains an important challenge to overcome, because the complexity of the zonal tissue organization in the meniscus has important roles in load bearing and shock absorption. Current tissue engineering solutions for meniscus reconstruction have failed to achieve and maintain the proper function in vivo because they have generated homogeneous tissues, leading to long-term joint degeneration. To address this challenge, we applied biomechanical and biochemical stimuli to mesenchymal stem cells seeded into a biomimetic scaffold to induce spatial regulation of fibrochondrocyte differentiation, resulting in physiological anisotropy in the engineered meniscus. Using a customized dynamic tension-compression loading system in conjunction with two growth factors, we induced zonal, layer-specific expression of type I and type II collagens with similar structure and function to those present in the native meniscus tissue. Engineered meniscus demonstrated long-term chondroprotection of the knee joint in a rabbit model. This study simultaneously applied biomechanical, biochemical, and structural cues to achieve anisotropic reconstruction of the meniscus, demonstrating the utility of anisotropic engineered meniscus for long-term knee chondroprotection in vivo.

NF-κB Transcription Factors Are Involved in Normal Erythropoiesis

Blood ◽  
1998 ◽  
Vol 91 (11) ◽  
pp. 4136-4144 ◽  
Author(s):  
Min-Ying Zhang ◽  
Shao-Cong Sun ◽  
Laurie Bell ◽  
Barbara A. Miller
Keyword(s):  
Transcription Factors ◽  
Nuclear Translocation ◽  
Luciferase Reporter ◽  
Erythroid Cells ◽  
Gm Csf ◽  
Luciferase Reporter Plasmid ◽  
Nuclear Extracts ◽  
Nuclear Levels ◽  
And Function

Abstract NF-κB/Rel designates a widely distributed family of transcription factors involved in immune and acute phase responses. Here, the expression and function of NF-κB factors in erythroid proliferation and differentiation were explored. In an erythroleukemia cell line, TF-1, high levels of p105/p50, p100/p52, p65, and IκBα were detected 24 hours after growth factor deprivation. In response to granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulation, significant induction of p52 expression was observed. GM-CSF also induced nuclear translocation of both p52 and p65. No induction of NF-κB factors was observed with erythropoietin stimulation of TF-1 cells. Overexpression of p52 and p65 in TF-1 cells by transient transfection resulted in significant induction of a κB-TATA-luciferase reporter plasmid, showing that these factors are functional in vivo in erythroid cells. To determine whether NF-κB factors may play a role in normal erythropoiesis, levels of these factors were determined in burst-forming unit-erythroid (BFU-E)–derived cells at different stages of differentiation. The NF-κB factors p105/p50, p100/p52, and p65 were highly expressed in early BFU-E–derived precursors, which are rapidly proliferating, and declined during maturation. Furthermore, nuclear levels of NF-κB factors p50, p52, and p65 were higher in less mature precursors (day 10 BFU-E–derived cells) compared with more differentiated (day 14) erythroblasts. In nuclear extracts from day 10 BFU-E–derived cells, p50, p52, and p65 were able to form complexes, which bound to κB sites in the promoters of both the c-myb and c-mycgenes, suggesting that c-myb and c-myc may be among the κB-containing genes regulated by NF-κB factors in normal erythroid cells. Taken together, these data show that NF-κB factors are modulated by GM-CSF and suggest they function to regulate specific κB containing genes involved in erythropoiesis.

scholarly journals Regulation of Transcription Factors and Repression of Sp1 by Prolactin Signaling Through the Short Isoform of Its Cognate Receptor

Endocrinology ◽  
2009 ◽  
Vol 150 (7) ◽  
pp. 3327-3335 ◽  
Author(s):  
Y. Sangeeta Devi ◽  
Aurora Shehu ◽  
Carlos Stocco ◽  
Julia Halperin ◽  
Jamie Le ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Signaling Pathway ◽  
Short Form ◽  
Binding Activity ◽  
In Vivo Model ◽  
Regulation Of Transcription ◽  
Signaling Mechanism ◽  
Dna Binding Activity ◽  
And Function

Prolactin (PRL) affects the development and function of the reproductive system by binding to two types of receptors, which differ by the size of their intracellular domain in rodents. Whereas the signaling pathway through the long form of the receptor (PRL-RL) is well characterized, signaling through the short form (PRL-RS) remains obscure. In this investigation, we examined transcription factors regulated by PRL in the ovary and decidua of mice expressing only PRL-RS in a PRL receptor null background. These mice provide a powerful in vivo model to study the selective signaling mechanism of PRL through PRL-RS independent of PRL-RL. We also examined the regulation of transcription factors in ovarian and uterine cell lines stably transfected with PRL-RS or PRL-RL. We focused our investigation on transcription factors similarly regulated in both these tissues and clearly established that signaling through PRL-RS does not activate the JaK/Stat in vivo but leads to severe down-regulation of Sp1 expression, DNA binding activity, and nuclear localization, events that appear to involve the calmodulin-dependent protein kinase pathway. Our in vivo and in culture data demonstrate that the PRL-RS activates a signaling pathway distinct from that of the PRL-RL.

Hypoxia results in an HIF-1-dependent induction of brain-specific aldolase C in lung epithelial cells

2006 ◽  
Vol 291 (5) ◽  
pp. L950-L956 ◽  
Author(s):  
Jyh-Chang Jean ◽  
Celeste B. Rich ◽  
Martin Joyce-Brady
Keyword(s):  
Hypoxia Inducible Factor ◽  
Fetal Lung ◽  
Lung Epithelial Cells ◽  
Mouse Lung ◽  
Developmentally Regulated ◽  
Specific Expression ◽  
Aldolase C ◽  
Expression Studies ◽  
Lung Epithelial ◽  
Responsive Element

Aldolase C (EC 4.1.2.13 ) is a brain-specific aldolase isoform and a putative target of the transcription factor hypoxia-inducible factor (HIF)-1. We identified aldolase C as a candidate hypoxia-regulated gene in mouse lung epithelial (MLE) cells using differential display. We show that the message accumulates in a robust fashion when MLE cells are exposed to 1% oxygen and is inversely related to oxygen content. Induction in hypoxia is dependent on protein synthesis. We localized a hypoxia-responsive element (HRE) in the aldolase C promoter using a series of deletion and heterologous expression studies. The HRE overlaps with a region of the proximal aldolase C promoter that is also related to its brain-specific expression. The HRE contains an Arnt (HIF-1β) and an HIF-1α site. We show that induction in hypoxia is dependent on the HIF-1 site and that HIF-1α protein is present, by gel-shift assay, within nuclear complexes of MLE cells in hypoxia. Aldolase C mRNA expression is developmentally regulated in the fetal lung, rapidly downregulated in the newborn lung at birth, and inducible in the adult lung when exposed to hypoxia. This pattern of regulation is not seen in the brain. This preservation of this HRE in the promoters of four other species suggests that aldolase C may function as a stress-response gene.

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