Six3-mediated auto repression and eye development requires its interaction with members of the Groucho-related family of co-repressors

Development ◽  
2002 ◽  
Vol 129 (12) ◽  
pp. 2835-2849 ◽  
Author(s):  
Changqi C. Zhu ◽  
Michael A. Dyer ◽  
Masanori Uchikawa ◽  
Hisato Kondoh ◽  
Oleg V. Lagutin ◽  
...  
Keyword(s):  
Gene Family ◽  
Molecular Mechanisms ◽  
Eye Development ◽  
System Development ◽  
Biological Significance ◽  
Wild Type ◽  
In Ovo ◽  
Retroviral Infection ◽  
Vertebrate Eye

Recent findings suggest that Six3, a member of the evolutionarily conserved So/Six homeodomain family, plays an important role in vertebrate visual system development. However, little is known about the molecular mechanisms by which this function is accomplished. Although several members of the So/Six gene family interact with members of the eyes absent (Eya) gene family and function as transcriptional activators, Six3 does not interact with any known member of the Eya family. Here, we report that Grg4 and Grg5, mouse counterparts of the Drosophila transcriptional co-repressor Groucho, interact with mouse Six3 and its closely related member Six6, which may also be involved in vertebrate eye development. The specificity of the interaction was validated by co-immunoprecipitation of Six3 and Grg4 complexes from cell lines. We also show that the interaction between Six3 and Grg5 requires the Q domain of Grg5 and a conserved phenylalanine residue present in an eh1-like motif located in the Six domain of Six3. The pattern of Grg5 expression in the mouse ventral forebrain and developing optic vesicles overlapped that previously reported for Six3 and Six6. Using PCR, we identified a specific DNA motif that is bound by Six3 and we demonstrated that Six3 acts as a potent transcriptional repressor upon its interaction with Groucho-related members. We also demonstrated that this interaction is required for Six3 auto repression. The biological significance of this interaction in the retina and lens was assessed by overexpression experiments using either wild type full-length Six3 cDNA or a mutated form of this gene in which the interaction with Groucho proteins was disrupted. Overexpression of wild type Six3 by in vivo retroviral infection of newborn rat retinae led to an altered photoreceptor phenotype, while the in ovo electroporation of chicken embryos resulted in failure of lens placode invagination and production of δ-crystallin-negative cells within the placode. These specific alterations were not seen when the mutated form of Six3 cDNA was used in similar experimental approaches, indicating that Six3 interaction with Groucho proteins plays an essential role in vertebrate eye development.

Engrailed defines the position of dorsal di-mesencephalic boundary by repressing diencephalic fate

Development ◽  
1999 ◽  
Vol 126 (22) ◽  
pp. 5127-5135 ◽  
Author(s):  
I. Araki ◽  
H. Nakamura
Keyword(s):  
Molecular Mechanisms ◽  
Chimeric Protein ◽  
Negative Regulator ◽  
Chick Embryos ◽  
Wild Type ◽  
In Ovo ◽  
Positive Form ◽  
In Ovo Electroporation ◽  
The Brain

Regionalization of a simple neural tube is a fundamental event during the development of central nervous system. To analyze in vivo the molecular mechanisms underlying the development of mesencephalon, we ectopically expressed Engrailed, which is expressed in developing mesencephalon, in the brain of chick embryos by in ovo electroporation. Misexpression of Engrailed caused a rostral shift of the di-mesencephalic boundary, and caused transformation of dorsal diencephalon into tectum, a derivative of dorsal mesencephalon. Ectopic Engrailed rapidly repressed Pax-6, a marker for diencephalon, which preceded the induction of mesencephalon-related genes such as Pax-2, Pax-5, Fgf8, Wnt-1 and EphrinA2. In contrast, a mutant Engrailed, En-2(F51rE), bearing mutation in EH1 domain, which has been shown to interact with a co-repressor, Groucho, did not show the phenotype induced by wild-type Engrailed. Furthermore, VP16-Engrailed chimeric protein, the dominant positive form of Engrailed, caused caudal shift of di-mesencephalic boundary and ectopic Pax-6 expression in mesencephalon. These data suggest that (1) Engrailed defines the position of dorsal di-mesencephalic boundary by directly repressing diencephalic fate, and (2) Engrailed positively regulates the expression of mesencephalon-related genes by repressing the expression of their negative regulator(s).

scholarly journals Zebrafish Models of Autosomal Recessive Ataxias

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 836
Author(s):  
Ana Quelle-Regaldie ◽  
Daniel Sobrido-Cameán ◽  
Antón Barreiro-Iglesias ◽  
María Jesús Sobrido ◽  
Laura Sánchez
Keyword(s):  
Animal Models ◽  
Autosomal Recessive ◽  
Molecular Mechanisms ◽  
System Development ◽  
Rapid Development ◽  
Nervous System Development ◽  
Central Nervous System Development ◽  
Cellular Processes ◽  
Recessive Disorders

Autosomal recessive ataxias are much less well studied than autosomal dominant ataxias and there are no clearly defined systems to classify them. Autosomal recessive ataxias, which are characterized by neuronal and multisystemic features, have significant overlapping symptoms with other complex multisystemic recessive disorders. The generation of animal models of neurodegenerative disorders increases our knowledge of their cellular and molecular mechanisms and helps in the search for new therapies. Among animal models, the zebrafish, which shares 70% of its genome with humans, offer the advantages of being small in size and demonstrating rapid development, making them optimal for high throughput drug and genetic screening. Furthermore, embryo and larval transparency allows to visualize cellular processes and central nervous system development in vivo. In this review, we discuss the contributions of zebrafish models to the study of autosomal recessive ataxias characteristic phenotypes, behavior, and gene function, in addition to commenting on possible treatments found in these models. Most of the zebrafish models generated to date recapitulate the main features of recessive ataxias.

scholarly journals Shh Plays an Inhibitory Role in Cusp Patterning by Regulation of Sostdc1

2018 ◽  
Vol 98 (1) ◽  
pp. 98-106 ◽  
Author(s):  
J. Kim ◽  
Y. Ahn ◽  
D. Adasooriya ◽  
E.J. Woo ◽  
H.J. Kim ◽  
...  
Keyword(s):  
Pattern Formation ◽  
Wnt Signaling ◽  
Molecular Mechanisms ◽  
Wild Type ◽  
Shh Signaling ◽  
Shh Pathway ◽  
Inhibitory Role ◽  
Crown Shape ◽  
Cusp Formation

Crown shapes in mammalian teeth vary considerably from species to species, and morphological characters in crown shape have been used to identify species. Cusp pattern is one of the characters in crown shape. In the processes governing the formation of cusp pattern, the Shh pathway has been implicated as an important player. Suppression of Shh signaling activity in vitro in explant assays appears to induce supernumerary cusp formation in wild-type tooth germs. However, the in vivo role of Shh signaling in cusp pattern formation and the molecular mechanisms by which Shh regulates cusp patterning are not clear. Here, through in vivo phenotypic analyses of mice in which Shh activity was suppressed and compared with wild-type mice, we characterized differences in the location, number, incidence, and shape of supernumerary cusps in molars at embryonic day 15.5. We found that the distances between cusps were reduced in molars of Shh activity–suppressed mice in vivo. These findings confirm and extend the previous idea that Shh acts as an inhibitor in the reaction-diffusion model for cusp pattern formation by negatively regulating the intercuspal distance. We uncovered a significant reduction of expression level of Sostdc1, which encodes a secreted modulator of Wnt signaling, after suppression of Shh activity. The supernumerary cusp formation in Sostdc1−/− mice and compound Sostdc1 and Lrp mutant mice indicates a strong association between Wnt and Shh signaling pathways in cusp patterning. In further support of this idea, there is a high degree of similarity in the supernumerary cusp patterns of mice lacking Sostdc1 or Shh at embryonic day 15.5. These results suggest that Shh plays an inhibitory role in cusp pattern formation by modulating Wnt signaling through the positive regulation of Sostdc1.

scholarly journals The PAXFOXO1s trigger fast trans-differentiation of chick embryonic neural cells into alveolar rhabdomyosarcoma with tissue invasive properties limited by S phase entry inhibition

2020 ◽  
Author(s):  
Gloria Gonzalez Curto ◽  
Audrey Der Vartanian ◽  
Youcef Frarma ◽  
Line Manceau ◽  
Lorenzo Baldi ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Alveolar Rhabdomyosarcoma ◽  
Neural Cells ◽  
Wild Type ◽  
In Ovo ◽  
Driver Genes ◽  
Chromosome Translocations ◽  
Neural Origin ◽  
Cell Cycle Inhibition

AbstractThe chromosome translocations generating PAX3FOXO1 and PAX7FOXO1 chimeric proteins are the primary hallmarks of the paediatric cancer, Alveolar Rhabdomyosarcoma (ARMS). Despite the ability of these transcription factors to remodel chromatin landscapes and promote the expression of tumour driver genes, they only inefficiently promote malignant transformation in vivo. The reason for this is unclear. To address this, we developed an in ovo model to follow the response of spinal cord progenitors to PAXFOXO1s. Our data demonstrate that PAXFOXO1s, but not wild-type PAX3 and PAX7, trigger the trans-differentiation of neural cells into ARMS-like cells with myogenic characteristics. In parallel expression of PAXFOXO1s remodels the neural pseudo-stratified epithelium into a cohesive mesenchyme capable of tissue invasion. Surprisingly, gain for PAXFOXO1s, as for wild-type PAX3/7, reduces the levels of CDK-CYCLIN activity and arrests cells in G1. Introduction of CYCLIN D1 or MYCN overcomes PAXFOXO1s mediated cell cycle inhibition and promotes tumour growth. Together, our findings reveal a mechanism underpinning the apparent limited oncogenicity of PAXFOXO1 fusion transcription factors and support a neural origin for ARMS.

scholarly journals Linc00426 accelerates lung adenocarcinoma progression by regulating miR-455-5p as a molecular sponge

2020 ◽  
Vol 11 (12) ◽  
Author(s):  
Hongli Li ◽  
Qingjie Mu ◽  
Guoxin Zhang ◽  
Zhixin Shen ◽  
Yuanyuan Zhang ◽  
...  
Keyword(s):  
Lung Adenocarcinoma ◽  
Molecular Mechanisms ◽  
Epithelial Mesenchymal Transition ◽  
Ectopic Expression ◽  
Tumor Development ◽  
Biological Significance ◽  
Mesenchymal Transition

AbstractIncreasing lines of evidence indicate the role of long non-coding RNAs (LncRNAs) in gene regulation and tumor development. Hence, it is important to elucidate the mechanisms of LncRNAs underlying the proliferation, metastasis, and invasion of lung adenocarcinoma (LUAD). We employed microarrays to screen LncRNAs in LUAD tissues with and without lymph node metastasis and revealed their effects on LUAD. Among them, Linc00426 was selected for further exploration in its expression, the biological significance, and the underlying molecular mechanisms. Linc00426 exhibits ectopic expression in LUAD tissues and cells. The ectopic expression has been clinically linked to tumor size, lymphatic metastasis, and tumor differentiation of patients with LUAD. The deregulation of Linc00426 contributes to a notable impairment in proliferation, invasion, metastasis, and epithelial–mesenchymal transition (EMT) in vitro and in vivo. Mechanistically, the deregulation of Linc00426 could reduce cytoskeleton rearrangement and matrix metalloproteinase expression. Meanwhile, decreasing the level of Linc00426 or increasing miR-455-5p could down-regulate the level of UBE2V1. Thus, Linc00426 may act as a competing endogenous RNA (ceRNA) to abate miR-455-5p-dependent UBE2V1 reduction. We conclude that Linc00426 accelerates LUAD progression by acting as a molecular sponge to regulate miR-455-5p, and may be a potential novel tumor marker for LUAD.

Identification of an octamer element required for in vivo expression of the TIE1 gene in endothelial cells

2001 ◽  
Vol 360 (1) ◽  
pp. 23-29 ◽  
Author(s):  
Stephane C. BOUTET ◽  
Thomas QUERTERMOUS ◽  
Bahaa M. FADEL
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Molecular Mechanisms ◽  
Vascular Development ◽  
Common Mechanism ◽  
Tyrosine Kinase Receptor ◽  
Wild Type ◽  
Binding Studies ◽  
In Vivo Expression

TIE1, an endothelial-cell-specific tyrosine kinase receptor, is required for the survival and growth of microvascular endothelial cells during the capillary sprouting phase of vascular development. To investigate the molecular mechanisms that regulate the expression of TIE1 in the endothelium, we analysed transgenic mouse embryos carrying wild-type or mutant TIE1 promoter/LacZ constructs. Our data indicate that an upstream DNA octamer element (5′-ATGCAAAT-3′) is required for the in vivo expression of TIE1 in embryonic endothelial cells. Transgenic embryos carrying the wild-type TIE1 promoter (−466 to +78bp) fused to LacZ and spanning the octamer element demonstrate endothelial-cell-specific expression of the reporter transgene. Point mutations introduced within the octamer element result in a significant decrease of endothelial LacZ expression, suggesting that the octamer site functions as a positive regulator for TIE1 gene expression in endothelial cells. DNA–protein binding studies show that the octamer element exhibits an endothelial-cell-specific pattern of binding via interaction with endothelial-cell-restricted factor(s). Our findings suggest an important role for the octamer element in regulating the expression of the TIE1 receptor in the embryonic endothelium and suggest a common mechanism for the regulation of the angiogenic and cell-specific TIE1 and TIE2 genes during vascular development.

scholarly journals Proteoglycans in host–pathogen interactions: molecular mechanisms and therapeutic implications

2010 ◽  
Vol 12 ◽  
Author(s):  
Allison H. Bartlett ◽  
Pyong Woo Park
Keyword(s):  
Cell Surface ◽  
Virulence Factors ◽  
Molecular Mechanisms ◽  
Biological Significance ◽  
Host Cells ◽  
Microbial Pathogens ◽  
Therapeutic Implications ◽  
Core Proteins

Many microbial pathogens subvert proteoglycans for their adhesion to host tissues, invasion of host cells, infection of neighbouring cells, dissemination into the systemic circulation, and evasion of host defence mechanisms. Where studied, specific virulence factors mediate these proteoglycan–pathogen interactions, which are thus thought to affect the onset, progression and outcome of infection. Proteoglycans are composites of glycosaminoglycan (GAG) chains attached covalently to specific core proteins. Proteoglycans are expressed ubiquitously on the cell surface, in intracellular compartments, and in the extracellular matrix. GAGs mediate the majority of ligand-binding activities of proteoglycans, and many microbial pathogens elaborate cell-surface and secreted factors that interact with GAGs. Some pathogens also modulate the expression and function of proteoglycans through known virulence factors. Several GAG-binding pathogens can no longer attach to and invade host cells whose GAG expression has been reduced by mutagenesis or enzymatic treatment. Furthermore, GAG antagonists have been shown to inhibit microbial attachment and host cell entry in vitro and reduce virulence in vivo. Together, these observations underscore the biological significance of proteoglycan–pathogen interactions in infectious diseases.

scholarly journals Decoding molecular markers and transcriptional circuitry of naive and primed states of human pluripotency

2020 ◽  
Author(s):  
Arindam Ghosh ◽  
Anup Som
Keyword(s):  
Transcription Factors ◽  
Molecular Mechanisms ◽  
System Development ◽  
Enrichment Analysis ◽  
Pathway Enrichment Analysis ◽  
List Type ◽  
Metabolic Processes ◽  
Primed State

ABSTRACTPluripotent stem cells (PSCs) have been observed to occur in two distinct states — naive and primed. Both naive and primed state PSCs can give rise to tissues of all the three germ layers in vitro but differ in their potential to generate germline chimera in vivo. Understanding the molecular mechanisms that govern these two states of pluripotency in human can open up a plethora of opportunities for studying early embryonic development and in biomedical applications. In this work, we use weighted gene co-expression network (WGCN) approach to identify the key molecular makers and their interactions that define the two distinct pluripotency states. Signed-hybrid WGCN was reconstructed from transcriptomic data (RNA-seq) of naive and primed state pluripotent samples. Our analysis revealed two sets of genes that are involved in establishment and maintenance of naive (4791 genes) and primed (5066 genes) states. The naive state genes were found to be enriched for biological processes and pathways related to metabolic processes while primed state genes were associated with system development. Further, we identified the top 10% genes by intra-modular connectivity as hubs and the hub transcription factors for each group, thus providing a three-tier list of genes associated with naive and primed states of pluripotency in human.HIGHLIGHTSWeighted gene co-expression network analysis (WGCNA) identified 4791 and 5066 genes to be involved in naive and primed states of human pluripotency respectively.Functional and pathway enrichment analysis revealed the naive genes were mostly related to metabolic processes and primed genes to system development.The top 10% genes based on intra-modular connectivity from each group were defined as hubs.Identified 52 and 33 transcription factors among the naive and primed module hubs respectively.The transcription factors might play a switch on-off mechanism in induction of the two pluripotent states.

Expression Of Mutant Spliceosomal Protein SF3B1 Results In Dysregulated Hematopoietic Maturation

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2773-2773
Author(s):  
Alexander C. Minella ◽  
Oscar Ramirez ◽  
Yanfei Xu ◽  
Tushar Murthy ◽  
Xiaodong Yang ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Conflicts Of Interest ◽  
Erythroid Differentiation ◽  
Retroviral Vectors ◽  
Peptide Sequence ◽  
Causative Role ◽  
Wild Type ◽  
Erythroid Maturation

Abstract Whole genome sequencing has recently revealed the prevalence of mutations in proteins directing splicing of RNA in up to half of the patients with Myelodysplastic Syndrome (MDS). Mutations in the protein SF3B1 are particularly common in MDS patients with the phenotypic abnormality termed ring sideroblasts (dysplastic erythroid precursors with perinculear rings formed by iron-laden mitochondria). The most common SF3B1 mutation in MDS patients results in a change from lysine to glutamic acid at amino acid position 700 (K700E). Given that splicing of RNA is a ubiquitous phenomenon, it is unclear how these mutations result in clonal proliferation and dysplastic hematopoiesis; two hallmark features of MDS. Furthermore, direct experimental evidence demonstrating a causative role for SF3B1 mutations in MDS-related phenotypes is lacking. To better understand how mutations of spliceosomal proteins contribute to MDS pathogenesis, we sought to define how expression of mutant SF3B1 changes erythroid maturation in vitro and in vivo. Native SF3B1 cDNA constructs are not amenable to bacterial propagation due to toxicity of its HEAT-domain repeats. We overcame this problem by codon optimization (changing the DNA sequence while preserving the native peptide sequence). Human cord blood derived CD34+ cells were transduced with retroviral vectors to express either the wild-type or K700E mutant of SF3B1. After a week of expansion in cytokines (IL-3, SCF and IL6), cells were induced to erythroid differentiation by addition of erythropoietin (EPO) and analyzed for surface markers of erythroid differentiation (CD 71, CD117, CD105, CD45 and CD235A) at regular intervals. K700E mutant expressing cells were found to have significantly reduced expression of CD105 when compared to wild-type SF3B1-expressing cells (average 50% recuction, n =8). CD105 or endoglin is a TGF-beta receptor accessory receptor expressed at high levels during intermediate stages of erythroid maturation. A more modest reduction of CD71 expression was also noted in K700E-SF3B1 cells. MDS bone marrow is known to express low levels of both CD105 and CD71 making our results clinically relevant. To further characterize how mutant SF3B1 may cause dysplastic hematopoiesis, we studied transduced and transplanted murine progenitor cells in vivo and in colony forming assays. Murine data demonstrate significantly reduced K700E-transduced hematopoietic progenitors (as defined by flow-cytometry) in vivo and impaired erythroid colony formation in vitro. Together, our results suggest that enforced expression of K700E-SF3B1 induces aberrant erythroid maturation and impairs homeostasis of hematopoietic precursor cells. Thus, we provide direct evidence that MDS-associated SF3B1 mutations perturb normal hematopoiesis and offer rationale for using our complementary experimental approach as a platform for elucidating the molecular mechanisms through which mutations in RNA splicing factors promote hematologic disease. Disclosures: No relevant conflicts of interest to declare.

The Ets-1 transcription factor is required for Stat1-mediated T-bet expression and IgG2a class switching in mouse B cells

Blood ◽  
2012 ◽  
Vol 119 (18) ◽  
pp. 4174-4181 ◽  
Author(s):  
Hai Vu Nguyen ◽  
Enguerran Mouly ◽  
Karine Chemin ◽  
Romain Luinaud ◽  
Raymonde Despres ◽  
...  
Keyword(s):  
Transcription Factor ◽  
B Cells ◽  
Molecular Mechanisms ◽  
Wild Type ◽  
Transcriptional Enhancer ◽  
T Box ◽  
Class Switch ◽  
Ifn Γ

Abstract In response to antigens and cytokines, mouse B cells undergo class-switch recombination (CSR) and differentiate into Ig-secreting cells. T-bet, a T-box transcription factor that is up-regulated in lymphocytes by IFN-γ or IL-27, was shown to regulate CSR to IgG2a after T cell–independent B-cell stimulations. However, the molecular mechanisms controlling this process remain unclear. In the present study, we show that inactivation of the Ets-1 transcription factor results in a severe decrease in IgG2a secretion in vivo and in vitro. No T-bet expression was observed in Ets-1–deficient (Ets-1−/−) B cells stimulated with IFN-γ and lipopolysaccharide, and forced expression of T-bet in these cells rescued IgG2a secretion. Furthermore, we identified a transcriptional enhancer in the T-bet locus with an activity in B cells that relies on ETS-binding sites. After IFN-γ stimulation of Ets-1−/− B cells, activated Stat1, which forms a complex with Ets-1 in wild-type cells, no longer binds to the T-bet enhancer or promotes histone modifications at this site. These results demonstrate that Ets-1 is critical for IgG2a CSR and acts as an essential cofactor for Stat1 in the regulation of T-bet expression in B cells.

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