scholarly journals The regulatory proteins DSCR6 and Ezh2 oppositely regulate Stat3 transcriptional activity in mesoderm patterning during Xenopus development

2020 ◽  
Vol 295 (9) ◽  
pp. 2724-2735
Author(s):  
Mafalda Loreti ◽  
De-Li Shi ◽  
Clémence Carron
Keyword(s):  
Cell Fate ◽  
Transcriptional Activity ◽  
Polycomb Group ◽  
Specific Gene ◽  
Lysine Methylation ◽  
Region Gene ◽  
Activity Increase ◽  
Dorsoventral Axis ◽  
Stat3 Phosphorylation ◽  
Mesoderm Formation

Embryonic cell fate specification and axis patterning requires integration of several signaling pathways that orchestrate region-specific gene expression. The transcription factor signal transducer and activator of transcription 3 (Stat3) plays important roles during early development, but it is unclear how Stat3 is activated. Here, using Xenopus as a model, we analyzed the post-translational regulation and functional consequences of Stat3 activation in dorsoventral axis patterning. We show that Stat3 phosphorylation, lysine methylation, and transcriptional activity increase before gastrulation and induce ventral mesoderm formation. Down syndrome critical region gene 6 (DSCR6), a RIPPLY family member that induces dorsal mesoderm by releasing repressive polycomb group proteins from chromatin, bound to the Stat3 C-terminal region and antagonized its transcriptional and ventralizing activities by interfering with its lysine methylation. Enhancer of zeste 2 polycomb-repressive complex 2 subunit (Ezh2) also bound to this region; however, its methyltransferase activity was required for Stat3 methylation and activation. Loss of Ezh2 resulted in dorsalization of ventral mesoderm and formation of a secondary axis. Furthermore, interference with Ezh2 phosphorylation also prevented Stat3 lysine methylation and transcriptional activity. Thus, inhibition of either Ezh2 phosphorylation or Stat3 lysine methylation compensated for the absence of DSCR6 function. These results reveal that DSCR6 and Ezh2 critically and post-translationally regulate Stat3 transcriptional activity. Ezh2 promotes Stat3 activation in ventral mesoderm formation independently of epigenetic regulation, whereas DSCR6 specifies dorsal fate by counteracting this ventralizing activity. This antagonism helps pattern the mesoderm along the dorsoventral axis, representing a critical facet of cell identity regulation during development.

scholarly journals Polycomb requires Tcp-1η chaperonin for maintaining gene silencing inDrosophila

2021 ◽  
Author(s):  
Najma Shaheen ◽  
Jawad Akhtar ◽  
Zain Umer ◽  
Muhammad Haider Farooq Khan ◽  
Murtaza Saleem ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Molecular Interaction ◽  
Hox Genes ◽  
Genetic Interaction ◽  
Expression Patterns ◽  
Polycomb Group ◽  
Gene Expression Patterns ◽  
Specific Gene ◽  
Cellular Memory

AbstractIn metazoans, heritable states of cell type specific gene expression patterns linked with specialization of various cell types constitute transcriptional cellular memory. Evolutionarily conserved Polycomb group (PcG) and trithorax group (trxG) proteins contribute to the transcriptional cellular memory by maintaining heritable patterns of repressed and active expression states, respectively. Although chromatin structure and modifications appear to play a fundamental role in maintenance of repression by PcG, the precise targeting mechanism and the specificity factors that bind PcG complexes to a defined region in chromosomes remain elusive. Here we report a serendipitous discovery that uncovers a direct molecular interaction between Polycomb (PC) and TCP-1 Ring Complex (TRiC) chaperonin subunit, Tcp-1η inDrosophila. Tcp-1η interacts with PC at chromatin to maintain repressed states of homeotic and non-homeotic targets of PcG, which supports a strong genetic interaction observed betweenPcandTcp-1ηmutants. Depletion of Tcp-1η results in dissociation of PC from chromatin and redistribution of an abundant amount of PC in cytoplasm. We propose that Tcp-1η is an important modulator of PC, which helps PC recruitment at chromatin and compromising Tcp-1η can directly influence an evolutionary highly conserved epigenetic network that supervises the appropriate cellular identities during development and homoeostasis of an organism.Significance StatementSilencing of key developmental genes, e.g, Hox genes, by PcG is a hallmark of differential gene expression patterns associated with cell fate determination. Here we describe a previously unknown molecular and genetic interaction of Polycomb (PC) with Tcp-1η subunit of TRiC chaperonin complex inDrosophila. Compromising Tcp-1η function results in de-repression of PcG targets and a concomitant loss of PC from chromatin. Moreover, depletion of Tcp-1η leads to redistribution of PC in cytoplasm. Molecular interaction of PC with Tcp-1η highlights a novel factor which helps PC recruitment at chromatin. We propose that Tcp-1η chaperonin is one of the specificity factors and part of the targeting mechanism that binds PC to specific regions on chromosomes.

scholarly journals Requirement for Ras/Rac1-Mediated p38 and c-Jun N-Terminal Kinase Signaling in Stat3 Transcriptional Activity Induced by the Src Oncoprotein

1999 ◽  
Vol 19 (11) ◽  
pp. 7519-7528 ◽  
Author(s):  
James Turkson ◽  
Tammy Bowman ◽  
Jalila Adnane ◽  
Yi Zhang ◽  
Julie Y. Djeu ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Signaling Pathways ◽  
Transcriptional Activity ◽  
Dominant Negative ◽  
Serine Phosphorylation ◽  
Specific Gene ◽  
Kinase Signaling ◽  
Src Tyrosine Kinase ◽  
Stat3 Phosphorylation

ABSTRACT Signal transducers and activators of transcription (STATs) are transcription factors that mediate normal biologic responses to cytokines and growth factors. However, abnormal activation of certain STAT family members, including Stat3, is increasingly associated with oncogenesis. In fibroblasts expressing the Src oncoprotein, activation of Stat3 induces specific gene expression and is required for cell transformation. Although the Src tyrosine kinase induces constitutive Stat3 phosphorylation on tyrosine, activation of Stat3-mediated gene regulation requires both tyrosine and serine phosphorylation of Stat3. We investigated the signaling pathways underlying the constitutive Stat3 activation in Src oncogenesis. Expression of Ras or Rac1 dominant negative protein blocks Stat3-mediated gene regulation induced by Src in a manner consistent with dependence on p38 and c-Jun N-terminal kinase (JNK). Both of these serine/threonine kinases and Stat3 serine phosphorylation are constitutively induced in Src-transformed fibroblasts. Furthermore, inhibition of p38 and JNK activities suppresses constitutive Stat3 serine phosphorylation and Stat3-mediated gene regulation. In vitro kinase assays with purified full-length Stat3 as the substrate show that both JNK and p38 can phosphorylate Stat3 on serine. Moreover, inhibition of p38 activity and thus of Stat3 serine phosphorylation results in suppression of transformation by v-Src but not v-Ras, consistent with a requirement for Stat3 serine phosphorylation in Src transformation. Our results demonstrate that Ras- and Rac1-mediated p38 and JNK signals are required for Stat3 transcriptional activity induced by the Src oncoprotein. These findings delineate a network of tyrosine and serine/threonine kinase signaling pathways that converge on Stat3 in the context of oncogenesis.

scholarly journals Functional Promiscuity of Gene Regulation by Serpentine Receptors in Dictyostelium discoideum

1998 ◽  
Vol 18 (10) ◽  
pp. 5744-5749 ◽  
Author(s):  
Irene Verkerke-Van Wijk ◽  
Ji-Yun Kim ◽  
Raymond Brandt ◽  
Peter N. Devreotes ◽  
Pauline Schaap
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Dictyostelium Discoideum ◽  
Developmental Regulation ◽  
Mutant Cell ◽  
Gene Induction ◽  
Specific Gene ◽  
Wild Type ◽  
Animal Development ◽  
Camp Stimulation

ABSTRACT Serpentine receptors such as smoothened and frizzled play important roles in cell fate determination during animal development. InDictyostelium discoideum, four serpentine cyclic AMP (cAMP) receptors (cARs) regulate expression of multiple classes of developmental genes. To understand their function, it is essential to know whether each cAR is coupled to a specific gene regulatory pathway or whether specificity results from the different developmental regulation of individual cARs. To distinguish between these possibilities, we measured gene induction in car1 car3 double mutant cell lines that express equal levels of either cAR1, cAR2, or cAR3 under a constitutive promoter. We found that all cARs efficiently mediate both aggregative gene induction by cAMP pulses and induction of postaggregative and prespore genes by persistent cAMP stimulation. Two exceptions to this functional promiscuity were observed. (i) Only cAR1 can mediate adenosine inhibition of cAMP-induced prespore gene expression, a phenomenon that was found earlier in wild-type cells. cAR1’s mediation of adenosine inhibition suggests that cAR1 normally mediates prespore gene induction. (ii) Only cAR2 allows entry into the prestalk pathway. Prestalk gene expression is induced by differentiation-inducing factor (DIF) but only after cells have been prestimulated with cAMP. We found that DIF-induced prestalk gene expression is 10 times higher in constitutive cAR2 expressors than in constitutive cAR1 or cAR3 expressors (which still have endogenous cAR2), suggesting that cAR2 mediates induction of DIF competence. Since in wild-type slugs cAR2 is expressed only in anterior cells, this could explain the so far puzzling observations that prestalk cells differentiate at the anterior region but that DIF levels are actually higher at the posterior region. After the initial induction of DIF competence, cAMP becomes a repressor of prestalk gene expression. This function can again be mediated by cAR1, cAR2, and cAR3.

Dimerization through the helix-loop-helix motif enhances phosphorylation of the transcription activation domains of myogenin

1994 ◽  
Vol 14 (9) ◽  
pp. 6232-6243
Author(s):  
J Zhou ◽  
E N Olson
Keyword(s):  
Transcriptional Activity ◽  
Transcription Activation ◽  
Bhlh Protein ◽  
Specific Gene ◽  
Phosphorylation Sites ◽  
Gene Products ◽  
Activation Domains ◽  
Helix Loop Helix ◽  
Carboxyl Terminal ◽  
Bhlh Proteins

The muscle-specific basic helix-loop-helix (bHLH) protein myogenin activates muscle transcription by binding to target sequences in muscle-specific promoters and enhancers as a heterodimer with ubiquitous bHLH proteins, such as the E2A gene products E12 and E47. We show that dimerization with E2A products potentiates phosphorylation of myogenin at sites within its amino- and carboxyl-terminal transcription activation domains. Phosphorylation of myogenin at these sites was mediated by the bHLH region of E2A products and was dependent on dimerization but not on DNA binding. Mutations of the dimerization-dependent phosphorylation sites resulted in enhanced transcriptional activity of myogenin, suggesting that their phosphorylation diminishes myogenin's transcriptional activity. The ability of E2A products to potentiate myogenin phosphorylation suggests that dimerization induces a conformational change in myogenin that unmasks otherwise cryptic phosphorylation sites or that E2A proteins recruit a kinase for which myogenin is a substrate. That phosphorylation of these dimerization-dependent sites diminished myogenin's transcriptional activity suggests that these sites are targets for a kinase that interferes with muscle-specific gene expression.

The Sox-domain containing geneDichaete/fish-hookacts in concert withvndandindto regulate cell fate in theDrosophilaneuroectoderm

Development ◽  
2002 ◽  
Vol 129 (5) ◽  
pp. 1165-1174 ◽  
Author(s):  
Guoyan Zhao ◽  
James B. Skeath
Keyword(s):  
Cell Fate ◽  
Nerve Cord ◽  
Double Mutant ◽  
Ventral Nerve Cord ◽  
Egf Receptor ◽  
Dorsoventral Axis ◽  
Mutant Analysis ◽  
Evolutionarily Conserved ◽  
Specific Manner ◽  
Important Regulator

In the Drosophila embryonic central nervous system, neural stem cells, called neuroblasts, acquire fates in a position-specific manner. Recent work has identified a set of genes that functions along the dorsoventral axis to enable neuroblasts that develop in different dorsoventral domains to acquire distinct fates. These genes include the evolutionarily conserved transcription factors ventral nerve cord defective and intermediate neuroblasts defective, as well as the Drosophila EGF receptor. We show that the Sox-domain-containing gene Dichaete/fish-hook also plays a crucial role to pattern the neuroectoderm along the DV axis. Dichaete is expressed in the medial and intermediate columns of the neuroectoderm, and mutant analysis indicates that Dichaete regulates cell fate and neuroblast formation in these domains. Molecular epistasis tests, double mutant analysis and dosage-sensitive interactions demonstrate that during these processes, Dichaete functions in parallel with ventral nerve cord defective and intermediate neuroblasts defective, and downstream of EGF receptor signaling to mediate its effect on development. These results identify Dichaete as an important regulator of dorsoventral pattern in the neuroectoderm, and indicate that Dichaete acts in concert with ventral nerve cord defective and intermediate neuroblasts defective to regulate pattern and cell fate in the neuroectoderm.

scholarly journals Depletion of L3MBTL1 promotes the erythroid differentiation of human hematopoietic progenitor cells: possible role in 20q− polycythemia vera

Blood ◽  
2010 ◽  
Vol 116 (15) ◽  
pp. 2812-2821 ◽  
Author(s):  
Fabiana Perna ◽  
Nadia Gurvich ◽  
Ruben Hoya-Arias ◽  
Omar Abdel-Wahab ◽  
Ross L. Levine ◽  
...  
Keyword(s):  
Polycythemia Vera ◽  
Progenitor Cells ◽  
Cell Fate ◽  
Myeloproliferative Neoplasms ◽  
Erythroid Differentiation ◽  
Polycomb Group ◽  
Human Cord Blood ◽  
Hematopoietic Stem ◽  
Cell Fate Decisions ◽  
Cd34 Cells

Abstract L3MBTL1, the human homolog of the Drosophila L(3)MBT polycomb group tumor suppressor gene, is located on chromosome 20q12, within the common deleted region identified in patients with 20q deletion-associated polycythemia vera, myelodysplastic syndrome, and acute myeloid leukemia. L3MBTL1 is expressed within hematopoietic CD34+ cells; thus, it may contribute to the pathogenesis of these disorders. To define its role in hematopoiesis, we knocked down L3MBTL1 expression in primary hematopoietic stem/progenitor (ie, CD34+) cells isolated from human cord blood (using short hairpin RNAs) and observed an enhanced commitment to and acceleration of erythroid differentiation. Consistent with this effect, overexpression of L3MBTL1 in primary hematopoietic CD34+ cells as well as in 20q− cell lines restricted erythroid differentiation. Furthermore, L3MBTL1 levels decrease during hemin-induced erythroid differentiation or erythropoietin exposure, suggesting a specific role for L3MBTL1 down-regulation in enforcing cell fate decisions toward the erythroid lineage. Indeed, L3MBTL1 knockdown enhanced the sensitivity of hematopoietic stem/progenitor cells to erythropoietin (Epo), with increased Epo-induced phosphorylation of STAT5, AKT, and MAPK as well as detectable phosphorylation in the absence of Epo. Our data suggest that haploinsufficiency of L3MBTL1 contributes to some (20q−) myeloproliferative neoplasms, especially polycythemia vera, by promoting erythroid differentiation.

scholarly journals Coronary blood vessels from distinct origins converge to equivalent states during mouse and human development

2021 ◽  
Author(s):  
Ragini S Phansalkar ◽  
Josephine Krieger ◽  
Mingming Zhao ◽  
Sai Saroja Kolluru ◽  
Robert C Jones ◽  
...  
Keyword(s):  
Blood Vessels ◽  
Cell Fate ◽  
Adult Mouse ◽  
Coronary Vessels ◽  
Lineage Tracing ◽  
Specific Gene ◽  
Cell Type ◽  
Functional Differences ◽  
Coronary Blood Vessels ◽  
Two Populations

Most cell fate trajectories during development follow a diverging, tree-like branching pattern, but the opposite can occur when distinct progenitors contribute to the same cell type. During this convergent differentiation, it is unknown if cells "remember" their origins transcriptionally or whether this influences cell behavior. Most coronary blood vessels of the heart develop from two different progenitor sources-the endocardium (Endo) and sinus venosus (SV)-but whether transcriptional or functional differences related to origin are retained is unknown. We addressed this by combining lineage tracing with single-cell RNA sequencing (scRNAseq) in embryonic and adult mouse hearts. Shortly after coronary development begins, capillary ECs transcriptionally segregated into two states that retained progenitor-specific gene expression. Later in development, when the coronary vasculature is well-established but still remodeling, capillary ECs again segregated into two populations, but transcriptional differences were related to tissue localization rather than lineage. Specifically, ECs in the heart septum expressed genes indicative of increased local hypoxia and decreased blood flow. Adult capillary ECs were more homogeneous and lacked indications of either lineage or location. In agreement, SV- and Endo-derived ECs in adult hearts displayed similar responses to injury. Finally, scRNAseq of developing human coronary vessels indicated that the human heart followed similar principles. Thus, over the course of development, transcriptional heterogeneity in coronary ECs is first influenced by lineage, then by location, until heterogeneity disappears in the homeostatic adult heart. These results highlight the plasticity of ECs during development, and the validity of the mouse as a model for human coronary development.

scholarly journals Integrative epigenomic and high-throughput functional enhancer profiling reveals determinants of enhancer heterogeneity in gastric cancer

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Taotao Sheng ◽  
Shamaine Wei Ting Ho ◽  
Wen Fong Ooi ◽  
Chang Xu ◽  
Manjie Xing ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Histone Modification ◽  
Cell Fate ◽  
Copy Number ◽  
Regulatory Region ◽  
Regulatory Elements ◽  
Specific Gene ◽  
Functional Assay ◽  
Enhancer Activity

Abstract Background Enhancers are distal cis-regulatory elements required for cell-specific gene expression and cell fate determination. In cancer, enhancer variation has been proposed as a major cause of inter-patient heterogeneity—however, most predicted enhancer regions remain to be functionally tested. Methods We analyzed 132 epigenomic histone modification profiles of 18 primary gastric cancer (GC) samples, 18 normal gastric tissues, and 28 GC cell lines using Nano-ChIP-seq technology. We applied Capture-based Self-Transcribing Active Regulatory Region sequencing (CapSTARR-seq) to assess functional enhancer activity. An Activity-by-contact (ABC) model was employed to explore the effects of histone acetylation and CapSTARR-seq levels on enhancer-promoter interactions. Results We report a comprehensive catalog of 75,730 recurrent predicted enhancers, the majority of which are GC-associated in vivo (> 50,000) and associated with lower somatic mutation rates inferred by whole-genome sequencing. Applying CapSTARR-seq to the enhancer catalog, we observed significant correlations between CapSTARR-seq functional activity and H3K27ac/H3K4me1 levels. Super-enhancer regions exhibited increased CapSTARR-seq signals compared to regular enhancers, even when decoupled from native chromatin contexture. We show that combining histone modification and CapSTARR-seq functional enhancer data improves the prediction of enhancer-promoter interactions and pinpointing of germline single nucleotide polymorphisms (SNPs), somatic copy number alterations (SCNAs), and trans-acting TFs involved in GC expression. We identified cancer-relevant genes (ING1, ARL4C) whose expression between patients is influenced by enhancer differences in genomic copy number and germline SNPs, and HNF4α as a master trans-acting factor associated with GC enhancer heterogeneity. Conclusions Our results indicate that combining histone modification and functional assay data may provide a more accurate metric to assess enhancer activity than either platform individually, providing insights into the relative contribution of genetic (cis) and regulatory (trans) mechanisms to GC enhancer functional heterogeneity.

scholarly journals Polycomb Requires Chaperonin Containing TCP-1 Subunit 7 for Maintaining Gene Silencing in Drosophila

2021 ◽  
Vol 9 ◽  
Author(s):  
Najma Shaheen ◽  
Jawad Akhtar ◽  
Zain Umer ◽  
Muhammad Haider Farooq Khan ◽  
Mahnoor Hussain Bakhtiari ◽  
...  
Keyword(s):  
Genetic Interaction ◽  
Expression Patterns ◽  
Cell Types ◽  
Polycomb Group ◽  
Specific Gene ◽  
Cellular Memory ◽  
Trithorax Group ◽  
T Complex ◽  
Ring Complex ◽  
Active Expression

In metazoans, heritable states of cell type-specific gene expression patterns linked with specialization of various cell types constitute transcriptional cellular memory. Evolutionarily conserved Polycomb group (PcG) and trithorax group (trxG) proteins contribute to the transcriptional cellular memory by maintaining heritable patterns of repressed and active expression states, respectively. Although chromatin structure and modifications appear to play a fundamental role in maintenance of repression by PcG, the precise targeting mechanism and the specificity factors that bind PcG complexes to defined regions in chromosomes remain elusive. Here, we report a serendipitous discovery that uncovers an interplay between Polycomb (Pc) and chaperonin containing T-complex protein 1 (TCP-1) subunit 7 (CCT7) of TCP-1 ring complex (TRiC) chaperonin in Drosophila. CCT7 interacts with Pc at chromatin to maintain repressed states of homeotic and non-homeotic targets of PcG, which supports a strong genetic interaction observed between Pc and CCT7 mutants. Depletion of CCT7 results in dissociation of Pc from chromatin and redistribution of an abundant amount of Pc in cytoplasm. We propose that CCT7 is an important modulator of Pc, which helps Pc recruitment at chromatin, and compromising CCT7 can directly influence an evolutionary conserved epigenetic network that supervises the appropriate cellular identities during development and homeostasis of an organism.

scholarly journals POGZ controls embryonic stem cell self-renewal and pluripotency by association with esBAF and HP1

2021 ◽  
Author(s):  
Xiaoyun Sun ◽  
Linxi Cheng ◽  
Yuhua Sun
Keyword(s):  
Cell Fate ◽  
Neurodevelopmental Disorders ◽  
Embryonic Stem ◽  
Autism Spectrum ◽  
Specific Gene ◽  
Open Chromatin ◽  
Cell Fate Determination ◽  
Chromatin Remodeler ◽  
Self Renewal ◽  
Fate Determination

AbstractPOGZ, which encodes a multi-domain transcription factor, has been found frequently mutated in neurodevelopmental disorders, particularly autism spectrum disorder (ASD) and intellectual disability (ID). However, little is known about its function in ESC self-renewal and pluripotency, cell fate determination as well as in transcriptional regulation. Here, using embryonic stem cells (ESCs) as model, we show that POGZ plays key roles in the maintenance of ESC and cell fate determination by association with the SWI-SNW chromatin remodeler complex and heterochromatin protein 1 (HP1) proteins. POGZ is essential for the maintenance of ESC undifferentiated state, and loss of POGZ leads to ESC differentiation, likely by up-regulation of primitive endoderm and mesoderm lineage genes and by down-regulation of pluripotency-related genes. Mechanistically, POGZ may control ESC-specific gene expression by association with chromatin remodeler complex esBAF and HP1s, and they can form a PBH triplex. POGZ functions primarily to maintain an open chromatin, as loss of POGZ leads to a reduced chromatin accessibility. Regulation of chromatin under control of POGZ depends on esBAF complex. POGZ is extensively co-localized with OCT4/NANOG genome wide. Taken together, we propose that POGZ is a pluripotency-associated factor, and its absence in ESCs causes failure to maintain a proper ESC-specific chromatin state and transcriptional circuitry of pluripotency, which eventually leads to ESC self-renewal and pluripotency defects. Our work provides important insights into the role of POGZ in ESC self-renewal and pluripotency as well as regulation of transcription, which will be useful for understanding the etiology of neurodevelopmental disorders by POGZ mutation.

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