Early embryonic expression ofFGF4/6/9gene and its role in the induction of mesenchyme and notochord inCiona savignyiembryos

Development ◽  
2002 ◽  
Vol 129 (7) ◽  
pp. 1729-1738 ◽  
Author(s):  
Kaoru S. Imai ◽  
Nori Satoh ◽  
Yutaka Satou
Keyword(s):  
Cell Differentiation ◽  
Nuclear Localization ◽  
Target Genes ◽  
Muscle Cells ◽  
Cell Stage ◽  
Ciona Savignyi ◽  
Mesenchyme Cell ◽  
Notochord Cells ◽  
Mesenchyme Cells ◽  
Endodermal Cells

In early Ciona savignyi embryos, nuclear localization of β-catenin is the first step of endodermal cell specification, and triggers the activation of various target genes. A cDNA for Cs-FGF4/6/9, a gene activated downstream of β-catenin signaling, was isolated and shown to encode an FGF protein with features of both FGF4/6 and FGF9/20. The early embryonic expression of Cs-FGF4/6/9 was transient and the transcript was seen in endodermal cells at the 16- and 32-cell stages, in notochord and muscle cells at the 64-cell stage, and in nerve cord and muscle cells at the 110-cell stage; the gene was then expressed again in cells of the nervous system after neurulation. When the gene function was suppressed with a specific antisense morpholino oligo, the differentiation of mesenchyme cells was completely blocked, and the fate of presumptive mesenchyme cells appeared to change into that of muscle cells. The inhibition of mesenchyme differentiation was abrogated by coinjection of the morpholino oligo and synthetic Cs-FGF4/6/9 mRNA. Downregulation of β-catenin nuclear localization resulted in the absence of mesenchyme cell differentiation due to failure of the formation of signal-producing endodermal cells. Injection of synthetic Cs-FGF4/6/9 mRNA in β-catenin-downregulated embryos evoked mesenchyme cell differentiation. These results strongly suggest that Cs-FGF4/6/9 produced by endodermal cells acts an inductive signal for the differentiation of mesenchyme cells. On the other hand, the role of Cs-FGF4/6/9 in the induction of notochord cells is partial; the initial process of the induction was inhibited by Cs-FGF4/6/9 morpholino oligo, but notochord-specific genes were expressed later to form a partial notochord.

FGF signals are involved in the differentiation of notochord cells and mesenchyme cells of the ascidianHalocynthia roretzi

Development ◽  
2001 ◽  
Vol 128 (14) ◽  
pp. 2711-2721 ◽  
Author(s):  
Yoshie Shimauchi ◽  
Seiko D. Murakami ◽  
Nori Satoh
Keyword(s):  
Receptor Gene ◽  
Epidermal Cells ◽  
Dominant Negative ◽  
Tyrosine Kinase Domain ◽  
Fgf Receptor ◽  
Dominant Negative Form ◽  
Notochord Cells ◽  
Mesenchyme Cells ◽  
Endodermal Cells ◽  
Negative Form

Differentiation of notochord cells and mesenchyme cells of the ascidian Halocynthia roretzi requires interactions with neighboring endodermal cells and previous experiments suggest that these interactions require fibroblast growth factor (FGF). In the present study, we examined the role of FGF in these interactions by disrupting signaling using the dominant negative form of the FGF receptor. An FGF receptor gene of H. roretzi (HrFGFR) is expressed both maternally and zygotically. The maternally expressed transcript was ubiquitously distributed in fertilized eggs and in early embryos. Zygotic expression became evident by the neurula stage and transcripts were detected in epidermal cells of the posterior half of embryos. Synthetic mRNA for the dominant negative form of FGFR, in which the intracellular tyrosine kinase domain was deleted, was injected into fertilized eggs to interfere with the possible function of HrFGFR. Injected eggs cleaved and gastrulated the same as the control embryos. Analyses of the expression of differentiation markers in the experimental embryos indicated that the differentiation of epidermal cells, muscle cells and endodermal cells was not affected significantly. However, manipulated embryos showed downregulation of notochord-specific Brachyury expression and failure of notochord cell differentiation, resulting in the development of tailbud embryos with shorted tails. The expression of an actin gene that is normally expressed in mesenchyme cells was also suppressed. These results suggest that FGF signals are involved in differentiation of notochord cells and mesenchyme cells in Halocynthia embryos. Furthermore, the patterning of a neuron-specific tubulin gene expression was disturbed, suggesting that the formation of the nervous system was directly affected by disrupting FGF signals or indirectly affected due to the disruption of normal notochord formation.

An FGF signal from endoderm and localized factors in the posterior-vegetal egg cytoplasm pattern the mesodermal tissues in the ascidian embryo

Development ◽  
2000 ◽  
Vol 127 (13) ◽  
pp. 2853-2862 ◽  
Author(s):  
G.J. Kim ◽  
A. Yamada ◽  
H. Nishida
Keyword(s):  
Marginal Zone ◽  
Normal Development ◽  
Cell Stage ◽  
Asymmetric Divisions ◽  
Notochord Cells ◽  
Ascidian Embryos ◽  
The Difference ◽  
Mesenchyme Cells ◽  
Time Required ◽  
Ascidian Embryo

The major mesodermal tissues of ascidian larvae are muscle, notochord and mesenchyme. They are derived from the marginal zone surrounding the endoderm area in the vegetal hemisphere. Muscle fate is specified by localized ooplasmic determinants, whereas specification of notochord and mesenchyme requires inducing signals from endoderm at the 32-cell stage. In the present study, we demonstrated that all endoderm precursors were able to induce formation of notochord and mesenchyme cells in presumptive notochord and mesenchyme blastomeres, respectively, indicating that the type of tissue induced depends on differences in the responsiveness of the signal-receiving blastomeres. Basic fibroblast growth factor (bFGF), but not activin A, induced formation of mesenchyme cells as well as notochord cells. Treatment of mesenchyme-muscle precursors isolated from early 32-cell embryos with bFGF promoted mesenchyme fate and suppressed muscle fate, which is a default fate assigned by the posterior-vegetal cytoplasm (PVC) of the eggs. The sensitivity of the mesenchyme precursors to bFGF reached a maximum at the 32-cell stage, and the time required for effective induction of mesenchyme cells was only 10 minutes, features similar to those of notochord induction. These results support the idea that the distinct tissue types, notochord and mesenchyme, are induced by the same signaling molecule originating from endoderm precursors. We also demonstrated that the PVC causes the difference in the responsiveness of notochord and mesenchyme precursor blastomeres. Removal of the PVC resulted in loss of mesenchyme and in ectopic notochord formation. In contrast, transplantation of the PVC led to ectopic formation of mesenchyme cells and loss of notochord. Thus, in normal development, notochord is induced by an FGF-like signal in the anterior margin of the vegetal hemisphere, where PVC is absent, and mesenchyme is induced by an FGF-like signal in the posterior margin, where PVC is present. The whole picture of mesodermal patterning in ascidian embryos is now known. We also discuss the importance of FGF induced asymmetric divisions, of notochord and mesenchyme precursor blastomeres at the 64-cell stage.

A forkhead gene related to HNF-3beta is required for gastrulation and axis formation in the ascidian embryo

Development ◽  
1997 ◽  
Vol 124 (18) ◽  
pp. 3609-3619 ◽  
Author(s):  
C.L. Olsen ◽  
W.R. Jeffery
Keyword(s):  
Muscle Cells ◽  
Single Copy ◽  
The Body ◽  
Axis Formation ◽  
Vegetal Pole ◽  
Tailbud Stage ◽  
Notochord Cells ◽  
Mesenchyme Cells ◽  
Forkhead Gene

We have isolated a member of the HNF-3/forkhead gene family in ascidians as a means to determine the role of winged-helix genes in chordate development. The MocuFH1 gene, isolated from a Molgula oculata cDNA library, exhibits a forkhead DNA-binding domain most similar to zebrafish axial and rodent HNF-3beta. MocuFH1 is a single copy gene but there is at least one other related forkhead gene in the M. oculata genome. The MocuFH1 gene is expressed in the presumptive endoderm, mesenchyme and notochord cells beginning during the late cleavage stages. During gastrulation, MocuFH1 expression occurs in the prospective endoderm cells, which invaginate at the vegetal pole, and in the presumptive notochord and mesenchyme cells, which involute over the anterior and lateral lips of the blastopore, respectively. However, this gene is not expressed in the presumptive muscle cells, which involute over the posterior lip of the blastopore. MocuFH1 expression continues in the same cell lineages during neurulation and axis formation, however, during the tailbud stage, MocuFH1 is also expressed in ventral cells of the brain and spinal cord. The functional role of the MocuFH1 gene was studied using antisense oligodeoxynucleotides (ODNs), which transiently reduce MocuFH1 transcript levels during gastrulation. Embryos treated with antisense ODNs cleave normally and initiate gastrulation. However, gastrulation is incomplete, some of the endoderm and notochord cells do not enter the embryo and undergo subsequent movements, and axis formation is abnormal. In contrast, the prospective muscle cells, which do not express MocuFH1, undergo involution and later express muscle actin and acetylcholinesterase, markers of muscle cell differentiation. The results suggest that MocuFH1 is required for morphogenetic movements of the endoderm and notochord precursor cells during gastrulation and axis formation. The effects of inhibiting MocuFH1 expression on embryonic axis formation in ascidians are similar to those reported for knockout mutations of HNF-3beta in the mouse, suggesting that HNF-3/forkhead genes have an ancient and fundamental role in organizing the body plan in chordates.

MicroRNAs Regulate Mature B Cell Differentiation

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 705-705
Author(s):  
Jenny Zhang ◽  
Dereje D. Jima ◽  
Cassandra L. Jacobs ◽  
Eva Gottwein ◽  
Grace Huang ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Target Genes ◽  
Expression Patterns ◽  
Microrna Expression ◽  
Seed Sequence ◽  
B Cell Differentiation ◽  
Cell Stage

Abstract Background: Mature B cell differentiation provides an important mechanism for the acquisition of adaptive immunity. Malignancies derived from mature B cells are common and constitute the majority of leukemias and lymphomas. MicroRNAs are known to play a role in oncogenesis, lineage-selection, and immune cell function, including early B cell differentiation. However, the full extent and function of microRNA expression during mature B cell differentiation and in B cell malignancies are not known. Methods: From normal young patients undergoing tonsillectomies, we sorted the mature B cell subsets (naive, germinal center, memory and plasma) using FACS, based on their expression of CD19, CD38, IgD and CD27. These sorted B cells were profiled for microRNA expression using a highly sensitive multiplexed real-time PCR assay, as well as for gene expression at the whole genome level using Affymetrix U133plus microarrays. miRNA targets can be predicted based on seed sequence matching of their 2–8 nt to the 3′UTR of gene transcripts. For each B cell stage, we experimentally validated microRNA regulation of predicted target genes of interest, LMO2, MYBL1 and PRDM1, by microRNA over-expression experiments and luciferase assays. Results: We found that microRNAs have a characteristic expression pattern that defines each mature B cell stage. Examination of both microRNA and mRNA expression showed that in each B cell population, the target genes predicted based on seed matching were expressed at lower levels, results that were highly significant (P<1E-10). We found that differential microRNA expression is important at every B cell stage transition, and differentially expressed microRNAs frequently target differentially expressed transcription factors. In the naive to germinal center B cell and germinal center B cell to memory cell transitions, we found that miR-223 had an inverse relationship with its predicted target genes LMO2 and MYBL1. To test this relationship predicted based on seed pairing, in Germinal Center-derived BJAB cells, we over-expressed miR-223 by introducing its precursor, and saw a subsequent knockdown of LMO2 and MYBL1 at both the mRNA and protein level. We confirmed seed sequence specificity by comparing miR-223 knockdown of luciferase reporter activity on the LMO2 3′UTR compared to its seed sequence mutant. We further found that miR-9 and miR-30 family members directly regulate PRDM1 (blimp1), a master regulator of the GC to PC transition. In U266 cells (PC-derived), introduction of miR-9 and miR-30 family precursor resulted in decreased PRDM1 protein expression, although transcript levels were not changed, consistent with previous evidence that miRNA can regulate at the post-transcriptional steps. We further profiled over 50 tumors derived from various B cell malignancies (small lymphocytic lymphoma, Burkitt lymphoma, and the molecular subsets of diffuse large B cell lymphoma) and found that these malignancies maintain the expression patterns of their respective lineage; microRNA expression profiles of normal B cells could correctly classify the lineage of these tumors in over 80% of the cases. In contrast to other malignancies, common lymphomas do not down-regulate microRNAs, but rather maintain the microRNA-expression patterns of their normal B-cell counterparts. Conclusion: Through concomitant microRNA and mRNA-profiling, we demonstrate a regulatory role for microRNAs at every stage in mature B-cell differentiation. Further, we have experimentally identified a direct role for the microRNA-regulation of key transcription factors in B-cell differentiation: LMO2, MYBL1 and PRDM1 (Blimp1). Thus, our data demonstrate that microRNAs may be important in maintaining the mature B-cell phenotype in normal and malignant B-cells.

Multiple functions of a Zic-like gene in the differentiation of notochord, central nervous system and muscle inCiona savignyiembryos

Development ◽  
2002 ◽  
Vol 129 (11) ◽  
pp. 2723-2732 ◽  
Author(s):  
Kaoru S. Imai ◽  
Yutaka Satou ◽  
Nori Satoh
Keyword(s):  
Target Gene ◽  
Single Gene ◽  
Experimental System ◽  
Cdna Clones ◽  
Embryonic Cells ◽  
Gene Encoding ◽  
Cell Stage ◽  
Multiple Functions ◽  
Ciona Savignyi ◽  
Notochord Cells

Multiple functions of a Zic-like zinc finger transcription factor gene (Cs-ZicL) were identified in Ciona savignyi embryos. cDNA clones for Cs-ZicL, a β-catenin downstream genes, were isolated and the gene was transiently expressed in the A-line notochord/nerve cord lineage and in B-line muscle lineage from the 32-cell stage and later in a-line CNS lineage from the 110-cell stage. Suppression of Cs-ZicL function with specific morpholino oligonucleotide indicated that Cs-ZicL is essential for the formation of A-line notochord cells but not of B-line notochord cells, essential for the CNS formation and essential for the maintenance of muscle differentiation. The expression of Cs-ZicL in the A-line cells is downstream of β-catenin and a β-catenin-target gene, Cs-FoxD, which is expressed in the endoderm cells from the 16-cell stage and is essential for the differentiation of notochord. In spite of its pivotal role in muscle specification, the expression of Cs-ZicL in the muscle precursors is independent of Cs-macho1, which is another Zic-like gene encoding a Ciona maternal muscle determinant, suggesting another genetic cascade for muscle specification independent of Cs-macho1. Cs-ZicL may provide a future experimental system to explore how the gene expression in multiple embryonic regions is controlled and how the single gene can perform different functions in multiple types of embryonic cells.

Fate maps and cell differentiation in the amphibian embryo – an experimental study

Development ◽  
1979 ◽  
Vol 54 (1) ◽  
pp. 113-130
Author(s):  
Ulf Landström ◽  
Søren Løvtrup
Keyword(s):  
Cell Differentiation ◽  
Striated Muscle ◽  
Heparan Sulphate ◽  
Fate Map ◽  
Amphibian Embryo ◽  
Undifferentiated Cells ◽  
Mesenchyme Cells ◽  
The One ◽  
Endodermal Cells ◽  
Insight Into

The aim of this paper is to test two different fate maps for the amphibian blastula with respect to their predictions concerning the process of cell differentiation. The first of these fate maps is the one proposed by Vogt, according to which all three germ layers can be projected on to the surface of the embryo. The second is a revision which claims that only endoderm and ectoderm are located in the surface, while the mesoderm is represented by free cells in the interior of the embryo. The testing has been performed by observing the differentiation of small explants of cells taken from various regions of the embryo. It was found that the spontaneous cell differentiation comprises three patterns: undifferentiated cells (free interior cells and circumpolar endodermal cells), fibroblast-like cells (the remaining endodermal cells) and epidermis (ectodermal cells). Further differentiation occurs only through induction, exerted either by the fibroblast-like endodermal cells or by heparan sulphate. When induced, the equatorial ectodermal cells give rise to swollen, hyaline cells (chordocytes), while the remaining ectodermal cells form a sequence of cell differentiation patterns, mesenchyme cells, nerve cells, melanophores and xanthophores. The free interior cells differentiate into striated muscle cells and elongated collagen-producing fibroblasts. Our results thus confirm the revised fate map, and they also give an insight into the mechanisms of the initial cell differentiations in the amphibian embryo.

scholarly journals Upregulation of COX4-2 via HIF-1α in Mitochondrial COX4-1 Deficiency

Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 452
Author(s):  
Liza Douiev ◽  
Chaya Miller ◽  
Shmuel Ruppo ◽  
Hadar Benyamini ◽  
Bassam Abu-Libdeh ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Oxidative Phosphorylation ◽  
Nuclear Localization ◽  
Target Genes ◽  
Compensatory Mechanism ◽  
Terminal Electron Acceptor ◽  
Human Foreskin Fibroblasts ◽  
Mitochondrial Respiratory Complex ◽  
Mrna Transcripts ◽  
Oxphos System

Cytochrome-c-oxidase (COX) subunit 4 (COX4) plays important roles in the function, assembly and regulation of COX (mitochondrial respiratory complex 4), the terminal electron acceptor of the oxidative phosphorylation (OXPHOS) system. The principal COX4 isoform, COX4-1, is expressed in all tissues, whereas COX4-2 is mainly expressed in the lungs, or under hypoxia and other stress conditions. We have previously described a patient with a COX4-1 defect with a relatively mild presentation compared to other primary COX deficiencies, and hypothesized that this could be the result of a compensatory upregulation of COX4-2. To this end, COX4-1 was downregulated by shRNAs in human foreskin fibroblasts (HFF) and compared to the patient’s cells. COX4-1, COX4-2 and HIF-1α were detected by immunocytochemistry. The mRNA transcripts of both COX4 isoforms and HIF-1 target genes were quantified by RT-qPCR. COX activity and OXPHOS function were measured by enzymatic and oxygen consumption assays, respectively. Pathways were analyzed by CEL-Seq2 and by RT-qPCR. We demonstrated elevated COX4-2 levels in the COX4-1-deficient cells, with a concomitant HIF-1α stabilization, nuclear localization and upregulation of the hypoxia and glycolysis pathways. We suggest that COX4-2 and HIF-1α are upregulated also in normoxia as a compensatory mechanism in COX4-1 deficiency.

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