scholarly journals The SCL gene is formed from a transcriptionally complex locus.

1990 ◽  
Vol 10 (12) ◽  
pp. 6426-6435 ◽  
Author(s):  
P D Aplan ◽  
C G Begley ◽  
V Bertness ◽  
M Nussmeier ◽  
A Ezquerra ◽  
...  
Keyword(s):  
Transcription Initiation ◽  
Structural Organization ◽  
Developmental Stages ◽  
Cpg Island ◽  
Cell Lineage ◽  
Hematopoietic Differentiation ◽  
Hematopoietic Development ◽  
Regulatory Interactions ◽  
Helix Loop Helix ◽  
Complex Locus

We describe the structural organization of the human SCL gene, a helix-loop-helix family member which we believe plays a fundamental role in hematopoietic differentiation. The SCL locus is composed of eight exons distributed over 16 kb. SCL shows a pattern of expression quite restricted to early hematopoietic tissues, although in malignant states expression of the gene may be somewhat extended into later developmental stages. A detailed analysis of the transcript(s) arising from the SCL locus revealed that (i) the 5' noncoding portion of the SCL transcript, which resides within a CpG island, has a complex pattern of alternative exon utilization as well as two distinct transcription initiation sites; (ii) the 5' portions of the SCL transcript contain features that suggest a possible regulatory role for these segments; (iii) the pattern of utilization of the 5' exons is cell lineage dependent; and (iv) all of the currently studied chromosomal aberrations that affect the SCL locus either structurally or functionally eliminate the normal 5' transcription initiation sites. These data suggest that the SCL gene, and specifically its 5' region, may be a target for regulatory interactions during early hematopoietic development.

The SCL gene is formed from a transcriptionally complex locus

1990 ◽  
Vol 10 (12) ◽  
pp. 6426-6435
Author(s):  
P D Aplan ◽  
C G Begley ◽  
V Bertness ◽  
M Nussmeier ◽  
A Ezquerra ◽  
...  
Keyword(s):  
Transcription Initiation ◽  
Structural Organization ◽  
Developmental Stages ◽  
Cpg Island ◽  
Cell Lineage ◽  
Hematopoietic Differentiation ◽  
Hematopoietic Development ◽  
Regulatory Interactions ◽  
Helix Loop Helix ◽  
Complex Locus

We describe the structural organization of the human SCL gene, a helix-loop-helix family member which we believe plays a fundamental role in hematopoietic differentiation. The SCL locus is composed of eight exons distributed over 16 kb. SCL shows a pattern of expression quite restricted to early hematopoietic tissues, although in malignant states expression of the gene may be somewhat extended into later developmental stages. A detailed analysis of the transcript(s) arising from the SCL locus revealed that (i) the 5' noncoding portion of the SCL transcript, which resides within a CpG island, has a complex pattern of alternative exon utilization as well as two distinct transcription initiation sites; (ii) the 5' portions of the SCL transcript contain features that suggest a possible regulatory role for these segments; (iii) the pattern of utilization of the 5' exons is cell lineage dependent; and (iv) all of the currently studied chromosomal aberrations that affect the SCL locus either structurally or functionally eliminate the normal 5' transcription initiation sites. These data suggest that the SCL gene, and specifically its 5' region, may be a target for regulatory interactions during early hematopoietic development.

scholarly journals Expression of the Id Family Helix-Loop-Helix Regulators During Growth and Development in the Hematopoietic System

Blood ◽  
1997 ◽  
Vol 89 (9) ◽  
pp. 3155-3165 ◽  
Author(s):  
Cathleen L. Cooper ◽  
Gerard Brady ◽  
Fillio Bilia ◽  
Norman N. Iscove ◽  
Peter J. Quesenberry
Keyword(s):  
Cell Lineage ◽  
Cell Types ◽  
Specific Cell ◽  
Proliferative Capacity ◽  
Limited Extent ◽  
Hematopoietic Stem ◽  
Hematopoietic Development ◽  
Helix Loop Helix ◽  
Specific Manner ◽  
Two Factors

Abstract To better understand the molecular mechanism(s) by which growth and differentiation of the primitive hematopoietic stem cell is initiated, as well as the means by which the maturing cell can commit to development along a specific cell lineage, we elected to study the Id family of helix-loop-helix (HLH) transcriptional regulators. Some members of the HLH family are expressed in a stage-specific manner during hematopoietic development and can regulate the ability of immature hematopoietic cells to terminally differentiate. None of the four Id family genes were detected in the most primitive progenitors. Id-1 was widely expressed in proliferating bi- and unipotential progenitors, but its expression was downregulated in cells of increasing maturity; conversely, Id-2 and, to a limited extent, Id-3 gene expression increased as cells matured and lost proliferative capacity. Id-2 expression ran counter to that of Id-1 not only during maturation, but during periods of cell growth and arrest as well. This is quite distinct from the nonhematopoietic tissues, in which these two factors are coordinately expressed and suggests that Id-1 and Id-2 might be regulating very different events during hematopoiesis than they regulate in other cell types.

Basic Biology of Trypanosoma Cruzi

2020 ◽  
Vol 26 ◽  
Author(s):  
Aline Araujo Zuma ◽  
Emile dos Santos Barrias ◽  
Wanderley de Souza
Keyword(s):  
Trypanosoma Cruzi ◽  
Trypanosoma Brucei ◽  
Cell Biology ◽  
Structural Organization ◽  
Developmental Stages ◽  
Endocytic Pathway ◽  
Host Cells ◽  
Cellular Organization ◽  
Basic Biology ◽  
Comparative Information

Abstract:: The present review addresses basic aspects of the biology of the pathogenic protozoa Trypanosoma cruzi and some comparative information with Trypanosoma brucei. Like eukaryotic cells, their cellular organization is similar to that of mammalian hosts. However, these parasites present structural particularities. That is why the following topics are emphasized in this paper: developmental stages of the life cycle in the vertebrate and invertebrate hosts; the cytoskeleton of the protozoa, especially the sub-pellicular microtubules; the flagellum and its attachment to the protozoan body through specialized junctions; the kinetoplast-mitochondrion complex, including its structural organization and DNA replication; the glycosome and its role in the metabolism of the cell; the acidocalcisome, describing its morphology, biochemistry, and functional role; the cytostome and the endocytic pathway; the organization of the endoplasmic reticulum and Golgi complex; the nucleus, describing its structural organization during interphase and division; and the process of interaction of the parasite with host cells. The unique characteristics of these structures also make them interesting chemotherapeutic targets. Therefore, further understanding of cell biology aspects contributes to the development of drugs for chemotherapy.

scholarly journals Crayfish hemocytes develop along the granular cell lineage

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fang Li ◽  
Zaichao Zheng ◽  
Hongyu Li ◽  
Rongrong Fu ◽  
Limei Xu ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Cell Lineage ◽  
Granular Cell ◽  
Marker Genes ◽  
Hematopoietic Tissue ◽  
Differentiated Cells ◽  
Stage Of Development ◽  
Almost All ◽  
Relationship Of

AbstractDespite the central role of hemocytes in crustacean immunity, the process of hemocyte differentiation and maturation remains unclear. In some decapods, it has been proposed that the two main types of hemocytes, granular cells (GCs) and semigranular cells (SGCs), differentiate along separate lineages. However, our current findings challenge this model. By tracking newly produced hemocytes and transplanted cells, we demonstrate that almost all the circulating hemocytes of crayfish belong to the GC lineage. SGCs and GCs may represent hemocytes of different developmental stages rather than two types of fully differentiated cells. Hemocyte precursors produced by progenitor cells differentiate in the hematopoietic tissue (HPT) for 3 ~ 4 days. Immature hemocytes are released from HPT in the form of SGCs and take 1 ~ 3 months to mature in the circulation. GCs represent the terminal stage of development. They can survive for as long as 2 months. The changes in the expression pattern of marker genes during GC differentiation support our conclusions. Further analysis of hemocyte phagocytosis indicates the existence of functionally different subpopulations. These findings may reshape our understanding of crustacean hematopoiesis and may lead to reconsideration of the roles and relationship of circulating hemocytes.

Microbial computational genomics of gene regulation

2002 ◽  
Vol 74 (6) ◽  
pp. 899-905 ◽  
Author(s):  
Julio Collado-Vides ◽  
Gabriel Moreno-Hagelsieb ◽  
Arturo Medrano-Soto
Keyword(s):  
Transcription Initiation ◽  
Transcription Unit ◽  
Microbial Genomes ◽  
E Coli ◽  
Regulatory Interactions ◽  
Living Bacterium ◽  
Complete Set ◽  
Operon Organization ◽  
Unit Organization ◽  
K 12

Escherichia coli is a free-living bacterium that condensates a large legacy of knowledge as a result of years of experimental work in molecular biology. It represents a point of departure for analyses and comparisons with the ever-increasing number of finished microbial genomes. For years, we have been gathering knowledge from the literature on transcriptional regulation and operon organization in E. coli K-12, and organizing it in a relational database, RegulonDB. RegulonDB contains information of 20­25 % of the expected total sets of regulatory interactions at the level of transcription initiation. We have used this knowledge to generate computational methods to predict the missing sets in the genome of E. coli, focusing on prediction of promoters, regulatory sites, regulatory proteins, operons, and transcription units. These predictions constitute separate pieces of a single puzzle. By putting them all together, we shall be able to predict the complete set of regulatory interactions and transcription unit organization of E. coli. Orthologous genes in other genomes of known co-regulated sets of genes in E. coli, along with their corresponding predicted operons, and their predicted transcriptional regulators, shall permit the extension of the previous goal to many more microbial genomes.

Demonstration of a phagocytic cell system belonging to the hemopoietic lineage and originating from the yolk sac in the early avian embryo

Development ◽  
1992 ◽  
Vol 115 (1) ◽  
pp. 157-168 ◽  
Author(s):  
M.A. Cuadros ◽  
P. Coltey ◽  
M. Carmen Nieto ◽  
C. Martin
Keyword(s):  
Acid Phosphatase ◽  
Developmental Stages ◽  
Cell Lineage ◽  
Cell System ◽  
Yolk Sac ◽  
Double Labelling ◽  
Avian Embryo ◽  
Phagocytic Cell ◽  
Phagocytic Capacity ◽  
Hemopoietic Cells

It is well established that hemopoietic cells arising from the yolk sac invade the avian embryo. To study the fate and role of these cells during the first 2.5-4.5 days of incubation, we constructed yolk sac chimeras (a chick embryo grafted on a quail yolk sac and vice versa) and immunostained them with antibodies specific to cells of quail hemangioblastic lineage (MB1 and QH1). This approach revealed that endothelial cells of the embryonic vessels are of intraembryonic origin. In contrast, numerous hemopoietic cells of yolk sac origin were seen in embryos ranging from 2.5 to 4.5 days of incubation. These cells were already present within the vessels and in the mesenchyme at the earliest developmental stages analyzed. Two hemopoietic cell types of yolk sac origin were distinguishable, undifferentiated cells and macrophage-like cells. The number of the latter cells increased progressively as development proceeded, and they showed marked acid phosphatase activity and phagocytic capacity, as revealed by the presence of numerous phagocytic inclusions in their cytoplasm. The macrophage-like cells were mostly distributed in the mesenchyme and also appeared within some organ primordia such as the neural tube, the liver anlage and the nephric rudiment. Comparison of the results in the two types of chimeras and the findings obtained with acid phosphatase/MB1 double labelling showed that some hemopoietic macrophage-like cells of intraembryonic origin were also present at the stages considered. These results support the existence in the early avian embryo of a phagocytic cell system of blood cell lineage, derived chiefly from the yolk sac. Cells belonging to this system perform phagocytosis in cell death and may also be involved in other morphogenetic processes.

scholarly journals The SCL/TAL-1 gene is expressed in progenitors of both the hematopoietic and vascular systems during embryogenesis

Blood ◽  
1994 ◽  
Vol 83 (5) ◽  
pp. 1200-1208 ◽  
Author(s):  
AR Kallianpur ◽  
JE Jordan ◽  
SJ Brandt
Keyword(s):  
T Cell ◽  
Neural Development ◽  
Fetal Liver ◽  
Chromosomal Rearrangements ◽  
Chromosomal Translocation ◽  
Cell Types ◽  
Hematopoietic Differentiation ◽  
Helix Loop Helix ◽  
Adult Mice ◽  
Rare Cells

Activation of the SCL (or TAL-1) gene as a result of chromosomal translocation or deletion is a frequent molecular lesion in acute T- cell leukemia. By virtue of its membership in the basic helix-loop- helix family of transcription factors, the SCL gene is a candidate to regulate events in hematopoietic differentiation. We have used polyclonal antibody raised against a bacterial expressed malE-SCL fusion protein to characterize SCL protein expression in postimplantation embryos and in neonatal and adult mice. SCL protein was detected at day 7.5 post coitum at both embryonic and extraembryonic sites, approximately 24 hours before the formation of recognizable hematopoietic elements. Expression then localized to blood islands of the yolk sac followed by localization to fetal liver and spleen, paralleling the hematopoietic activity of these tissues during development. SCL protein was detected in erythroblasts in fetal and adult spleen, myeloid cells and megakaryocytes in spleen and bone marrow, mast cells in skin, and in rare cells in fetal and adult thymus. In addition, SCL protein was noted in endothelial progenitors in blood islands and in endothelial cells and angioblasts in a number of organs at times coincident with their vascularization. SCL expression was also observed in other nonhematopoietic cell types in the developing skeletal and nervous systems. These results show that SCL expression is one of the earliest markers of mammalian hematopoietic development and are compatible with a role for this transcription factor in terminal differentiation of the erythroid and megakaryocytic lineages. SCL expression by cells in the thymus suggests that the gene may be active at some stage of T-cell differentiation and may be relevant to its involvement by chromosomal rearrangements in T- lymphoid leukemias. Finally, expression of the gene in developing brain, cartilage, and vascular endothelium indicates SCL may have actions in neural development, osteogenesis, and vasculogenesis, as well as in hematopoietic differentiation.

scholarly journals Identification and sequence analysis of a new member of the mouse HSP70 gene family and characterization of its unique cellular and developmental pattern of expression in the male germ line.

1988 ◽  
Vol 8 (7) ◽  
pp. 2925-2932 ◽  
Author(s):  
Z F Zakeri ◽  
D J Wolgemuth ◽  
C R Hunt
Keyword(s):  
Heat Shock ◽  
Gene Family ◽  
Developmental Stages ◽  
Germ Line ◽  
Cell Lineage ◽  
Hsp70 Gene ◽  
Coding Region ◽  
Male Germ Line ◽  
Sequence Organization

A unique member of the mouse HSP70 gene family has been isolated and characterized with respect to its DNA sequence organization and expression. The gene contains extensive similarity to a heat shock-inducible HSP70 gene within the coding region but diverges in both 3' and 5' nontranslated regions. The gene does not yield transcripts in response to heat shock in mouse L cells. Rather, the gene appears to be activated uniquely in the male germ line. Analysis of RNA from different developmental stages and from enriched populations of spermatogenic cells revealed that this gene is expressed during the prophase stage of meiosis. A transcript different in size from the major heat-inducible mouse transcripts is most abundant in meiotic prophase spermatocytes and decreases in abundance in postmeiotic stages of spermatogenesis. This pattern of expression is distinct from that observed for another member of this gene family, which was previously shown to be expressed abundantly in postmeiotic germ cells. These observations suggest that specific HSP70 gene family members play distinct roles in the differentiation of the germ cell lineage in mammals.

Modelling transcriptional feedback loops: the role of Gro/TLE1 in Hes1 oscillations

2006 ◽  
Vol 364 (1842) ◽  
pp. 1155-1170 ◽  
Author(s):  
Samuel Bernard ◽  
Branka Čajavec ◽  
Laurent Pujo-Menjouet ◽  
Michael C Mackey ◽  
Hanspeter Herzel
Keyword(s):  
Transcription Initiation ◽  
Periodic Pattern ◽  
Transcriptional Repressors ◽  
Helix Loop Helix ◽  
Family Protein ◽  
Theoretical Predictions ◽  
Numerical Bifurcation ◽  
Enhancer Of Split ◽  
Transcriptional Feedback

The transcriptional repressor Hes1, a basic helix-loop-helix family protein, periodically changes its expression in the presomitic mesoderm. Its periodic pattern of expression is retained in a number of cultured murine cell lines. In this paper, we introduce an extended mathematical model for Hes1 oscillatory expression that includes regulation of Hes1 transcription by Drosophila Groucho (Gro) or its vertebrate counterpart, the transducine-like enhancer of split/Groucho-related gene product 1 (TLE1). Gro/TLE1 is a necessary corepressor required by a number of DNA-binding transcriptional repressors, including Hes1. Models of direct repression via Hes1 typically display an expression overshoot after transcription initiation which is not seen in the experimental data. However, numerical simulation and theoretical predictions of our model show that the cofactor Gro/TLE1 reduces the overshoot and is thus necessary for a rapid and finely tuned response of Hes1 to activation signals. Further, from detailed linear stability and numerical bifurcation analysis and simulations, we conclude that the cooperativity coefficient ( h ) for Hes1 self-repression should be large (i.e. h ≥4). Finally, we introduce the characteristic turnaround duration, and show that for our model the duration of the repression loop is between 40 and 60 min.

scholarly journals Ordered progression of stage-specific miRNA profiles in the mouse B2 B-cell lineage

Blood ◽  
2011 ◽  
Vol 117 (20) ◽  
pp. 5340-5349 ◽  
Author(s):  
Diana C. Spierings ◽  
Daniel McGoldrick ◽  
Ann Marie Hamilton-Easton ◽  
Geoffrey Neale ◽  
Elizabeth P. Murchison ◽  
...  
Keyword(s):  
B Cell ◽  
Mirna Expression ◽  
Developmental Stages ◽  
Wide Spectrum ◽  
Expression Profiles ◽  
Cell Lineage ◽  
Cell Development ◽  
B Cell Development ◽  
Novel Mirna ◽  
Micro Rnas

Abstract Micro-RNAs (miRNAs) have been recognized as critical regulators of gene expression, and deregulation of miRNA expression has been implicated in a wide spectrum of diseases. To provide a framework for the role of miRNAs in B-cell development and malignancy, we deep-sequenced miRNAs from B1 cells and 10 developmental stages that can be identified within the mouse B2 B-cell lineage. The expression profiles of the 232 known miRNAs that are expressed during B-cell development display stage-specific induction patterns, yet hierarchical clustering analysis showed relationships that are in full agreement with the model of the B2 B-cell developmental pathway. Analysis of exemplary miRNA expression profiles (miR-150, miR-146a, miR-155, miR-181) confirmed that our data are in agreement with previous results. The high resolution of the expression data allowed for the identification of the sequential expression of oncomir-1/miR-17-92 and its paralogs miR-106a-363 and miR-106b-25 in subsequent developmental stages in the BM. Further, we have identified and validated 45 novel miRNAs and 6 novel miRNA candidates expressed in developing B cells.

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