Identification and Characterization of Genes Involved in Embryonic Crystal Cell Formation During Drosophila Hematopoiesis

Milchanowski, Allison B.; Henkenius, Amy L.; Narayanan, Maya; Hartenstein, Volker; Banerjee, Utpal

doi:10.1534/genetics.104.028639

Cited by 28 publications

(26 citation statements)

References 96 publications

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“…Indeed, the Srp/Lz complex is necessary and sufficient to induce the differentiation of this blood cell lineage (26,28,70). Also, a mutation in med13 was previously reported to impair crystal cell development (54). To assess the function of the four CDK8 module subunits during this process, we first used available null alleles of the corresponding genes (48,67).…”

Section: Resultsmentioning

confidence: 99%

A Genome-Wide RNA Interference Screen Identifies a Differential Role of the Mediator CDK8 Module Subunits for GATA/ RUNX-Activated Transcription in Drosophila

Gobert

Osman

Bras

et al. 2010

Molecular and Cellular Biology

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Transcription factors of the RUNX and GATA families play key roles in the control of cell fate choice and differentiation, notably in the hematopoietic system. During Drosophila hematopoiesis, the RUNX factor Lozenge and the GATA factor Serpent cooperate to induce crystal cell differentiation. We used Serpent/ Lozenge-activated transcription as a paradigm to identify modulators of GATA/RUNX activity by a genomewide RNA interference screen in cultured Drosophila blood cells. Among the 129 factors identified, several belong to the Mediator complex. Mediator is organized in three modules plus a regulatory "CDK8 module," composed of Med12, Med13, CycC, and Cdk8, which has long been thought to behave as a single functional entity. Interestingly, our data demonstrate that Med12 and Med13 but not CycC or Cdk8 are essential for Serpent/Lozenge-induced transactivation in cell culture. Furthermore, our in vivo analysis of crystal cell development show that, while the four CDK8 module subunits control the emergence and the proliferation of this lineage, only Med12 and Med13 regulate its differentiation. We thus propose that Med12/Med13 acts as a coactivator for Serpent/Lozenge during crystal cell differentiation independently of CycC/Cdk8. More generally, we suggest that the set of conserved factors identified herein may regulate GATA/RUNX activity in mammals.During hematopoiesis, multipotent progenitors or stem cells generate a large spectrum of specialized cell types through the progressive deployment of cell-specific gene expression programs (59). In that respect, it is of particular interest to understand how combinatorial inputs from general and lineage-specific transcription factors converge to modulate RNA polymerase II machinery and establish the gene expression programs intrinsic to cell diversification. Over the last decade, cross-species conservation has shown that Drosophila is a valuable model system to gain insights into the mechanisms controlling blood cell fate choice and differentiation at the transcriptional level (36). Indeed, several key transcription factors and cofactors regulating blood cell development in vertebrates also participate in hematopoiesis in Drosophila.Reminiscent of the situation in vertebrates, hematopoiesis in the fruit fly occurs in two temporally and spatially distinct waves: blood cell progenitors (prohemocytes) arise first from the head mesoderm in the early embryo and then from a specialized organ, the lymph gland, in the larva (36). These progenitors differentiate into two main cell types, most closely related to vertebrate myeloid lineages: plasmatocytes, which function as macrophages, and crystal cells, which participate in melanization and clotting (53). So far, we have a better understanding of the transcriptional network controlling blood cell development in the embryo. In particular, it appears that transcription factors of the GATA and RUNX families, which regulate several steps of hematopoiesis in vertebrates, act together to control Drosophila blood cell fate choice and...

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Section: Resultsmentioning

confidence: 99%

A Genome-Wide RNA Interference Screen Identifies a Differential Role of the Mediator CDK8 Module Subunits for GATA/ RUNX-Activated Transcription in Drosophila

Gobert

Osman

Bras

et al. 2010

Molecular and Cellular Biology

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“…It has been studied in processes including axon pruning, sperm development, and sperm individualization. In the context of fly immunity, cbx has been identified from a genetic screen to possibly have a role in crystal cell development, a type of immune cell in the fly (Milchanowski et al 2004). The identification of this gene may reveal a role for crystal cells in the host defense against bacterial infection.…”

Section: Resultsmentioning

confidence: 99%

Identification of Drosophila Mutants Altering Defense of and Endurance to Listeria monocytogenes Infection

2008

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We extended the use of Drosophila beyond being a model for signaling pathways required for pattern recognition immune signaling and show that the fly can be used to identify genes required for pathogenesis and host-pathogen interactions. We performed a forward genetic screen to identify Drosophila mutations altering sensitivity to the intracellular pathogen Listeria monocytogenes. We recovered 18 mutants with increased susceptibility to infection, none of which were previously shown to function in a Drosophila immune response. Using secondary screens, we divided these mutants into two groups: In the first group, mutants have reduced endurance to infections but show no change in bacterial growth. This is a new fly immunity phenotype that is not commonly studied. In the second group, mutants have a typical defense defect in which bacterial growth is increased and survival is decreased. By further challenging mutant flies with L. monocytogenes mutants, we identified subgroups of fly mutants that affect specific stages of the L. monocytogenes life cycle, exit from the vacuole, or actin-based movement. There is no overlap between our genes and the hundreds of genes identified in Drosophila S2 cells fighting L. monocytogenes infection, using genomewide RNAi screens in vitro. By using a whole-animal model and screening for host survival, we revealed genes involved in physiologies different from those that were found in previous screens, which all had defects in defensive immune signaling. I NTRACELLULAR pathogens are responsible for a large group of infectious diseases; for example, .500 million people worldwide suffer from tuberculosis, AIDS, and malaria each year (http:/ /www.who.int). By residing in a host cell, these pathogens protect themselves from some host immune responses and drug therapies. The ability to enter and survive within a host cell requires a close and intricate interaction between pathogen and host; by manipulating host processes, pathogens can prevent immune responses or subvert host processes to aid in infection.Listeria monocytogenes is a gram-positive, facultative intracellular bacterium and is the cause of listeriosis, a serious food-borne disease. L. monocytogenes has been widely used as a model pathogen to better understand the molecular and cellular aspects of intracellular pathogenesis and mammalian cell-mediated immunity. In vitro studies using cultured cells as a model host defined the L. monocytogenes intracellular life cycle and virulence factors (Cossart and Lecuit 1998;Portnoy et al. 1988;Kreft and Vazquez-Boland 2001;Vazquez-Boland et al. 2001) and demonstrated that L. monocytogenes can enter professional phagocytes or nonphagocytic cells (Cossart et al. 2003). Entry into nonphagocytic cells is dependent on surface proteins called internalins (Cossart and Lecuit 1998;Lecuit et al. 1999Lecuit et al. , 2001. Upon entry, a single-membrane vacuole forms around the bacterium (Cossart and Lecuit 1998). Secretion of a pore-forming cytotoxin, listeriolysin O (LLO), disrupts the phag...

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“…Haemocytes, which originate from the haemocyte anlagen in the cellular blastoderm, are first distinguished at ES8 in the head mesoderm (Holz et al, 2003;Paladi and Tepass, 2004;Tepass et al, 1994). Of all embryonic haemocytes, 95% are plasmatocytes that migrate and differentiate into macrophages (Lebestky et al, 2000;Milchanowski et al, 2004;Tepass et al, 1994). Differentiation of haemocyte precursors into plasmatocytes is dependent upon the expression of the Glial Cell Missing (gcm) transcription factor (Bernardoni et al, 1997;Hosoya et al, 1995).…”

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confidence: 99%

Haemocyte-derived SPARC is required for collagen-IV-dependent stability of basal laminae inDrosophilaembryos

Martinek

Shahab

Saathoff

et al. 2008

Journal of Cell Science

120

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The authors wish to publish the following addendum to J. Cell Sci. 121, 1671-1680.Further characterization of the SPARC-null fly line Df(3R)nm136, generated by P-element mutagenesis, has revealed that the line carries a secondary mutation in the neuralized locus, in addition to an absence of SPARC. We have confirmed in a wild-type neuralized background that the absence of SPARC leads to a reduction of collagen IV in basal lamina in stage 17 mutant embryos. The absence of SPARC does not affect neural development during embryogenesis.

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Identification and Characterization of Genes Involved in Embryonic Crystal Cell Formation During Drosophila Hematopoiesis

Cited by 28 publications

References 96 publications

A Genome-Wide RNA Interference Screen Identifies a Differential Role of the Mediator CDK8 Module Subunits for GATA/ RUNX-Activated Transcription in Drosophila

A Genome-Wide RNA Interference Screen Identifies a Differential Role of the Mediator CDK8 Module Subunits for GATA/ RUNX-Activated Transcription in Drosophila

Identification of Drosophila Mutants Altering Defense of and Endurance to Listeria monocytogenes Infection

Haemocyte-derived SPARC is required for collagen-IV-dependent stability of basal laminae inDrosophilaembryos

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