Mechanical stress to Drosophila larvae stimulates a cellular immune response through the JAK/STAT signaling pathway.

Acute inflammation can cause serious tissue damage and disease in physiologically-challenged organisms. The precise mechanisms leading to these detrimental effects remain to be determined. In this study, we utilize a reproducible means to induce cellular immune activity in Drosophila larvae in response to mechanical stress.

The mir-7 and bag of marbles genes regulate Hedgehog pathway signaling in blood cell progenitors in Drosophila larval lymph glands.

Hedgehog (Hh) pathway signaling is crucial for the maintenance of blood cell progenitors in the lymph gland hematopoietic organ present in Drosophila third instar larvae. Previous studies from our lab have likewise shown the importance of the mir-7 and bag of marbles (bam) genes in maintaining the progenitor state. Thus, we sought to investigate a possible interaction between the Hh pathway and mir-7/bam in the prohemocyte population within this hematopoietic tissue.

The nociception genes painless and Piezo are required for the cellular immune response of Drosophila larvae to wasp parasitization.

In vertebrates, interaction between the nervous system and immune system is important to protect a challenged host from stress inputs from external sources. In this study, we demonstrate that sensory neurons are involved in the cellular immune response elicited by wasp infestation of Drosophila larvae. Multidendritic class IV neurons sense contacts from external stimuli and induce avoidance behaviors for host defense.

Screening and Analysis of Janelia FlyLight Project Enhancer-Gal4 Strains Identifies Multiple Gene Enhancers Active During Hematopoiesis in Normal and Wasp-Challenged Larvae.

A GFP expression screen has been conducted on >1000 Janelia FlyLight Project enhancer-Gal4 lines to identify transcriptional enhancers active in the larval hematopoietic system. A total of 190 enhancers associated with 87 distinct genes showed activity in cells of the third instar larval lymph gland and hemolymph. That is, gene enhancers were active in cells of the lymph gland posterior signaling center (PSC), medullary zone (MZ), and/or cortical zone (CZ), while certain of the transcriptional control regions were active in circulating hemocytes.

Bag of Marbles controls the size and organization of the Drosophila hematopoietic niche through interactions with the Insulin-like growth factor pathway and Retinoblastoma-family protein.

Bag of Marbles (Bam) is known to function as a positive regulator of hematopoietic progenitor maintenance in the lymph gland blood cell-forming organ during Drosophila hematopoiesis. Here, we demonstrate a key function for Bam in cells of the lymph gland posterior signaling center (PSC), a cellular domain proven to function as a hematopoietic niche. Bam is expressed in PSC cells, and gene loss-of-function results in PSC overgrowth and disorganization, indicating that Bam plays a crucial role in controlling the proper development of the niche.

bantam miRNA is important for Drosophila blood cell homeostasis and a regulator of proliferation in the hematopoietic progenitor niche.

The Drosophila hematopoietic system is utilized in this study to gain novel insights into the process of growth control of the hematopoietic progenitor niche in blood development. The niche microenvironment is an essential component controlling the balance between progenitor populations and differentiated, mature blood cells and has been shown to lead to hematopoietic malignancies in humans when misregulated. MicroRNAs are one class of regulators associated with blood malignancies; however, there remains a relative paucity of information about the role of miRNAs in the niche.

Knockdown of SCF(Skp2) function causes double-parked accumulation in the nucleus and DNA re-replication in Drosophila plasmatocytes.

In Drosophila, circulating hemocytes are derived from the cephalic mesoderm during the embryonic wave of hematopoiesis. These cells are contributed to the larva and persist through metamorphosis into the adult. To analyze this population of hemocytes, we considered data from a previously published RNAi screen in the hematopoietic niche, which suggested several members of the SCF complex play a role in lymph gland development.

Correction: Gene Regulatory Networks Controlling Hematopoietic Progenitor Niche Cell Production and Differentiation in the Drosophila Lymph Gland.

[This corrects the article DOI: 10.1371/journal.pone.

Gene regulatory networks controlling hematopoietic progenitor niche cell production and differentiation in the Drosophila lymph gland.

Hematopoiesis occurs in two phases in Drosophila, with the first completed during embryogenesis and the second accomplished during larval development. The lymph gland serves as the venue for the final hematopoietic program, with this larval tissue well-studied as to its cellular organization and genetic regulation. While the medullary zone contains stem-like hematopoietic progenitors, the posterior signaling center (PSC) functions as a niche microenvironment essential for controlling the decision between progenitor maintenance versus cellular differentiation.

Spire, an actin nucleation factor, regulates cell division during Drosophila heart development.

The Drosophila dorsal vessel is a beneficial model system for studying the regulation of early heart development. Spire (Spir), an actin-nucleation factor, regulates actin dynamics in many developmental processes, such as cell shape determination, intracellular transport, and locomotion. Through protein expression pattern analysis, we demonstrate that the absence of spir function affects cell division in Myocyte enhancer factor 2-, Tinman (Tin)-, Even-skipped- and Seven up (Svp)-positive heart cells.

Transcriptional regulation of eater gene expression in Drosophila blood cells.

Eater is a transmembrane protein that mediates phagocytosis in Drosophila. eater was identified in a microarray analysis of genes downregulated in S2 cells, in which Serpent had been knocked down by RNAi. The gene was shown to be expressed predominantly in plasmatocytes after embryonic development.

Serpent, suppressor of hairless and U-shaped are crucial regulators of hedgehog niche expression and prohemocyte maintenance during Drosophila larval hematopoiesis.

The lymph gland is a specialized organ for hematopoiesis, utilized during larval development in Drosophila. This tissue is composed of distinct cellular domains populated by blood cell progenitors (the medullary zone), niche cells that regulate the choice between progenitor quiescence and hemocyte differentiation [the posterior signaling center (PSC)], and mature blood cells of distinct lineages (the cortical zone). Cells of the PSC express the Hedgehog (Hh) signaling molecule, which instructs cells within the neighboring medullary zone to maintain a hematopoietic precursor state while preventing hemocyte differentiation.

Specific cell ablation in Drosophila using the toxic viral protein M2(H37A).

The expression of toxic viral proteins for the purpose of eliminating distinct populations of cells, while leaving the rest of an organism unaffected, is a valuable method for analyzing development. Using the Gal4-UAS system, we employed the M2(H37A) toxic ion channel of the influenza-A virus to selectively ablate the Drosophila eye-antennal imaginal discs, hemocytes, dorsal vessel and nervous tissue, and comparatively monitored the effects of expressing the apoptosis-promoting protein Reaper in identical cell populations. In this report, we demonstrate the effectiveness of M2(H37A)-mediated ablation as a new means to selectively eliminate cells of interest during Drosophila development.

CF2 represses Actin 88F gene expression and maintains filament balance during indirect flight muscle development in Drosophila.

The zinc finger protein CF2 is a characterized activator of muscle structural genes in the body wall muscles of the Drosophila larva. To investigate the function of CF2 in the indirect flight muscle (IFM), we examined the phenotypes of flies bearing five homozygous viable mutations. The gross structure of the IFM was not affected, but the stronger hypomorphic alleles caused an increase of up to 1.

New hemocyte-specific enhancer-reporter transgenes for the analysis of hematopoiesis in Drosophila.

Based on environmental challenges or altered genetic composition, Drosophila larvae can produce up to three types of blood cells that express genetic programs essential for their distinct functions. Using transcriptional enhancers for genes expressed exclusively in plasmatocytes, crystal cells, or lamellocytes, several new hemocyte-specific enhancer-reporter transgenes were generated to facilitate the analysis of Drosophila hematopoiesis. This approach took advantage of fluorescent variants of insulated P-element reporter vectors for multilabeling cell analyses; two additional color variants were generated in these studies.

Characterization of a lamellocyte transcriptional enhancer located within the misshapen gene of Drosophila melanogaster.

Drosophila has emerged as an excellent model system in which to study cellular and genetic aspects of hematopoiesis. Under normal developmental conditions and in wild-type genetic backgrounds, Drosophila possesses two types of blood cells, crystal cells and plasmatocytes. Upon infestation by a parasitic wasp or in certain altered genetic backgrounds, a third hemocyte class called the lamellocyte becomes apparent.

Second chromosome genes required for heart development in Drosophila melanogaster.

Heart development is an evolutionarily conserved process. The cardiac organ of Drosophila melanogaster is the dorsal vessel, a linear contractile tissue with cellular and morphogenetic similarities to the primitive heart tube formed at an early stage of vertebrate heart formation. Abundant evidence shows comparable intercellular signaling pathways and transcription factor networks are utilized in Drosophila and vertebrates, to specify cardiac progenitor cells and instruct their differentiation and function in forming the mature heart.

The Friend of GATA protein U-shaped functions as a hematopoietic tumor suppressor in Drosophila.

Drosophila has emerged as an important model system to discover and analyze genes controlling hematopoiesis. One regulatory network known to control hemocyte differentiation is the Janus kinase (JAK)/Signal Transducer and Activator of Transcription (STAT) signal-transduction pathway. A constitutive activation mutation of the Janus kinase Hopscotch (hopscotch(Tumorous-lethal); hop(Tum-l)) results in a leukemia-like over-proliferation of hemocytes and copious differentiation of lamellocytes during larval stages.

Identification of a crystal cell-specific enhancer of the black cells prophenoloxidase gene in Drosophila.

In Drosophila, Black cells (Bc) encodes a Prophenoloxidase and is expressed late in the maturation of crystal cells, which are blood cells involved in wound healing and immune encapsulation. Enhancer analysis of Bc revealed a 1,025-bp upstream sequence that regulates gene expression in a crystal cell exclusive pattern. Expression of this fragment is altered by mutations in the GATA family serpent (srp) and RUNX family lozenge (lz) genes; Srp and Lz are required for crystal cell specification.

Requirement of the LIM homeodomain transcription factor tailup for normal heart and hematopoietic organ formation in Drosophila melanogaster.

Dorsal vessel morphogenesis in Drosophila melanogaster serves as a superb system with which to study the cellular and genetic bases of heart tube formation. We used a cardioblast-expressed Toll-GFP transgene to screen for additional genes involved in heart development and identified tailup as a locus essential for normal dorsal vessel formation. tailup, related to vertebrate islet1, encodes a LIM homeodomain transcription factor expressed in all cardioblasts and pericardial cells of the heart tube as well as in associated lymph gland hematopoietic organs and alary muscles that attach the dorsal vessel to the epidermis.

U-shaped protein domains required for repression of cardiac gene expression in Drosophila.

U-shaped is a zinc finger protein that functions predominantly as a negative transcriptional regulator of cell fate determination during Drosophila development. In the early stages of dorsal vessel formation, the protein acts to control cardioblast specification, working as a negative attenuator of the cardiogenic GATA factor Pannier. Pannier and the homeodomain protein Tinman normally work together to specify heart cells and activate cardioblast gene expression.

Heart development in Drosophila.

The Drosophila heart, also called the dorsal vessel, is an organ for hemolymph circulation that resembles the vertebrate heart at its transient linear tube stage. Dorsal vessel morphogenesis shares several similarities with early events of vertebrate heart development and has proven to be an insightful system for the study of cardiogenesis due to its relatively simple structure and the productive use of Drosophila genetic approaches. In this review, we summarize published findings on Drosophila heart development in terms of the regulators and genetic pathways required for cardiac cell specification and differentiation, and organ formation and function.

Regulation of Drosophila friend of GATA gene, u-shaped, during hematopoiesis: a direct role for serpent and lozenge.

Friend of GATA proteins interact with GATA factors to regulate development in a variety of tissues. We analyzed cis- and trans-regulation of the Drosophila gene, u-shaped, to better understand the transcriptional control of this important gene family during hematopoiesis. Using overlapping genomic fragments driving tissue-specific reporter-gene (lacZ) expression, we identified two minimal hematopoietic enhancers within the 7.

Calcineurin function is required for myofilament formation and troponin I isoform transition in Drosophila indirect flight muscle.

Mutations in the Drosophila calcineurin B2 gene cause the collapse of indirect flight muscles during mid stages of pupal development. Examination of cell fate-specific markers indicates that unlike mutations in genes such as vestigial, calcineurin B2 does not cause a shift in cell fate from indirect flight muscle to direct flight muscle. Genetic and molecular analyses indicate a severe reduction of myosin heavy chain gene expression in calcineurin B2 mutants, which accounts at least in part for the muscle collapse.