Background. Juvenile hormone (JH) has been demonstrated to control adult lifespan in a number of non-model insects where surgical removal of the corpora allata eliminates the hormones source. In contrast, little is known about how juvenile hormone affects adult Drosophila melanogaster. Previous work suggests that insulin signaling may modulate Drosophila aging in part through its impact on juvenile hormone titer, but no data yet addresses whether reduction of juvenile hormone is sufficient to control Drosophila life span. Here we adapt a recent genetic approach to knock out the corpora allata in adult Drosophila melanogaster and characterize adult life history phenotypes produced by reduction of juvenile hormone. With this system we test potential explanations for how juvenile hormone modulates aging.
Juvenile hormone regulation of Drosophila aging.
Sex
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Core transcriptional regulatory circuit controlled by the TAL1 complex in human T cell acute lymphoblastic leukemia.
Disease, Cell line
View SamplesThe oncogenic transcription factor TAL1/SCL is aberrantly overexpressed in over 40% of cases of T-cell acute lymphoblastic leukemia (T-ALL), emphasizing the importance of the TAL1-regulated transcriptional program in the molecular pathogenesis of T-ALL. Here we identify the core transcriptional regulatory circuit controlled by TAL1 and its regulatory partners HEB, E2A, GATA3, ETS1 and RUNX1 in T-ALL cells. We find that TAL1 forms an interconnected auto-regulatory loop with its partners, which contributes to the sustained upregulation of its direct target genes. Importantly, we also find the MYB oncogenic transcription factor is directly activated by the TAL1 complex and positively regulates many of the same target genes, thus forming a feed-forward positive regulatory loop that further promotes the TAL1-regulated oncogenic program.
Core transcriptional regulatory circuit controlled by the TAL1 complex in human T cell acute lymphoblastic leukemia.
Cell line
View SamplesMammalian insulin and IGF induce similar but not identical changes in gene expression downstream of their respective receptors. Signaling bias at the receptor differentiates the two similar ligands, though the precise mechanism is not entirely understood. We used Drosophila insulin-like peptides DILP2 and DILP5 to determine how similar insulin-like ligands regulate similar and distinct patterns of gene expression in S2 cells by RNA-Seq. Overall, DILP2 and DILP5 stimulate many of the same changes in gene expression. However, some genes are uniquely regulated by DILP2 or by DILP5. Shared and distinct gene targets were validated by q-RT-PCR with indepedent replicates. Some unique gene targets of DILP2 are involved in sugar metabolism, which is functionally related in vivo to DILP2 and not DILP5. We find that gene expression is largely regulated in parallel by DILP2 and DILP5 but some key unique targets may lead to differential physiological functions for the two insulin-like genes. Overall design: mRNA profiles from S2 cells treated with DILP2, DILP5 or solvent were sequenced on an Illumina HiSeq2500
<i>Drosophila</i> Insulin-Like Peptides DILP2 and DILP5 Differentially Stimulate Cell Signaling and Glycogen Phosphorylase to Regulate Longevity.
Cell line, Treatment, Subject
View SamplesPreviously we and other teams have found that 20E modulates the induction and expression of antimicrobial peptides (AMPs) in immune-challenged Drosophila cell culture or whole animals.
Ecdysone triggered PGRP-LC expression controls Drosophila innate immunity.
Specimen part
View SamplesJuvenile hormone (JH) and 20-hydroxy-ecdysone (20E) are highly versatile hormones, coordinating development, growth, and reproduction in insects. Pulses of 20E provide key signals for initiating developmental and physiological transitions, while JH promotes or inhibits these signals in a stage-specific manner. Previous evidence suggests that JH and 20E might modulate innate immunity, but whether and how these hormones interact to regulate the immune response remains unclear. Here we show that JH and 20E have antagonistic effects on the expression of antimicrobial peptides (AMPs) in Drosophila melanogaster. In S2* cells challenged with bacterial peptidoglycans, 20E induces promoter activity and expression of AMPs in a dose-dependent manner, while JH III and its synthetic analogs (JHa) methoprene and pyriproxyfen abolish this 20E-dependent response. Using microarrays and GFP reporter gene assays in adult flies, we confirm that JH is a hormonal immuno-suppressor in vivo. When silencing both partners of the ecdysone receptor (EcR ) / ultraspiracle (USP) heterodimer with RNAi in S2* cells, 20E fails to activate Diptericin (Dpt) expression, suggesting that 20E regulates expression of this gene through EcR / USP signaling. In contrast, silencing methoprene-tolerant (MET), a candidate JH receptor, does not impair the immuno-suppressive action of JH III and JHa, indicating that in this context MET does not function as a JH receptor. Our results suggest that the balance of 20E and JH is a major determinant of immune homeostasis in insects.
Hormonal regulation of the humoral innate immune response in Drosophila melanogaster.
Sex
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Characterization of a novel OTX2-driven stem cell program in Group 3 and Group 4 medulloblastoma.
Cell line
View SamplesMedulloblastoma (MB) is the most common malignant primary pediatric brain cancer. Among the most aggressive subtypes, Group 3 and Group 4 originate from stem/progenitor cells, frequently metastasize, and often display the worst prognosis, yet, as the names imply, we know the least about the molecular mechanisms driving their progression. Here, we show that the transcription factor orthodenticle homeobox 2 (OTX2) promotes self-renewal while inhibiting differentiation in vitro and increases tumor-initiating capacity from MB stem cell populations in vivo. Characterization of the OTX2 regulatory network revealed a novel relationship between OTX2 and genes associated with multiple axon guidance signaling pathways in Group 3 and Group 4 MB stem/progenitor cells. In particular, OTX2 levels were negatively correlated with semaphorin (SEMA) signaling, as expression of 9 SEMA pathway genes is upregulated following OTX2 knockdown with some being potential direct OTX2 targets. Importantly, this negative correlation between OTX2 and SEMA pathway genes was also observed in patient samples, with lower expression of SEMA4D associated with poor outcome in Group 3 and 4 tumors. Functional studies using established and newly derived MB cell lines demonstrated that increased levels of SEMA pathway genes are associated with decreased self-renewal and growth, and that RHO signaling, known to mediate the effects of SEMA genes, is contributing to the OTX2 KD phenotype. Our study provides critical mechanistic insight into the networks controlled by OTX2 in self-renewing MB cells and reveals novel roles for axon guidance genes and their downstream effectors as putative tumor suppressors and therapeutic targets in Group 3 and Group 4 MB.
Characterization of a novel OTX2-driven stem cell program in Group 3 and Group 4 medulloblastoma.
Cell line
View SamplesTargeted molecular therapy has yielded remarkable outcomes in certain cancers, but specific therapeutic targets remain elusive for many others. As a result of two independent RNA interference (RNAi) screens, we identified pathway dependence on a member of the JAK tyrosine kinase family, TYK2, and its downstream effector STAT1 in T-cell acute lymphoblastic leukemia (T-ALL). Gene knockdown experiments consistently demonstrated TYK2 dependence in both T-ALL primary specimens and cell lines, and a small-molecule inhibitor of JAK kinase activity induced T-ALL cell death. Activation of this TYK2-STAT1 pathway in T-ALL cell lines occurs by gain-of-function TYK2 mutations or activation of IL-10 receptor signaling, and this pathway mediates T-ALL cell survival through upregulation of the anti-apoptotic protein BCL2. These findings indicate that in many T-ALL cases, the leukemic cells are dependent upon the TYK2-STAT1-BCL2 pathway for continued survival, supporting the development of molecular therapies targeting TYK2 and other components of this pathway.
TYK2-STAT1-BCL2 pathway dependence in T-cell acute lymphoblastic leukemia.
Specimen part, Cell line
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Microcephaly gene links trithorax and REST/NRSF to control neural stem cell proliferation and differentiation.
Time
View Samples