GFP reporters detect the activation of the Drosophila JAK/STAT pathway in vivo

Bach, Erika A.; Ekas, Laura A.; Ayala-Camargo, Aidee; Flaherty, Maria Sol; Lee, Haeryun; Perrimon, Norbert; Baeg, Gyeong-Hun

doi:10.1016/j.modgep.2006.08.003

Cited by 345 publications

(408 citation statements)

References 46 publications

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“…During eye development, the pathway promotes growth of the early eye field, contributes to initiation and movement of the morphogenetic furrow and to regional eye specification, transduces information from the dorsal-ventral axis to direct ommatidial rotation, and regulates specification and maintenance of the optic lobe neuroepithelium (Luo et al 1999;Zeidler et al 1999 Identification of hop, Stat92E, Socs36E, and Socs44A in our genetic screen ( Table 1) and finding that GMR-driven knockdown of these genes produces axon mistargeting phenotypes (Figure 2, A-E) suggested that the Jak/Stat pathway is also active in postmitotic photoreceptors. In support of this, expression of the 10xStat-eGFP pathway activity reporter suggests that early expression of the ligand, upd, which is absent by the third instar, enables sustained Jak/Stat signaling in the photoreceptors at the time they are sending out their axons (Bach et al 2007). As predicted, GMR-Gal4-driven knockdown of the receptor dome, but not of the upd ligands, produced significant mistargeting defects (Figure 3, A-C).…”

Section: Resultssupporting

confidence: 66%

Retinal Axon Guidance Requires Integration of Eya and the Jak/Stat Pathway into Phosphotyrosine-Based Signaling Circuitries in Drosophila

2016

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The transcriptional coactivator and phosphatase eyes absent (Eya) is dynamically compartmentalized between the nucleus and cytoplasm. Although the nuclear transcriptional circuits within which Eya operates have been extensively characterized, understanding of its cytoplasmic functions and interactions remains limited. Our previous work showed that phosphorylation of Drosophila Eya by the Abelson tyrosine kinase can recruit Eya to the cytoplasm and that eya-abelson interactions are required for photoreceptor axons to project to correct layers in the brain. Based on these observations, we postulated that photoreceptor axon targeting might provide a suitable context for identifying the cytoplasmic signaling cascades with which Eya interacts. Using a dosesensitive eya misexpression background, we performed an RNA interference-based genetic screen to identify suppressors. Included among the top 10 hits were nonreceptor tyrosine kinases and multiple members of the Jak/Stat signaling network (hop, Stat92E, Socs36E, and Socs44A), a pathway not previously implicated in axon targeting. Individual loss-of-function phenotypes combined with analysis of axonal projections in Stat92E null clones confirmed the importance of photoreceptor autonomous Jak/Stat signaling. Experiments in cultured cells detected cytoplasmic complexes between Eya and Hop, Socs36E and Socs44A; the latter interaction required both the Src homology 2 motif in Socs44A and tyrosine phosphorylated Eya, suggesting direct binding and validating the premise of the screen. Taken together, our data provide new insight into the cytoplasmic phosphotyrosine signaling networks that operate during photoreceptor axon guidance and suggest specific points of interaction with Eya.KEYWORDS SH2; genetic screen; retinal determination network; eye development; Socs44A A remarkable feature of multicellular animal development is that the complexity and diversity in tissue type and patterning is achieved using fewer than a dozen signaling pathways, including Notch, receptor tyrosine kinase, Wnt, Hedgehog, TGFb, Jak/Stat, and Hippo. These cascades are repeatedly deployed in different contexts to regulate the majority of the critical proliferation, survival, specification, and differentiation decisions (reviewed in Voas and Rebay 2004;Housden and Perrimon 2014). One strategy to achieve context-specific developmental regulation is for proteins and pathways to function together in interconnected networks. Further, individual proteins within these networks may encode multiple independent functions that can be executed in distinct parts of the cell, cell types, or stages of development. In this way, even a modest number of individual proteins and core pathways can create vast combinatorial possibilities.Eyes absent (Eya), a protein conserved from plants to humans, presents an ideal model to study integration because its multifunctionality and dynamic subcellular localization provide opportunities for interaction with many signaling pathways (reviewed in Jemc andRebay 2007 an...

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Section: Resultssupporting

confidence: 66%

Retinal Axon Guidance Requires Integration of Eya and the Jak/Stat Pathway into Phosphotyrosine-Based Signaling Circuitries in Drosophila

2016

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“…We also examined the activation of JAK/STAT signaling by using GFP reporter flies that harbor a GFP gene downstream of two STAT-binding sequences (2×STAT-GFP; Fig. 2C) (23). The larvae of 2×STAT-GFP-bearing senju 1 showed constitutive activation of the JAK/STAT pathway.…”

Section: Resultsmentioning

confidence: 99%

Dynamic regulation of innate immune responses in Drosophila by Senju-mediated glycosylation

Yamamoto-Hino

Muraoka

Kondo

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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The innate immune system is the first line of defense encountered by invading pathogens. Delayed and/or inadequate innate immune responses can result in failure to combat pathogens, whereas excessive and/or inappropriate responses cause runaway inflammation. Therefore, immune responses are tightly regulated from initiation to resolution and are repressed during the steady state. It is well known that glycans presented on pathogens play important roles in pathogen recognition and the interactions between host molecules and microbes; however, the function of glycans of host organisms in innate immune responses is less well known. Here, we show that innate immune quiescence and strength of the immune response are controlled by host glycosylation involving a novel UDPgalactose transporter called Senju. In senju mutants, reduced expression of galactose-containing glycans resulted in hyperactivation of the Toll signaling pathway in the absence of immune challenges. Genetic epistasis and biochemical analyses revealed that Senju regulates the Toll signaling pathway at a step that converts Toll ligand Spatzle to its active form. Interestingly, Toll activation in immune-challenged wild type (WT) flies reduced the expression of galactose-containing glycans. Suppression of the degalactosylation by senju overexpression resulted in reduced induction of Toll-dependent expression of an antimicrobial peptide, Drosomycin, and increased susceptibility to infection with Gram-positive bacteria. These data suggest that Senju-mediated galactosylation suppresses undesirable Toll signaling activation during the steady state; however, Toll activation in response to infection leads to degalactosylation, which raises the immune response to an adequate level and contributes to the prompt elimination of pathogens.innate immunity | glycosylation | Toll pathway | nucleotide sugar transporter | galactose

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“…In younger wing discs (second to third instar), WTSTDpZ expression in the pouch appeared somewhat more dependent on STAT92E than in the third-instar tissue (Fig. S2), possibly reflecting the underlying shift in the STAT92E activation pattern based on the gradually shifting distribution of the ligand upd during development (7,18). A control in which stat92E Ϫ/Ϫ clones were induced in the MTSTDpZ background had no effect on reporter expression (data not shown).…”

Section: Stat92ementioning

confidence: 94%

STAT92E is a positive regulator ofDrosophilainhibitor of apoptosis 1 (DIAP/1) and protects against radiation-induced apoptosis

Betz¹,

Ryoo

Steller

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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The proapoptotic factors Reaper, Hid, Grim, and Sickle regulate apoptosis in Drosophila by inhibiting the antiapoptotic factor DIAP1 (Drosophila inhibitor of apoptosis 1). Heat, UV light, x-rays, and developmental signals can all increase the proapoptotic factors, but the control of transcription of the diap1 gene is unclear. We show that in imaginal discs the single Drosophila STAT protein (STAT92E) when activated can directly increase DIAP1 through binding to STAT DNA-binding sites in the diap1 promoter. The STAT92E contribution to DIAP1 production is required for cell survival after x-irradiation but not under unstressed conditions. Because DIAP1 prevents apoptosis after a variety of stresses, STAT92E may have a role in regulating stress responses in general.Jak STAT ͉ stress ͉ cancer ͉ survival T he regulation of apoptosis is highly conserved in animals and is thought to limit the risk of genomic instability and cancer. Its function depends on the balanced levels of proapoptotic and antiapoptotic proteins (1).The Drosophila proapoptotic factors Reaper, Hid, Grim, and Sickle [also called IAP-binding motif (IBM) proteins] are specifically increased by a variety of agents, both intrinsic developmental signals and extrinsic events (e.g., heat, UV, and ionizing radiation) (2). Inhibition by the IBM proteins of the antiapoptotic activity of DIAP1 (Drosophila inhibitor of apoptosis 1) (3, 4) releases Dronc (the Drosophila caspase 9 ortholog) and drice/dcp1 (caspase 3 ortholog), triggering apoptosis. Proteinprotein interactions of DIAP1 with the IBM proteins and with caspases have received extensive examination (2, 5). However, to our knowledge, direct transcriptional regulation by specific transcription factor(s) of the widely expressed diap1 gene has not been described.Two of the seven human STAT family members are antiapoptotic and their overactivity is correlated with cancer, heightening the previously unrecognized antiapoptotic role of STAT92E. The simpler Jak-STAT pathway in Drosophila consists of the ligands unpaired 1, 2, and 3 and the receptor domeless, with which one Jak family kinase, hopscotch, is associated. Mutations in the pathway affect a wide variety of processes including a positive effect on the cell cycle (6-8).We now report that the full-length tyrosine-phosphorylated STAT92E isoform participates in blocking apoptosis in vivo by acting through highly conserved STAT DNA-binding sites in the diap1 promoter to maintain normal DIAP1 levels. In developing eye and wing discs, STAT92E, although not critical for maintaining basal levels of DIAP1 for survival under unstressed conditions, increases DIAP1 to levels required to combat stressinduced apoptosis.

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GFP reporters detect the activation of the Drosophila JAK/STAT pathway in vivo

Cited by 345 publications

References 46 publications

Retinal Axon Guidance Requires Integration of Eya and the Jak/Stat Pathway into Phosphotyrosine-Based Signaling Circuitries in Drosophila

Retinal Axon Guidance Requires Integration of Eya and the Jak/Stat Pathway into Phosphotyrosine-Based Signaling Circuitries in Drosophila

Dynamic regulation of innate immune responses in Drosophila by Senju-mediated glycosylation

STAT92E is a positive regulator ofDrosophilainhibitor of apoptosis 1 (DIAP/1) and protects against radiation-induced apoptosis

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