Search Results (27)

We identified Murashka, a RING finger protein, in an oogenesis screen as a regulator of Drosophila ovary germline stem cell niche development. Mutant alleles of murashka exhibited an enlarged niche phenotype reminiscent of increased Notch signalling and displayed genetic interactions with Notch alleles, and with polychaetoid, a regulator of Notch during niche development. These interactions uncovered both positive and negative impacts on Notch in different genetic backgrounds. In S2 cells, Murashka formed a complex with Notch and colocalised with Notch in the secretory pathway. Murashka expression in S2 cells down-regulated Notch signalling levels but could result in increased fold induction due to the proportionally greater decrease in basal ligand-independent activity. In vivo Murashka expression had different outcomes on different Notch target genes. We observed a decrease in the expression of vestigial along the anterior/posterior boundary of the wing imaginal disc, but not of wingless at the dorsal/ventral boundary. Instead, weak ectopic wingless was observed, which was synergistically increased by the coexpression of Deltex, a positive regulator of ligand-independent signalling. Our results identify a novel developmental role for murashka, a gene previously only associated with a function in long-term memory, and indicate a regulatory role for Murashka through a physical interaction with Notch that has context-dependent outcomes. Murashka adds to a growing number of ubiquitin ligase regulators which interact with Notch at different locations within its secretory and endocytic trafficking pathways. Full article

Bis(4-hydroxyphenyl) methane (BPF), as a bisphenolic compound, has toxic effects on organisms such as endocrine disruption and immobilization of growth and development. This study evaluated the effect concentrations of BPF on Chironomus tentans and investigated the impact of BPF exposure at various sub-lethal concentrations on the growth, development, and reproductive capacity of different instars of C. tentans. The results demonstrated that exposure at concentrations of 2.0, 2.5, 3.0, and 4.0 mg·L⁻¹ delayed pupation, inhibited the development of imaginal discs, and caused an initial rise followed by a decline in the expression levels of genes related to larval development (ecr, usp, e74). Additionally, exposure at concentrations of 1.0, 1.5, and 2.0 mg·L⁻¹ led to fluctuations in the expression levels of genes related to adult development and reproduction (ecr, kr-h1, foxo, inr, pdk, akt, and vg) in both female and male adults, with varying degrees of effect. Furthermore, BPF exposure inhibited male fertility, causing significant damage to the gonadal tissues, though it did not affect the final hatching of eggs. These findings indicate that BPF exhibits developmental and reproductive toxicity in C. tentans, with 2.0 mg·L⁻¹ identified as the lowest effective concentration at which BPF affects pupation in midges. Full article

Cancer cells expand rapidly in response to altered intercellular and signaling interactions to achieve the hallmarks of cancer. Impaired cell polarity combined with activated oncogenes is known to promote several hallmarks of cancer, e.g., activating invasion by increased activity of Jun N-terminal kinase (JNK) and sustained proliferative signaling by increased activity of Hippo effector Yorkie (Yki). Thus, JNK, Yki, and their downstream transcription factors have emerged as synergistic drivers of tumor growth through pro-tumor signaling and intercellular interactions like cell competition. However, little is known about the signals that converge onto JNK and Yki in tumor cells and enable tumor cells to achieve the hallmarks of cancer. Here, using mosaic models of cooperative oncogenesis (Ras^V12,scrib⁻) in Drosophila, we show that Ras^V12,scrib⁻ tumor cells grow through the activation of a previously unidentified network comprising Wingless (Wg), Dronc, JNK, and Yki. We show that Ras^V12,scrib⁻ cells show increased Wg, Dronc, JNK, and Yki signaling, and all these signals are required for the growth of Ras^V12,scrib⁻ tumors. We report that Wg and Dronc converge onto a JNK–Yki self-reinforcing positive feedback signal-amplification loop that promotes tumor growth. We found that the Wg–Dronc–Yki–JNK molecular network is specifically activated in polarity-impaired tumor cells and not in normal cells, in which apical-basal polarity remains intact. Our findings suggest that the identification of molecular networks may provide significant insights into the key biologically meaningful changes in signaling pathways and paradoxical signals that promote tumorigenesis. Full article

Cell cycle progression during development is meticulously coordinated with differentiation. This is particularly evident in the Drosophila 3rd instar eye imaginal disc, where the cell cycle is synchronized and arrests at the G1 phase in the non-proliferative region (NPR), setting the stage for photoreceptor cell differentiation. Here, we identify the transcription factor Nuclear Factor-YC (NF-YC) as a crucial player in this finely tuned progression, elucidating its specific role in the synchronized movement of the morphogenetic furrow. Depletion of NF-YC leads to extended expression of Cyclin A (CycA) and Cyclin B (CycB) from the FMW to the NPR. Notably, NF-YC knockdown resulted in decreased expression of Eyes absent (Eya) but did not affect Decapentaplegic (Dpp) and Hedgehog (Hh). Our findings highlight the role of NF-YC in restricting the expression of CycA and CycB in the NPR, thereby facilitating cell-cycle synchronization. Moreover, we identify the transcriptional cofactor Eya as a downstream target of NF-YC, revealing a new regulatory pathway in Drosophila eye development. This study expands our understanding of NF-YC’s role from cell cycle control to encompass developmental processes. Full article

The oriental fruit fly, Bactrocera dorsalis (Hendel), is a notorious invasive pest that has raised concerns worldwide. Validamycin has been demonstrated to be a very strong inhibitor against trehalase in a variety of organisms. However, whether validamycin can inhibit trehalase activity to suppress trehalose hydrolysis and affect any other relevant physiological pathways in B. dorsalis remains unknown. In this study, the effects of validamycin injection on the synthesis and metabolism of trehalose and chitin were evaluated. The results show that validamycin injection significantly affected trehalase activity and caused trehalose accumulation. In addition, the downstream pathways of trehalose hydrolysis, including the synthesis and metabolism of chitin, were also remarkably affected as the expressions of the key genes in these pathways were significantly regulated and the chitin contents were changed accordingly. Intriguingly, the upstream trehalose synthesis was also affected by validamycin injection due to the variations in the expression levels of key genes, especially BdTPPC1. Moreover, BdTPPC1 was predicted to have a binding affinity to validamycin, and the subsequent in vitro recombinant enzyme activity assay verified the inhibitory effect of validamycin on BdTPPC1 activity for the first time. These findings collectively indicate that validamycin can be considered as a promising potential insecticide for the management of B. dorsalis. Full article

Oncogenic mutations in the small GTPase Ras contribute to ~30% of human cancers. However, tissue growth induced by oncogenic Ras is restrained by the induction of cellular senescence, and additional mutations are required to induce tumor progression. Therefore, identifying cooperating cancer genes is of paramount importance. Recently, the tensin family of focal adhesion proteins, TNS1-4, have emerged as regulators of carcinogenesis, yet their role in cancer appears somewhat controversial. Around 90% of human cancers are of epithelial origin. We have used the Drosophila wing imaginal disc epithelium as a model system to gain insight into the roles of two orthologs of human TNS2 and 4, blistery (by) and PVRAP, in epithelial cancer progression. We have generated null mutations in PVRAP and found that, as is the case for by and mammalian tensins, PVRAP mutants are viable. We have also found that elimination of either PVRAP or by potentiates Ras^V12-mediated wing disc hyperplasia. Furthermore, our results have unraveled a mechanism by which tensins may limit Ras oncogenic capacity, the regulation of cell shape and growth. These results demonstrate that Drosophila tensins behave as suppressors of Ras-driven tissue hyperplasia, suggesting that the roles of tensins as modulators of cancer progression might be evolutionarily conserved. Full article

Drosophila melanogaster imaginal discs are larval internal structures that become the external organs of the adult. They have been used to study numerous developmental processes for more than fifty years. Dissecting these imaginal discs for collection is challenging, as the size of third-instar larvae organs is typically less than 1 mm. Certain experimental applications of the organs require many cells, which requires researchers to spend several hours dissecting them. This paper proposes an alternative to dissection in the form of a mass enrichment protocol. The protocol enables the recovery of many wing imaginal discs by grinding large quantities of third-instar larvae and separating the organs using filtration and a density gradient. The wing imaginal discs collected with this protocol in less than three hours are as well preserved as those collected by dissection. The dissociation and filtration of the extract allow the isolation of a large amount of wing imaginal disc cells. Full article

Polyamines are small organic cations that are essential for many biological processes such as cell proliferation and cell cycle progression. While the metabolism of polyamines has been well studied, the mechanisms by which polyamines are transported into and out of cells are poorly understood. Here, we describe a novel role of Chmp1, a vesicular trafficking protein, in the transport of polyamines using a well-defined leg imaginal disc assay in Drosophila melanogaster larvae. We show that Chmp1 overexpression had no effect on leg development in Drosophila, but does attenuate the negative impact on leg development of Ant44, a cytotoxic drug known to enter cells through the polyamine transport system (PTS), suggesting that the overexpression of Chmp1 downregulated the PTS. Moreover, we showed that the addition of spermine did not rescue the leg development in Chmp1-overexpressing leg discs treated with difluoromethylornithine (DFMO), an inhibitor of polyamine metabolism, while putrescine and spermidine did, suggesting that there may be unique mechanisms of import for individual polyamines. Thus, our data provide novel insight into the underlying mechanisms that are involved in polyamine transport and highlight the utility of the Drosophila imaginal disc assay as a fast and easy way to study potential players involved in the PTS. Full article

The loss-of-function conditions for an l(3)malignant brain tumour (l(3)mbt) in larvae reared at 29 °C results in malignant brain tumours and hyperplastic imaginal discs. Unlike the former that have been extensively characterised, little is known about the latter. Here we report the results of a study of the hyperplastic l(3)mbt mutant wing imaginal discs. We identify the l(3)mbt wing disc tumour transcriptome and find it to include genes involved in reactive oxygen species (ROS) metabolism. Furthermore, we show the presence of oxidative stress in l(3)mbt hyperplastic discs, even in apoptosis-blocked conditions, but not in l(3)mbt brain tumours. We also find that chemically blocking oxidative stress in l(3)mbt wing discs reduces the incidence of wing disc overgrowths. Our results reveal the involvement of oxidative stress in l(3)mbt wing discs hyperplastic growth. Full article

The Drosophila imaginal disc has been an excellent model for the study of developmental gene regulation. In particular, long non-coding RNAs (lncRNAs) have gained widespread attention in recent years due to their important role in gene regulation. Their specific spatiotemporal expressions further support their role in developmental processes and diseases. In this study, we explored the role of a novel lncRNA in Drosophila leg development by dissecting and dissociating w¹¹¹⁸ third-instar larval third leg (L3) discs into single cells and single nuclei, and performing single-cell RNA-sequencing (scRNA-seq) and single-cell assays for transposase-accessible chromatin (scATAC-seq). Single-cell transcriptomics analysis of the L3 discs across three developmental timepoints revealed different cell types and identified lncRNA:CR33938 as a distal specific gene with high expression in late development. This was further validated by fluorescence in-situ hybridization (FISH). The scATAC-seq results reproduced the single-cell transcriptomics landscape and elucidated the distal cell functions at different timepoints. Furthermore, overexpression of lncRNA:CR33938 in the S2 cell line increased the expression of leg development genes, further elucidating its potential role in development. Full article

This paper explores the intersection of personal responsibility, futility, and faith in visual representations of nuclear apocalypse. In two films produced during the late Cold War, Testament (1983) and When the Wind Blows (1986), the protagonists attempt to follow public guidance, maintain daily routines as their health and communities break down, and make muddled connections to religious faith. In Testament, a mother is left to care for her children in suburban California for months after an unexplained nuclear attack isolates and contaminates the town. In When the Wind Blows, a retired couple living in the British countryside diligently follow government instructions to “protect and survive”, while quickly succumbing to radiation poisoning. In a contrasting post-Cold War visual representation, the speculative artwork of the artists Erich Berger and Mari Keto imagine the storage of nuclear waste as a personal responsibility. In OpenCare (2016), waste is encased in steel pellets mounted on a bronze disc, and a series of artifacts and instructions assist in determining continued toxicity. While Testament and When the Wind Blows project the futility of personal responsibility and faith in nuclear survival, Berger and Keto’s system envisions a deep nuclear future requiring continued personal management and care. Full article

Mutations in the insulin gene (INS) are frequently associated with human permanent neonatal diabetes mellitus. However, the mechanisms underlying the onset of this genetic disease is not sufficiently decoded. We induced expression of two types of human mutant INSs in Drosophila using its ectopic expression system and investigated the resultant responses in development. Expression of the wild-type preproinsulin in the insulin-producing cells (IPCs) throughout the larval stage led to a stimulation of the overall and wing growth. However, ectopic expression of human mutant preproinsulins, hINS^C96Y and hINS^{LB15YB16delinsH}, neither of which secreted from the β-cells, could not stimulate the Drosophila growth. Furthermore, neither of the mutant polypeptides induced caspase activation leading to apoptosis. Instead, they induced expression of several markers indicating the activation of unfolded protein response, such as ER stress-dependent Xbp1 mRNA splicing and ER chaperone induction. We newly found that the mutant polypeptides induced the expression of Growth arrest and DNA-damage-inducible 45 (Gadd45) in imaginal disc cells. ER stress induced by hINS^C96Y also activated the JAK-STAT signaling, involved in inflammatory responses. Collectively, we speculate that the diabetes-like growth defects appeared as a consequence of the human mutant preproinsulin expression was involved in dysfunction of the IPCs, rather than apoptosis. Full article

Since their discovery, heat shock proteins (HSPs) have been identified in all domains of life, which demonstrates their importance and conserved functional role in maintaining protein homeostasis. Mitochondria possess several members of the major HSP sub-families that perform essential tasks for keeping the organelle in a fully functional and healthy state. In humans, the mitochondrial HSP70 chaperone system comprises a central molecular chaperone, mtHSP70 or mortalin (HSPA9), which is actively involved in stabilizing and importing nuclear gene products and in refolding mitochondrial precursor proteins, and three co-chaperones (HSP70-escort protein 1—HEP1, tumorous imaginal disc protein 1—TID-1, and Gro-P like protein E—GRPE), which regulate and accelerate its protein folding functions. In this review, we summarize the roles of mitochondrial molecular chaperones with particular focus on the human mtHsp70 and its co-chaperones, whose deregulated expression, mutations, and post-translational modifications are often considered to be the main cause of neurological disorders, genetic diseases, and malignant growth. Full article

Nucleolar stress occurs when ribosome production or function declines. Nucleolar stress in stem cells or progenitor cells often leads to disease states called ribosomopathies. Drosophila offers a robust system to explore how nucleolar stress causes cell cycle arrest, apoptosis, or autophagy depending on the cell type. We provide an overview of nucleolar stress in Drosophila by depleting nucleolar phosphoprotein of 140 kDa (Nopp140), a ribosome biogenesis factor (RBF) in nucleoli and Cajal bodies (CBs). The depletion of Nopp140 in eye imaginal disc cells generates eye deformities reminiscent of craniofacial deformities associated with the Treacher Collins syndrome (TCS), a human ribosomopathy. We show the activation of c-Jun N-terminal Kinase (JNK) in Drosophila larvae homozygous for a Nopp140 gene deletion. JNK is known to induce the expression of the pro-apoptotic Hid protein and autophagy factors Atg1, Atg18.1, and Atg8a; thus, JNK is a central regulator in Drosophila nucleolar stress. Ribosome abundance declines upon Nopp140 loss, but unusual cytoplasmic granules accumulate that resemble Processing (P) bodies based on marker proteins, Decapping Protein 1 (DCP1) and Maternal expression at 31B (Me31B). Wild type brain neuroblasts (NBs) express copious amounts of endogenous coilin, but coilin levels decline upon nucleolar stress in most NB types relative to the Mushroom body (MB) NBs. MB NBs exhibit resilience against nucleolar stress as they maintain normal coilin, Deadpan, and EdU labeling levels. Full article

Although RAS family genes play essential roles in tumorigenesis, effective treatments targeting RAS-related tumors are lacking, partly because of an incomplete understanding of the complex signaling crosstalk within RAS-related tumors. Here, we performed a large-scale genetic screen in Drosophila eye imaginal discs and identified Misshapen (Msn) as a tumor suppressor that synergizes with oncogenic Ras (Ras^V12) to induce c-Jun N-terminal kinase (JNK) activation and Hippo inactivation, then subsequently leads to tumor overgrowth and invasion. Moreover, ectopic Msn expression activates Hippo signaling pathway and suppresses Hippo signaling disruption-induced overgrowth. Importantly, we further found that Msn acts downstream of protocadherin Fat (Ft) to regulate Hippo signaling. Finally, we identified msn as a Yki/Sd target gene that regulates Hippo pathway in a negative feedback manner. Together, our findings identified Msn as a tumor suppressor and provide a novel insight into RAS-related tumorigenesis that may be relevant to human cancer biology. Full article