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Guo H, Swan M, He B. An optogenetic tool to inhibit RhoA in Drosophila embryos. STAR Protoc 2023; 4:101972. [PMID: 36598852 PMCID: PMC9826882 DOI: 10.1016/j.xpro.2022.101972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/10/2022] [Accepted: 12/09/2022] [Indexed: 01/05/2023] Open
Abstract
We describe a protocol for optogenetic inhibition of the small GTPase Rho1 (RhoA) in Drosophila embryos, which allows rapid and spatially confined inactivation of Rho1 and Rho1-mediated actomyosin contractility. We provide step-by-step instruction for optogenetic manipulations of Drosophila embryos using confocal and multiphoton imaging systems. This tool is useful for determining the site- and stage-specific function of Rho1 in Drosophila embryos and for studying the immediate tissue response to acute elimination of cellular contractility. For complete details on the use and execution of this protocol, please refer to Guo et al. (2022).1.
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Affiliation(s)
- Hanqing Guo
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - Michael Swan
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Bing He
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.
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2
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Guo H, Swan M, He B. Optogenetic inhibition of actomyosin reveals mechanical bistability of the mesoderm epithelium during Drosophila mesoderm invagination. eLife 2022; 11:69082. [PMID: 35195065 PMCID: PMC8896829 DOI: 10.7554/elife.69082] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Accepted: 02/22/2022] [Indexed: 12/05/2022] Open
Abstract
Apical constriction driven by actin and non-muscle myosin II (actomyosin) provides a well-conserved mechanism to mediate epithelial folding. It remains unclear how contractile forces near the apical surface of a cell sheet drive out-of-the-plane bending of the sheet and whether myosin contractility is required throughout folding. By optogenetic-mediated acute inhibition of actomyosin, we find that during Drosophila mesoderm invagination, actomyosin contractility is critical to prevent tissue relaxation during the early, ‘priming’ stage of folding but is dispensable for the actual folding step after the tissue passes through a stereotyped transitional configuration. This binary response suggests that Drosophila mesoderm is mechanically bistable during gastrulation. Computer modeling analysis demonstrates that the binary tissue response to actomyosin inhibition can be recapitulated in the simulated epithelium that undergoes buckling-like deformation jointly mediated by apical constriction in the mesoderm and in-plane compression generated by apicobasal shrinkage of the surrounding ectoderm. Interestingly, comparison between wild-type and snail mutants that fail to specify the mesoderm demonstrates that the lateral ectoderm undergoes apicobasal shrinkage during gastrulation independently of mesoderm invagination. We propose that Drosophila mesoderm invagination is achieved through an interplay between local apical constriction and mechanical bistability of the epithelium that facilitates epithelial buckling.
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Affiliation(s)
- Hanqing Guo
- Department of Biological Sciences, Dartmouth College, Hanover, United States
| | - Michael Swan
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Bing He
- Department of Biological Sciences, Dartmouth College, Hanover, United States
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3
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Zhang X, Li P, Ding Z, Wang H, Wang J, Han L, Ding S. The putative tumor suppressor, miR-199a, regulated by Snail, modulates clear cell renal cell carcinoma aggressiveness by repressing ROCK1. Onco Targets Ther 2017; 11:103-112. [PMID: 29343969 PMCID: PMC5749572 DOI: 10.2147/ott.s147184] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Background Aberrant expression of miR-199a has been frequently reported in cancer studies; however, its role in renal cell carcinoma (RCC) has not been examined in detail. Results Here, we showed that miR-199a was downregulated in RCC and associated with poor prognostic phenotype. Using luciferase and western blot assays we identified that Rho-associated coiled coil-containing protein kinases 1 (ROCK1) was a direct target gene for miR-199a. miR-199a regulated proliferation, invasion, and apoptosis of clear cell renal cell carcinoma (ccRCC) cells by modulating ROCK1 expression. Interestingly, we also found that miR-199a was modulated by snail in ccRCC cells. Snail elevated ROCK1 expression by repressing miR-199a activity. Conclusion Altogether, our results identify a crucial tumor suppressive role of miR-199a in the progression of ccRCC and suggest that miR-199a might be an anticancer therapeutic target for ccRCC patients.
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Affiliation(s)
- Xiao Zhang
- Department of Oncology, Affiliated Hospital of Jining Medical University, Jining, Shandong
| | - Peng Li
- Department of Oncology, Affiliated Hospital of Jining Medical University, Jining, Shandong
| | - Zhen Ding
- Department of Oncology, Affiliated Hospital of Jining Medical University, Jining, Shandong
| | - Huili Wang
- Department of Oncology, Affiliated Hospital of Jining Medical University, Jining, Shandong
| | - Junye Wang
- Department of Oncology, Affiliated Hospital of Jining Medical University, Jining, Shandong
| | - Lei Han
- Department of Oncology, Affiliated Hospital of Jining Medical University, Jining, Shandong
| | - Shangwei Ding
- Department of Ultrasound, Dongguan People's Hospital Affiliated to Southern Medical University, Dongguan, Guangdong, China
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4
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Iordanou E, Chandran RR, Yang Y, Essak M, Blackstone N, Jiang L. The novel Smad protein Expansion regulates the receptor tyrosine kinase pathway to control Drosophila tracheal tube size. Dev Biol 2014; 393:93-108. [PMID: 24973580 DOI: 10.1016/j.ydbio.2014.06.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 06/01/2014] [Accepted: 06/17/2014] [Indexed: 10/25/2022]
Abstract
Tubes with distinct shapes and sizes are critical for the proper function of many tubular organs. Here we describe a unique phenotype caused by the loss of a novel, evolutionarily-conserved, Drosophila Smad-like protein, Expansion. In expansion mutants, unicellular and intracellular tracheal branches develop bubble-like cysts with enlarged apical membranes. Cysts in unicellular tubes are enlargements of the apical lumen, whereas cysts in intracellular tubes are cytoplasmic vacuole-like compartments. The cyst phenotype in expansion mutants is similar to, but weaker than, that observed in double mutants of Drosophila type III receptor tyrosine phosphatases (RPTPs), Ptp4E and Ptp10D. Ptp4E and Ptp10D negatively regulate the receptor tyrosine kinase (RTK) pathways, especially epithelial growth factor receptor (EGFR) and fibroblast growth factor receptor/breathless (FGFR, Btl) signaling to maintain the proper size of unicellular and intracellular tubes. We show Exp genetically interacts with RTK signaling, the downstream targets of RPTPs. Cyst size and number in expansion mutants is enhanced by increased RTK signaling and suppressed by reduced RTK signaling. Genetic interaction studies strongly suggest that Exp negatively regulates RTK (EGFR, Btl) signaling to ensure proper tube sizes. Smad proteins generally function as intermediate components of the transforming growth factor-β (TGF-β, DPP) signaling pathway. However, no obvious genetic interaction between expansion and TGF-β (DPP) signaling was observed. Therefore, Expansion does not function as a typical Smad protein. The expansion phenotype demonstrates a novel role for Smad-like proteins in epithelial tube formation.
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Affiliation(s)
- Ekaterini Iordanou
- Department of Biological Sciences, Oakland University, Rochester, MI 48309, USA
| | - Rachana R Chandran
- Department of Biological Sciences, Oakland University, Rochester, MI 48309, USA
| | - Yonghua Yang
- Department of Biological Sciences, Oakland University, Rochester, MI 48309, USA
| | - Mina Essak
- Department of Biological Sciences, Oakland University, Rochester, MI 48309, USA
| | - Nicholas Blackstone
- Department of Biological Sciences, Oakland University, Rochester, MI 48309, USA
| | - Lan Jiang
- Department of Biological Sciences, Oakland University, Rochester, MI 48309, USA.
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5
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Swope D, Kramer J, King TR, Cheng YS, Kramer SG. Cdc42 is required in a genetically distinct subset of cardiac cells during Drosophila dorsal vessel closure. Dev Biol 2014; 392:221-32. [PMID: 24949939 DOI: 10.1016/j.ydbio.2014.05.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 05/19/2014] [Accepted: 05/29/2014] [Indexed: 10/25/2022]
Abstract
The embryonic heart tube is formed by the migration and subsequent midline convergence of two bilateral heart fields. In Drosophila the heart fields are organized into two rows of cardioblasts (CBs). While morphogenesis of the dorsal ectoderm, which lies directly above the Drosophila dorsal vessel (DV), has been extensively characterized, the migration and concomitant fundamental factors facilitating DV formation remain poorly understood. Here we provide evidence that DV closure occurs at multiple independent points along the A-P axis of the embryo in a "buttoning" pattern, divergent from the zippering mechanism observed in the overlying epidermis during dorsal closure. Moreover, we demonstrate that a genetically distinct subset of CBs is programmed to make initial contact with the opposing row. To elucidate the cellular mechanisms underlying this process, we examined the role of Rho GTPases during cardiac migration using inhibitory and overexpression approaches. We found that Cdc42 shows striking cell-type specificity during DV formation. Disruption of Cdc42 function specifically prevents CBs that express the homeobox gene tinman from completing their dorsal migration, resulting in a failure to make connections with their partnering CBs. Conversely, neighboring CBs that express the orphan nuclear receptor, seven-up, are not sensitive to Cdc42 inhibition. Furthermore, this phenotype was specific to Cdc42 and was not observed upon perturbation of Rac or Rho function. Together with the observation that DV closure occurs through the initial contralateral pairing of tinman-expressing CBs, our studies suggest that the distinct buttoning mechanism we propose for DV closure is elaborated through signaling pathways regulating Cdc42 activity in this cell type.
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Affiliation(s)
- David Swope
- Department of Pathology and Laboratory Medicine, Rutgers-Robert Wood Johnson Medical School, 675 Hoes Lane West, Piscataway, NJ 08854, USA
| | - Joseph Kramer
- Department of Pathology and Laboratory Medicine, Rutgers-Robert Wood Johnson Medical School, 675 Hoes Lane West, Piscataway, NJ 08854, USA
| | - Tiffany R King
- Department of Pathology and Laboratory Medicine, Rutgers-Robert Wood Johnson Medical School, 675 Hoes Lane West, Piscataway, NJ 08854, USA; Graduate Program in Cell and Developmental Biology, Rutgers Graduate School of Biomedical Sciences at Robert Wood Johnson Medical School, 675 Hoes Lane West, Piscataway, NJ 08854, USA
| | - Yi-Shan Cheng
- Department of Pathology and Laboratory Medicine, Rutgers-Robert Wood Johnson Medical School, 675 Hoes Lane West, Piscataway, NJ 08854, USA
| | - Sunita G Kramer
- Department of Pathology and Laboratory Medicine, Rutgers-Robert Wood Johnson Medical School, 675 Hoes Lane West, Piscataway, NJ 08854, USA; Graduate Program in Cell and Developmental Biology, Rutgers Graduate School of Biomedical Sciences at Robert Wood Johnson Medical School, 675 Hoes Lane West, Piscataway, NJ 08854, USA.
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6
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Sass GL, Ostrow BD. Disruption of the protein kinase N gene of drosophila melanogaster results in the recessive delorean allele (pkndln) with a negative impact on wing morphogenesis. G3 (BETHESDA, MD.) 2014; 4:643-56. [PMID: 24531729 PMCID: PMC4059237 DOI: 10.1534/g3.114.010579] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 02/07/2014] [Indexed: 12/15/2022]
Abstract
We describe the delorean mutation of the Drosophila melanogaster protein kinase N gene (pkn(dln)) with defects in wing morphology. Flies homozygous for the recessive pkn(dln) allele have a composite wing phenotype that exhibits changes in relative position and shape of the wing blade as well as loss of specific vein and bristle structures. The pkn(dln) allele is the result of a P-element insertion in the first intron of the pkn locus, and the delorean wing phenotype is contingent upon the interaction of insertion-bearing alleles in trans. The presence of the insertion results in production of a novel transcript that initiates from within the 3' end of the P-element. The delorean-specific transcript is predicted to produce a wild-type PKN protein. The delorean phenotype is not the result of a reduction in pkn expression, as it could not be recreated using a variety of wing-specific drivers of pkn-RNAi expression. Rather, it is the presence of the delorean-specific transcript that correlates with the mutant phenotype. We consider the delorean wing phenotype to be due to a pairing-dependent, recessive mutation that behaves as a dosage-sensitive, gain of function. Our analysis of genetic interactions with basket and nemo reflects an involvement of pkn and Jun-terminal kinase signaling in common processes during wing differentiation and places PKN as a potential effector of Rho1's involvement in the Jun-terminal kinase pathway. The delorean phenotype, with its associated defects in wing morphology, provides evidence of a role for PKN in adult morphogenetic processes.
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Affiliation(s)
- Georgette L. Sass
- Department of Biology, Grand Valley State University, Allendale, Michigan 49401
| | - Bruce D. Ostrow
- Department of Biology, Grand Valley State University, Allendale, Michigan 49401
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7
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Targeting the Dbl and dock-family RhoGEFs: a yeast-based assay to identify cell-active inhibitors of Rho-controlled pathways. Enzymes 2013; 33 Pt A:169-91. [PMID: 25033805 DOI: 10.1016/b978-0-12-416749-0.00008-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The Ras-like superfamily of low molecular weight GTPases is made of five major families (Arf/Sar, Rab, Ran, Ras, and Rho), highly conserved across evolution. This is in keeping with their roles in basic cellular functions (endo/exocytosis, vesicular trafficking, nucleocytoplasmic trafficking, cell signaling, proliferation and apoptosis, gene regulation, F-actin dynamics), whose alterations are associated with various types of diseases, in particular cancer, neurodegenerative, cardiovascular, and infectious diseases. For these reasons, Ras-like pathways are of great potential in therapeutics and identifying inhibitors that decrease signaling activity is under intense research. Along this line, guanine exchange factors (GEFs) represent attractive targets. GEFs are proteins that promote the active GTP-bound state of GTPases and represent the major entry points whereby extracellular cues are converted into Ras-like signaling. We previously developed the yeast exchange assay (YEA), an experimental setup in the yeast in which activity of a mammalian GEF can be monitored by auxotrophy and color reporter genes. This assay was further engineered for medium-throughput screening of GEF inhibitors, which can readily select for cell-active and specific compounds. We report here on the successful identification of inhibitors against Dbl and CZH/DOCK-family members, GEFs for Rho GTPases, and on the experimental setup to screen for inhibitors of GEFs of the Arf family. We also discuss on inhibitors developed using virtual screening (VS), which target the GEF/GTPase interface with high efficacy and specificity. We propose that using VS and YEA in combination may represent a method of choice for identifying specific and cell-active GEF inhibitors.
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8
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Neisch AL, Formstecher E, Fehon RG. Conundrum, an ARHGAP18 orthologue, regulates RhoA and proliferation through interactions with Moesin. Mol Biol Cell 2013; 24:1420-33. [PMID: 23468526 PMCID: PMC3639053 DOI: 10.1091/mbc.e12-11-0800] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
RhoA, a small GTPase, regulates epithelial integrity and morphogenesis by controlling filamentous actin assembly and actomyosin contractility. Another important cytoskeletal regulator, Moesin (Moe), an ezrin, radixin, and moesin (ERM) protein, has the ability to bind to and organize cortical F-actin, as well as the ability to regulate RhoA activity. ERM proteins have previously been shown to interact with both RhoGEF (guanine nucleotide exchange factors) and RhoGAP (GTPase activating proteins), proteins that control the activation state of RhoA, but the functions of these interactions remain unclear. We demonstrate that Moe interacts with an unusual RhoGAP, Conundrum (Conu), and recruits it to the cell cortex to negatively regulate RhoA activity. In addition, we show that cortically localized Conu can promote cell proliferation and that this function requires RhoGAP activity. Surprisingly, Conu's ability to promote growth also appears dependent on increased Rac activity. Our results reveal a molecular mechanism by which ERM proteins control RhoA activity and suggest a novel linkage between the small GTPases RhoA and Rac in growth control.
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Affiliation(s)
- Amanda L Neisch
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
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9
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Khoo P, Allan K, Willoughby L, Brumby AM, Richardson HE. In Drosophila, RhoGEF2 cooperates with activated Ras in tumorigenesis through a pathway involving Rho1-Rok-Myosin-II and JNK signalling. Dis Model Mech 2013; 6:661-78. [PMID: 23324326 PMCID: PMC3634650 DOI: 10.1242/dmm.010066] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The Ras oncogene contributes to ≈ 30% of human cancers, but alone is not sufficient for tumorigenesis. In a Drosophila screen for oncogenes that cooperate with an activated allele of Ras (Ras(ACT)) to promote tissue overgrowth and invasion, we identified the GTP exchange factor RhoGEF2, an activator of Rho-family signalling. Here, we show that RhoGEF2 also cooperates with an activated allele of a downstream effector of Ras, Raf (Raf(GOF)). We dissect the downstream pathways through which RhoGEF2 cooperates with Ras(ACT) (and Raf(GOF)), and show that RhoGEF2 requires Rho1, but not Rac, for tumorigenesis. Furthermore, of the Rho1 effectors, we show that RhoGEF2 + Ras (Raf)-mediated tumorigenesis requires the Rho kinase (Rok)-Myosin-II pathway, but not Diaphanous, Lim kinase or protein kinase N. The Rho1-Rok-Myosin-II pathway leads to the activation of Jun kinase (JNK), in cooperation with Ras(ACT). Moreover, we show that activation of Rok or Myosin II, using constitutively active transgenes, is sufficient for cooperative tumorigenesis with Ras(ACT), and together with Ras(ACT) leads to strong activation of JNK. Our results show that Rok-Myosin-II activity is necessary and sufficient for Ras-mediated tumorigenesis. Our observation that activation of Myosin II, which regulates Filamentous actin (F-actin) contractility without affecting F-actin levels, cooperates with Ras(ACT) to promote JNK activation and tumorigenesis, suggests that increased cell contractility is a key factor in tumorigenesis. Furthermore, we show that signalling via the Tumour necrosis factor (TNF; also known as Egr)-ligand-JNK pathway is most likely the predominant pathway that activates JNK upon Rok activation. Overall, our analysis highlights the need for further analysis of the Rok-Myosin-II pathway in cooperation with Ras in human cancers.
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Affiliation(s)
- Peytee Khoo
- Cell Cycle and Development Laboratory, Research Division, Peter MacCallum Cancer Center, Melbourne, Victoria, Australia
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10
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Jeon M, Scott MP, Zinn K. Interactions between Type III receptor tyrosine phosphatases and growth factor receptor tyrosine kinases regulate tracheal tube formation in Drosophila. Biol Open 2012; 1:548-58. [PMID: 23213447 PMCID: PMC3509443 DOI: 10.1242/bio.2012471] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The respiratory (tracheal) system of the Drosophila melanogaster larva is an intricate branched network of air-filled tubes. Its developmental logic is similar in some ways to that of the vertebrate vascular system. We previously described a unique embryonic tracheal tubulogenesis phenotype caused by loss of both of the Type III receptor tyrosine phosphatases (RPTPs), Ptp4E and Ptp10D. In Ptp4E Ptp10D double mutants, the linear tubes in unicellular and terminal tracheal branches are converted into bubble-like cysts that incorporate apical cell surface markers. This tube geometry phenotype is modulated by changes in the activity or expression of the epidermal growth factor receptor (Egfr) tyrosine kinase (TK). Ptp10D physically interacts with Egfr. Here we demonstrate that the Ptp4E Ptp10D phenotype is the consequence of the loss of negative regulation by the RPTPs of three growth factor receptor TKs: Egfr, Breathless and Pvr. Reducing the activity of any of the three kinases by tracheal expression of dominant-negative mutants suppresses cyst formation. By competing dominant-negative and constitutively active kinase mutants against each other, we show that the three RTKs have partially interchangeable activities, so that increasing the activity of one kinase can compensate for the effects of reducing the activity of another. This implies that SH2-domain downstream effectors that are required for the phenotype are likely to be able to interact with phosphotyrosine sites on all three receptor TKs. We also show that the phenotype involves increases in signaling through the MAP kinase and Rho GTPase pathways.
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Affiliation(s)
- Mili Jeon
- Division of Biology 114-96, California Institute of Technology , 1200 East California Boulevard, Pasadena, CA 91125 , USA ; Departments of Developmental Biology, Genetics, and Bioengineering, Howard Hughes Medical Institute, 318 Campus Drive, Stanford University School of Medicine , Palo Alto, CA 94305 , USA
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11
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Forgetting is regulated through Rac activity in Drosophila. Cell 2010; 140:579-89. [PMID: 20178749 DOI: 10.1016/j.cell.2009.12.044] [Citation(s) in RCA: 160] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Revised: 11/06/2009] [Accepted: 12/22/2009] [Indexed: 11/23/2022]
Abstract
Initially acquired memory dissipates rapidly if not consolidated. Such memory decay is thought to result either from the inherently labile nature of newly acquired memories or from interference by subsequently attained information. Here we report that a small G protein Rac-dependent forgetting mechanism contributes to both passive memory decay and interference-induced forgetting in Drosophila. Inhibition of Rac activity leads to slower decay of early memory, extending it from a few hours to more than one day, and to blockade of interference-induced forgetting. Conversely, elevated Rac activity in mushroom body neurons accelerates memory decay. This forgetting mechanism does not affect memory acquisition and is independent of Rutabaga adenylyl cyclase-mediated memory formation mechanisms. Endogenous Rac activation is evoked on different time scales during gradual memory loss in passive decay and during acute memory removal in reversal learning. We suggest that Rac's role in actin cytoskeleton remodeling may contribute to memory erasure.
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12
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Patch K, Stewart SR, Welch A, Ward RE. A second-site noncomplementation screen for modifiers of Rho1 signaling during imaginal disc morphogenesis in Drosophila. PLoS One 2009; 4:e7574. [PMID: 19862331 PMCID: PMC2764050 DOI: 10.1371/journal.pone.0007574] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2009] [Accepted: 09/16/2009] [Indexed: 12/03/2022] Open
Abstract
Background Rho1 is a small GTPase of the Ras superfamily that serves as the central component in a highly conserved signaling pathway that regulates tissue morphogenesis during development in all animals. Since there is tremendous diversity in the upstream signals that can activate Rho1 as well as the effector molecules that carry out its functions, it is important to define relevant Rho1-interacting genes for each morphogenetic event regulated by this signaling pathway. Previous work from our lab and others has shown that Rho signaling is necessary for the morphogenesis of leg imaginal discs during metamorphosis in Drosophila, although a comprehensive identification of Rho1-interacting genes has not been attempted for this process. Methodology/Principal Findings We characterized an amorphic allele of Rho1 that displays a poorly penetrant dominant malformed leg phenotype and is capable of being strongly enhanced by Rho1-interacting heterozygous mutations. We then used this allele in a second-site noncomplementation screen with the Exelixis collection of molecularly defined deficiencies to identify Rho1-interacting genes necessary for leg morphogenesis. In a primary screen of 461 deficiencies collectively uncovering ∼50% of the Drosophila genome, we identified twelve intervals harboring Rho1-interacting genes. Through secondary screening we identified six Rho1-interacting genes including three that were previously identified (RhoGEF2, broad, and stubbloid), thereby validating the screen. In addition, we identified Cdc42, Rheb and Sc2 as novel Rho1-interacting genes involved in adult leg development. Conclusions/Significance This screen identified well-known and novel Rho1-interacting genes necessary for leg morphogenesis, thereby increasing our knowledge of this important signaling pathway. We additionally found that Rheb may have a unique function in leg morphogenesis that is independent of its regulation of Tor.
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Affiliation(s)
- Kistie Patch
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, United States of America
| | - Shannon R. Stewart
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, United States of America
| | - Aaron Welch
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, United States of America
| | - Robert E. Ward
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, United States of America
- * E-mail:
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13
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Warner SJ, Longmore GD. Distinct functions for Rho1 in maintaining adherens junctions and apical tension in remodeling epithelia. ACTA ACUST UNITED AC 2009; 185:1111-25. [PMID: 19506041 PMCID: PMC2711606 DOI: 10.1083/jcb.200901029] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Maintenance and remodeling of adherens junctions (AJs) and cell shape in epithelia are necessary for the development of functional epithelia and are commonly altered during cancer progression/metastasis. Although formation of nascent AJs has received much attention, whether shared mechanisms are responsible for the maintenance and remodeling of AJs in dynamic epithelia, particularly in vivo, is not clear. Using clonal analysis in the postmitotic Drosophila melanogaster pupal eye epithelium, we demonstrate that Rho1 is required to maintain AJ integrity independent of its role in sustaining apical cell tension. Rho1 depletion in a remodeling postmitotic epithelium disrupts AJs but only when depleted in adjacent cells. Surprisingly, neither of the Rho effectors, Rok or Dia, is necessary downstream of Rho1 to maintain AJs; instead, Rho1 maintains AJs by inhibiting Drosophila epithelial cadherin endocytosis in a Cdc42/Par6-dependent manner. In contrast, depletion of Rho1 in single cells decreases apical tension, and Rok and myosin are necessary, while Dia function also contributes, downstream of Rho1 to sustain apical cell tension.
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Affiliation(s)
- Stephen J Warner
- Department of Medicine, Washington University, St. Louis, MO 63110, USA
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14
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Ricardo S, Lehmann R. An ABC transporter controls export of a Drosophila germ cell attractant. Science 2009; 323:943-6. [PMID: 19213920 DOI: 10.1126/science.1166239] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Directed cell migration, which is critical for embryonic development, leukocyte trafficking, and cell metastasis, depends on chemoattraction. 3-hydroxy-3-methylglutaryl coenzyme A reductase regulates the production of an attractant for Drosophila germ cells that may itself be geranylated. Chemoattractants are commonly secreted through a classical, signal peptide-dependent pathway, but a geranyl-modified attractant would require an alternative pathway. In budding yeast, pheromones produced by a-cells are farnesylated and secreted in a signal peptide-independent manner, requiring the adenosine triphosphate-binding cassette (ABC) transporter Ste6p. Here we show that Drosophila germ cell migration uses a similar pathway, demonstrating that invertebrate germ cells, like yeast cells, are attracted to lipid-modified peptides. Components of this unconventional export pathway are highly conserved, suggesting that this pathway may control the production of similarly modified chemoattractants in organisms ranging from yeast to humans.
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Affiliation(s)
- Sara Ricardo
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute, Department of Cell Biology, New York University School of Medicine, New York University, 540 First Avenue, New York, NY 10016, USA
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15
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Sánchez-Soriano N, Tear G, Whitington P, Prokop A. Drosophila as a genetic and cellular model for studies on axonal growth. Neural Dev 2007; 2:9. [PMID: 17475018 PMCID: PMC1876224 DOI: 10.1186/1749-8104-2-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2007] [Accepted: 05/02/2007] [Indexed: 11/10/2022] Open
Abstract
One of the most fascinating processes during nervous system development is the establishment of stereotypic neuronal networks. An essential step in this process is the outgrowth and precise navigation (pathfinding) of axons and dendrites towards their synaptic partner cells. This phenomenon was first described more than a century ago and, over the past decades, increasing insights have been gained into the cellular and molecular mechanisms regulating neuronal growth and navigation. Progress in this area has been greatly assisted by the use of simple and genetically tractable invertebrate model systems, such as the fruit fly Drosophila melanogaster. This review is dedicated to Drosophila as a genetic and cellular model to study axonal growth and demonstrates how it can and has been used for this research. We describe the various cellular systems of Drosophila used for such studies, insights into axonal growth cones and their cytoskeletal dynamics, and summarise identified molecular signalling pathways required for growth cone navigation, with particular focus on pathfinding decisions in the ventral nerve cord of Drosophila embryos. These Drosophila-specific aspects are viewed in the general context of our current knowledge about neuronal growth.
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Affiliation(s)
- Natalia Sánchez-Soriano
- The Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
| | - Guy Tear
- MRC Centre for Developmental Neurobiology, Guy's Campus, King's College, London, UK
| | - Paul Whitington
- Department of Anatomy and Cell Biology, University of Melbourne, Victoria, Australia
| | - Andreas Prokop
- The Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
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16
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Coisy-Quivy M, Sanguesa-Ferrer J, Weill M, Johnson DS, Donnay JM, Hipskind R, Fort P, Philips A. Identification of Rho GTPases implicated in terminal differentiation of muscle cells in ascidia. Biol Cell 2007; 98:577-88. [PMID: 16756514 DOI: 10.1042/bc20060032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND INFORMATION Members of the Rho GTPase family mediate changes in the actin cytoskeleton and are also implicated in developmental processes, including myogenesis. Nevertheless, a comprehensive analysis of these proteins during myofibrillogenesis has never been performed in any organism. RESULTS Using the ascidian model to identify the role of Rho GTPases on myofibrillogenesis, we show that transcripts for all Rho GTPases are detected in muscle cells of the embryo. We find that activation of RhoA, TC10 and Cdc42 (cell division cycle 42) disturbs the polarity of muscle cells, whereas that of other Rho GTPases induced cell positioning defects. Moreover, dominant negative version of five Rho GTPases, RhoA, Rac2, RCL2 (Rac- and Cdc42-like 2), TC10 and WRCH (Wnt-1 responsive Cdc42 homologue), impaired the formation of mature myofibrils. CONCLUSIONS Taken together, our results show that several Rho GTPase-dependent pathways are required to control the spatial localization of muscle cells in the embryo and to coordinate myofibril assembly. This stresses the importance of analysing the entire Rho family when studying a new biological process.
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Affiliation(s)
- Marjorie Coisy-Quivy
- CRBM, CNRS-FRE2593, IFR122, 1919 route de Mende, 34293 Montpellier cedex 5, France
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17
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Bidla G, Dushay MS, Theopold U. Crystal cell rupture after injury in Drosophila requires the JNK pathway, small GTPases and the TNF homolog Eiger. J Cell Sci 2007; 120:1209-15. [PMID: 17356067 DOI: 10.1242/jcs.03420] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The prophenoloxidase-activating cascade is a key component of arthropod immunity. Drosophila prophenoloxidase is stored in crystal cells, a specialized class of blood cells from which it is released through cell rupture. Within minutes after bleeding, prophenoloxidase is activated leading to visible melanization of the clot matrix. Using crystal cell rupture and melanization as readouts to screen mutants in signal transduction pathways, we show that prophenoloxidase release requires Jun N-terminal kinase, small Rho GTPases and Eiger, the Drosophila homolog of tumor necrosis factor. We also provide evidence that in addition to microbial products, endogenous signals from dying hemocytes contribute to triggering and/or assembly of the prophenoloxidase-activating cascade, and that this process can be inhibited in vitro and in vivo using the viral apoptotic inhibitor p35. Our results provide a more comprehensive view of immune signal transduction pathways, with implications for immune reactions where cell death is used as a terminal mode of cell activation.
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Affiliation(s)
- Gawa Bidla
- Department of Molecular Biology and Functional Genomics, University of Stockholm, Svante Arrheniusväg 16-18, SE 10691 Stockholm, Sweden
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18
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Rothenfluh A, Threlkeld RJ, Bainton RJ, Tsai LTY, Lasek AW, Heberlein U. Distinct behavioral responses to ethanol are regulated by alternate RhoGAP18B isoforms. Cell 2006; 127:199-211. [PMID: 17018286 DOI: 10.1016/j.cell.2006.09.010] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Revised: 05/19/2006] [Accepted: 09/04/2006] [Indexed: 01/19/2023]
Abstract
In most organisms, low ethanol doses induce increased activity, while high doses are sedating. To investigate the underlying mechanisms, we isolated Drosophila mutants with altered ethanol responsiveness. Mutations in white rabbit (whir), disrupting RhoGAP18B, are strongly resistant to the sedating effects of ethanol. This resistance can be suppressed by reducing the levels of Rho1 or Rac, implicating these GTPases in the behavioral response to ethanol. Indeed, expression of constitutively active forms of Rho1 or Rac1 in adult flies results in ethanol resistance similar to that observed in whir mutants. The whir locus produces several transcripts, RA-RD, which are predicted to encode three distinct RhoGAPs that share only the GAP domain. The RC transcript mediates the sedating effects of ethanol, while the RA transcript regulates its stimulant effects. Thus, distinct RhoGAPs, encoded by the same gene, regulate different manifestations of acute ethanol intoxication.
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Affiliation(s)
- Adrian Rothenfluh
- Department of Anatomy, University of California, San Francisco, San Francisco, CA 94143, USA.
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Magie CR, Parkhurst SM. Rho1 regulates signaling events required for proper Drosophila embryonic development. Dev Biol 2005; 278:144-54. [PMID: 15649467 PMCID: PMC3125077 DOI: 10.1016/j.ydbio.2004.10.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2004] [Revised: 10/19/2004] [Accepted: 10/28/2004] [Indexed: 12/15/2022]
Abstract
The Rho small GTPase has been implicated in many cellular processes, including actin cytoskeletal regulation and transcriptional activation. The molecular mechanisms underlying Rho function in many of these processes are not yet clear. Here we report that in Drosophila, reduction of maternal Rho1 compromises signaling pathways consistent with defects in membrane trafficking events. These mutants fail to maintain expression of the segment polarity genes engrailed (en), wingless (wg), and hedgehog (hh), contributing to a segmentation phenotype. Formation of the Wg protein gradient involves the internalization of Wg into vesicles. The number of these Wg-containing vesicles is reduced in maternal Rho1 mutants, suggesting a defect in endocytosis. Consistent with this, stripes of cytoplasmic beta-catenin that accumulate in response to Wg signaling are narrower in these mutants relative to wild type. Additionally, the amount of extracellular Wg protein is reduced in maternal Rho1 mutants, indicating a defect in secretion. Signaling pathways downregulated by endocytosis, such as the epidermal growth factor receptor (EGFR) and Torso pathways, are hyperactivated in maternal Rho1 mutants, consistent with a general role for Rho1 in regulating signaling events governing proper patterning during Drosophila development.
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Affiliation(s)
- Craig R Magie
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, A1-162, PO Box 19024, Seattle, WA 98109-1024, USA
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