1
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Kwok SH, Liu Y, Bilder D, Kim J. Paraneoplastic renal dysfunction in fly cancer models driven by inflammatory activation of stem cells. bioRxiv 2024:2024.03.21.586173. [PMID: 38585959 PMCID: PMC10996499 DOI: 10.1101/2024.03.21.586173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Tumors can induce systemic disturbances in distant organs, leading to physiological changes that enhance host morbidity. In Drosophila cancer models, tumors have been known for decades to cause hypervolemic 'bloating' of the abdominal cavity. Here we use allograft and transgenic tumors to show that hosts display fluid retention associated with autonomously defective secretory capacity of fly renal tubules, which function analogous to those of the human kidney. Excretion from these organs is blocked by abnormal cells that originate from inappropriate activation of normally quiescent renal stem cells (RSCs). Blockage is initiated by IL-6-like oncokines that perturb renal water-transporting cells, and trigger a damage response in RSCs that proceeds pathologically. Thus, a chronic inflammatory state produced by the tumor causes paraneoplastic fluid dysregulation by altering cellular homeostasis of host renal units.
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Affiliation(s)
- Sze Hang Kwok
- School of Biomedical Sciences, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Yuejiang Liu
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley CA, 94720, USA
| | - David Bilder
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley CA, 94720, USA
| | - Jung Kim
- School of Biomedical Sciences, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley CA, 94720, USA
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2
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Hsi TC, Ong KL, Sepers JJ, Kim J, Bilder D. Systemic coagulopathy promotes host lethality in a new Drosophila tumor model. Curr Biol 2023; 33:3002-3010.e6. [PMID: 37354901 DOI: 10.1016/j.cub.2023.05.071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 04/12/2023] [Accepted: 05/31/2023] [Indexed: 06/26/2023]
Abstract
Malignant tumors trigger a complex network of inflammatory and wound repair responses, prompting Dvorak's characterization of tumors as "wounds that never heal."1 Some of these responses lead to profound defects in blood clotting, such as disseminated intravascular coagulopathy (DIC), which correlate with poor prognoses.2,3,4 Here, we demonstrate that a new tumor model in Drosophila provokes phenotypes that resemble coagulopathies observed in patients. Fly ovarian tumors overproduce multiple secreted components of the clotting cascade and trigger hypercoagulation of fly blood (hemolymph). Hypercoagulation occurs shortly after tumor induction and is transient; it is followed by a hypocoagulative state that is defective in wound healing. Cellular clotting regulators accumulate on the tumor over time and are depleted from the body, suggesting that hypocoagulation is caused by exhaustion of host clotting components. We show that rescuing coagulopathy by depleting a tumor-produced clotting factor improves survival of tumor-bearing flies, despite the fact that flies have an open (non-vascular) circulatory system. As clinical studies suggest that lethality in patients with high serum levels of clotting components can be independent of thrombotic events,5,6 our work establishes a platform for identifying alternative mechanisms by which tumor-driven coagulopathy triggers early mortality. Moreover, it opens up exploration of other conserved mechanisms of host responses to chronic wounds.
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Affiliation(s)
- Tsai-Ching Hsi
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Katy L Ong
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Jorian J Sepers
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Jung Kim
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - David Bilder
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA.
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3
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Ku HY, Harris LK, Bilder D. Specialized cells that sense tissue mechanics to regulate Drosophila morphogenesis. Dev Cell 2023; 58:211-223.e5. [PMID: 36708706 DOI: 10.1016/j.devcel.2023.01.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 09/10/2022] [Accepted: 01/05/2023] [Indexed: 01/28/2023]
Abstract
Shaping of developing organs requires dynamic regulation of force and resistance to achieve precise outcomes, but how organs monitor tissue mechanical properties is poorly understood. We show that in developing Drosophila follicles (egg chambers), a single pair of cells performs such monitoring to drive organ shaping. These anterior polar cells secrete a matrix metalloproteinase (MMP) that specifies the appropriate degree of tissue elongation, rather than hyper- or hypo-elongated organs. MMP production is negatively regulated by basement membrane (BM) mechanical properties, which are sensed through focal adhesion signaling and autonomous contractile activity; MMP then reciprocally regulates BM remodeling, particularly at the anterior region. Changing BM properties at remote locations alone is sufficient to induce a remodeling response in polar cells. We propose that this small group of cells senses both local and distant stiffness cues to produce factors that pattern the organ's BM mechanics, ensuring proper tissue shape and reproductive success.
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Affiliation(s)
- Hui-Yu Ku
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Leigh K Harris
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - David Bilder
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
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Gerlach SU, de Vreede G, Bilder D. PTP10D-mediated cell competition is not obligately required for elimination of polarity-deficient clones. Biol Open 2022; 11:281302. [PMID: 36355597 PMCID: PMC9672856 DOI: 10.1242/bio.059525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 10/11/2022] [Indexed: 11/12/2022] Open
Abstract
Animal organs maintain tissue integrity and ensure removal of aberrant cells through several types of surveillance mechanisms. One prominent example is the elimination of polarity-deficient mutant cells within developing Drosophila imaginal discs. This has been proposed to require heterotypic cell competition dependent on the receptor tyrosine phosphatase PTP10D within the mutant cells. We report here experiments to test this requirement in various contexts and find that PTP10D is not obligately required for the removal of scribble (scrib) mutant and similar polarity-deficient cells. Our experiments used identical stocks with which another group can detect the PTP10D requirement, and our results do not vary under several husbandry conditions including high and low protein food diets. Although we are unable to identify the source of the discrepant results, we suggest that the role of PTP10D in polarity-deficient cell elimination may not be absolute.
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Affiliation(s)
- Stephan U. Gerlach
- University of California-Berkeley Department of Molecular and Cell Biology , , Berkeley, CA 94720 , USA
| | - Geert de Vreede
- University of California-Berkeley Department of Molecular and Cell Biology , , Berkeley, CA 94720 , USA
| | - David Bilder
- University of California-Berkeley Department of Molecular and Cell Biology , , Berkeley, CA 94720 , USA
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Abstract
The compartmentalized domains of polarized epithelial cells arise from mutually antagonistic actions between the apical Par complex and the basolateral Scrib module. In Drosophila, the Scrib module proteins Scribble (Scrib) and Discs-large (Dlg) are required to limit Lgl phosphorylation at the basolateral cortex, but how Scrib and Dlg could carry out such a ‘protection’ activity is not clear. We tested Protein Phosphatase 1α (PP1) as a potential mediator of this activity, but demonstrate that a significant component of Scrib and Dlg regulation of Lgl is PP1 independent, and found no evidence for a Scrib-Dlg-PP1 protein complex. However, the Dlg SH3 domain plays a role in Lgl protection and, in combination with the N-terminal region of the Dlg HOOK domain, in recruitment of Scrib to the membrane. We identify a ‘minimal Dlg’ comprised of the SH3 and HOOK domains that is both necessary and sufficient for Scrib localization and epithelial polarity function in vivo. This article has an associated First Person interview with the first author of the paper. Summary: A minimal SH3-HOOK fragment of Dlg is sufficient to support epithelial polarity through mechanisms independent of the PP1 phosphatase.
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Affiliation(s)
- Mark J Khoury
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley CA 94720, USA
| | - David Bilder
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley CA 94720, USA
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de Vreede G, Gerlach SU, Bilder D. Epithelial monitoring through ligand-receptor segregation ensures malignant cell elimination. Science 2022; 376:297-301. [PMID: 35420935 DOI: 10.1126/science.abl4213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Animals have evolved mechanisms, such as cell competition, to remove dangerous or nonfunctional cells from a tissue. Tumor necrosis factor signaling can eliminate clonal malignancies from Drosophila imaginal epithelia, but why this pathway is activated in tumor cells but not normal tissue is unknown. We show that the ligand that drives elimination is present in basolateral circulation but remains latent because it is spatially segregated from its apically localized receptor. Polarity defects associated with malignant transformation cause receptor mislocalization, allowing ligand binding and subsequent apoptotic signaling. This process occurs irrespective of the neighboring cells' genotype and is thus distinct from cell competition. Related phenomena at epithelial wound sites are required for efficient repair. This mechanism of polarized compartmentalization of ligand and receptor can generally monitor epithelial integrity to promote tissue homeostasis.
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Affiliation(s)
- Geert de Vreede
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Stephan U Gerlach
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - David Bilder
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
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7
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Abstract
Scribble (Scrib), Discs-large (Dlg), and Lethal giant larvae (Lgl) are basolateral regulators of epithelial polarity and tumor suppressors whose molecular mechanisms of action remain unclear. We used proximity biotinylation to identify proteins localized near Dlg in the Drosophila wing imaginal disc epithelium. In addition to expected membrane- and cytoskeleton-associated protein classes, nuclear proteins were prevalent in the resulting mass spectrometry dataset, including all four members of the nucleosome remodeling factor (NURF) chromatin remodeling complex. Subcellular fractionation demonstrated a nuclear pool of Dlg and proximity ligation confirmed its position near the NURF complex. Genetic analysis showed that NURF activity is also required for the overgrowth of dlg tumors, and this growth suppression correlated with a reduction in Hippo pathway gene expression. Together, these data suggest a nuclear role for Dlg in regulating chromatin and transcription through a more direct mechanism than previously thought.
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Affiliation(s)
- Katherine A Sharp
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley CA 94720
| | - Mark J Khoury
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley CA 94720
| | | | - David Bilder
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley CA 94720
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Abstract
There is a large gap between the deep understanding of mechanisms driving tumour growth and the reasons why patients ultimately die of cancer. It is now appreciated that interactions between the tumour and surrounding non-tumour (sometimes referred to as host) cells play critical roles in mortality as well as tumour progression, but much remains unknown about the underlying molecular mechanisms, especially those that act beyond the tumour microenvironment. Drosophila has a track record of high-impact discoveries about cell-autonomous growth regulation, and is well suited to now probe mysteries of tumour - host interactions. Here, we review current knowledge about how fly tumours interact with microenvironmental stroma, circulating innate immune cells and distant organs to influence disease progression. We also discuss reciprocal regulation between tumours and host physiology, with a particular focus on paraneoplasias. The fly's simplicity along with the ability to study lethality directly provide an opportunity to shed new light on how cancer actually kills.
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Affiliation(s)
- David Bilder
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
| | - Katy Ong
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Tsai-Ching Hsi
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Kavya Adiga
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Jung Kim
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
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Kim J, Chuang HC, Wolf NK, Nicolai CJ, Raulet DH, Saijo K, Bilder D. Tumor-induced disruption of the blood-brain barrier promotes host death. Dev Cell 2021; 56:2712-2721.e4. [PMID: 34496290 DOI: 10.1016/j.devcel.2021.08.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 06/29/2021] [Accepted: 08/12/2021] [Indexed: 11/24/2022]
Abstract
Cancer patients often die from symptoms that manifest at a distance from any tumor. Mechanisms underlying these systemic physiological perturbations, called paraneoplastic syndromes, may benefit from investigation in non-mammalian systems. Using a non-metastatic Drosophila adult model, we find that malignant-tumor-produced cytokines drive widespread host activation of JAK-STAT signaling and cause premature lethality. STAT activity is particularly high in cells of the blood-brain barrier (BBB), where it induces aberrant BBB permeability. Remarkably, inhibiting STAT in the BBB not only rescues barrier function but also extends the lifespan of tumor-bearing hosts. We identify BBB damage in other pathological conditions that cause elevated inflammatory signaling, including obesity and infection, where BBB permeability also regulates host survival. IL-6-dependent BBB dysfunction is further seen in a mouse tumor model, and it again promotes host morbidity. Therefore, BBB alterations constitute a conserved lethal tumor-host interaction that also underlies other physiological morbidities.
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Affiliation(s)
- Jung Kim
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Hsiu-Chun Chuang
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Natalie K Wolf
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Christopher J Nicolai
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - David H Raulet
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Kaoru Saijo
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA; Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA 94720, USA
| | - David Bilder
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA.
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10
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Abstract
A polarized architecture is central to both epithelial structure and function. In many cells, polarity involves mutual antagonism between the Par complex and the Scribble (Scrib) module. While molecular mechanisms underlying Par-mediated apical determination are well-understood, how Scrib module proteins specify the basolateral domain remains unknown. Here, we demonstrate dependent and independent activities of Scrib, Discs-large (Dlg), and Lethal giant larvae (Lgl) using the Drosophila follicle epithelium. Our data support a linear hierarchy for localization, but rule out previously proposed protein-protein interactions as essential for polarization. Cortical recruitment of Scrib does not require palmitoylation or polar phospholipid binding but instead an independent cortically stabilizing activity of Dlg. Scrib and Dlg do not directly antagonize atypical protein kinase C (aPKC), but may instead restrict aPKC localization by enabling the aPKC-inhibiting activity of Lgl. Importantly, while Scrib, Dlg, and Lgl are each required, all three together are not sufficient to antagonize the Par complex. Our data demonstrate previously unappreciated diversity of function within the Scrib module and begin to define the elusive molecular functions of Scrib and Dlg.
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Affiliation(s)
- Mark J Khoury
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - David Bilder
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
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11
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Servais L, Shieh P, Dowling J, Kuntz N, Müller-Felber W, Smith B, Bönnemann C, Muntoni F, Bilder D, Duong T, Graham R, Jain M, Lawlor M, MacBean V, Noursalehi M, Pitts T, Rafferty G, Rico S, Prasad S. P.105INCEPTUS pre-phase 1, prospective, non-interventional, natural history run-in study to evaluate subjects aged 4 years and younger with X-linked myotubular myopathy (XLMTM). Neuromuscul Disord 2019. [DOI: 10.1016/j.nmd.2019.06.161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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12
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Rico S, Bilder D, Duong T, James E, Noursalehi M, Bergman S, Harding G, Mannix S, Phillips D, Abel C, Prasad S. CONGENITAL MYOPATHIES (CNM). Neuromuscul Disord 2018. [DOI: 10.1016/j.nmd.2018.06.166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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13
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Chen DY, Crest J, Bilder D. A Cell Migration Tracking Tool Supports Coupling of Tissue Rotation to Elongation. Cell Rep 2018; 21:559-569. [PMID: 29045826 DOI: 10.1016/j.celrep.2017.09.083] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 08/30/2017] [Accepted: 09/25/2017] [Indexed: 12/17/2022] Open
Abstract
Cell migration is indispensable to morphogenesis and homeostasis. Live imaging allows mechanistic insights, but long-term observation can alter normal biology, and tools to track movements in vivo without perturbation are lacking. We develop here a tool called M-TRAIL (matrix-labeling technique for real-time and inferred location), which reveals migration histories in fixed tissues. Using clones that overexpress GFP-tagged extracellular matrix (ECM) components, motility trajectories are mapped based on durable traces deposited onto basement membrane. We applied M-TRAIL to Drosophila follicle rotation, comparing in vivo and ex vivo migratory dynamics. The rate, trajectory, and cessation of rotation in wild-type (WT) follicles measured in vivo and ex vivo were identical, as was rotation failure in fat2 mutants. However, follicles carrying intracellularly truncated Fat2, previously reported to lack rotation ex vivo, in fact rotate in vivo at a reduced speed, thus revalidating the hypothesis that rotation is required for tissue elongation. The M-TRAIL approach could be applied to track and quantitate in vivo cell motility in other tissues and organisms.
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Affiliation(s)
- Dong-Yuan Chen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Justin Crest
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - David Bilder
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
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14
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de Vreede G, Morrison HA, Houser AM, Boileau RM, Andersen D, Colombani J, Bilder D. A Drosophila Tumor Suppressor Gene Prevents Tonic TNF Signaling through Receptor N-Glycosylation. Dev Cell 2018; 45:595-605.e4. [PMID: 29870719 PMCID: PMC5995582 DOI: 10.1016/j.devcel.2018.05.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 04/17/2018] [Accepted: 05/07/2018] [Indexed: 01/18/2023]
Abstract
Drosophila tumor suppressor genes have revealed molecular pathways that control tissue growth, but mechanisms that regulate mitogenic signaling are far from understood. Here we report that the Drosophila TSG tumorous imaginal discs (tid), whose phenotypes were previously attributed to mutations in a DnaJ-like chaperone, are in fact driven by the loss of the N-linked glycosylation pathway component ALG3. tid/alg3 imaginal discs display tissue growth and architecture defects that share characteristics of both neoplastic and hyperplastic mutants. Tumorous growth is driven by inhibited Hippo signaling, induced by excess Jun N-terminal kinase (JNK) activity. We show that ectopic JNK activation is caused by aberrant glycosylation of a single protein, the fly tumor necrosis factor (TNF) receptor homolog, which results in increased binding to the continually circulating TNF. Our results suggest that N-linked glycosylation sets the threshold of TNF receptor signaling by modifying ligand-receptor interactions and that cells may alter this modification to respond appropriately to physiological cues.
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Affiliation(s)
- Geert de Vreede
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Holly A Morrison
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Alexandra M Houser
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Ryan M Boileau
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Ditte Andersen
- University Nice Sophia Antipolis, CNRS, Inserm, iBV, Nice 06108, France
| | - Julien Colombani
- University Nice Sophia Antipolis, CNRS, Inserm, iBV, Nice 06108, France
| | - David Bilder
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, CA 94720, USA.
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15
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Kim J, Bilder D, Neufeld TP. Mechanical stress regulates insulin sensitivity through integrin-dependent control of insulin receptor localization. Genes Dev 2018; 32:156-164. [PMID: 29440263 PMCID: PMC5830928 DOI: 10.1101/gad.305870.117] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 01/02/2018] [Indexed: 12/22/2022]
Abstract
Kim et al. show that insulin signaling in Drosophila adipocytes is abolished in the absence of physical activity and mechanical stress. The insulin receptor and downstream components are recruited to the plasma membrane upon stress sensing mediated by integrins. Insulin resistance, the failure to activate insulin signaling in the presence of ligand, leads to metabolic diseases, including type 2 diabetes. Physical activity and mechanical stress have been shown to protect against insulin resistance, but the molecular mechanisms remain unclear. Here, we address this relationship in the Drosophila larval fat body, an insulin-sensitive organ analogous to vertebrate adipose tissue and livers. We found that insulin signaling in Drosophila fat body cells is abolished in the absence of physical activity and mechanical stress even when excess insulin is present. Physical movement is required for insulin sensitivity in both intact larvae and fat bodies cultured ex vivo. Interestingly, the insulin receptor and other downstream components are recruited to the plasma membrane in response to mechanical stress, and this membrane localization is rapidly lost upon disruption of larval or tissue movement. Sensing of mechanical stimuli is mediated in part by integrins, whose activation is necessary and sufficient for mechanical stress-dependent insulin signaling. Insulin resistance develops naturally during the transition from the active larval stage to the immotile pupal stage, suggesting that regulation of insulin sensitivity by mechanical stress may help coordinate developmental programming with metabolism.
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Affiliation(s)
- Jung Kim
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455, USA.,Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA
| | - David Bilder
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA
| | - Thomas P Neufeld
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455, USA
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16
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Abstract
How organ-shaping mechanical imbalances are generated is a central question of morphogenesis, with existing paradigms focusing on asymmetric force generation within cells. We show here that organs can be sculpted instead by patterning anisotropic resistance within their extracellular matrix (ECM). Using direct biophysical measurements of elongating Drosophila egg chambers, we document robust mechanical anisotropy in the ECM-based basement membrane (BM) but not in the underlying epithelium. Atomic force microscopy (AFM) on wild-type BM in vivo reveals an anterior–posterior (A–P) symmetric stiffness gradient, which fails to develop in elongation-defective mutants. Genetic manipulation shows that the BM is instructive for tissue elongation and the determinant is relative rather than absolute stiffness, creating differential resistance to isotropic tissue expansion. The stiffness gradient requires morphogen-like signaling to regulate BM incorporation, as well as planar-polarized organization to homogenize it circumferentially. Our results demonstrate how fine mechanical patterning in the ECM can guide cells to shape an organ. DOI:http://dx.doi.org/10.7554/eLife.24958.001 All organs have specific shapes and architectures that are necessary for them to work properly. Many different factors are responsible for arranging the right cells into the correct positions to make an organ. These include physical forces that act within and around cells to pull them into the right shape and location. A structure called the extracellular matrix surrounds cells and provides them with support; it can also guide cell movements. It is not clear whether the extracellular matrix plays only a passive role or a more active, instructive role in shaping organs, in part, because it is difficult to measure the physical forces within densely packed cells. The ovaries of the fruit fly Drosophila melanogaster provide a simple system in which to study how organs take their shape. Crest et al. developed a method to measure forces in the fly ovary as it changes from being an initially spherical group of cells to its final elongated tube shape. The results revealed that, during this process, the extracellular matrix becomes gradually stiffer from one end of the ovary to the other. This change is the main factor responsible for the cell rearrangements that shape the developing organ. This work reveals that, along with providing structural support to cells, the mechanical properties of the matrix also actively guide how organs form. In the future, these findings may aid efforts to grow organs in a laboratory and to regenerate organs in human patients. DOI:http://dx.doi.org/10.7554/eLife.24958.002
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Affiliation(s)
- Justin Crest
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, United States
| | - Alba Diz-Muñoz
- Department of Bioengineering and Biophysics Program, University of California-Berkeley, Berkeley, United States
| | - Dong-Yuan Chen
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, United States
| | - Daniel A Fletcher
- Department of Bioengineering and Biophysics Program, University of California-Berkeley, Berkeley, United States
| | - David Bilder
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, United States
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17
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Chen DY, Lipari KR, Dehghan Y, Streichan SJ, Bilder D. Symmetry Breaking in an Edgeless Epithelium by Fat2-Regulated Microtubule Polarity. Cell Rep 2016; 15:1125-33. [PMID: 27134170 DOI: 10.1016/j.celrep.2016.04.014] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 02/29/2016] [Accepted: 03/29/2016] [Indexed: 12/22/2022] Open
Abstract
Planar cell polarity (PCP) information is a critical determinant of organ morphogenesis. While PCP in bounded epithelial sheets is increasingly well understood, how PCP is organized in tubular and acinar tissues is not. Drosophila egg chambers (follicles) are an acinus-like "edgeless epithelium" and exhibit a continuous, circumferential PCP that does not depend on pathways active in bounded epithelia; this follicle PCP directs formation of an ellipsoid rather than a spherical egg. Here, we apply an imaging algorithm to "unroll" the entire 3D tissue surface and comprehensively analyze PCP onset. This approach traces chiral symmetry breaking to plus-end polarity of microtubules in the germarium, well before follicles form and rotate. PCP germarial microtubules provide chiral information that predicts the direction of whole-tissue rotation as soon as independent follicles form. Concordant microtubule polarity, but not microtubule alignment, requires the atypical cadherin Fat2, which acts at an early stage to translate plus-end bias into coordinated actin-mediated collective cell migration. Because microtubules are not required for PCP or migration after follicle rotation initiates, while dynamic actin and extracellular matrix are, polarized microtubules lie at the beginning of a handoff mechanism that passes early chiral PCP of the cytoskeleton to a supracellular planar polarized extracellular matrix and elongates the organ.
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Affiliation(s)
- Dong-Yuan Chen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200, USA
| | - Katherine R Lipari
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200, USA
| | - Yalda Dehghan
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200, USA
| | - Sebastian J Streichan
- Kavli Institute of Theoretical Physics, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - David Bilder
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200, USA.
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18
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Figueroa-Clarevega A, Bilder D. Malignant Drosophila tumors interrupt insulin signaling to induce cachexia-like wasting. Dev Cell 2015; 33:47-55. [PMID: 25850672 DOI: 10.1016/j.devcel.2015.03.001] [Citation(s) in RCA: 148] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 12/24/2014] [Accepted: 02/27/2015] [Indexed: 02/07/2023]
Abstract
Tumors kill patients not only through well-characterized perturbations to their local environment but also through poorly understood pathophysiological interactions with distant tissues. Here, we use a Drosophila tumor model to investigate the elusive mechanisms underlying such long-range interactions. Transplantation of tumors into adults induces robust wasting of adipose, muscle, and gonadal tissues that are distant from the tumor, phenotypes that resemble the cancer cachexia seen in human patients. Notably, malignant, but not benign, tumors induce peripheral wasting. We identify the insulin growth factor binding protein (IGFBP) homolog ImpL2, an antagonist of insulin signaling, as a secreted factor mediating wasting. ImpL2 is sufficient to drive tissue loss, and insulin activity is reduced in peripheral tissues of tumor-bearing hosts. Importantly, knocking down ImpL2, specifically in the tumor, ameliorates wasting phenotypes. We propose that the tumor-secreted IGFBP creates insulin resistance in distant tissues, thus driving a systemic wasting response.
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Affiliation(s)
| | - David Bilder
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200, USA.
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19
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Bunker BD, Nellimoottil TT, Boileau RM, Classen AK, Bilder D. The transcriptional response to tumorigenic polarity loss in Drosophila. eLife 2015; 4. [PMID: 25719210 PMCID: PMC4369581 DOI: 10.7554/elife.03189] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 02/25/2015] [Indexed: 12/14/2022] Open
Abstract
Loss of polarity correlates with progression of epithelial cancers, but how plasma membrane misorganization drives oncogenic transcriptional events remains unclear. The polarity regulators of the Drosophila Scribble (Scrib) module are potent tumor suppressors and provide a model for mechanistic investigation. RNA profiling of Scrib mutant tumors reveals multiple signatures of neoplasia, including altered metabolism and dedifferentiation. Prominent among these is upregulation of cytokine-like Unpaired (Upd) ligands, which drive tumor overgrowth. We identified a polarity-responsive enhancer in upd3, which is activated in a coincident manner by both JNK-dependent Fos and aPKC-mediated Yki transcription. This enhancer, and Scrib mutant overgrowth in general, are also sensitive to activity of the Polycomb Group (PcG), suggesting that PcG attenuation upon polarity loss potentiates select targets for activation by JNK and Yki. Our results link epithelial organization to signaling and epigenetic regulators that control tissue repair programs, and provide insight into why epithelial polarity is tumor-suppressive. DOI:http://dx.doi.org/10.7554/eLife.03189.001 The cavities and organs within our body are lined with epithelial cells, which connect to each other to form continuous barriers. These cells have a highly polarized structure in which different components are found at the top and bottom of cells. In the fruit fly and most other animals, three genes known as the Scribble module control the polarity of epithelial cells. If these genes are faulty, the cells lose their polarity, break the epithelial barrier, and grow rapidly to form a tumor. Most malignant tumors that form from epithelial cells have lost normal cell polarity, so understanding how the organization and growth of epithelial cells are linked is a critical question. It is not clear how the loss of cell polarity can drive tumor formation. Here, Bunker et al. used a technique called RNA sequencing to study the expression of genes in tumor cells that have mutations in the Scribble module. Hundreds of genes in the tumor cells had different levels of expression from the levels seen in normal fly cells. One of these is a gene called upd3, which was expressed much more highly in tumor cells than in normal cells. This gene activates a signaling pathway—called the JAK/STAT pathway—that promotes cell growth and division in many animals. Bunker et al. found that experimentally lowering the activity of the JAK/STAT pathway reduced the growth of the tumor cells that had lost normal polarity. Further experiments show that disrupting the layer of epithelial cells activates two other signaling pathways that work together to switch on the upd3 gene when cell polarity is lost. Proteins belonging to the Polycomb Group also control the expression of upd3 and other genes involved in cell growth by altering how genetic material is packaged in cells. The similarities between this response and the response to tissue damage suggest that the loss of polarity drives tumor formation through an unstoppable wound-healing reaction. Therefore, Bunker et al.'s findings link the formation of epithelial tumors to the signaling pathways that control the repair of damaged tissues. DOI:http://dx.doi.org/10.7554/eLife.03189.002
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Affiliation(s)
- Brandon D Bunker
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Tittu T Nellimoottil
- University of Southern California, Department of Biological Sciences, Los Angeles, United States
| | - Ryan M Boileau
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Anne K Classen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - David Bilder
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
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20
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Skwarek LC, Windler SL, de Vreede G, Rogers GC, Bilder D. The F-box protein Slmb restricts the activity of aPKC to polarize epithelial cells. Development 2014; 141:2978-83. [PMID: 25053431 DOI: 10.1242/dev.109694] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The Par-3/Par-6/aPKC complex is the primary determinant of apical polarity in epithelia across animal species, but how the activity of this complex is restricted to allow polarization of the basolateral domain is less well understood. In Drosophila, several multiprotein modules antagonize the Par complex through a variety of means. Here we identify a new mechanism involving regulated protein degradation. Strong mutations in supernumerary limbs (slmb), which encodes the substrate adaptor of an SCF-class E3 ubiquitin ligase, cause dramatic loss of polarity in imaginal discs accompanied by tumorous proliferation defects. Slmb function is required to restrain apical aPKC activity in a manner that is independent of endolysosomal trafficking and parallel to the Scribble module of junctional scaffolding proteins. The involvement of the Slmb E3 ligase in epithelial polarity, specifically limiting Par complex activity to distinguish the basolateral domain, points to parallels with polarization of the C. elegans zygote.
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Affiliation(s)
- Lara C Skwarek
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720-3200, USA
| | - Sarah L Windler
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720-3200, USA
| | - Geert de Vreede
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720-3200, USA
| | - Gregory C Rogers
- Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, University of Arizona, Tucson, AZ 85724, USA
| | - David Bilder
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720-3200, USA
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21
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de Vreede G, Schoenfeld JD, Windler SL, Morrison H, Lu H, Bilder D. The Scribble module regulates retromer-dependent endocytic trafficking during epithelial polarization. Development 2014; 141:2796-802. [PMID: 25005475 DOI: 10.1242/dev.105403] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Scribble (Scrib) module proteins are major regulators of cell polarity, but how they influence membrane traffic is not known. Endocytosis is also a key regulator of polarity through roles that remain unclear. Here we link Scrib to a specific arm of the endocytic trafficking system. Drosophila mutants that block AP-2-dependent endocytosis share many phenotypes with Scrib module mutants, but Scrib module mutants show intact internalization and endolysosomal transport. However, defective traffic of retromer pathway cargo is seen, and retromer components show strong genetic interactions with the Scrib module. The Scrib module is required for proper retromer localization to endosomes and promotes appropriate cargo sorting into the retromer pathway via both aPKC-dependent and -independent mechanisms. We propose that the Scrib module regulates epithelial polarity by influencing endocytic itineraries of Crumbs and other retromer-dependent cargo.
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Affiliation(s)
- Geert de Vreede
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3200, USA
| | - Joshua D Schoenfeld
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3200, USA
| | - Sarah L Windler
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3200, USA
| | - Holly Morrison
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3200, USA
| | - Han Lu
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3200, USA
| | - David Bilder
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3200, USA
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22
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Morelli E, Ginefra P, Mastrodonato V, Beznoussenko GV, Rusten TE, Bilder D, Stenmark H, Mironov AA, Vaccari T. Multiple functions of the SNARE protein Snap29 in autophagy, endocytic, and exocytic trafficking during epithelial formation in Drosophila. Autophagy 2014; 10:2251-68. [PMID: 25551675 PMCID: PMC4502674 DOI: 10.4161/15548627.2014.981913] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 05/27/2014] [Accepted: 07/14/2014] [Indexed: 11/19/2022] Open
Abstract
How autophagic degradation is linked to endosomal trafficking routes is little known. Here we screened a collection of uncharacterized Drosophila mutants affecting membrane transport to identify new genes that also have a role in autophagy. We isolated a loss of function mutant in Snap29 (Synaptosomal-associated protein 29 kDa), the gene encoding the Drosophila homolog of the human protein SNAP29 and have characterized its function in vivo. Snap29 contains 2 soluble NSF attachment protein receptor (SNARE) domains and a asparagine-proline-phenylalanine (NPF motif) at its N terminus and rescue experiments indicate that both SNARE domains are required for function, whereas the NPF motif is in part dispensable. We find that Snap29 interacts with SNARE proteins, localizes to multiple trafficking organelles, and is required for protein trafficking and for proper Golgi apparatus morphology. Developing tissue lacking Snap29 displays distinctive epithelial architecture defects and accumulates large amounts of autophagosomes, highlighting a major role of Snap29 in autophagy and secretion. Mutants for autophagy genes do not display epithelial architecture or secretion defects, suggesting that the these alterations of the Snap29 mutant are unlikely to be caused by the impairment of autophagy. In contrast, we find evidence of elevated levels of hop-Stat92E (hopscotch-signal transducer and activator of transcription protein at 92E) ligand, receptor, and associated signaling, which might underlie the epithelial defects. In summary, our findings support a role of Snap29 at key steps of membrane trafficking, and predict that signaling defects may contribute to the pathogenesis of cerebral dysgenesis, neuropathy, ichthyosis, and palmoplantar keratoderma (CEDNIK), a human congenital syndrome due to loss of Snap29.
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Key Words
- Atg, autophagy-related
- CEDNIK, cerebral dysgenesis, neuropathy, ichthyosis, and palmoplantar keratoderma
- CFP, cyan fluorescent protein
- E(spl)mβ-HLH, enhancer of split mβ, helix-loop-helix
- EM, electron microscopy
- ESCRT, endosomal sorting complex required for transport
- FE, follicular epithelium
- GFP, green fluorescent protein
- MENE, mutant eye no eclosion
- MVB, multivesicular body
- N, Notch
- NECD, N extracellular domain
- NPF, asparagine-proline-phenylalanine
- Notch
- SNARE
- SNARE, soluble NSF attachment protein receptor
- Snap29
- Snap29, synaptosomal-associated protein 29 kDa
- Socs36E, suppressor of cytokine signaling at 36E
- Syb, Synaptobrevin
- Syx, syntaxin
- V-ATPase, vacuolar H+-ATPase
- Vamp, vesicle-associated membrane protein
- Vps25, vacuolar protein sorting 25
- WT, wild type
- autophagy
- dome
- dome, domeless
- histone H3, His3
- hop-Stat92E, hopscotch-signal transducer and activator of transcription protein at 92E
- os, outstretched
- ref(2)P, refractory to sigma P
- trafficking
- usnp
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Affiliation(s)
- Elena Morelli
- IFOM - The FIRC Institute of Molecular Oncology; Milan, Italy
| | | | | | | | - Tor Erik Rusten
- Centre for Cancer Biomedicine; Oslo University Hospital; Oslo, Norway
| | - David Bilder
- Department of Molecular and Cell Biology; University of California; Berkeley, CA USA
| | - Harald Stenmark
- Centre for Cancer Biomedicine; Oslo University Hospital; Oslo, Norway
| | | | - Thomas Vaccari
- IFOM - The FIRC Institute of Molecular Oncology; Milan, Italy
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23
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Abstract
Adult animals rely on populations of stem cells to ensure organ function throughout their lifetime. Stem cells are governed by signals from stem cell niches, and much is known about how single niches promote stemness and direct stem cell behavior. However, most organs contain a multitude of stem cell-niche units, which are often distributed across the entire expanse of the tissue. Beyond the biology of individual stem cell-niche interactions, the next challenge is to uncover the tissue-level processes that orchestrate spatial control of stem-based renewal, repair, and remodeling throughout a whole organ. Here we examine what is known about higher order mechanisms for interniche coordination in epithelial organs, whose simple geometry offers a promising entry point for understanding the regulation of niche number, distribution, and activity. We also consider the potential existence of stem cell territories and how tissue architecture may influence niche coordination.
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Affiliation(s)
- Lucy Erin O'Brien
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305;
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24
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Buster DW, Daniel SG, Nguyen HQ, Windler SL, Skwarek LC, Peterson M, Roberts M, Meserve JH, Hartl T, Klebba JE, Bilder D, Bosco G, Rogers GC. SCFSlimb ubiquitin ligase suppresses condensin II-mediated nuclear reorganization by degrading Cap-H2. J Cell Biol 2013; 201:49-63. [PMID: 23530065 PMCID: PMC3613687 DOI: 10.1083/jcb.201207183] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 03/04/2013] [Indexed: 12/21/2022] Open
Abstract
Condensin complexes play vital roles in chromosome condensation during mitosis and meiosis. Condensin II uniquely localizes to chromatin throughout the cell cycle and, in addition to its mitotic duties, modulates chromosome organization and gene expression during interphase. Mitotic condensin activity is regulated by phosphorylation, but mechanisms that regulate condensin II during interphase are unclear. Here, we report that condensin II is inactivated when its subunit Cap-H2 is targeted for degradation by the SCF(Slimb) ubiquitin ligase complex and that disruption of this process dramatically changed interphase chromatin organization. Inhibition of SCF(Slimb) function reorganized interphase chromosomes into dense, compact domains and disrupted homologue pairing in both cultured Drosophila cells and in vivo, but these effects were rescued by condensin II inactivation. Furthermore, Cap-H2 stabilization distorted nuclear envelopes and dispersed Cid/CENP-A on interphase chromosomes. Therefore, SCF(Slimb)-mediated down-regulation of condensin II is required to maintain proper organization and morphology of the interphase nucleus.
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Affiliation(s)
- Daniel W. Buster
- Department of Cellular and Molecular Medicine, Arizona Cancer Center, and Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721
| | - Scott G. Daniel
- Department of Cellular and Molecular Medicine, Arizona Cancer Center, and Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721
| | - Huy Q. Nguyen
- Department of Cellular and Molecular Medicine, Arizona Cancer Center, and Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Sarah L. Windler
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Lara C. Skwarek
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Maureen Peterson
- Department of Cellular and Molecular Medicine, Arizona Cancer Center, and Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Meredith Roberts
- Department of Cellular and Molecular Medicine, Arizona Cancer Center, and Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721
| | - Joy H. Meserve
- Department of Cellular and Molecular Medicine, Arizona Cancer Center, and Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721
| | - Tom Hartl
- Department of Cellular and Molecular Medicine, Arizona Cancer Center, and Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721
| | - Joseph E. Klebba
- Department of Cellular and Molecular Medicine, Arizona Cancer Center, and Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721
| | - David Bilder
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Giovanni Bosco
- Department of Cellular and Molecular Medicine, Arizona Cancer Center, and Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Gregory C. Rogers
- Department of Cellular and Molecular Medicine, Arizona Cancer Center, and Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721
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25
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Abstract
Tissue and organ architectures are incredibly diverse, yet our knowledge of the morphogenetic behaviors that generate them is relatively limited. Recent studies have revealed unexpected mechanisms that drive axis elongation in the Drosophila egg, including an unconventional planar polarity signaling pathway, a distinctive type of morphogenetic movement termed "global tissue rotation," a molecular corset-like role of extracellular matrix, and oscillating basal cellular contractions. We review here what is known about Drosophila egg elongation, compare it to other instances of morphogenesis, and highlight several issues of general developmental relevance.
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Affiliation(s)
- David Bilder
- Department of Molecular & Cell Biology, 379 Life Sciences Addition #3200, University of California, Berkeley, Berkeley, CA 94720-3200, USA.
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26
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Bilder D. David Bilder: Getting to know epithelia inside and out. Interviewed by Caitlin Sedwick. J Cell Biol 2011; 193:956-7. [PMID: 21670209 PMCID: PMC3115797 DOI: 10.1083/jcb.1936pi] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Bilder explores epithelial form and function in Drosophila using forward genetic screens.
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27
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Banks SML, Cho B, Eun SH, Lee JH, Windler SL, Xie X, Bilder D, Fischer JA. The functions of auxilin and Rab11 in Drosophila suggest that the fundamental role of ligand endocytosis in notch signaling cells is not recycling. PLoS One 2011; 6:e18259. [PMID: 21448287 PMCID: PMC3063240 DOI: 10.1371/journal.pone.0018259] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 02/23/2011] [Indexed: 12/03/2022] Open
Abstract
Notch signaling requires ligand internalization by the signal sending cells. Two endocytic proteins, epsin and auxilin, are essential for ligand internalization and signaling. Epsin promotes clathrin-coated vesicle formation, and auxilin uncoats clathrin from newly internalized vesicles. Two hypotheses have been advanced to explain the requirement for ligand endocytosis. One idea is that after ligand/receptor binding, ligand endocytosis leads to receptor activation by pulling on the receptor, which either exposes a cleavage site on the extracellular domain, or dissociates two receptor subunits. Alternatively, ligand internalization prior to receptor binding, followed by trafficking through an endosomal pathway and recycling to the plasma membrane may enable ligand activation. Activation could mean ligand modification or ligand transcytosis to a membrane environment conducive to signaling. A key piece of evidence supporting the recycling model is the requirement in signaling cells for Rab11, which encodes a GTPase critical for endosomal recycling. Here, we use Drosophila Rab11 and auxilin mutants to test the ligand recycling hypothesis. First, we find that Rab11 is dispensable for several Notch signaling events in the eye disc. Second, we find that Drosophila female germline cells, the one cell type known to signal without clathrin, also do not require auxilin to signal. Third, we find that much of the requirement for auxilin in Notch signaling was bypassed by overexpression of both clathrin heavy chain and epsin. Thus, the main role of auxilin in Notch signaling is not to produce uncoated ligand-containing vesicles, but to maintain the pool of free clathrin. Taken together, these results argue strongly that at least in some cell types, the primary function of Notch ligand endocytosis is not for ligand recycling.
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Affiliation(s)
- Susan M. L. Banks
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - Bomsoo Cho
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - Suk Ho Eun
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - Ji-Hoon Lee
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - Sarah L. Windler
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Xuanhua Xie
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - David Bilder
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Janice A. Fischer
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
- * E-mail:
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28
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Abstract
Polarized cell behaviors drive axis elongation in animal embryos, but the mechanisms underlying elongation of many tissues remain unknown. Eggs of Drosophila undergo elongation from a sphere to an ellipsoid during oogenesis. We used live imaging of follicles (developing eggs) to elucidate the cellular basis of egg elongation. We find that elongating follicles undergo repeated rounds of circumferential rotation around their long axes. Follicle epithelia mutant for integrin or collagen IV fail to rotate and elongate, which results in round eggs. We present evidence that polarized rotation is required to build a polarized, fibrillar extracellular matrix (ECM) that constrains tissue shape. Thus, global tissue rotation is a morphogenetic behavior that uses planar polarity information in the ECM to control tissue elongation.
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Affiliation(s)
- Saori L Haigo
- Department of Molecular and Cell Biology, 379 Life Sciences Addition no. 3200, University of California, Berkeley, Berkeley, CA 94720-3200, USA
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29
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Vaccari T, Duchi S, Cortese K, Tacchetti C, Bilder D. The vacuolar ATPase is required for physiological as well as pathological activation of the Notch receptor. Development 2010; 137:1825-32. [PMID: 20460366 PMCID: PMC2867318 DOI: 10.1242/dev.045484] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/25/2010] [Indexed: 01/23/2023]
Abstract
Evidence indicates that endosomal entry promotes signaling by the Notch receptor, but the mechanisms involved are not clear. In a search for factors that regulate Notch activation in endosomes, we isolated mutants in Drosophila genes that encode subunits of the vacuolar ATPase (V-ATPase) proton pump. Cells lacking V-ATPase function display impaired acidification of the endosomal compartment and a correlated failure to degrade endocytic cargoes. V-ATPase mutant cells internalize Notch and accumulate it in the lysosome, but surprisingly also show a substantial loss of both physiological and ectopic Notch activation in endosomes. V-ATPase activity is required in signal-receiving cells for Notch signaling downstream of ligand activation but upstream of gamma-secretase-dependent S3 cleavage. These data indicate that V-ATPase, probably via acidification of early endosomes, promotes not only the degradation of Notch in the lysosome but also the activation of Notch signaling in endosomes. The results also suggest that the ionic properties of the endosomal lumen might regulate Notch cleavage, providing a rationale for physiological as well as pathological endocytic control of Notch activity.
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Affiliation(s)
- Thomas Vaccari
- Molecular and Cell Biology, University of California, LSA #3200, Berkeley, CA 94720, USA
- IFOM, Istituto FIRC di Oncologia Molecolare, via Adamello 16, 20139, Milano, Italy
| | - Serena Duchi
- IFOM, Istituto FIRC di Oncologia Molecolare, via Adamello 16, 20139, Milano, Italy
| | - Katia Cortese
- Centro di Ricerca MicroSCoBio/IFOM Fondazione Istituto FIRC di Oncologia Molecolare, Dipartimento di Medicina Sperimentale, Università di Genova, Via de Toni 14, 16132, Genoa, Italy
| | - Carlo Tacchetti
- Centro di Ricerca MicroSCoBio/IFOM Fondazione Istituto FIRC di Oncologia Molecolare, Dipartimento di Medicina Sperimentale, Università di Genova, Via de Toni 14, 16132, Genoa, Italy
| | - David Bilder
- Molecular and Cell Biology, University of California, LSA #3200, Berkeley, CA 94720, USA
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30
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Shivas JM, Morrison HA, Bilder D, Skop AR. Polarity and endocytosis: reciprocal regulation. Trends Cell Biol 2010; 20:445-52. [PMID: 20493706 DOI: 10.1016/j.tcb.2010.04.003] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Revised: 04/09/2010] [Accepted: 04/13/2010] [Indexed: 10/19/2022]
Abstract
The establishment and maintenance of polarized plasma membrane domains is essential for cellular function and proper development of organisms. The molecules and pathways involved in determining cell polarity are remarkably well conserved between animal species. Historically, exocytic mechanisms have received primary emphasis among trafficking routes responsible for cell polarization. Accumulating evidence now reveals that endocytosis plays an equally important role in the proper localization of key polarity proteins. Intriguingly, some polarity proteins can also regulate the endocytic machinery. Here, we review emerging evidence for the reciprocal regulation between polarity proteins and endocytic pathways, and discuss possible models for how these distinct processes could interact to create separate cellular domains.
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Affiliation(s)
- Jessica M Shivas
- Laboratory of Genetics, University of Wisconsin, Madison, WI 53706, USA
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31
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Bilder D. Function follows form: Linking epithelial polarity, growth control and morphogenesis in Drosophila. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.65.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- David Bilder
- Molecular & Cell BiologyUniversity of California ‐ BerkeleyBerkeleyCA
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32
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Windler SL, Bilder D. Endocytic internalization routes required for delta/notch signaling. Curr Biol 2010; 20:538-43. [PMID: 20226669 DOI: 10.1016/j.cub.2010.01.049] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Revised: 01/25/2010] [Accepted: 01/25/2010] [Indexed: 12/15/2022]
Abstract
The internalization of transmembrane receptors from the cell surface plays a central role in signal regulation. Receptor internalization can occur through different routes; however, because of the difficulty in selectively blocking these routes in vivo, their roles in signaling are poorly understood. Here we use null mutations in Drosophila dynamin, clathrin, and AP-2 adaptor subunits to analyze internalization requirements for the Delta ligand and its receptor, Notch. Bulk Notch is internalized via AP-2-dependent endocytosis, but signaling by Notch requires AP-2-independent clathrin-dependent endocytosis, highlighting a distinction between Notch endocytic routes required for degradation versus signaling activation. Signaling by Delta requires dynamin, but whether this generates a pulling force of Delta on Notch or allows for Delta entry into a recycling pathway to gain signaling competence is widely debated. Surprisingly, we show that signaling by Delta in germline cells can occur by clathrin-independent endocytosis, when endosomal entry is blocked, and when activity of Rab11 or its effectors is reduced, suggesting that Delta need not pass through a recognized recycling pathway to achieve signaling competence. The absolute requirement for dynamin-dependent endocytosis but not endosomal entry or Rab11 activity supports "pulling force" rather than "recycling" models for Delta activation.
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Affiliation(s)
- Sarah L Windler
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200, USA
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Abstract
Psychological and psychiatric problems are well documented across the lifespan of individuals with early-treated phenylketonuria (PKU). Early-treated children and adolescents tend to display attentional problems, school problems, lower achievement motivation, decreased social competence, decreased autonomy, and low-self-esteem. As they enter adulthood, early-treated individuals may carry forward low self-esteem and lack of autonomy but also tend to develop depressed mood, generalized anxiety, phobias, decreased positive emotions, social maturity deficits, and social isolation. The correlation between level of metabolic control and severity of symptoms suggests a biological basis of psychiatric dysfunction. Additionally, psychosocial factors such as the burden of living with a chronic illness may contribute to psychological and psychiatric outcomes in PKU. The lack of a PKU-specific psychiatric phenotype combined with the observation that not everyone with PKU is affected highlights the complexity of the problem. More research on psychiatric and psychological outcomes in PKU is required. Of particular importance is the routine monitoring of emotional, behavioral, and psychosocial symptoms in individuals with this metabolic disorder. Longitudinal studies are required to evaluate the impact of new and emerging therapies on psychiatric and psychosocial functioning in PKU. Unidentified or untreated emotional and behavioral symptoms may have a significant, lifelong impact on the quality of life and social status of patients.
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Vaccari T, Bilder D. At the crossroads of polarity, proliferation and apoptosis: the use of Drosophila to unravel the multifaceted role of endocytosis in tumor suppression. Mol Oncol 2009; 3:354-65. [PMID: 19560990 PMCID: PMC2755045 DOI: 10.1016/j.molonc.2009.05.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2009] [Accepted: 05/25/2009] [Indexed: 11/27/2022] Open
Abstract
Endocytosis is an important regulator of cell-cell signaling and endocytic trafficking has been increasingly implicated in control of tumor suppression. Recent insights from Drosophila indicate that impairment of multiple trafficking steps which lead to receptor degradation can cause tumor formation in epithelial organs. These tumors are characterized by sustained activation of a number of mitogenic signaling pathways, and by subversion of epithelial polarity and the apoptotic response. Cooperation between such alterations, as well as tumor-host interactions, is also observed. The recapitulation of several hallmarks of human cancers in fly tumors provides a framework to understand the role of defective endocytosis in cancer.
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Affiliation(s)
- Thomas Vaccari
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
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Vaccari T, Rusten TE, Menut L, Nezis IP, Brech A, Stenmark H, Bilder D. Comparative analysis of ESCRT-I, ESCRT-II and ESCRT-III function in Drosophila by efficient isolation of ESCRT mutants. J Cell Sci 2009; 122:2413-23. [PMID: 19571114 PMCID: PMC2704878 DOI: 10.1242/jcs.046391] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/16/2009] [Indexed: 11/20/2022] Open
Abstract
ESCRT proteins were initially isolated in yeast as a single functional set of conserved components controlling endosomal cargo sorting and multivesicular body (MVB) biogenesis. Recent work has suggested that metazoan ESCRT proteins might have more functionally diverse roles, but the limited availability of ESCRT mutants in species other than yeast has hampered a thorough analysis. Here, we used a genetic screening strategy based on both cell-autonomous and non-autonomous growth-promotion phenotypes to isolate null mutations in nearly half of the ESCRT-encoding genes of Drosophila, including components of ESCRT-I, ESCRT-II and ESCRT-III complexes. All ESCRT components are required for trafficking of ubiquitylated proteins and are required to prevent excess Notch and EGFR signaling. However, cells lacking certain ESCRT-III components accumulate fewer ubiquitylated molecules in endosomes and display reduced degrees of cell proliferation compared with those lacking components of ESCRT-I and ESCRT-II. Moreover, although we find by ultrastructural analysis that MVB formation is impaired in ESCRT-I and ESCRT-II mutant cells, MVB biogenesis still occurs to some degree in ESCRT-III mutant cells. This work highlights the multiple cell biological and developmental roles of ESCRT proteins in Drosophila, suggests that the metazoan ESCRT-I, ESCRT-II and ESCRT-III complexes do not serve identical functions, and provides the basis for an extensive analysis of metazoan ESCRT function.
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Affiliation(s)
- Thomas Vaccari
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94702, USA.
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Morrison HA, Dionne H, Rusten TE, Brech A, Fisher WW, Pfeiffer BD, Celniker SE, Stenmark H, Bilder D. Regulation of early endosomal entry by the Drosophila tumor suppressors Rabenosyn and Vps45. Mol Biol Cell 2008; 19:4167-76. [PMID: 18685079 DOI: 10.1091/mbc.e08-07-0716] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The small GTPase Rab5 has emerged as an important regulator of animal development, and it is essential for endocytic trafficking. However, the mechanisms that link Rab5 activation to cargo entry into early endosomes remain unclear. We show here that Drosophila Rabenosyn (Rbsn) is a Rab5 effector that bridges an interaction between Rab5 and the Sec1/Munc18-family protein Vps45, and we further identify the syntaxin Avalanche (Avl) as a target for Vps45 activity. Rbsn and Vps45, like Avl and Rab5, are specifically localized to early endosomes and are required for endocytosis. Ultrastructural analysis of rbsn, Vps45, avl, and Rab5 null mutant cells, which show identical defects, demonstrates that all four proteins are required for vesicle fusion to form early endosomes. These defects lead to loss of epithelial polarity in mutant tissues, which overproliferate to form neoplastic tumors. This work represents the first characterization of a Rab5 effector as a tumor suppressor, and it provides in vivo evidence for a Rbsn-Vps45 complex on early endosomes that links Rab5 to the SNARE fusion machinery.
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Affiliation(s)
- Holly A Morrison
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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Abstract
Intense investigation has identified an elaborate protein network controlling epithelial polarity. Although precise subcellular targeting of apical and basolateral determinants is required for epithelial architecture, little is known about how the individual determinant proteins become localized within the cell. Through a genetic screen for epithelial defects in the Drosophila follicle cells, we have found that the cytoplasmic Dynein motor is an essential regulator of apico–basal polarity. Our data suggest that Dynein acts through the cytoplasmic scaffolding protein Stardust (Sdt) to localize the transmembrane protein Crumbs, in part through the apical targeting of specific sdt mRNA isoforms. We have mapped the sdt mRNA localization signal to an alternatively spliced coding exon. Intriguingly, the presence or absence of this exon corresponds to a developmental switch in sdt mRNA localization in which apical transcripts are only found during early stages of epithelial development, while unlocalized transcripts predominate in mature epithelia. This work represents the first demonstration that Dynein is required for epithelial polarity and suggests that mRNA localization may have a functional role in the regulation of apico–basal organization. Moreover, we introduce a unique mechanism in which alternative splicing of a coding exon is used to control mRNA localization during development. Cells within epithelial sheets are highly polarized with distinct apical and basolateral membrane domains. This cellular organization is critical to both epithelial form and function, and a failure to maintain epithelial polarity is often linked to tumor progression. The protein network that establishes and maintains the two membrane domains relies on the precise subcellular localization of its molecular components, but little is known about how these proteins are targeted to their sites of action. We have shown that the localization of the apical determinant protein Stardust depends on the microtubule motor Dynein. While investigating the relationship between Dynein and Stardust, we also made two unexpected observations about stardust mRNA regulation. First, the mechanism by which Dynein localizes Stardust may depend, in part, on the apical targeting of the stardust mRNA. Second, some stardust mRNA is apically localized during early stages of epithelial development, but the selective removal of the apical localization signal leads to the sole production of uniformly localized transcripts in mature epithelial cells. Together, these results introduce roles for Dynein in apico–basal polarity regulation and raise important questions about the role of mRNA localization in the targeting of polarity determinant proteins and epithelial maturation.
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Affiliation(s)
- Sally Horne-Badovinac
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California, United States of America
| | - David Bilder
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California, United States of America
- * To whom correspondence should be addressed. E-mail:
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Vaccari T, Lu H, Kanwar R, Fortini ME, Bilder D. Endosomal entry regulates Notch receptor activation in Drosophila melanogaster. J Cell Biol 2008; 180:755-62. [PMID: 18299346 PMCID: PMC2265571 DOI: 10.1083/jcb.200708127] [Citation(s) in RCA: 211] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2007] [Accepted: 01/25/2008] [Indexed: 11/26/2022] Open
Abstract
Signaling through the transmembrane receptor Notch is widely used throughout animal development and is a major regulator of cell proliferation and differentiation. During canonical Notch signaling, internalization and recycling of Notch ligands controls signaling activity, but the involvement of endocytosis in activation of Notch itself is not well understood. To address this question, we systematically assessed Notch localization, processing, and signaling in a comprehensive set of Drosophila melanogaster mutants that block access of cargo to different endocytic compartments. We find that gamma-secretase cleavage and signaling of endogenous Notch is reduced in mutants that impair entry into the early endosome but is enhanced in mutants that increase endosomal retention. In mutants that block endosomal entry, we also uncover an alternative, low-efficiency Notch trafficking route that can contribute to signaling. Our data show that endosomal access of the Notch receptor is critical to achieve physiological levels of signaling and further suggest that altered residence in distinct endocytic compartments could underlie pathologies involving aberrant Notch pathway activation.
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Affiliation(s)
- Thomas Vaccari
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
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39
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Rusten TE, Vaccari T, Lindmo K, Rodahl LMW, Nezis IP, Sem-Jacobsen C, Wendler F, Vincent JP, Brech A, Bilder D, Stenmark H. ESCRTs and Fab1 regulate distinct steps of autophagy. Curr Biol 2007; 17:1817-25. [PMID: 17935992 DOI: 10.1016/j.cub.2007.09.032] [Citation(s) in RCA: 248] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Revised: 09/16/2007] [Accepted: 09/17/2007] [Indexed: 11/16/2022]
Abstract
Eukaryotes use autophagy to turn over organelles, protein aggregates, and cytoplasmic constituents. The impairment of autophagy causes developmental defects, starvation sensitivity, the accumulation of protein aggregates, neuronal degradation, and cell death [1, 2]. Double-membraned autophagosomes sequester cytoplasm and fuse with endosomes or lysosomes in higher eukaryotes [3], but the importance of the endocytic pathway for autophagy and associated disease is not known. Here, we show that regulators of endosomal biogenesis and functions play a critical role in autophagy in Drosophila melanogaster. Genetic and ultrastructural analysis showed that subunits of endosomal sorting complex required for transport (ESCRT)-I, -II and -III, as well as their regulatory ATPase Vps4 and the endosomal PtdIns(3)P 5-kinase Fab1, all are required for autophagy. Although the loss of ESCRT or Vps4 function caused the accumulation of autophagosomes, probably because of inhibited fusion with the endolysosomal system, Fab1 activity was necessary for the maturation of autolysosomes. Importantly, reduced ESCRT functions aggravated polyglutamine-induced neurotoxicity in a model for Huntington's disease. Thus, this study links ESCRT function with autophagy and aggregate-induced neurodegeneration, thereby providing a plausible explanation for the fact that ESCRT mutations are involved in inherited neurodegenerative disease in humans [4].
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Affiliation(s)
- Tor Erik Rusten
- Centre for Cancer Biomedicine, University of Oslo, N-0310 Oslo, Norway
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40
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Horne-Badovinac S, Bilder D. Dynein is required for epithelial polarity and the apical localization of stardust mRNA. Dev Biol 2007. [DOI: 10.1016/j.ydbio.2007.03.478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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41
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Abstract
Inactivating mutations in the Drosophila tumor-suppressor genes result in tissue overgrowth. This can occur because the mutant tissue either grows faster than wild-type tissue and/or continues to grow beyond a time when wild-type tissue stops growing. There are three general classes of tumor-suppressor genes that regulate the growth of imaginal disc epithelia. Mutations in the hyperplastic tumor-suppressor genes result in increased cell proliferation but do not disrupt normal tissue architecture. These genes include pten, Tsc1, Tsc2, and components of the hippo/salvador/warts pathway. Mutations in a second class of genes, the neoplastic tumor-suppressor genes, disrupt proteins that function either as scaffolds at cell-cell junctions (scribble, discs large, lgl) or as components of the endocytic pathway (avalanche, rab5, ESCRT components). For the third group, the nonautonomous tumor-suppressor genes, mutant cells stimulate the proliferation of adjacent wild-type cells. Understanding the interactions between these three classes of genes will improve our understanding of how cell and tissue growth are coordinated during organismal development and perturbed in disease states such as cancer.
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Affiliation(s)
- Iswar K Hariharan
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA.
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Vaccari T, Bilder D. The Drosophila tumor suppressor vps25 prevents nonautonomous overproliferation by regulating notch trafficking. Dev Cell 2006; 9:687-98. [PMID: 16256743 DOI: 10.1016/j.devcel.2005.09.019] [Citation(s) in RCA: 292] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2005] [Revised: 09/01/2005] [Accepted: 09/29/2005] [Indexed: 01/05/2023]
Abstract
Cell-cell signaling coordinates proliferation of metazoan tissues during development, and its alteration can induce malignant transformation. Endocytosis regulates signaling by controlling the levels and activity of transmembrane receptors, both prior to and following ligand engagement. Here, we identify Vps25, a component of the ESCRT machinery that regulates endocytic sorting of signaling receptors, as an unconventional type of Drosophila tumor suppressor. vps25 mutant cells undergo autonomous neoplastic-like transformation, but they also stimulate nonautonomous cell proliferation. Endocytic trafficking defects in vps25 cells cause endosomal accumulation of the signaling receptor Notch and enhanced Notch signaling. Increased Notch activity leads to ectopic production of the mitogenic JAK-STAT pathway ligand Unpaired, which is secreted from mutant cells to induce overproliferation of the surrounding epithelium. Our data show that defects in endocytic sorting can both transform cells and, through heterotypic signaling, alter the behavior of neighboring wild-type tissue.
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Affiliation(s)
- Thomas Vaccari
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA
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Sun X, Barolo S, Bilder D, Montgomery M, Sinha N. Emerging from the fog: Hypotheses and paradigms in developmental biology—The Society for Developmental Biology 2005 Annual Meeting Report. Dev Biol 2006; 289:273-82. [PMID: 16337185 DOI: 10.1016/j.ydbio.2005.10.039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2005] [Accepted: 10/17/2005] [Indexed: 10/25/2022]
Abstract
The Society for Developmental Biology 64th annual meeting took place by the beautiful San Francisco Bay from July 27th to August 1st, 2005. Organized under the leadership of Judith Kimble (SDB President, U. Wisconsin-Madison), the meeting attracted over one thousand developmental biologists from all over the world. They gathered to present data, exchange ideas and enjoy basking in the warm sun on the piers. Strong themes emerged from the diverse subjects discussed at the meeting, demonstrating exciting trends towards the unifying goal of understanding the progression from a single cell to an adult organism. Cell and Tissue Polarity was a recurring topic at the meeting. Questions like "is there polarity", "how is it achieved" and "how is it linked to stem cell maintenance" were discussed. Post-transcriptional regulation involving protein degradation and microRNA (miRNA) modulation of gene expression was featured in the context of transition between meiosis to mitosis and asymmetries in the embryo. It is apparent that Evolutionary Developmental Biology, once a major driving influence in the early days of the field, continues to enjoy a renaissance as researchers familiar with traditional model organisms are increasingly attracted to the field and as modern genetic and molecular approaches are applied to an increasingly varied assortment of organisms. The attention is beginning to pay off as laboratories are starting to generate significant results shedding light into how developmental programs are altered to generate morphological diversity. In the Satellite Symposium on Plant Development held on July 27th, 2005, the overriding theme was on the identity and maintenance of Stem Cells in Plants. Finally, researchers working on diverse organisms have shown a strong effort to address Developmental Coordination: on the subcellular, cellular and tissue levels. Advanced imaging techniques are combined with traditional genetic methods to scrutinize and compare dynamic processes in four dimensions. This tremendous increase in resolution has facilitated the identification of key signaling mechanisms that embryos utilize to form coordinated body plans. For an exceptional effort in keeping with Society tradition, the 2005 annual meeting also offered opportunities to address broader issues revolving around education and professional development as well as a special session on embryonic stem cell research. Throughout the 5-day meeting, participants found time to honor the contributions of colleagues, exchange career and grant planning strategies, contemplate the big picture and recognize the efforts of young investigators, postdoctoral fellows and students.
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Affiliation(s)
- Xin Sun
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA.
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Abstract
Intracellular protein transport is a key factor in epithelial cell polarity. Here we report that mutations in two core components of the vesicle trafficking machinery - a syntaxin and a Rab protein - cause an expansion of the apical membrane domain of Drosophila melanogaster epithelia; this polarity defect is coupled with overproliferation to form neoplastic tumours. Surprisingly, these proteins are associated with the endocytic, and not the exocytic, pathway. The syntaxin Avalanche (Avl) localizes to early endosomes, and loss of avl results in the cellular accumulation of specific membrane proteins, including the Notch signalling receptor and the polarity determinant Crumbs (Crb). Protein accumulation results from a failure in endosomal entry and progression towards lysosomal degradation; these and other avl phenotypes are also detected in Rab5 null mutant cells. Overexpression of Crb alone is sufficient to induce overproliferation of wild-type imaginal tissue, suggesting that polarity alterations in avl and Rab5 mutants directly contribute to tumour formation. Our findings reveal a critical and specific role for endocytic traffic in the control of both apico-basal polarity and cell proliferation.
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Affiliation(s)
- Han Lu
- Department of Molecular and Cell Biology, University of California-Berkeley, 142 LSA #3200 Berkeley, CA 94720-3200 USA
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45
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Abstract
Cell polarity and cell proliferation can be coupled in animal tissues, but how they are coupled is not understood. In Drosophila imaginal discs, loss of the neoplastic tumor suppressor gene scribble (scrib), which encodes a multidomain scaffolding protein, disrupts epithelial organization and also causes unchecked proliferation. Using an allelic series of mutations along with rescuing transgenes, we have identified domain requirements for polarity, proliferation control, and other Scrib functions. The leucine-rich repeats (LRR) tether Scrib to the plasma membrane, are both necessary and sufficient to organize a polarized epithelial monolayer, and are required for all proliferation control. The PDZ domains, which recruit the LRR to the junctional complex, are dispensable for overall epithelial organization. PDZ domain absence leads to mild polarity defects accompanied by moderate overproliferation, but the PDZ domains alone are insufficient to provide any Scrib function in mutant discs. We suggest a model in which Scrib, via the activity of the LRR, governs proliferation primarily by regulating apicobasal polarity.
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Affiliation(s)
- Jennifer Zeitler
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
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46
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Abstract
Epithelial cells use a striking array of morphogenetic behaviors to sculpt organs and body plans during development. Although it is clear that epithelial morphogenesis is largely driven by cytoskeletal rearrangements and changes in cell adhesion, little is known about how these processes are coordinated to construct complex biological structures from simple sheets of cells. The follicle cell epithelium of the Drosophila egg chamber exhibits a diverse range of epithelial movements in a genetically accessible tissue, making it an outstanding system for the study of epithelial morphogenesis. In this review, we move chronologically through the process of oogenesis, highlighting the dynamic movements of the follicle cells. We discuss the cellular architecture and patterning events that set the stage for morphogenesis, detail individual cellular movements, and focus on current knowledge of the cellular processes that drive follicle cell behavior.
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Affiliation(s)
- Sally Horne-Badovinac
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720-3200, USA
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47
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Abstract
Mammalian epithelial tumors lose polarity as they progress toward malignancy, but whether polarity loss might causally contribute to cancer has remained unclear. In Drosophila, mutations in the "neoplastic tumor suppressor genes" (nTSGs) scribble, discs-large, and lethal giant larvae disrupt polarity of epithelia and neuroblasts, and simultaneously induce extensive overproliferation of these cells, which exhibit malignant-like characteristics. Herein I review what is known about the role of the fly nTSGs in controlling cell polarity and cell proliferation. Incorporating data from mammalian studies, I consider how polarity and proliferation can be coupled, and how disruption of polarity could promote cancer.
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Affiliation(s)
- David Bilder
- Department of Molecular and Cell Biology, University of California, Berkeley, 94720-3200, USA.
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Sasamura T, Sasaki N, Miyashita F, Nakao S, Ishikawa HO, Ito M, Kitagawa M, Harigaya K, Spana E, Bilder D, Perrimon N, Matsuno K. neurotic, a novel maternal neurogenic gene, encodes an O-fucosyltransferase that is essential for Notch-Delta interactions. Development 2003; 130:4785-95. [PMID: 12917292 DOI: 10.1242/dev.00679] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Notch signalling, which is highly conserved from nematodes to mammals, plays crucial roles in many developmental processes. In the Drosophila embryo, deficiency in Notch signalling results in neural hyperplasia, commonly referred to as the neurogenic phenotype. We identify a novel maternal neurogenic gene, neurotic, and show that it is essential for Notch signalling. neurotic encodes a Drosophila homolog of mammalian GDP-fucose protein O-fucosyltransferase, which adds fucose sugar to epidermal growth factor-like repeats and is known to play a crucial role in Notch signalling. neurotic functions in a cell-autonomous manner, and genetic epistasis tests reveal that Neurotic is required for the activity of the full-length but not an activated form of Notch. Further, we show that neurotic is required for Fringe activity, which encodes a fucose-specific beta1, 3 N-acetylglucosaminyltransferase, previously shown to modulate Notch receptor activity. Finally, Neurotic is essential for the physical interaction of Notch with its ligand Delta, and for the ability of Fringe to modulate this interaction in Drosophila cultured cells. We present an unprecedented example of an absolute requirement of a protein glycosylation event for a ligand-receptor interaction. Our results suggest that O-fucosylation catalysed by Neurotic is also involved in the Fringe-independent activities of Notch and may provide a novel on-off mechanism that regulates ligand-receptor interactions.
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Affiliation(s)
- Takeshi Sasamura
- PRESTO, Japan Science and Technology Corporation, Noda, Chiba, Japan
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Affiliation(s)
- David Bilder
- Department of Molecular and Cell Biology, University of California-Berkeley, 142 Life Sciences Addition #3200, Berkeley, CA 94720-3200, USA.
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50
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Ghiglione C, Amundadottir L, Andresdottir M, Bilder D, Diamonti JA, Noselli S, Perrimon N, Carraway III KL. Mechanism of inhibition of the Drosophila and mammalian EGF receptors by the transmembrane protein Kekkon 1. Development 2003; 130:4483-93. [PMID: 12900463 DOI: 10.1242/dev.00617] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The transmembrane protein Kekkon 1 (Kek1) has previously been shown to act in a negative feedback loop to downregulate the Drosophila Epidermal Growth Factor Receptor (DER) during oogenesis. We show that this protein plays a similar role in other DER-mediated developmental processes. Structure-function analysis reveals that the extracellular Leucine-Rich Repeat (LRR) domains of Kek1 are critical for its function through direct association with DER, whereas its cytoplasmic domain is required for apical subcellular localization. In addition, the use of chimeric proteins between Kek1 extracellular and transmembrane domains fused to DER intracellular domain indicates that Kek1 forms an heterodimer with DER in vivo. To characterize more precisely the mechanism underlying the Kek1/DER interaction, we used mammalian ErbB/EGFR cell-based assays. We show that Kek1 is capable of physically interacting with each of the known members of the mammalian ErbB receptor family and that the Kek1/EGFR interaction inhibits growth factor binding, receptor autophosphorylation and Erk1/2 activation in response to EGF. Finally, in vivo experiments show that Kek1 expression potently suppresses the growth of mouse mammary tumor cells derived from aberrant ErbB receptors activation, but does not interfere with the growth of tumor cells derived from activated Ras. Our results underscore the possibility that Kek1 may be used experimentally to inhibit ErbB receptors and point to the possibility that, as yet uncharacterized, mammalian transmembrane LRR proteins might act as modulators of growth factor signalling.
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