1
|
Karkali K, Saunders TE, Panayotou G, Martín-Blanco E. JNK signaling in pioneer neurons organizes ventral nerve cord architecture in Drosophila embryos. Nat Commun 2023; 14:675. [PMID: 36750572 PMCID: PMC9905486 DOI: 10.1038/s41467-023-36388-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 01/30/2023] [Indexed: 02/09/2023] Open
Abstract
Morphogenesis of the Central Nervous System (CNS) is a complex process that obeys precise architectural rules. Yet, the mechanisms dictating these rules remain unknown. Analyzing morphogenesis of the Drosophila embryo Ventral Nerve Cord (VNC), we observe that a tight control of JNK signaling is essential for attaining the final VNC architecture. JNK signaling in a specific subset of pioneer neurons autonomously regulates the expression of Fasciclin 2 (Fas 2) and Neurexin IV (Nrx IV) adhesion molecules, probably via the transcription factor zfh1. Interfering at any step in this cascade affects fasciculation along pioneer axons, leading to secondary cumulative scaffolding defects during the structural organization of the axonal network. The global disorder of architectural landmarks ultimately influences nervous system condensation. In summary, our data point to JNK signaling in a subset of pioneer neurons as a key element underpinning VNC architecture, revealing critical milestones on the mechanism of control of its structural organization.
Collapse
Affiliation(s)
- Katerina Karkali
- Instituto de Biología Molecular de Barcelona (CSIC), Parc Cientific de Barcelona, Baldiri Reixac 10-12, 08028, Barcelona, Spain.,Mechanobiology Institute and Department of Biological Sciences, 5 Engineering Drive 1, National University of Singapore, Singapore, 117411, Singapore.,BSRC Alexander Fleming, 34 Fleming Street, 16672, Vari, Greece
| | - Timothy E Saunders
- Mechanobiology Institute and Department of Biological Sciences, 5 Engineering Drive 1, National University of Singapore, Singapore, 117411, Singapore.,Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK
| | | | - Enrique Martín-Blanco
- Instituto de Biología Molecular de Barcelona (CSIC), Parc Cientific de Barcelona, Baldiri Reixac 10-12, 08028, Barcelona, Spain. .,Mechanobiology Institute and Department of Biological Sciences, 5 Engineering Drive 1, National University of Singapore, Singapore, 117411, Singapore.
| |
Collapse
|
2
|
Karkali K, Martin-Blanco E. Dissection of the Regulatory Elements of the Complex Expression Pattern of Puckered, a Dual-Specificity JNK Phosphatase. Int J Mol Sci 2021; 22:ijms222212205. [PMID: 34830088 PMCID: PMC8623796 DOI: 10.3390/ijms222212205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 10/19/2021] [Accepted: 11/09/2021] [Indexed: 11/16/2022] Open
Abstract
For developmental processes, we know most of the gene networks controlling specific cell responses. We still have to determine how these networks cooperate and how signals become integrated. The JNK pathway is one of the key elements modulating cellular responses during development. Yet, we still know little about how the core components of the pathway interact with additional regulators or how this network modulates cellular responses in the whole organism in homeostasis or during tissue morphogenesis. We have performed a promoter analysis, searching for potential regulatory sequences of puckered (puc) and identified different specific enhancers directing gene expression in different tissues and at different developmental times. Remarkably, some of these domains respond to the JNK activity, but not all. Altogether, these analyses show that puc expression regulation is very complex and that JNK activities participate in non-previously known processes during the development of Drosophila.
Collapse
|
3
|
Interaction between Ras and Src clones causes interdependent tumor malignancy via Notch signaling in Drosophila. Dev Cell 2021; 56:2223-2236.e5. [PMID: 34324859 DOI: 10.1016/j.devcel.2021.07.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 05/31/2021] [Accepted: 07/02/2021] [Indexed: 02/07/2023]
Abstract
Cancer tissue often comprises multiple tumor clones with distinct oncogenic alterations such as Ras or Src activation, yet the mechanism by which tumor heterogeneity drives cancer progression remains elusive. Here, we show in Drosophila imaginal epithelium that clones of Ras- or Src-activated benign tumors interact with each other to mutually promote tumor malignancy. Mechanistically, Ras-activated cells upregulate the cell-surface ligand Delta while Src-activated cells upregulate its receptor Notch, leading to Notch activation in Src cells. Elevated Notch signaling induces the transcriptional repressor Zfh1/ZEB1, which downregulates E-cadherin and cell death gene hid, leading to Src-activated invasive tumors. Simultaneously, Notch activation in Src cells upregulates the cytokine Unpaired/IL-6, which activates JAK-STAT signaling in neighboring Ras cells. Elevated JAK-STAT signaling upregulates the BTB-zinc-finger protein Chinmo, which downregulates E-cadherin and thus generates Ras-activated invasive tumors. Our findings provide a mechanistic explanation for how tumor heterogeneity triggers tumor progression via cell-cell interactions.
Collapse
|
4
|
Straub J, Gregor A, Sauerer T, Fliedner A, Distel L, Suchy C, Ekici AB, Ferrazzi F, Zweier C. Genetic interaction screen for severe neurodevelopmental disorders reveals a functional link between Ube3a and Mef2 in Drosophila melanogaster. Sci Rep 2020; 10:1204. [PMID: 31988313 PMCID: PMC6985129 DOI: 10.1038/s41598-020-58182-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 01/13/2020] [Indexed: 11/09/2022] Open
Abstract
Neurodevelopmental disorders (NDDs) are clinically and genetically extremely heterogeneous with shared phenotypes often associated with genes from the same networks. Mutations in TCF4, MEF2C, UBE3A, ZEB2 or ATRX cause phenotypically overlapping, syndromic forms of NDDs with severe intellectual disability, epilepsy and microcephaly. To characterize potential functional links between these genes/proteins, we screened for genetic interactions in Drosophila melanogaster. We induced ubiquitous or tissue specific knockdown or overexpression of each single orthologous gene (Da, Mef2, Ube3a, Zfh1, XNP) and in pairwise combinations. Subsequently, we assessed parameters such as lethality, wing and eye morphology, neuromuscular junction morphology, bang sensitivity and climbing behaviour in comparison between single and pairwise dosage manipulations. We found most stringent evidence for genetic interaction between Ube3a and Mef2 as simultaneous dosage manipulation in different tissues including glia, wing and eye resulted in multiple phenotype modifications. We subsequently found evidence for physical interaction between UBE3A and MEF2C also in human cells. Systematic pairwise assessment of the Drosophila orthologues of five genes implicated in clinically overlapping, severe NDDs and subsequent confirmation in a human cell line revealed interactions between UBE3A/Ube3a and MEF2C/Mef2, thus contributing to the characterization of the underlying molecular commonalities.
Collapse
Affiliation(s)
- Jonas Straub
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Anne Gregor
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Tatjana Sauerer
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Anna Fliedner
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Laila Distel
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Christine Suchy
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Arif B Ekici
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Fulvia Ferrazzi
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Christiane Zweier
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany.
| |
Collapse
|
5
|
Identification of raw as a regulator of glial development. PLoS One 2018; 13:e0198161. [PMID: 29813126 PMCID: PMC5973607 DOI: 10.1371/journal.pone.0198161] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Accepted: 05/15/2018] [Indexed: 12/18/2022] Open
Abstract
Glial cells perform numerous functions to support neuron development and function, including axon wrapping, formation of the blood brain barrier, and enhancement of synaptic transmission. We have identified a novel gene, raw, which functions in glia of the central and peripheral nervous systems in Drosophila. Reducing Raw levels in glia results in morphological defects in the brain and ventral nerve cord, as well as defects in neuron function, as revealed by decreased locomotion in crawling assays. Examination of the number of glia along peripheral nerves reveals a reduction in glial number upon raw knockdown. The reduced number of glia along peripheral nerves occurs as a result of decreased glial proliferation. As Raw has been shown to negatively regulate Jun N-terminal kinase (JNK) signaling in other developmental contexts, we examined the expression of a JNK reporter and the downstream JNK target, matrix metalloproteinase 1 (mmp1), and found that raw knockdown results in increased reporter activity and Mmp1 levels. These results are consistent with previous studies showing increased Mmp levels lead to nerve cord defects similar to those observed upon raw knockdown. In addition, knockdown of puckered, a negative feedback regulator of JNK signaling, also causes a decrease in glial number. Thus, our studies have resulted in the identification of a new regulator of gliogenesis, and demonstrate that increased JNK signaling negatively impacts glial development.
Collapse
|
6
|
MRL proteins cooperate with activated Ras in glia to drive distinct oncogenic outcomes. Oncogene 2017; 36:4311-4322. [PMID: 28346426 PMCID: PMC5537612 DOI: 10.1038/onc.2017.68] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 01/16/2017] [Accepted: 02/10/2017] [Indexed: 12/13/2022]
Abstract
The Mig10/RIAM/Lpd (MRL) adapter protein Lpd regulates actin dynamics through interactions with Scar/WAVE and Ena/VASP proteins to promote the formation of cellular protrusions and to stimulate invasive migration. However, the ability of MRL proteins to interact with multiple actin regulators and to promote serum response factor (SRF) signalling has raised the question of whether MRL proteins employ alternative downstream mechanisms to drive oncogenic processes in a context-dependent manner. Here, using a Drosophila model, we show that overexpression of either human Lpd or its Drosophila orthologue Pico can promote growth and invasion of RasV12-induced cell tumours in the brain. Notably, effects were restricted to two populations of Repo-positive glial cells: an invasive population, characterized by JNK-dependent elevation of Mmp1 expression, and a hyperproliferative population lacking elevated JNK signalling. JNK activation was not triggered by reactive immune cell signalling, implicating the involvement of an intrinsic stress response. The ability to promote dissemination of RasV12-induced tumours was shared by a subset of actin regulators, including, most prominently, Chicadee/Profilin, which directly interacts with Pico, and, Mal, a cofactor for serum response factor that responds to changes in G:F actin dynamics. Suppression of Mal activity partially abrogated the ability of pico to promote invasion of RasV12 tumours. Furthermore, we found that larval glia are enriched for serum response factor expression, explaining the apparent sensitivity of glial cells to Pico/RasV12 overexpression. Taken together, our findings indicate that MRL proteins cooperate with oncogenic Ras to promote formation of glial tumours, and that, in this context, Mal/serum response factor activation is rate-limiting for tumour dissemination.
Collapse
|
7
|
La Fortezza M, Schenk M, Cosolo A, Kolybaba A, Grass I, Classen AK. JAK/STAT signalling mediates cell survival in response to tissue stress. Development 2016; 143:2907-19. [DOI: 10.1242/dev.132340] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Accepted: 06/23/2016] [Indexed: 12/31/2022]
Abstract
Tissue homeostasis relies on the ability of tissues to respond to stress. Tissue regeneration and tumour models in Drosophila have shown that JNK is a prominent stress-response pathway promoting injury-induced apoptosis and compensatory proliferation. A central question remaining unanswered is how both responses are balanced by activation of a single pathway. JAK/STAT signalling, a potential JNK target, is implicated in promoting compensatory proliferation. While we observe JAK/STAT activation in imaginal discs upon damage, our data demonstrates that JAK/STAT and its downstream effector Zfh2 promote survival of JNK-signalling cells instead. The JNK component fos and the pro-apoptotic gene hid are regulated in a JAK/STAT-dependent manner. This molecular pathway restrains JNK-induced apoptosis and spatial propagation of JNK-signalling, thereby limiting the extent of tissue damage, as well as facilitating systemic and proliferative responses to injury. We find that the pro-survival function of JAK/STAT also drives tumour growth under conditions of chronic stress. Our study defines JAK/STAT function in tissue stress and illustrates how crosstalk between conserved signalling pathways establishes an intricate equilibrium between proliferation, apoptosis and survival to restore tissue homeostasis.
Collapse
Affiliation(s)
- Marco La Fortezza
- Ludwig-Maximilians-University Munich, Faculty of Biology, Grosshaderner Strasse 2-4, 82152 Planegg-Martinsried, Germany
| | - Madlin Schenk
- Ludwig-Maximilians-University Munich, Faculty of Biology, Grosshaderner Strasse 2-4, 82152 Planegg-Martinsried, Germany
| | - Andrea Cosolo
- Ludwig-Maximilians-University Munich, Faculty of Biology, Grosshaderner Strasse 2-4, 82152 Planegg-Martinsried, Germany
| | - Addie Kolybaba
- Ludwig-Maximilians-University Munich, Faculty of Biology, Grosshaderner Strasse 2-4, 82152 Planegg-Martinsried, Germany
| | - Isabelle Grass
- Ludwig-Maximilians-University Munich, Faculty of Biology, Grosshaderner Strasse 2-4, 82152 Planegg-Martinsried, Germany
| | - Anne-Kathrin Classen
- Ludwig-Maximilians-University Munich, Faculty of Biology, Grosshaderner Strasse 2-4, 82152 Planegg-Martinsried, Germany
| |
Collapse
|
8
|
Zeb family members and boundary cap cells underlie developmental plasticity of sensory nociceptive neurons. Dev Cell 2015; 33:343-50. [PMID: 25942625 DOI: 10.1016/j.devcel.2015.03.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 01/19/2015] [Accepted: 03/25/2015] [Indexed: 11/20/2022]
Abstract
Dorsal root ganglia (DRG) sensory neurons arise from heterogeneous precursors that differentiate in two neurogenic waves, respectively controlled by Neurog2 and Neurog1. We show here that transgenic mice expressing a Zeb1/2 dominant-negative form (DBZEB) exhibit reduced numbers of nociceptors and altered pain sensitivity. This reflects an early impairment of Neurog1-dependent neurogenesis due to the depletion of specific sensory precursor pools, which is slightly later partially compensated by the contribution of boundary cap cells (BCCs). Indeed, combined DBZEB expression and genetic BCCs ablation entirely deplete second wave precursors and, in turn, nociceptors, thus recapitulating the Neurog1(-/-) neuronal phenotype. Altogether, our results uncover roles for Zeb family members in the developing DRGs; they show that the Neurog1-dependent sensory neurogenesis can be functionally partitioned in two successive phases; and finally, they illustrate plasticity in the developing peripheral somatosensory system supported by the BCCs, thereby providing a rationale for sensory precursor diversity.
Collapse
|
9
|
|
10
|
Hegarty SV, Sullivan AM, O'Keeffe GW. Zeb2: A multifunctional regulator of nervous system development. Prog Neurobiol 2015; 132:81-95. [PMID: 26193487 DOI: 10.1016/j.pneurobio.2015.07.001] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 07/14/2015] [Accepted: 07/15/2015] [Indexed: 12/19/2022]
Abstract
Zinc finger E-box binding homeobox (Zeb) 2 is a transcription factor, identified due its ability to bind Smad proteins, and consists of multiple functional domains which interact with a variety of transcriptional co-effectors. The complex nature of the Zeb2, both at its genetic and protein levels, underlie its multifunctional properties, with Zeb2 capable of acting individually or as part of a transcriptional complex to repress, and occasionally activate, target gene expression. This review introduces Zeb2 as an essential regulator of nervous system development. Zeb2 is expressed in the nervous system throughout its development, indicating its importance in neurogenic and gliogenic processes. Indeed, mutation of Zeb2 has dramatic neurological consequences both in animal models, and in humans with Mowat-Wilson syndrome, which results from heterozygous ZEB2 mutations. The mechanisms by which Zeb2 regulates the induction of the neuroectoderm (CNS primordium) and the neural crest (PNS primordium) are reviewed herein. We then describe how Zeb2 acts to direct the formation, delamination, migration and specification of neural crest cells. Zeb2 regulation of the development of a number of cerebral regions, including the neocortex and hippocampus, are then described. The diverse molecular mechanisms mediating Zeb2-directed development of various neuronal and glial populations are reviewed. The role of Zeb2 in spinal cord and enteric nervous system development is outlined, while its essential function in CNS myelination is also described. Finally, this review discusses how the neurodevelopmental defects of Zeb2 mutant mice delineate the developmental dysfunctions underpinning the multiple neurological defects observed in Mowat-Wilson syndrome patients.
Collapse
Affiliation(s)
- Shane V Hegarty
- Department of Anatomy & Neuroscience, University College Cork, Cork, Ireland.
| | - Aideen M Sullivan
- Department of Anatomy & Neuroscience, University College Cork, Cork, Ireland
| | - Gerard W O'Keeffe
- Department of Anatomy & Neuroscience, University College Cork, Cork, Ireland
| |
Collapse
|
11
|
Schmidt I, Franzdóttir SR, Edenfeld G, Rodrigues F, Zierau A, Klämbt C. Transcriptional regulation of peripheral glial cell differentiation in the embryonic nervous system of drosophila. Glia 2011; 59:1264-72. [DOI: 10.1002/glia.21123] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Accepted: 11/18/2010] [Indexed: 11/07/2022]
|
12
|
Hidalgo A, Kato K, Sutcliffe B, McIlroy G, Bishop S, Alahmed S. Trophic neuron-glia interactions and cell number adjustments in the fruit fly. Glia 2010; 59:1296-303. [PMID: 21732425 DOI: 10.1002/glia.21092] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 09/20/2010] [Indexed: 11/09/2022]
Abstract
Trophic interactions between neurons and enwrapping glia, and between neurons and target cells, provide plasticity to the mammalian nervous system. Here, we review evidence that analogous cell interactions operate in the development of the nervous system of the fruit-fly Drosophila. Homologues of the canonical mammalian trophic factors also maintain neuronal and glial survival in Drosophila, adjusting cell populations to enable appropriate function, and revealing commonalities in nervous system development across the animals. There are also differences between neuron-glia interactions in flies and humans, not surprisingly, because we are only related to flies through a remote common ancestor. Nevertheless, the shared cellular and molecular mechanisms underlying developmental plasticity and enwrapping glial functions, strengthen the opportunity to use Drosophila to understand the brain, to model brain diseases and to understand the involvement of glial cells in nervous system regeneration.
Collapse
Affiliation(s)
- Alicia Hidalgo
- Neurodevelopment Group, School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom.
| | | | | | | | | | | |
Collapse
|