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Jaglarz MK, Kuziak A, Jankowska W. The pattern of the follicle cell diversification in ovarian follicles of the true fruit flies, Tephritidae. J Anat 2024. [PMID: 38817113 DOI: 10.1111/joa.14065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 05/03/2024] [Accepted: 05/07/2024] [Indexed: 06/01/2024] Open
Abstract
In flies (Diptera), the ovary displays several distinct patterns of the follicular epithelium formation and diversification. Two main patterns have been identified in the true flies or Brachycera, namely the Rhagio type and the Drosophila type. These patterns align with the traditional division of Brachycera into Orthorrhapha and Cyclorrhapha. However, studies of the follicular epithelium morphogenesis in cyclorrhaphans other than Drosophila are scarce. We characterise the developmental changes associated with the emergence of follicle cell (FC) diversity in two cyclorrhaphans belonging to the family Tephritidae (Brachycera, Cyclorrhapha). Our analysis revealed that the diversification of FCs in these species shows characteristics of both the Rhagio and Drosophila types. First, a distinct cluster of FCs, consisting of polar cells and border-like cells, differentiates at the posterior pole of the ovarian follicle. This feature is unique to the Rhagio type and has only been reported in species representing the Orthorrhapha group. Second, morphological criteria have identified a significantly smaller number of subpopulations of FCs than in Drosophila. Furthermore, while the general pattern of FC migration is similar to that of Drosophila, the distinctive migration of the anterior-dorsal FCs is absent. In the studied tephritids, the migration of the anterior polar cell/border cell cluster towards the anterior pole of the oocyte is followed by the posterior migration of the main body cuboidal FCs to cover the expanding oocyte. Finally, during the onset of vitellogenesis, a distinct subset of FCs migrates towards the centre of the ovarian follicle to cover the oocyte's anterior pole. Our study also highlights specific actions of some FCs that accompany the migration process, which has not been previously documented in cyclorrhaphans. These results support the hypothesis that the posterior and centripetal migrations of morphologically unique FC subsets arose in the common ancestor of Cyclorrhapha. These events appear to have occurred fairly recently in the evolutionary timeline of Diptera.
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Affiliation(s)
- Mariusz K Jaglarz
- Department of Developmental Biology and Invertebrate Morphology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Kraków, Poland
| | - Agata Kuziak
- Department of Microbiology, Faculty of Medicine, Jagiellonian University Medical College, Kraków, Poland
| | - Wladyslawa Jankowska
- Department of Developmental Biology and Invertebrate Morphology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Kraków, Poland
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2
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Castro Colabianchi AM, González Pérez NG, Franchini LF, López SL. A maternal dorsoventral prepattern revealed by an asymmetric distribution of ventralizing molecules before fertilization in Xenopus laevis. Front Cell Dev Biol 2024; 12:1365705. [PMID: 38572484 PMCID: PMC10987785 DOI: 10.3389/fcell.2024.1365705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 03/07/2024] [Indexed: 04/05/2024] Open
Abstract
The establishment of the embryonic dorsoventral axis in Xenopus occurs when the radial symmetry around the egg's animal-vegetal axis is broken to give rise to the typical symmetry of Bilaterians. We have previously shown that the Notch1 protein is ventrally enriched during early embryogenesis in Xenopus laevis and zebrafish and exerts ventralizing activity through β-Catenin destabilization and the positive regulation of ventral center genes in X. laevis. These findings led us to further investigate when these asymmetries arise. In this work, we show that the asymmetrical distribution of Notch1 protein and mRNA precedes cortical rotation and even fertilization in X. laevis. Moreover, we found that in unfertilized eggs transcripts encoded by the ventralizing gene bmp4 are also asymmetrically distributed in the animal hemisphere and notch1 transcripts accumulate consistently on the same side of the eccentric maturation point. Strikingly, a Notch1 asymmetry orthogonal to the animal-vegetal axis appears during X. laevis oogenesis. Thus, we show for the first time a maternal bias in the distribution of molecules that are later involved in ventral patterning during embryonic axialization, strongly supporting the hypothesis of a dorsoventral prepattern or intrinsic bilaterality of Xenopus eggs before fertilization.
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Affiliation(s)
- Aitana M. Castro Colabianchi
- Universidad de Buenos Aires, Facultad de Medicina, Departamento de Biología Celular e Histología / 1° U.A. Departamento de Histología, Embriología, Biología Celular y Genética, Laboratorio de Embriología Molecular “Prof. Dr. Andrés E. Carrasco”, Buenos Aires, Argentina
- CONICET–Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencias “Prof. E. De Robertis” (IBCN), Buenos Aires, Argentina
| | - Nicolás G. González Pérez
- Universidad de Buenos Aires, Facultad de Medicina, Departamento de Biología Celular e Histología / 1° U.A. Departamento de Histología, Embriología, Biología Celular y Genética, Laboratorio de Embriología Molecular “Prof. Dr. Andrés E. Carrasco”, Buenos Aires, Argentina
- CONICET–Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencias “Prof. E. De Robertis” (IBCN), Buenos Aires, Argentina
| | - Lucía F. Franchini
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI) “Dr. Héctor N. Torres”, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Silvia L. López
- Universidad de Buenos Aires, Facultad de Medicina, Departamento de Biología Celular e Histología / 1° U.A. Departamento de Histología, Embriología, Biología Celular y Genética, Laboratorio de Embriología Molecular “Prof. Dr. Andrés E. Carrasco”, Buenos Aires, Argentina
- CONICET–Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencias “Prof. E. De Robertis” (IBCN), Buenos Aires, Argentina
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3
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Uttekar B, Verma RK, Tomer D, Rikhy R. Mitochondrial morphology dynamics and ROS regulate apical polarity and differentiation in Drosophila follicle cells. Development 2024; 151:dev201732. [PMID: 38345270 DOI: 10.1242/dev.201732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 01/23/2024] [Indexed: 03/01/2024]
Abstract
Mitochondrial morphology dynamics regulate signaling pathways during epithelial cell formation and differentiation. The mitochondrial fission protein Drp1 affects the appropriate activation of EGFR and Notch signaling-driven differentiation of posterior follicle cells in Drosophila oogenesis. The mechanisms by which Drp1 regulates epithelial polarity during differentiation are not known. In this study, we show that Drp1-depleted follicle cells are constricted in early stages and present in multiple layers at later stages with decreased levels of apical polarity protein aPKC. These defects are suppressed by additional depletion of mitochondrial fusion protein Opa1. Opa1 depletion leads to mitochondrial fragmentation and increased reactive oxygen species (ROS) in follicle cells. We find that increasing ROS by depleting the ROS scavengers, mitochondrial SOD2 and catalase also leads to mitochondrial fragmentation. Further, the loss of Opa1, SOD2 and catalase partially restores the defects in epithelial polarity and aPKC, along with EGFR and Notch signaling in Drp1-depleted follicle cells. Our results show a crucial interaction between mitochondrial morphology, ROS generation and epithelial cell polarity formation during the differentiation of follicle epithelial cells in Drosophila oogenesis.
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Affiliation(s)
- Bhavin Uttekar
- Biology, Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune 411008, India
| | - Rahul Kumar Verma
- Biology, Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune 411008, India
| | - Darshika Tomer
- Biology, Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune 411008, India
| | - Richa Rikhy
- Biology, Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune 411008, India
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4
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Lepesant JA, Roland-Gosselin F, Guillemet C, Bernard F, Guichet A. The Importance of the Position of the Nucleus in Drosophila Oocyte Development. Cells 2024; 13:201. [PMID: 38275826 PMCID: PMC10814754 DOI: 10.3390/cells13020201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 01/12/2024] [Accepted: 01/16/2024] [Indexed: 01/27/2024] Open
Abstract
Oogenesis is a developmental process leading to the formation of an oocyte, a haploid gamete, which upon fertilisation and sperm entry allows the male and the female pronuclei to fuse and give rise to a zygote. In addition to forming a haploid gamete, oogenesis builds up a store of proteins, mRNAs, and organelles in the oocyte needed for the development of the future embryo. In several species, such as Drosophila, the polarity axes determinants of the future embryo must be asymmetrically distributed prior to fertilisation. In the Drosophila oocyte, the correct positioning of the nucleus is essential for establishing the dorsoventral polarity axis of the future embryo and allowing the meiotic spindles to be positioned in close vicinity to the unique sperm entry point into the oocyte.
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Affiliation(s)
| | | | | | | | - Antoine Guichet
- Université Paris Cité, CNRS, Institut Jacques Monod, 75013 Paris, France; (J.-A.L.); (F.R.-G.); (C.G.); (F.B.)
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5
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Berg C, Sieber M, Sun J. Finishing the egg. Genetics 2024; 226:iyad183. [PMID: 38000906 PMCID: PMC10763546 DOI: 10.1093/genetics/iyad183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 09/27/2023] [Indexed: 11/26/2023] Open
Abstract
Gamete development is a fundamental process that is highly conserved from early eukaryotes to mammals. As germ cells develop, they must coordinate a dynamic series of cellular processes that support growth, cell specification, patterning, the loading of maternal factors (RNAs, proteins, and nutrients), differentiation of structures to enable fertilization and ensure embryonic survival, and other processes that make a functional oocyte. To achieve these goals, germ cells integrate a complex milieu of environmental and developmental signals to produce fertilizable eggs. Over the past 50 years, Drosophila oogenesis has risen to the forefront as a system to interrogate the sophisticated mechanisms that drive oocyte development. Studies in Drosophila have defined mechanisms in germ cells that control meiosis, protect genome integrity, facilitate mRNA trafficking, and support the maternal loading of nutrients. Work in this system has provided key insights into the mechanisms that establish egg chamber polarity and patterning as well as the mechanisms that drive ovulation and egg activation. Using the power of Drosophila genetics, the field has begun to define the molecular mechanisms that coordinate environmental stresses and nutrient availability with oocyte development. Importantly, the majority of these reproductive mechanisms are highly conserved throughout evolution, and many play critical roles in the development of somatic tissues as well. In this chapter, we summarize the recent progress in several key areas that impact egg chamber development and ovulation. First, we discuss the mechanisms that drive nutrient storage and trafficking during oocyte maturation and vitellogenesis. Second, we examine the processes that regulate follicle cell patterning and how that patterning impacts the construction of the egg shell and the establishment of embryonic polarity. Finally, we examine regulatory factors that control ovulation, egg activation, and successful fertilization.
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Affiliation(s)
- Celeste Berg
- Department of Genome Sciences, University of Washington, Seattle, WA 98195-5065USA
| | - Matthew Sieber
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390USA
| | - Jianjun Sun
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT 06269USA
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6
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Abstract
By the time a Drosophila egg is laid, both major body axes have already been defined and it contains all the nutrients needed to develop into a free-living larva in 24 h. By contrast, it takes almost a week to make an egg from a female germline stem cell, during the complex process of oogenesis. This review will discuss key symmetry-breaking steps in Drosophila oogenesis that lead to the polarisation of both body axes: the asymmetric divisions of the germline stem cells; the selection of the oocyte from the 16-cell germline cyst; the positioning of the oocyte at the posterior of the cyst; Gurken signalling from the oocyte to polarise the anterior-posterior axis of the somatic follicle cell epithelium around the developing germline cyst; the signalling back from the posterior follicle cells to polarise the anterior-posterior axis of the oocyte; and the migration of the oocyte nucleus that specifies the dorsal-ventral axis. Since each event creates the preconditions for the next, I will focus on the mechanisms that drive these symmetry-breaking steps, how they are linked and the outstanding questions that remain to be answered.
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7
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Spradling AC, Niu W, Yin Q, Pathak M, Maurya B. Conservation of oocyte development in germline cysts from Drosophila to mouse. eLife 2022; 11:83230. [PMID: 36445738 PMCID: PMC9708067 DOI: 10.7554/elife.83230] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 11/17/2022] [Indexed: 11/30/2022] Open
Abstract
Recent studies show that pre-follicular mouse oogenesis takes place in germline cysts, highly conserved groups of oogonial cells connected by intercellular bridges that develop as nurse cells as well as an oocyte. Long studied in Drosophila and insect gametogenesis, female germline cysts acquire cytoskeletal polarity and traffic centrosomes and organelles between nurse cells and the oocyte to form the Balbiani body, a conserved marker of polarity. Mouse oocyte development and nurse cell dumping are supported by dynamic, cell-specific programs of germline gene expression. High levels of perinatal germ cell death in this species primarily result from programmed nurse cell turnover after transfer rather than defective oocyte production. The striking evolutionary conservation of early oogenesis mechanisms between distant animal groups strongly suggests that gametogenesis and early embryonic development in vertebrates and invertebrates share even more in common than currently believed.
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Affiliation(s)
- Allan C Spradling
- Carnegie Institution for Science/Howard Hughes Medical Institute, Baltimore, United States
| | - Wanbao Niu
- Carnegie Institution for Science/Howard Hughes Medical Institute, Baltimore, United States
| | - Qi Yin
- Carnegie Institution for Science/Howard Hughes Medical Institute, Baltimore, United States
| | - Madhulika Pathak
- Carnegie Institution for Science/Howard Hughes Medical Institute, Baltimore, United States
| | - Bhawana Maurya
- Carnegie Institution for Science/Howard Hughes Medical Institute, Baltimore, United States
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8
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Region-Based Segmentation and Classification for Ovarian Cancer Detection Using Convolution Neural Network. CONTRAST MEDIA & MOLECULAR IMAGING 2022; 2022:5968939. [PMID: 36475297 PMCID: PMC9701126 DOI: 10.1155/2022/5968939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 07/15/2022] [Accepted: 07/18/2022] [Indexed: 11/21/2022]
Abstract
Ovarian cancer is a serious sickness for elderly women. According to data, it is the seventh leading cause of death in women as well as the fifth most frequent disease worldwide. Many researchers classified ovarian cancer using Artificial Neural Networks (ANNs). Doctors consider classification accuracy to be an important aspect of making decisions. Doctors consider improved classification accuracy for providing proper treatment. Early and precise diagnosis lowers mortality rates and saves lives. On basis of ROI (region of interest) segmentation, this research presents a novel annotated ovarian image classification utilizing FaRe-ConvNN (rapid region-based Convolutional neural network). The input photos were divided into three categories: epithelial, germ, and stroma cells. This image is segmented as well as preprocessed. After that, FaRe-ConvNN is used to perform the annotation procedure. For region-based classification, the method compares manually annotated features as well as trained feature in FaRe-ConvNN. This will aid in the analysis of higher accuracy in disease identification, as human annotation has lesser accuracy in previous studies; therefore, this effort will empirically prove that ML classification will provide higher accuracy. Classification is done using a combination of SVC and Gaussian NB classifiers after the region-based training in FaRe-ConvNN. The ensemble technique was employed in feature classification due to better data indexing. To diagnose ovarian cancer, the simulation provides an accurate portion of the input image. FaRe-ConvNN has a precision value of more than 95%, SVC has a precision value of 95.96%, and Gaussian NB has a precision value of 97.7%, with FR-CNN enhancing precision in Gaussian NB. For recall/sensitivity, SVC is 94.31 percent and Gaussian NB is 97.7 percent, while for specificity, SVC is 97.39 percent and Gaussian NB is 98.69 percent using FaRe-ConvNN.
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9
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Subcellular spatial transcriptomics identifies three mechanistically different classes of localizing RNAs. Nat Commun 2022; 13:6355. [PMID: 36289223 PMCID: PMC9606379 DOI: 10.1038/s41467-022-34004-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 10/03/2022] [Indexed: 12/25/2022] Open
Abstract
Intracellular RNA localization is a widespread and dynamic phenomenon that compartmentalizes gene expression and contributes to the functional polarization of cells. Thus far, mechanisms of RNA localization identified in Drosophila have been based on a few RNAs in different tissues, and a comprehensive mechanistic analysis of RNA localization in a single tissue is lacking. Here, by subcellular spatial transcriptomics we identify RNAs localized in the apical and basal domains of the columnar follicular epithelium (FE) and we analyze the mechanisms mediating their localization. Whereas the dynein/BicD/Egl machinery controls apical RNA localization, basally-targeted RNAs require kinesin-1 to overcome a default dynein-mediated transport. Moreover, a non-canonical, translation- and dynein-dependent mechanism mediates apical localization of a subgroup of dynein-activating adaptor-encoding RNAs (BicD, Bsg25D, hook). Altogether, our study identifies at least three mechanisms underlying RNA localization in the FE, and suggests a possible link between RNA localization and dynein/dynactin/adaptor complex formation in vivo.
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10
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Eya-controlled affinity between cell lineages drives tissue self-organization during Drosophila oogenesis. Nat Commun 2022; 13:6377. [PMID: 36289235 PMCID: PMC9605976 DOI: 10.1038/s41467-022-33845-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 10/05/2022] [Indexed: 12/25/2022] Open
Abstract
Cooperative morphogenesis of cell lineages underlies the development of functional units and organs. To study mechanisms driving the coordination of lineages, we investigated soma-germline interactions during oogenesis. From invertebrates to vertebrates, oocytes develop as part of a germline cyst that consists of the oocyte itself and so-called nurse cells, which feed the oocyte and are eventually removed. The enveloping somatic cells specialize to facilitate either oocyte maturation or nurse cell removal, which makes it essential to establish the right match between germline and somatic cells. We uncover that the transcriptional regulator Eya, expressed in the somatic lineage, controls bilateral cell-cell affinity between germline and somatic cells in Drosophila oogenesis. Employing functional studies and mathematical modelling, we show that differential affinity and the resulting forces drive somatic cell redistribution over the germline surface and control oocyte growth to match oocyte and nurse cells with their respective somatic cells. Thus, our data demonstrate that differential affinity between cell lineages is sufficient to drive the complex assembly of inter-lineage functional units and underlies tissue self-organization during Drosophila oogenesis.
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11
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Riparbelli MG, Persico V, Callaini G. Cell-to-Cell Interactions during Early Drosophila Oogenesis: An Ultrastructural Analysis. Cells 2022; 11:cells11172658. [PMID: 36078066 PMCID: PMC9454453 DOI: 10.3390/cells11172658] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 08/24/2022] [Accepted: 08/25/2022] [Indexed: 11/27/2022] Open
Abstract
Drosophila oogenesis requires the subsequent growth of distinct egg chambers each containing a group of sixteen germline cells surrounded by a simple epithelium of follicle cells. The oocyte occupies a posterior position within the germ cells, thus giving a distinct asymmetry to the egg chamber. Although this disposition is critical for the formation of the anterior–posterior axis of the embryo, the interplay between somatic and germ cells during the early stages of oogenesis remains an open question. We uncover by stage 2, when the egg chambers leaved the germarium, some unique spatial interactions between the posterior follicle cells and the oocyte. These interactions are restricted to the surface of the oocyte over the centriole cluster that formed during early oogenesis. Moreover, the posterior follicle cells in front of the oocyte display a convoluted apical membrane with extensive contacts, whereas the other follicle cells have a flat apical surface without obvious surface protrusions. In addition, the germ cells located at the posterior end of the egg chamber have very elongated protrusions that come into contact with each other or with facing follicle cells. These observations point to distinct polarization events during early oogenesis supporting previous molecular data of an inherent asymmetry between the anterior and the posterior regions of the egg chambers.
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12
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Milas A, Telley IA. Polarity Events in the Drosophila melanogaster Oocyte. Front Cell Dev Biol 2022; 10:895876. [PMID: 35602591 PMCID: PMC9117655 DOI: 10.3389/fcell.2022.895876] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 04/19/2022] [Indexed: 11/13/2022] Open
Abstract
Cell polarity is a pre-requirement for many fundamental processes in animal cells, such as asymmetric cell division, axon specification, morphogenesis and epithelial tissue formation. For all these different processes, polarization is established by the same set of proteins, called partitioning defective (Par) proteins. During development in Drosophila melanogaster, decision making on the cellular and organism level is achieved with temporally controlled cell polarization events. The initial polarization of Par proteins occurs as early as in the germline cyst, when one of the 16 cells becomes the oocyte. Another marked event occurs when the anterior–posterior axis of the future organism is defined by Par redistribution in the oocyte, requiring external signaling from somatic cells. Here, we review the current literature on cell polarity events that constitute the oogenesis from the stem cell to the mature egg.
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Affiliation(s)
- Ana Milas
- *Correspondence: Ana Milas, ; Ivo A. Telley,
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13
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Ronchi P, Mizzon G, Machado P, D’Imprima E, Best BT, Cassella L, Schnorrenberg S, Montero MG, Jechlinger M, Ephrussi A, Leptin M, Mahamid J, Schwab Y. High-precision targeting workflow for volume electron microscopy. J Cell Biol 2021; 220:e202104069. [PMID: 34160561 PMCID: PMC8225610 DOI: 10.1083/jcb.202104069] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/27/2021] [Accepted: 06/06/2021] [Indexed: 02/07/2023] Open
Abstract
Cells are 3D objects. Therefore, volume EM (vEM) is often crucial for correct interpretation of ultrastructural data. Today, scanning EM (SEM) methods such as focused ion beam (FIB)-SEM are frequently used for vEM analyses. While they allow automated data acquisition, precise targeting of volumes of interest within a large sample remains challenging. Here, we provide a workflow to target FIB-SEM acquisition of fluorescently labeled cells or subcellular structures with micrometer precision. The strategy relies on fluorescence preservation during sample preparation and targeted trimming guided by confocal maps of the fluorescence signal in the resin block. Laser branding is used to create landmarks on the block surface to position the FIB-SEM acquisition. Using this method, we acquired volumes of specific single cells within large tissues such as 3D cultures of mouse mammary gland organoids, tracheal terminal cells in Drosophila melanogaster larvae, and ovarian follicular cells in adult Drosophila, discovering ultrastructural details that could not be appreciated before.
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Affiliation(s)
- Paolo Ronchi
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Giulia Mizzon
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Pedro Machado
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Edoardo D’Imprima
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Benedikt T. Best
- Directors’ Research, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Lucia Cassella
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, Heidelberg, Germany
| | - Sebastian Schnorrenberg
- Advanced Light Microscopy Facility, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Marta G. Montero
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Martin Jechlinger
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Anne Ephrussi
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Maria Leptin
- Directors’ Research, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Julia Mahamid
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Yannick Schwab
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
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14
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Germline soma communication mediated by gap junction proteins regulates epithelial morphogenesis. PLoS Genet 2021; 17:e1009685. [PMID: 34343194 PMCID: PMC8330916 DOI: 10.1371/journal.pgen.1009685] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 06/28/2021] [Indexed: 01/22/2023] Open
Abstract
Gap junction (GJ) proteins, the primary constituents of GJ channels, are conserved determinants of patterning. Canonically, a GJ channel, made up of two hemi-channels contributed by the neighboring cells, facilitates transport of metabolites/ions. Here we demonstrate the involvement of GJ proteins during cuboidal to squamous epithelial transition displayed by the anterior follicle cells (AFCs) from Drosophila ovaries. Somatically derived AFCs stretch and flatten when the adjacent germline cells start increasing in size. GJ proteins, Innexin2 (Inx2) and Innexin4 (Inx4), functioning in the AFCs and germline respectively, promote the shape transformation by modulating calcium levels in the AFCs. Our observations suggest that alterations in calcium flux potentiate STAT activity to influence actomyosin-based cytoskeleton, possibly resulting in disassembly of adherens junctions. Our data have uncovered sequential molecular events underlying the cuboidal to squamous shape transition and offer unique insight into how GJ proteins expressed in the neighboring cells contribute to morphogenetic processes. Shape transitions between different subtypes of epithelial cells i.e., cuboidal, squamous and columnar are ubiquitous and are essential during organogenesis across animal kingdom. We demonstrate that heteromeric combination of gap junction proteins, Drosophila Innexin2 and Drosophila Innexin 4 (also known as Zero population growth or Zpg), expressed in the soma and germline of fly egg respectively, mediates the shape transition of cuboidal follicle cells to squamous fate. Interestingly, the two gap junction proteins likely participate as constituents of a calcium channel. Further, we show that somatic follicle cells and germline nurse cells communicate through calcium fluxes that activates STAT in the follicle cells. Activated STAT modulates the levels/ activity of junctional complexes thus aiding shape transition of cuboidal cells to squamous fate. These findings provide novel insights into how communication between different cell types with distinct origins achieve shape transitions essential for proper organ assemblies.
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15
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Nguyen TNM, Choo A, Baxter SW. Lessons from Drosophila: Engineering Genetic Sexing Strains with Temperature-Sensitive Lethality for Sterile Insect Technique Applications. INSECTS 2021; 12:243. [PMID: 33805657 PMCID: PMC8001749 DOI: 10.3390/insects12030243] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 03/05/2021] [Accepted: 03/09/2021] [Indexed: 12/29/2022]
Abstract
A major obstacle of sterile insect technique (SIT) programs is the availability of robust sex-separation systems for conditional removal of females. Sterilized male-only releases improve SIT efficiency and cost-effectiveness for agricultural pests, whereas it is critical to remove female disease-vector pests prior to release as they maintain the capacity to transmit disease. Some of the most successful Genetic Sexing Strains (GSS) reared and released for SIT control were developed for Mediterranean fruit fly (Medfly), Ceratitis capitata, and carry a temperature sensitive lethal (tsl) mutation that eliminates female but not male embryos when heat treated. The Medfly tsl mutation was generated by random mutagenesis and the genetic mechanism causing this valuable heat sensitive phenotype remains unknown. Conditional temperature sensitive lethal mutations have also been developed using random mutagenesis in the insect model, Drosophila melanogaster, and were used for some of the founding genetic research published in the fields of neuro- and developmental biology. Here we review mutations in select D. melanogaster genes shibire, Notch, RNA polymerase II 215kDa, pale, transformer-2, Dsor1 and CK2α that cause temperature sensitive phenotypes. Precise introduction of orthologous point mutations in pest insect species with CRISPR/Cas9 genome editing technology holds potential to establish GSSs with embryonic lethality to improve and advance SIT pest control.
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Affiliation(s)
- Thu N. M. Nguyen
- Bio21 Institute, School of BioSciences, University of Melbourne, Melbourne, VIC 3052, Australia;
- School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia;
| | - Amanda Choo
- School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia;
| | - Simon W. Baxter
- Bio21 Institute, School of BioSciences, University of Melbourne, Melbourne, VIC 3052, Australia;
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16
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Yalonetskaya A, Mondragon AA, Hintze ZJ, Holmes S, McCall K. Nuclear degradation dynamics in a nonapoptotic programmed cell death. Cell Death Differ 2020; 27:711-724. [PMID: 31285547 PMCID: PMC7206136 DOI: 10.1038/s41418-019-0382-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Revised: 05/28/2019] [Accepted: 06/17/2019] [Indexed: 01/01/2023] Open
Abstract
Nuclear degradation is a major event during programmed cell death (PCD). The breakdown of nuclear components has been well characterized during apoptosis, one form of PCD. Many nonapoptotic forms of PCD have been identified, but our understanding of nuclear degradation during those events is limited. Here, we take advantage of Drosophila oogenesis to investigate nuclear degeneration during stress-induced apoptotic and developmental nonapoptotic cell death in the same cell type in vivo. We find that nuclear Lamin, a caspase substrate, dissociates from the nucleus as an early event during apoptosis, but remains associated with nuclei during nonapoptotic cell death. Lamin reveals a series of changes in nuclear architecture during nonapoptotic death, including nuclear crenellations and involutions. Stretch follicle cells contribute to these architecture changes, and phagocytic and lysosome-associated machinery in stretch follicle cells promote Lamin degradation. More specifically, we find that the lysosomal cathepsin CP1 facilitates Lamin degradation.
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Affiliation(s)
- Alla Yalonetskaya
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA, 02215, USA
| | - Albert A Mondragon
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA, 02215, USA
- Program in Molecular Biology, Cell Biology, and Biochemistry, Boston University, Boston, MA, 02215, USA
| | - Zackary J Hintze
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA, 02215, USA
| | - Susan Holmes
- Department of Statistics, Stanford University, Stanford, CA, 94305, USA
| | - Kimberly McCall
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA, 02215, USA.
- Program in Molecular Biology, Cell Biology, and Biochemistry, Boston University, Boston, MA, 02215, USA.
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17
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Merkle JA, Wittes J, Schüpbach T. Signaling between somatic follicle cells and the germline patterns the egg and embryo of Drosophila. Curr Top Dev Biol 2019; 140:55-86. [PMID: 32591083 DOI: 10.1016/bs.ctdb.2019.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In Drosophila, specification of the embryonic body axes requires signaling between the germline and the somatic follicle cells. These signaling events are necessary to properly localize embryonic patterning determinants in the egg or eggshell during oogenesis. There are three maternal patterning systems that specify the anterior-posterior axis, and one that establishes the dorsal-ventral axis. We will first review oogenesis, focusing on the establishment of the oocyte and nurse cells and patterning of the follicle cells into different subpopulations. We then describe how two coordinated signaling events between the oocyte and follicle cells establish polarity of the oocyte and localize the anterior determinant bicoid, the posterior determinant oskar, and Gurken/epidermal growth factor (EGF), which breaks symmetry to initiate dorsal-ventral axis establishment. Next, we review how dorsal-ventral asymmetry of the follicle cells is transmitted to the embryo. This process also involves Gurken-EGF receptor (EGFR) signaling between the oocyte and follicle cells, leading to ventrally-restricted expression of the sulfotransferase Pipe. These events promote the ventral processing of Spaetzle, a ligand for Toll, which ultimately sets up the embryonic dorsal-ventral axis. We then describe the activation of the terminal patterning system by specialized polar follicle cells. Finally, we present open questions regarding soma-germline signaling during Drosophila oogenesis required for cell identity and embryonic axis formation.
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Affiliation(s)
- Julie A Merkle
- Department of Biology, University of Evansville, Evansville, IN, United States
| | - Julia Wittes
- Department of Biological Sciences, Columbia University, New York, NY, United States
| | - Trudi Schüpbach
- Department of Molecular Biology, Princeton University, Princeton, NJ, United States.
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18
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Extracellular matrix stiffness cues junctional remodeling for 3D tissue elongation. Nat Commun 2019; 10:3339. [PMID: 31350387 PMCID: PMC6659696 DOI: 10.1038/s41467-019-10874-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 05/25/2019] [Indexed: 12/12/2022] Open
Abstract
Organs are sculpted by extracellular as well as cell-intrinsic forces, but how collective cell dynamics are orchestrated in response to environmental cues is poorly understood. Here we apply advanced image analysis to reveal extracellular matrix-responsive cell behaviors that drive elongation of the Drosophila follicle, a model system in which basement membrane stiffness instructs three-dimensional tissue morphogenesis. Through in toto morphometric analyses of wild type and round egg mutants, we find that neither changes in average cell shape nor oriented cell division are required for appropriate organ shape. Instead, a major element is the reorientation of elongated cells at the follicle anterior. Polarized reorientation is regulated by mechanical cues from the basement membrane, which are transduced by the Src tyrosine kinase to alter junctional E-cadherin trafficking. This mechanosensitive cellular behavior represents a conserved mechanism that can elongate edgeless tubular epithelia in a process distinct from those that elongate bounded, planar epithelia. The extracellular matrix can shape developing organs, but how external forces direct intercellular morphogenesis is unclear. Here, the authors use 3D imaging to show that elongation of the Drosophila egg chamber involves polarized cell reorientation signalled by changes in stiffness of the surrounding extracellular matrix.
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Electrochemical patterns during Drosophila oogenesis: ion-transport mechanisms generate stage-specific gradients of pH and membrane potential in the follicle-cell epithelium. BMC DEVELOPMENTAL BIOLOGY 2019; 19:12. [PMID: 31226923 PMCID: PMC6588877 DOI: 10.1186/s12861-019-0192-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 06/06/2019] [Indexed: 12/14/2022]
Abstract
Background Alterations of bioelectrical properties of cells and tissues are known to function as wide-ranging signals during development, regeneration and wound-healing in several species. The Drosophila follicle-cell epithelium provides an appropriate model system for studying the potential role of electrochemical signals, like intracellular pH (pHi) and membrane potential (Vmem), during development. Therefore, we analysed stage-specific gradients of pHi and Vmem as well as their dependence on specific ion-transport mechanisms. Results Using fluorescent indicators, we found distinct alterations of pHi- and Vmem-patterns during stages 8 to 12 of oogenesis. To determine the roles of relevant ion-transport mechanisms in regulating pHi and Vmem and in establishing stage-specific antero-posterior and dorso-ventral gradients, we used inhibitors of Na+/H+-exchangers and Na+-channels (amiloride), V-ATPases (bafilomycin), ATP-sensitive K+-channels (glibenclamide), voltage-dependent L-type Ca2+-channels (verapamil), Cl−-channels (9-anthroic acid) and Na+/K+/2Cl−-cotransporters (furosemide). Either pHi or Vmem or both parameters were affected by each tested inhibitor. While the inhibition of Na+/H+-exchangers (NHE) and amiloride-sensitive Na+-channels or of V-ATPases resulted in relative acidification, inhibiting the other ion-transport mechanisms led to relative alkalisation. The most prominent effects on pHi were obtained by inhibiting Na+/K+/2Cl−-cotransporters or ATP-sensitive K+-channels. Vmem was most efficiently hyperpolarised by inhibiting voltage-dependent L-type Ca2+-channels or ATP-sensitive K+-channels, whereas the impact of the other ion-transport mechanisms was smaller. In case of very prominent effects of inhibitors on pHi and/or Vmem, we also found strong influences on the antero-posterior and dorso-ventral pHi- and/or Vmem-gradients. For example, inhibiting ATP-sensitive K+-channels strongly enhanced both pHi-gradients (increasing alkalisation) and reduced both Vmem-gradients (increasing hyperpolarisation). Similarly, inhibiting Na+/K+/2Cl−-cotransporters strongly enhanced both pHi-gradients and reduced the antero-posterior Vmem-gradient. To minor extents, both pHi-gradients were enhanced and both Vmem-gradients were reduced by inhibiting voltage-dependent L-type Ca2+-channels, whereas only both pHi-gradients were reduced (increasing acidification) by inhibiting V-ATPases or NHE and Na+-channels. Conclusions Our data show that in the Drosophila follicle-cell epithelium stage-specific pHi- and Vmem-gradients develop which result from the activity of several ion-transport mechanisms. These gradients are supposed to represent important bioelectrical cues during oogenesis, e.g., by serving as electrochemical prepatterns in modifying cell polarity and cytoskeletal organisation. Electronic supplementary material The online version of this article (10.1186/s12861-019-0192-x) contains supplementary material, which is available to authorized users.
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20
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Kamath AD, Deehan MA, Frydman HM. Polar cell fate stimulates Wolbachia intracellular growth. Development 2018; 145:dev.158097. [PMID: 29467241 DOI: 10.1242/dev.158097] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 02/12/2018] [Indexed: 11/20/2022]
Abstract
Bacteria are crucial partners in the development and evolution of vertebrates and invertebrates. A large fraction of insects harbor Wolbachia, bacterial endosymbionts that manipulate host reproduction to favor their spreading. Because they are maternally inherited, Wolbachia are under selective pressure to reach the female germline and infect the offspring. However, Wolbachia infection is not limited to the germline. Somatic cell types, including stem cell niches, have higher Wolbachia loads compared with the surrounding tissue. Here, we show a novel Wolbachia tropism to polar cells (PCs), specialized somatic cells in the Drosophila ovary. During oogenesis, all stages of PC development are easily visualized, facilitating the investigation of the kinetics of Wolbachia intracellular growth. Wolbachia accumulation is triggered by particular events of PC morphogenesis, including differentiation from progenitors and between stages 8 and 9 of oogenesis. Moreover, induction of ectopic PC fate is sufficient to promote Wolbachia accumulation. We found that Wolbachia PC tropism is evolutionarily conserved across most Drosophila species, but not in Culex mosquitos. These findings highlight the coordination of endosymbiont tropism with host development and cell differentiation.
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Affiliation(s)
- Ajit D Kamath
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Mark A Deehan
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Horacio M Frydman
- Department of Biology, Boston University, Boston, MA 02215, USA .,National Emerging Infectious Disease Laboratory, Boston University, Boston, MA 02118, USA
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21
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Borensztejn A, Mascaro A, Wharton KA. JAK/STAT signaling prevents excessive apoptosis to ensure maintenance of the interfollicular stalk critical for Drosophila oogenesis. Dev Biol 2018; 438:1-9. [PMID: 29571611 DOI: 10.1016/j.ydbio.2018.03.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 03/12/2018] [Accepted: 03/19/2018] [Indexed: 12/21/2022]
Abstract
Apoptosis not only eliminates cells that are damaged or dangerous but also cells whose function during development in patterning or organogenesis is complete. The successful formation of germ cells is essential for the perpetuation of a species. The production of an oocyte often depends on signaling between germline and somatic cells, but also between specialized types of somatic cells. In Drosophila, each developing egg chamber is separated from the next by a single file of interfollicular somatic cells. Little is known about the function of the interfollicular stalk, although its presumed role in separating egg chambers is to ensure that patterning cues from one egg chamber do not impact or disrupt the development of adjacent egg chambers. We found that cells comprising the stalk undergo a progressive decrease in number during oogenesis through an apoptotic-dependent loss. The extent of programmed cell death is restricted by JAK/STAT signaling in a cell-autonomous manner to ensure that the stalk is maintained. Both a failure to undergo the normal reduction in stalk cell number, or to prevent excessive stalk cell apoptosis results in a decrease in fecundity. Thus, activation of JAK/STAT signaling in the Drosophila interfollicular stalk emerges as a model to study the tight regulation of signaling-dependent apoptosis.
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Affiliation(s)
- Antoine Borensztejn
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Alexandra Mascaro
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Kristi A Wharton
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI 02912, USA.
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22
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Gilbert SF. Achilles and the tortoise: Some caveats to mathematical modeling in biology. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 137:37-45. [PMID: 29366714 DOI: 10.1016/j.pbiomolbio.2018.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 01/13/2018] [Accepted: 01/17/2018] [Indexed: 11/29/2022]
Abstract
Mathematical modeling has recently become a much-lauded enterprise, and many funding agencies seek to prioritize this endeavor. However, there are certain dangers associated with mathematical modeling, and knowledge of these pitfalls should also be part of a biologist's training in this set of techniques. (1) Mathematical models are limited by known science; (2) Mathematical models can tell what can happen, but not what did happen; (3) A model does not have to conform to reality, even if it is logically consistent; (4) Models abstract from reality, and sometimes what they eliminate is critically important; (5) Mathematics can present a Platonic ideal to which biologically organized matter strives, rather than a trial-and-error bumbling through evolutionary processes. This "Unity of Science" approach, which sees biology as the lowest physical science and mathematics as the highest science, is part of a Western belief system, often called the Great Chain of Being (or Scala Natura), that sees knowledge emerge as one passes from biology to chemistry to physics to mathematics, in an ascending progression of reason being purification from matter. This is also an informal model for the emergence of new life. There are now other informal models for integrating development and evolution, but each has its limitations.
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Affiliation(s)
- Scott F Gilbert
- Department of Biology, Swarthmore College, Swarthmore, PA, 19081, USA.
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23
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Bernard F, Lepesant JA, Guichet A. Nucleus positioning within Drosophila egg chamber. Semin Cell Dev Biol 2017; 82:25-33. [PMID: 29056490 DOI: 10.1016/j.semcdb.2017.10.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 10/09/2017] [Accepted: 10/12/2017] [Indexed: 12/12/2022]
Abstract
Both types of Drosophila egg chamber germ cells, i.e. oocyte and nurse cells, have to control their nucleus positions in order to produce a viable gamete. Interestingly, while actin microfilaments are crucial to position the nuclei in nurse cells, these are the microtubules that are important for oocyte nucleus to migrate and adopt the correct position. In this review, we discuss the mechanisms underlying these positioning processes in the two cell types with respect to the organization and dynamics of the actin and microtubule skeleton. In the nurse cells it is essential to keep firmly the nuclei in a central position to prevent them from obstructing the ring canals when the cytoplasmic content of the cells is dumped into the oocyte cells toward the end of oogenesis. This is achieved by the assembly of thick filopodia-like actin cables anchored to the plasma membrane, which grow inwardly and eventually encase tightly the nuclei in a cage-like structure. In the oocyte, the migration at an early stage of oogenesis of the nucleus from a posterior location to an anchorage site at an asymmetric anterior position, is an essential step in the setting up of the dorsoventral polarity axis of the future embryo. This process is controlled by an interplay between MT networks that just start to be untangled. Although both mechanisms have evolved to fulfill cell-type specific cell processes in the context of fly oogenesis, interesting parallels can be drawn with other nuclear positioning mechanisms in the mouse oocyte and the developing muscle respectively.
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Affiliation(s)
- Fred Bernard
- Institut Jacques Monod, CNRS UMR 7592, Université Paris-Diderot, Sorbonne Paris Cité, 75205, Paris Cedex, France.
| | - Jean-Antoine Lepesant
- Institut Jacques Monod, CNRS UMR 7592, Université Paris-Diderot, Sorbonne Paris Cité, 75205, Paris Cedex, France.
| | - Antoine Guichet
- Institut Jacques Monod, CNRS UMR 7592, Université Paris-Diderot, Sorbonne Paris Cité, 75205, Paris Cedex, France.
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24
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Ku HY, Sun YH. Notch-dependent epithelial fold determines boundary formation between developmental fields in the Drosophila antenna. PLoS Genet 2017; 13:e1006898. [PMID: 28708823 PMCID: PMC5533456 DOI: 10.1371/journal.pgen.1006898] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Revised: 07/28/2017] [Accepted: 06/26/2017] [Indexed: 12/19/2022] Open
Abstract
Compartment boundary formation plays an important role in development by separating adjacent developmental fields. Drosophila imaginal discs have proven valuable for studying the mechanisms of boundary formation. We studied the boundary separating the proximal A1 segment and the distal segments, defined respectively by Lim1 and Dll expression in the eye-antenna disc. Sharp segregation of the Lim1 and Dll expression domains precedes activation of Notch at the Dll/Lim1 interface. By repressing bantam miRNA and elevating the actin regulator Enable, Notch signaling then induces actomyosin-dependent apical constriction and epithelial fold. Disruption of Notch signaling or the actomyosin network reduces apical constriction and epithelial fold, so that Dll and Lim1 cells become intermingled. Our results demonstrate a new mechanism of boundary formation by actomyosin-dependent tissue folding, which provides a physical barrier to prevent mixing of cells from adjacent developmental fields. During development, boundary formation between adjacent developmental fields is important to maintain the integrity of complex organs and tissues. We examined how boundaries become established between adjacent developmental fields—which are defined by expression of distinct selector genes and developmental fates—using the Drosophila eye-antennal disc as a model. We show that boundary formation is a progressive process. We focused our analysis on the antennal A1 fold that separates the A1 and A2-Ar segments, corresponding to the evolutionarily conserved segregation between coxopodite and telopodite segments of arthropod appendages. We describe a clear temporal and causal sequence of events from selector gene expression to establishment of a lineage-restricting boundary. We found that Notch activation at the boundary between adjacent fields of selector gene expression triggers actomyosin-mediated cell apical constriction, which induces the formation of an epithelial fold and prevents intermixing of cells from adjacent fields. Our findings describe a novel mechanism by which epithelial fold provides a physical barrier for cell segregation.
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Affiliation(s)
- Hui-Yu Ku
- Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Y. Henry Sun
- Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
- * E-mail:
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25
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Duhart JC, Parsons TT, Raftery LA. The repertoire of epithelial morphogenesis on display: Progressive elaboration of Drosophila egg structure. Mech Dev 2017; 148:18-39. [PMID: 28433748 DOI: 10.1016/j.mod.2017.04.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 04/07/2017] [Accepted: 04/12/2017] [Indexed: 12/26/2022]
Abstract
Epithelial structures are foundational for tissue organization in all metazoans. Sheets of epithelial cells form lateral adhesive junctions and acquire apico-basal polarity perpendicular to the surface of the sheet. Genetic analyses in the insect model, Drosophila melanogaster, have greatly advanced our understanding of how epithelial organization is established, and how it is modulated during tissue morphogenesis. Major insights into collective cell migrations have come from analyses of morphogenetic movements within the adult follicular epithelium that cooperates with female germ cells to build a mature egg. Epithelial follicle cells progress through tightly choreographed phases of proliferation, patterning, reorganization and migrations, before they differentiate to form the elaborate structures of the eggshell. Distinct structural domains are organized by differential adhesion, within which lateral junctions are remodeled to further shape the organized epithelia. During collective cell migrations, adhesive interactions mediate supracellular organization of planar polarized macromolecules, and facilitate crawling over the basement membrane or traction against adjacent cell surfaces. Comparative studies with other insects are revealing the diversification of morphogenetic movements for elaboration of epithelial structures. This review surveys the repertoire of follicle cell morphogenesis, to highlight the coordination of epithelial plasticity with progressive differentiation of a secretory epithelium. Technological advances will keep this tissue at the leading edge for interrogating the precise spatiotemporal regulation of normal epithelial reorganization events, and provide a framework for understanding pathological tissue dysplasia.
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Affiliation(s)
- Juan Carlos Duhart
- School of Life Sciences, University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154-4004, United States
| | - Travis T Parsons
- School of Life Sciences, University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154-4004, United States
| | - Laurel A Raftery
- School of Life Sciences, University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154-4004, United States.
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26
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Determination of EGFR Signaling Output by Opposing Gradients of BMP and JAK/STAT Activity. Curr Biol 2016; 26:2572-2582. [DOI: 10.1016/j.cub.2016.07.073] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 07/25/2016] [Accepted: 07/27/2016] [Indexed: 11/24/2022]
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27
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Zobel T, Brinkmann K, Koch N, Schneider K, Seemann E, Fleige A, Qualmann B, Kessels MM, Bogdan S. Cooperative functions of the two F-BAR proteins Cip4 and Nostrin in the regulation of E-cadherin in epithelial morphogenesis. J Cell Sci 2016; 128:499-515. [PMID: 25413347 DOI: 10.1242/jcs.155929] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
F-BAR proteins are prime candidates to regulate membrane curvature and dynamics during different developmental processes. Here, we analyzed nostrin, a so-far-unknown Drosophila melanogaster F-BAR protein related to Cip4. Genetic analyses revealed a strong synergism between nostrin and cip4 functions.Whereas single mutant flies are viable and fertile, combined loss of nostrin and cip4 results in reduced viability and fertility. Double mutant escaper flies show enhanced wing polarization defects and females exhibit strong egg chamber encapsulation defects. Live imaging analysis suggests that the observed phenotypes are caused by an impaired turnover of E-cadherin at the membrane. Simultaneous knockdown of Cip4 and Nostrin strongly increases the formation of tubular E-cadherin vesicles at adherens junctions. Cip4 and Nostrin localize at distinct membrane subdomains. Both proteins prefer similar membrane curvatures but seem to form distinct membrane coats and do not heterooligomerize. Our data suggest an important synergistic function of both F-BAR proteins in membrane dynamics. We propose a cooperative recruitment model, in which Cip4 initially promotes membrane invagination and early-actin-based endosomal motility, and Nostrin makes contacts with microtubules through the kinesin Khc-73 for trafficking of recycling endosomes.
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28
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Multiple Roles for Egalitarian in Polarization of the Drosophila Egg Chamber. Genetics 2016; 203:415-32. [PMID: 27017624 DOI: 10.1534/genetics.115.184622] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 03/20/2016] [Indexed: 01/08/2023] Open
Abstract
The Drosophila egg chamber provides a useful model for examining mechanisms by which cell fates are specified and maintained in the context of a complex tissue. The egg chamber is also an excellent model for understanding the mechanism by which cytoskeletal filaments are organized and the critical interplay between cytoskeletal organization, polarity establishment, and cell fate specification. Previous work has shown that Egalitarian (Egl) is required for specification and maintenance of oocyte fate. Mutants in egl either completely fail to specify an oocyte, or if specified, the oocyte eventually reverts back to nurse cell fate. Due to this very early role for Egl in egg chamber maturation, it is unclear whether later stages of egg chamber development also require Egl function. In this report, we have depleted Egl at specific stages of egg chamber development. We demonstrate that in early-stage egg chambers, Egl has an additional role in organization of oocyte microtubules. In the absence of Egl function, oocyte microtubules completely fail to reorganize. As such, the localization of microtubule motors and their cargo is disrupted. In addition, Egl also appears to function in regulating the translation of critical polarity determining messenger RNAs (mRNAs). Finally, we demonstrate that in midstage egg chambers, Egl does not appear to be required for microtubule organization, but rather for the correct spatial localization of oskar, bicoid, and gurken mRNAs.
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29
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Dunst S, Kazimiers T, von Zadow F, Jambor H, Sagner A, Brankatschk B, Mahmoud A, Spannl S, Tomancak P, Eaton S, Brankatschk M. Endogenously tagged rab proteins: a resource to study membrane trafficking in Drosophila. Dev Cell 2015; 33:351-65. [PMID: 25942626 PMCID: PMC4431667 DOI: 10.1016/j.devcel.2015.03.022] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 01/21/2015] [Accepted: 03/29/2015] [Indexed: 11/25/2022]
Abstract
Membrane trafficking is key to the cell biological mechanisms underlying development. Rab GTPases control specific membrane compartments, from core secretory and endocytic machinery to less-well-understood compartments. We tagged all 27 Drosophila Rabs with YFP(MYC) at their endogenous chromosomal loci, determined their expression and subcellular localization in six tissues comprising 23 cell types, and provide this data in an annotated, searchable image database. We demonstrate the utility of these lines for controlled knockdown and show that similar subcellular localization can predict redundant functions. We exploit this comprehensive resource to ask whether a common Rab compartment architecture underlies epithelial polarity. Strikingly, no single arrangement of Rabs characterizes the five epithelia we examine. Rather, epithelia flexibly polarize Rab distribution, producing membrane trafficking architectures that are tissue- and stage-specific. Thus, the core machinery responsible for epithelial polarization is unlikely to rely on polarized positioning of specific Rab compartments.
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Affiliation(s)
- Sebastian Dunst
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Tom Kazimiers
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany; HHMI Janelia Research Campus, Ashburn, VA 20147, USA
| | - Felix von Zadow
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Helena Jambor
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Andreas Sagner
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany; MRC National Institute for Medical Research, London NW7 1AA, UK
| | - Beate Brankatschk
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany; Paul Langerhans Institute, Dresden 01307, Germany
| | - Ali Mahmoud
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Stephanie Spannl
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Pavel Tomancak
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany.
| | - Suzanne Eaton
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany.
| | - Marko Brankatschk
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany.
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30
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Discs large 5, an Essential Gene in Drosophila, Regulates Egg Chamber Organization. G3-GENES GENOMES GENETICS 2015; 5:943-52. [PMID: 25795662 PMCID: PMC4426378 DOI: 10.1534/g3.115.017558] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Discs large 5 (Dlg5) is a member of the MAGUK family of proteins that typically serve as molecular scaffolds and mediate signaling complex formation and localization. In vertebrates, Dlg5 has been shown to be responsible for polarization of neural progenitors and to associate with Rab11-positive vesicles in epithelial cells. In Drosophila, however, the function of Dlg5 is not well-documented. We have identified dlg5 as an essential gene that shows embryonic lethality. dlg5 embryos display partial loss of primordial germ cells (PGCs) during gonad coalescence between stages 12 and 15 of embryogenesis. Loss of Dlg5 in germline and somatic stem cells in the ovary results in the depletion of both cell lineages. Reduced expression of Dlg5 in the follicle cells of the ovary leads to a number of distinct phenotypes, including defects in egg chamber budding, stalk cell overgrowth, and ectopic polar cell induction. Interestingly, loss of Dlg5 in follicle cells results in abnormal distribution of a critical component of cell adhesion, E-cadherin, shown to be essential for proper organization of egg chambers.
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31
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Brigaud I, Duteyrat JL, Chlasta J, Le Bail S, Couderc JL, Grammont M. Transforming Growth Factor β/activin signalling induces epithelial cell flattening during Drosophila oogenesis. Biol Open 2015; 4:345-54. [PMID: 25681395 PMCID: PMC4359740 DOI: 10.1242/bio.201410785] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Although the regulation of epithelial morphogenesis is essential for the formation of tissues and organs in multicellular organisms, little is known about how signalling pathways control cell shape changes in space and time. In the Drosophila ovarian epithelium, the transition from a cuboidal to a squamous shape is accompanied by a wave of cell flattening and by the ordered remodelling of E-cadherin-based adherens junctions. We show that activation of the TGFβ pathway is crucial to determine the timing, the degree and the dynamic of cell flattening. Within these cells, TGFβ signalling controls cell-autonomously the formation of Actin filament and the localisation of activated Myosin II, indicating that internal forces are generated and used to remodel AJ and to promote cytoskeleton rearrangement. Our results also reveal that TGFβ signalling controls Notch activity and that its functions are partly executed through Notch. Thus, we demonstrate that the cells that undergo the cuboidal-to-squamous transition produce active cell-shaping mechanisms, rather than passively flattening in response to a global force generated by the growth of the underlying cells. Thus, our work on TGFβ signalling provides new insights into the mechanisms through which signal transduction cascades orchestrate cell shape changes to generate proper organ structure.
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Affiliation(s)
- Isabelle Brigaud
- Université Lyon 1, Lyon and Centre de Génétique Moléculaire et Cellulaire, CNRS UMR 5534, Villeurbanne, France
| | - Jean-Luc Duteyrat
- Université Lyon 1, Lyon and Centre de Génétique Moléculaire et Cellulaire, CNRS UMR 5534, Villeurbanne, France
| | - Julien Chlasta
- Université Lyon 1, Lyon and Centre de Génétique Moléculaire et Cellulaire, CNRS UMR 5534, Villeurbanne, France Laboratoire Joliot Curie, CNRS, ENS Lyon, Université Claude Bernard Lyon 1, Université de Lyon, Lyon, France
| | - Sandrine Le Bail
- CNRS 6293, Clermont University, Inserm U1103, UMR GReD, UFR Médecine, Clermont-Ferrand F-63001, France
| | - Jean-Louis Couderc
- CNRS 6293, Clermont University, Inserm U1103, UMR GReD, UFR Médecine, Clermont-Ferrand F-63001, France
| | - Muriel Grammont
- Université Lyon 1, Lyon and Centre de Génétique Moléculaire et Cellulaire, CNRS UMR 5534, Villeurbanne, France Laboratoire Joliot Curie, CNRS, ENS Lyon, Université Claude Bernard Lyon 1, Université de Lyon, Lyon, France
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32
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Abstract
The Drosophila melanogaster ovary has served as a popular and successful model for understanding a wide range of biological processes: stem cell function, germ cell development, meiosis, cell migration, morphogenesis, cell death, intercellular signaling, mRNA localization, and translational control. This review provides a brief introduction to Drosophila oogenesis, along with a survey of its diverse biological topics and the advanced genetic tools that continue to make this a popular developmental model system.
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33
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Abstract
Localization and the associated translational control of mRNA is a well established mechanism for segregating cellular protein expression. Drosophila has been instrumental in deciphering the prevailing mechanisms of mRNA localization and regulation. This review will discuss the diverse roles of mRNA localization in the Drosophila germline, the cis-elements and cellular components regulating localization and the superimposition of translational regulatory mechanisms. Despite a history of discovery, there are still many fundamental questions regarding mRNA localization that remain unanswered. Take home messages, outstanding questions and future approaches that will likely lead to resolving these unknowns in the future are summarized at the end.
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Affiliation(s)
- Timothy T Weil
- a Department of Zoology ; University of Cambridge ; Cambridge , UK
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34
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Gómez-Lamarca MJ, Cobreros-Reguera L, Ibáñez-Jiménez B, Palacios IM, Martín-Bermudo MD. Integrins regulate epithelial cell differentiation by modulating Notch activity. J Cell Sci 2014; 127:4667-78. [PMID: 25179603 DOI: 10.1242/jcs.153122] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Coordinating exit from the cell cycle with differentiation is crucial for proper development and tissue homeostasis. Failure to do so can lead to aberrant organogenesis and tumorigenesis. However, little is known about the developmental signals that regulate the switch from cell cycle exit to differentiation. Signals downstream of two key developmental pathways, Notch and Salvador-Warts-Hippo (SWH), and signals downstream of myosin activity regulate this switch during the development of the follicle cell epithelium of the Drosophila ovary. Here, we have identified a fourth player, the integrin signaling pathway. Elimination of integrin function blocks the mitosis-to-endocycle switch and differentiation in posterior follicle cells (PFCs), by regulation of the cyclin-dependent kinase inhibitor (CKI) dacapo. In addition, integrin-mutant PFCs show defective Notch signaling and endocytosis. Furthermore, integrins act in PFCs by modulating the activity of the Notch pathway, as reducing the amount of Hairless, the major antagonist of Notch, or misexpressing Notch intracellular domain rescues the cell cycle and differentiation defects. Taken together, our findings reveal a direct involvement of integrin signaling on the spatial and temporal regulation of epithelial cell differentiation during development.
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Affiliation(s)
- M Jesús Gómez-Lamarca
- Centro Andaluz de Biología del Desarrollo CSIC-University Pablo de Olavide, Sevilla 41013, Spain
| | - Laura Cobreros-Reguera
- Centro Andaluz de Biología del Desarrollo CSIC-University Pablo de Olavide, Sevilla 41013, Spain
| | - Beatriz Ibáñez-Jiménez
- Centro Andaluz de Biología del Desarrollo CSIC-University Pablo de Olavide, Sevilla 41013, Spain
| | - Isabel M Palacios
- The Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - María D Martín-Bermudo
- Centro Andaluz de Biología del Desarrollo CSIC-University Pablo de Olavide, Sevilla 41013, Spain
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35
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Regulation of broad by the Notch pathway affects timing of follicle cell development. Dev Biol 2014; 392:52-61. [PMID: 24815210 DOI: 10.1016/j.ydbio.2014.04.024] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 04/23/2014] [Accepted: 04/29/2014] [Indexed: 12/20/2022]
Abstract
During Drosophila oogenesis, activation of Notch signaling in the follicular epithelium (FE) around stage 6 of oogenesis is essential for entry into the endocycle and a series of other changes such as cell differentiation and migration of subsets of the follicle cells. Notch induces the expression of zinc finger protein Hindsight and suppresses homeodomain protein Cut to regulate the mitotic/endocycle (ME) switch. Here we report that broad (br), encoding a small group of zinc-finger transcription factors resulting from alternative splicing, is a transcriptional target of Notch nuclear effector Suppressor of Hairless (Su(H)). The early pattern of Br in the FE, uniformly expressed except in the polar cells, is established by Notch signaling around stage 6, through the binding of Su(H) to the br early enhancer (brE) region. Mutation of the Su(H) binding site leads to a significant reduction of brE reporter expression in follicle cells undergoing the endocycle. Chromatin immunoprecipitation results further confirm Su(H) binding to the br early enhancer. Consistent with its expression in follicle cells during midoogenesis, loss of br function results in a delayed entry into the endocycle. Our findings suggest an important role of br in the timing of follicle cell development, and its transcriptional regulation by the Notch pathway.
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36
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A genetic screen based on in vivo RNA imaging reveals centrosome-independent mechanisms for localizing gurken transcripts in Drosophila. G3-GENES GENOMES GENETICS 2014; 4:749-60. [PMID: 24531791 PMCID: PMC4059244 DOI: 10.1534/g3.114.010462] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We have screened chromosome arm 3L for ethyl methanesulfonate−induced mutations that disrupt localization of fluorescently labeled gurken (grk) messenger (m)RNA, whose transport along microtubules establishes both major body axes of the developing Drosophila oocyte. Rapid identification of causative mutations by single-nucleotide polymorphism recombinational mapping and whole-genomic sequencing allowed us to define nine complementation groups affecting grk mRNA localization and other aspects of oogenesis, including alleles of elg1, scaf6, quemao, nudE, Tsc2/gigas, rasp, and Chd5/Wrb, and several null alleles of the armitage Piwi-pathway gene. Analysis of a newly induced kinesin light chain allele shows that kinesin motor activity is required for both efficient grk mRNA localization and oocyte centrosome integrity. We also show that initiation of the dorsoanterior localization of grk mRNA precedes centrosome localization, suggesting that microtubule self-organization contributes to breaking axial symmetry to generate a unique dorsoventral axis.
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37
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Boisclair Lachance JF, Peláez N, Cassidy JJ, Webber JL, Rebay I, Carthew RW. A comparative study of Pointed and Yan expression reveals new complexity to the transcriptional networks downstream of receptor tyrosine kinase signaling. Dev Biol 2013; 385:263-78. [PMID: 24240101 DOI: 10.1016/j.ydbio.2013.11.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 11/05/2013] [Indexed: 11/29/2022]
Abstract
The biochemical regulatory network downstream of receptor tyrosine kinase (RTK) signaling is controlled by two opposing ETS family members: the transcriptional activator Pointed (Pnt) and the transcriptional repressor Yan. A bistable switch model has been invoked to explain how pathway activation can drive differentiation by shifting the system from a high-Yan/low-Pnt activity state to a low-Yan/high-Pnt activity state. Although the model explains yan and pnt loss-of-function phenotypes in several different cell types, how Yan and Pointed protein expression dynamics contribute to these and other developmental transitions remains poorly understood. Toward this goal we have used a functional GFP-tagged Pnt transgene (Pnt-GFP) to perform a comparative study of Yan and Pnt protein expression throughout Drosophila development. Consistent with the prevailing model of the Pnt-Yan network, we found numerous instances where Pnt-GFP and Yan adopt a mutually exclusive pattern of expression. However we also observed many examples of co-expression. While some co-expression occurred in cells where RTK signaling is presumed low, other co-expression occurred in cells with high RTK signaling. The instances of co-expressed Yan and Pnt-GFP in tissues with high RTK signaling cannot be explained by the current model, and thus they provide important contexts for future investigation of how context-specific differences in RTK signaling, network topology, or responsiveness to other signaling inputs, affect the transcriptional response.
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Affiliation(s)
- Jean-François Boisclair Lachance
- Ben May Department for Cancer Research, University of Chicago, Chicago, IL 60637, USA; The Chicago Center for Systems Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Nicolás Peláez
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA; The Chicago Center for Systems Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Justin J Cassidy
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA; The Chicago Center for Systems Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Jemma L Webber
- Ben May Department for Cancer Research, University of Chicago, Chicago, IL 60637, USA; The Chicago Center for Systems Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Ilaria Rebay
- Ben May Department for Cancer Research, University of Chicago, Chicago, IL 60637, USA; The Chicago Center for Systems Biology, The University of Chicago, Chicago, IL 60637, USA.
| | - Richard W Carthew
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA; The Chicago Center for Systems Biology, The University of Chicago, Chicago, IL 60637, USA.
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38
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Response to the dorsal anterior gradient of EGFR signaling in Drosophila oogenesis is prepatterned by earlier posterior EGFR activation. Cell Rep 2013; 4:791-802. [PMID: 23972992 DOI: 10.1016/j.celrep.2013.07.038] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 06/21/2013] [Accepted: 07/26/2013] [Indexed: 11/22/2022] Open
Abstract
Spatially restricted epidermal growth factor receptor (EGFR) activity plays a central role in patterning the follicular epithelium of the Drosophila ovary. In midoogenesis, localized EGFR activation is achieved by the graded dorsal anterior localization of its ligand, Gurken. Graded EGFR activity determines multiple dorsal anterior fates along the dorsal-ventral axis but cannot explain the sharp posterior limit of this domain. Here, we show that posterior follicle cells express the T-box transcription factors Midline and H15, which render cells unable to adopt a dorsal anterior fate in response to EGFR activation. The posterior expression of Midline and H15 is itself induced in early oogenesis by posteriorly localized EGFR signaling, defining a feedback loop in which early induction of Mid and H15 confers a molecular memory that fundamentally alters the outcome of later EGFR signaling. Spatial regulation of the EGFR pathway thus occurs both through localization of the ligand and through localized regulation of the cellular response.
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39
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Efficient EGFR signaling and dorsal-ventral axis patterning requires syntaxin dependent Gurken trafficking. Dev Biol 2012; 373:349-58. [PMID: 23127433 DOI: 10.1016/j.ydbio.2012.10.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 10/26/2012] [Accepted: 10/27/2012] [Indexed: 11/22/2022]
Abstract
Vesicle trafficking plays a crucial role in the establishment of cell polarity in various cellular contexts, including axis-pattern formation in the developing egg chamber of Drosophila. The EGFR ligand, Gurken (Grk), is first localized at the posterior of young oocytes for anterior-posterior axis formation and later in the dorsal anterior region for induction of the dorsal-ventral (DV) axis, but regulation of Grk localization by membrane trafficking in the oocyte remains poorly understood. Here, we report that Syntaxin 1A (Syx1A) is required for efficient trafficking of Grk protein for DV patterning. We show that Syx1A is associated with the Golgi membrane and is required for the transportation of Grk-containing vesicles along the microtubules to their dorsal anterior destination in the oocyte. Our studies reveal that the Syx1A dependent trafficking of Grk protein is required for efficient EGFR signaling during DV patterning.
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40
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Simakov DSA, Cheung LS, Pismen LM, Shvartsman SY. EGFR-dependent network interactions that pattern Drosophila eggshell appendages. Development 2012; 139:2814-20. [PMID: 22782725 DOI: 10.1242/dev.077669] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Similar to other organisms, Drosophila uses its Epidermal Growth Factor Receptor (EGFR) multiple times throughout development. One crucial EGFR-dependent event is patterning of the follicular epithelium during oogenesis. In addition to providing inductive cues necessary for body axes specification, patterning of the follicle cells initiates the formation of two respiratory eggshell appendages. Each appendage is derived from a primordium comprising a patch of cells expressing broad (br) and an adjacent stripe of cells expressing rhomboid (rho). Several mechanisms of eggshell patterning have been proposed in the past, but none of them can explain the highly coordinated expression of br and rho. To address some of the outstanding issues in this system, we synthesized the existing information into a revised mathematical model of follicle cell patterning. Based on the computational model analysis, we propose that dorsal appendage primordia are established by sequential action of feed-forward loops and juxtacrine signals activated by the gradient of EGFR signaling. The model describes pattern formation in a large number of mutants and points to several unanswered questions related to the dynamic interaction of the EGFR and Notch pathways.
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Affiliation(s)
- David S A Simakov
- Department of Chemical Engineering, Technion-Israel Institute of Technology, Israel
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41
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Abstract
The ramified architectures of organs such as the mammary gland and lung are generated via branching morphogenesis, a developmental process through which individual cells bud and pinch off of pre-existing epithelial sheets. Although specified by signaling programs, organ development requires integration of all aspects of the microenvironment. We describe the essential role of endogenous cellular contractility in the formation of branching tubes. We also highlight the role of exogenous forces in normal and aberrant branching.
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Affiliation(s)
- Celeste M Nelson
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA.
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42
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Marga F, Jakab K, Khatiwala C, Shepherd B, Dorfman S, Hubbard B, Colbert S, Gabor F. Toward engineering functional organ modules by additive manufacturing. Biofabrication 2012; 4:022001. [PMID: 22406433 DOI: 10.1088/1758-5082/4/2/022001] [Citation(s) in RCA: 185] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Tissue engineering is emerging as a possible alternative to methods aimed at alleviating the growing demand for replacement tissues and organs. A major pillar of most tissue engineering approaches is the scaffold, a biocompatible network of synthetic or natural polymers, which serves as an extracellular matrix mimic for cells. When the scaffold is seeded with cells it is supposed to provide the appropriate biomechanical and biochemical conditions for cell proliferation and eventual tissue formation. Numerous approaches have been used to fabricate scaffolds with ever-growing complexity. Recently, novel approaches have been pursued that do not rely on artificial scaffolds. The most promising ones utilize matrices of decellularized organs or methods based on multicellular self-assembly, such as sheet-based and bioprinting-based technologies. We briefly overview some of the scaffold-free approaches and detail one that employs biological self-assembly and bioprinting. We describe the technology and its specific applications to engineer vascular and nerve grafts.
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Affiliation(s)
- Francoise Marga
- Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211, USA
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43
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Tworzydlo W, Kisiel E. A very simple mode of follicular cell diversification in Euborellia fulviceps (Dermaptera, Anisolabididae) involves actively migrating cells. Zoolog Sci 2012; 28:802-8. [PMID: 22035302 DOI: 10.2108/zsj.28.802] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The ovaries of Euborellia fulviceps are composed of five elongated ovarioles of meroistic-polytrophic type. The individual ovariole has three discernible regions: the terminal filament, germarium, and vitellarium. The terminal filament is a stalk of flattened, disc-shaped somatic cells. In the germarium, germline cells in subsequent stages of differentiation are located, and the vitellarium comprises numerous ovarian follicles arranged linearly. The individual ovarian follicles within the vitellarium are separated by prominent interfollicular stalks. The follicles are composed by two germline cells only: an oocyte and a single, polyploid nurse cell, which are surrounded by a monolayer of somatic follicular cells (FCs). During subsequent stages of oogenesis, initially uniform follicular epithelium begins to diversify into morphologically and physiologically distinct subpopulations. In E. fulviceps, the FC diversification mode is rather simple and leads to the formation of only three different FC subpopulations: (1) cuboidal FCs covering the oocyte, (2) stretched FCs surrounding the nurse cell and (3) FCs actively migrating between oocyte and a nurse cell. We found that FCs from the latter subpopulation send long and thin filopodium-like and microtubule-rich processes penetrating between the oocyte and nurse cell membranes. This suggests that, in E. fulviceps, cells from at least one FCs subpopulation show the ability to change position within an ovarian follicle by means of active migration.
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Affiliation(s)
- Waclaw Tworzydlo
- Department of Developmental Biology and Morphology of Invertebrates, Institute of Zoology, Jagiellonian University, Gronostajowa 9, 30-387 Krakow, Poland.
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44
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Cheung LS, Schüpbach T, Shvartsman SY. Pattern formation by receptor tyrosine kinases: analysis of the Gurken gradient in Drosophila oogenesis. Curr Opin Genet Dev 2011; 21:719-25. [PMID: 21862318 DOI: 10.1016/j.gde.2011.07.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 07/21/2011] [Indexed: 12/11/2022]
Abstract
Spatial patterns of cell differentiation in developing tissues can be controlled by receptor tyrosine kinase (RTK) signaling gradients, which may form when locally secreted ligands activate uniformly expressed receptors. Graded activation of RTKs can span multiple cell diameters, giving rise to spatiotemporal patterns of signaling through the Extracellular Signal Regulated/Mitogen Activated Protein Kinase (ERK/MAPK), which connects receptor activation to multiple aspects of tissue morphogenesis. This general mechanism has been identified in numerous developmental contexts, from body axis specification in insects to patterning of the mammalian neocortex. We review recent quantitative studies of this mechanism in Drosophila oogenesis, an established genetic model of signaling through the Epidermal Growth Factor Receptor (EGFR), a highly conserved RTK.
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Affiliation(s)
- Lily S Cheung
- Department of Chemical and Biological Engineering and Lewis-Sigler Institute for Integrative Genomics, Princeton University, NJ J08544, USA
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45
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Zartman JJ, Cheung LS, Niepielko MG, Bonini C, Haley B, Yakoby N, Shvartsman SY. Pattern formation by a moving morphogen source. Phys Biol 2011; 8:045003. [PMID: 21750363 DOI: 10.1088/1478-3975/8/4/045003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
During Drosophila melanogaster oogenesis, the follicular epithelium that envelops the germline cyst gives rise to an elaborate eggshell, which houses the future embryo and mediates its interaction with the environment. A prominent feature of the eggshell is a pair of dorsal appendages, which are needed for embryo respiration. Morphogenesis of this structure depends on broad, a zinc-finger transcription factor, regulated by the EGFR pathway. While much has been learned about the mechanisms of broad regulation by EGFR, current understanding of processes that shape the spatial pattern of broad expression is incomplete. We propose that this pattern is defined by two different phases of EGFR activation: an early, posterior-to-anterior gradient of EGFR signaling sets the posterior boundary of broad expression, while the anterior boundary is set by a later phase of EGFR signaling, distributed in a dorsoventral gradient. This model can explain the wild-type pattern of broad in D. melanogaster, predicts how this pattern responds to genetic perturbations, and provides insight into the mechanisms driving diversification of eggshell patterning. The proposed model of the broad expression pattern can be used as a starting point for the quantitative analysis of a large number of gene expression patterns in Drosophila oogenesis.
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Affiliation(s)
- Jeremiah J Zartman
- Department of Chemical and Biological Engineering, Lewis Sigler Institute for Integrative Genomics, Carl Icahn Laboratory, Washington Road, Princeton University, Princeton, NJ 08544, USA.
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46
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Sun Y, Yan Y, Denef N, Schüpbach T. Regulation of somatic myosin activity by protein phosphatase 1β controls Drosophila oocyte polarization. Development 2011; 138:1991-2001. [PMID: 21490061 DOI: 10.1242/dev.062190] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Drosophila body axes are established in the oocyte during oogenesis. Oocyte polarization is initiated by Gurken, which signals from the germline through the epidermal growth factor receptor (Egfr) to the posterior follicle cells (PFCs). In response the PFCs generate an unidentified polarizing signal that regulates oocyte polarity. We have identified a loss-of-function mutation of flapwing, which encodes the catalytic subunit of protein phosphatase 1β (PP1β) that disrupts oocyte polarization. We show that PP1β, by regulating myosin activity, controls the generation of the polarizing signal. Excessive myosin activity in the PFCs causes oocyte mispolarization and defective Notch signaling and endocytosis in the PFCs. The integrated activation of JAK/STAT and Egfr signaling results in the sensitivity of PFCs to defective Notch. Interestingly, our results also demonstrate a role of PP1β in generating the polarizing signal independently of Notch, indicating a direct involvement of somatic myosin activity in axis formation.
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Affiliation(s)
- Yi Sun
- Howard Hughes Medical Institute, Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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47
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Wilson MJ, Abbott H, Dearden PK. The evolution of oocyte patterning in insects: multiple cell-signaling pathways are active during honeybee oogenesis and are likely to play a role in axis patterning. Evol Dev 2011; 13:127-37. [DOI: 10.1111/j.1525-142x.2011.00463.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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48
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49
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Doerflinger H, Vogt N, Torres IL, Mirouse V, Koch I, Nüsslein-Volhard C, St Johnston D. Bazooka is required for polarisation of the Drosophila anterior-posterior axis. Development 2010; 137:1765-73. [PMID: 20430751 DOI: 10.1242/dev.045807] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Drosophila anterior-posterior (AP) axis is determined by the polarisation of the stage 9 oocyte and the subsequent localisation of bicoid and oskar mRNAs to opposite poles of the cell. Oocyte polarity has been proposed to depend on the same PAR proteins that generate AP polarity in C. elegans, with a complex of Bazooka (Baz; Par-3), Par-6 and aPKC marking the anterior and lateral cortex, and Par-1 defining the posterior. The function of the Baz complex in oocyte polarity has remained unclear, however, because although baz-null mutants block oocyte determination, egg chambers that escape this early arrest usually develop normal polarity at stage 9. Here, we characterise a baz allele that produces a penetrant polarity phenotype at stage 9 without affecting oocyte determination, demonstrating that Baz is essential for axis formation. The dynamics of Baz, Par-6 and Par-1 localisation in the oocyte indicate that the axis is not polarised by a cortical contraction as in C. elegans, and instead suggest that repolarisation of the oocyte is triggered by posterior inactivation of aPKC or activation of Par-1. This initial asymmetry is then reinforced by mutual inhibition between the anterior Baz complex and posterior Par-1 and Lgl. Finally, we show that mutation of the aPKC phosphorylation site in Par-1 results in the uniform cortical localisation of Par-1 and the loss of cortical microtubules. Since non-phosphorylatable Par-1 is epistatic to uninhibitable Baz, Par-1 seems to function downstream of the other PAR proteins to polarize the oocyte microtubule cytoskeleton.
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Affiliation(s)
- Hélène Doerflinger
- The Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, UK
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Jakab K, Marga F, Norotte C, Murphy K, Vunjak-Novakovic G, Forgacs G. Tissue engineering by self-assembly and bio-printing of living cells. Biofabrication 2010; 2:022001. [PMID: 20811127 PMCID: PMC3635954 DOI: 10.1088/1758-5082/2/2/022001] [Citation(s) in RCA: 321] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Biofabrication of living structures with desired topology and functionality requires the interdisciplinary effort of practitioners of the physical, life and engineering sciences. Such efforts are being undertaken in many laboratories around the world. Numerous approaches are pursued, such as those based on the use of natural or artificial scaffolds, decellularized cadaveric extracellular matrices and, most lately, bioprinting. To be successful in this endeavor, it is crucial to provide in vitro micro-environmental clues for the cells resembling those in the organism. Therefore, scaffolds, populated with differentiated cells or stem cells, of increasing complexity and sophistication are being fabricated. However, no matter how sophisticated scaffolds are, they can cause problems stemming from their degradation, eliciting immunogenic reactions and other a priori unforeseen complications. It is also being realized that ultimately the best approach might be to rely on the self-assembly and self-organizing properties of cells and tissues and the innate regenerative capability of the organism itself, not just simply prepare tissue and organ structures in vitro followed by their implantation. Here we briefly review the different strategies for the fabrication of three-dimensional biological structures, in particular bioprinting. We detail a fully biological, scaffoldless, print-based engineering approach that uses self-assembling multicellular units as bio-ink particles and employs early developmental morphogenetic principles, such as cell sorting and tissue fusion.
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Affiliation(s)
- Karoly Jakab
- Department of Physics & Astronomy, University of Missouri, Columbia, MO 65211, USA
| | - Francoise Marga
- Department of Physics & Astronomy, University of Missouri, Columbia, MO 65211, USA
| | - Cyrille Norotte
- Department of Biology, University of Missouri, Columbia, MO 65211, USA
| | - Keith Murphy
- Organovo, Inc., 5871 Oberlin Drive, San Diego, CA 92121, USA
| | | | - Gabor Forgacs
- Department of Physics & Astronomy, University of Missouri, Columbia, MO 65211, USA
- Department of Biology, University of Missouri, Columbia, MO 65211, USA
- Department of Biomedical Engineering, University of Missouri, Columbia, MO 65211, USA
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