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Hauptman G, Reichert MC, Abdal Rhida MA, Evans TA. Characterization of enhancer fragments in Drosophila robo2. Fly (Austin) 2022; 16:312-346. [PMID: 36217698 PMCID: PMC9559326 DOI: 10.1080/19336934.2022.2126259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 09/13/2022] [Accepted: 09/14/2022] [Indexed: 01/05/2023] Open
Abstract
Receptor proteins of the Roundabout (Robo) family regulate axon guidance decisions during nervous system development. Among the three Drosophila robo family genes (robo1, robo2 and robo3), robo2 displays a dynamic expression pattern and regulates multiple axon guidance outcomes, including preventing midline crossing in some axons, promoting midline crossing in others, forming lateral longitudinal axon pathways, and regulating motor axon guidance. The identity and location of enhancer elements regulating robo2's complex and dynamic expression pattern in different neural cell types are unknown. Here, we characterize a set of 17 transgenic lines expressing GAL4 under the control of DNA sequences derived from noncoding regions in and around robo2, to identify enhancers controlling specific aspects of robo2 expression in the embryonic ventral nerve cord. We identify individual fragments that confer expression in specific cell types where robo2 is known to function, including early pioneer neurons, midline glia and lateral longitudinal neurons. Our results indicate that robo2's dynamic expression pattern is specified by a combination of enhancer elements that are active in different subsets of cells. We show that robo2's expression in lateral longitudinal axons represents two genetically separable subsets of neurons, and compare their axon projections with each other and with Fasciclin II (FasII), a commonly used marker of longitudinal axon pathways. In addition, we provide a general description of each fragment's expression in embryonic tissues outside of the nervous system, to serve as a resource for other researchers interested in robo2 expression and its functional roles outside the central nervous system.
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Affiliation(s)
- Gina Hauptman
- Department of Biological Sciences, University of Arkansas, Fayetteville
| | - Marie C. Reichert
- Department of Biological Sciences, University of Arkansas, Fayetteville
| | - Muna A. Abdal Rhida
- Department of Biological Sciences, University of Arkansas, Fayetteville
- Department of Biology, Wasit University, Iraq
| | - Timothy A. Evans
- Department of Biological Sciences, University of Arkansas, Fayetteville
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2
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Laws KM, Bashaw GJ. Diverse roles for axon guidance pathways in adult tissue architecture and function. NATURAL SCIENCES (WEINHEIM, GERMANY) 2022; 2:e20220021. [PMID: 37456985 PMCID: PMC10346896 DOI: 10.1002/ntls.20220021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
Classical axon guidance ligands and their neuronal receptors were first identified due to their fundamental roles in regulating connectivity in the developing nervous system. Since their initial discovery, it has become clear that these signaling molecules play important roles in the development of a broad array of tissue and organ systems across phylogeny. In addition to these diverse developmental roles, there is a growing appreciation that guidance signaling pathways have important functions in adult organisms, including the regulation of tissue integrity and homeostasis. These roles in adult organisms include both tissue-intrinsic activities of guidance molecules, as well as systemic effects on tissue maintenance and function mediated by the nervous and vascular systems. While many of these adult functions depend on mechanisms that mirror developmental activities, such as regulating adhesion and cell motility, there are also examples of adult roles that may reflect signaling activities that are distinct from known developmental mechanisms, including the contributions of guidance signaling pathways to lineage commitment in the intestinal epithelium and bone remodeling in vertebrates. In this review, we highlight studies of guidance receptors and their ligands in adult tissues outside of the nervous system, focusing on in vivo experimental contexts. Together, these studies lay the groundwork for future investigation into the conserved and tissue-specific mechanisms of guidance receptor signaling in adult tissues.
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Affiliation(s)
- Kaitlin M. Laws
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Current address: Department of Biology, Randolph-Macon College, Ashland, VA 23005, USA
| | - Greg J. Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Zhao T, Xiao Y, Huang B, Ran MJ, Duan X, Wang YF, Lu Y, Yu XQ. A dual role of lola in Drosophila ovary development: regulating stem cell niche establishment and repressing apoptosis. Cell Death Dis 2022; 13:756. [PMID: 36056003 PMCID: PMC9440207 DOI: 10.1038/s41419-022-05195-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 08/13/2022] [Accepted: 08/17/2022] [Indexed: 01/21/2023]
Abstract
In Drosophila ovary, niche is composed of somatic cells, including terminal filament cells (TFCs), cap cells (CCs) and escort cells (ECs), which provide extrinsic signals to maintain stem cell renewal or initiate cell differentiation. Niche establishment begins in larval stages when terminal filaments (TFs) are formed, but the underlying mechanism for the development of TFs remains largely unknown. Here we report that transcription factor longitudinals lacking (Lola) is essential for ovary morphogenesis. We showed that Lola protein was expressed abundantly in TFCs and CCs, although also in other cells, and lola was required for the establishment of niche during larval stage. Importantly, we found that knockdown expression of lola induced apoptosis in adult ovary, and that lola affected adult ovary morphogenesis by suppressing expression of Regulator of cullins 1b (Roc1b), an apoptosis-related gene that regulates caspase activation during spermatogenesis. These findings significantly expand our understanding of the mechanisms controlling niche establishment and adult oogenesis in Drosophila.
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Affiliation(s)
- Ting Zhao
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, PR China
| | - Yanhong Xiao
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, South China Normal University, Guangzhou, PR China
| | - Bo Huang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, PR China
| | - Mao-Jiu Ran
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, PR China
| | - Xin Duan
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, PR China
| | - Yu-Feng Wang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, PR China
| | - Yuzhen Lu
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, South China Normal University, Guangzhou, PR China.
| | - Xiao-Qiang Yu
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, South China Normal University, Guangzhou, PR China.
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4
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Visceral mesoderm signaling regulates assembly position and function of the Drosophila testis niche. Dev Cell 2022; 57:1009-1023.e5. [PMID: 35390292 PMCID: PMC9050945 DOI: 10.1016/j.devcel.2022.03.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 02/07/2022] [Accepted: 03/14/2022] [Indexed: 12/20/2022]
Abstract
Tissue homeostasis often requires a properly placed niche to support stem cells. Morphogenetic processes that position a niche are just being described. For the Drosophila testis, we recently showed that pro-niche cells, specified at disparate positions during early gonadogenesis, must assemble into one collective at the anterior of the gonad. We now find that Slit and FGF signals emanating from adjacent visceral mesoderm regulate assembly. In response to signaling, niche cells express islet, which we find is also required for niche assembly. Without signaling, niche cells specified furthest from the anterior are unable to migrate, remaining dispersed. The function of such niches is severely disrupted, with niche cells evading cell cycle quiescence, compromised in their ability to signal the incipient stem cell pool, and failing to orient stem cell divisions properly. Our work identifies both extrinsic signaling and intrinsic responses required for proper assembly and placement of the testis niche.
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Martinot E, Boerboom D. Slit/Robo signaling regulates Leydig cell steroidogenesis. Cell Commun Signal 2021; 19:8. [PMID: 33478524 PMCID: PMC7819258 DOI: 10.1186/s12964-020-00696-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 12/10/2020] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND First identified as a regulator of neuronal axon guidance, Slit/Robo signaling has since been implicated in additional physiologic and pathologic processes, such as angiogenesis, organogenesis and cancer progression. However, its roles in the regulation of testis function have been little explored. METHODS Immunohistochemistry and RT-qPCR analyses were performed to detect the expression of Slit/Robo signaling effectors in the adult mouse testis. To identify the roles and mechanisms of Slit/Robo signaling in the regulation of steroidogenesis, RT-qPCR, immunoblotting and hormone measurements were carried out using Leydig cells (primary cultures and the MA10 cell line) treated with exogenous SLIT ligands, and testes from Robo1-null mice. RESULTS Slit1, -2 and -3 and Robo1 and -2 expression was detected in the adult mouse testis, particularly in Leydig cells. In vitro treatment of Leydig cells with exogenous SLIT ligands led to a decrease in the expression of the steroidogenic genes Star, Cyp11a1, and Cyp17a1. SLIT2 treatment decreased the phosphorylation of the key steroidogenic gene regulator CREB, possibly in part by suppressing AKT activity. Furthermore, SLIT2 treatment reduced the responsiveness of MA10 cells to luteinizing hormone by decreasing the expression of Lhcgr. Consistent with these in vitro results, an increase in testicular Star mRNA levels and intra-testicular testosterone concentrations were found in Robo1-null mice. Finally, we showed that the expression of the Slit and Robo genes in Leydig cells is enhanced by testosterone treatment in vitro, by an AR-independent mechanism. CONCLUSION Taken together, these results suggest that Slit/Robo signaling represents a novel mechanism that regulates Leydig cell steroidogenesis. It may act in an autocrine/paracrine manner to mediate negative feedback by testosterone on its own synthesis. Video Abstract.
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Affiliation(s)
- Emmanuelle Martinot
- Département de Biomédecine Vétérinaire, Centre de Recherche en Reproduction Et Fertilité, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC Canada
| | - Derek Boerboom
- Département de Biomédecine Vétérinaire, Centre de Recherche en Reproduction Et Fertilité, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC Canada
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Tian K, Henderson RE, Parker R, Brown A, Johnson JE, Bateman JR. Two modes of transvection at the eyes absent gene of Drosophila demonstrate plasticity in transcriptional regulatory interactions in cis and in trans. PLoS Genet 2019; 15:e1008152. [PMID: 31075100 PMCID: PMC6530868 DOI: 10.1371/journal.pgen.1008152] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 05/22/2019] [Accepted: 04/23/2019] [Indexed: 01/10/2023] Open
Abstract
For many genes, proper gene expression requires coordinated and dynamic interactions between multiple regulatory elements, each of which can either promote or silence transcription. In Drosophila, the complexity of the regulatory landscape is further complicated by the tight physical pairing of homologous chromosomes, which can permit regulatory elements to interact in trans, a phenomenon known as transvection. To better understand how gene expression can be programmed through cis- and trans-regulatory interactions, we analyzed transvection effects for a collection of alleles of the eyes absent (eya) gene. We find that trans-activation of a promoter by the eya eye-specific enhancers is broadly supported in many allelic backgrounds, and that the availability of an enhancer to act in trans can be predicted based on the molecular lesion of an eya allele. Furthermore, by manipulating promoter availability in cis and in trans, we demonstrate that the eye-specific enhancers of eya show plasticity in their promoter preference between two different transcriptional start sites, which depends on promoter competition between the two potential targets. Finally, we show that certain alleles of eya demonstrate pairing-sensitive silencing resulting from trans-interactions between Polycomb Response Elements (PREs), and genetic and genomic data support a general role for PcG proteins in mediating transcriptional silencing at eya. Overall, our data highlight how eya gene regulation relies upon a complex but plastic interplay between multiple enhancers, promoters, and PREs. Gene regulation requires interactions between regions of DNA known as regulatory elements, which, in combination, determine where and when a gene will be active or silenced. Some genes use just a few regulatory elements, whereas others rely on highly complex interactions between many different elements that are poorly understood. While we typically imagine regulatory elements interacting with one another along the length of a single chromosome, in a curious phenomenon called transvection, elements can communicate between two different chromosomes that are held in close proximity. Here, we use the study of transvection to better understand how different regulatory elements contribute to the expression of eyes absent (eya), a gene required for proper eye development in Drosophila. Our data show that a class of elements that initiate eya gene expression, called promoters, will compete with one another for activation by eya’s enhancers, a second class of regulatory element, with the promoter that is closest to the enhancers being the favored target for activation. Furthermore, our study of transvection uncovers an important role for a silencing element, called a PRE, in opposing eya gene expression. Overall, our study sheds new light on how different elements combine to produce patterned expression of eya.
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Affiliation(s)
- Katherine Tian
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
| | - Rachel E. Henderson
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
| | - Reyna Parker
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
| | - Alexia Brown
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
| | - Justine E. Johnson
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
| | - Jack R. Bateman
- Biology Department, Bowdoin College, Brunswick, Maine, United States of America
- * E-mail:
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7
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Identification of raw as a regulator of glial development. PLoS One 2018; 13:e0198161. [PMID: 29813126 PMCID: PMC5973607 DOI: 10.1371/journal.pone.0198161] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Accepted: 05/15/2018] [Indexed: 12/18/2022] Open
Abstract
Glial cells perform numerous functions to support neuron development and function, including axon wrapping, formation of the blood brain barrier, and enhancement of synaptic transmission. We have identified a novel gene, raw, which functions in glia of the central and peripheral nervous systems in Drosophila. Reducing Raw levels in glia results in morphological defects in the brain and ventral nerve cord, as well as defects in neuron function, as revealed by decreased locomotion in crawling assays. Examination of the number of glia along peripheral nerves reveals a reduction in glial number upon raw knockdown. The reduced number of glia along peripheral nerves occurs as a result of decreased glial proliferation. As Raw has been shown to negatively regulate Jun N-terminal kinase (JNK) signaling in other developmental contexts, we examined the expression of a JNK reporter and the downstream JNK target, matrix metalloproteinase 1 (mmp1), and found that raw knockdown results in increased reporter activity and Mmp1 levels. These results are consistent with previous studies showing increased Mmp levels lead to nerve cord defects similar to those observed upon raw knockdown. In addition, knockdown of puckered, a negative feedback regulator of JNK signaling, also causes a decrease in glial number. Thus, our studies have resulted in the identification of a new regulator of gliogenesis, and demonstrate that increased JNK signaling negatively impacts glial development.
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8
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Li J, Su X, Wang Y, Yang W, Pan Y, Su C, Zhang X. Genome-wide identification and expression analysis of the BTB domain-containing protein gene family in tomato. Genes Genomics 2017; 40:1-15. [PMID: 29892895 DOI: 10.1007/s13258-017-0604-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 08/03/2017] [Indexed: 01/01/2023]
Abstract
BTB (broad-complex, tramtrack, and bric-a-brac) family proteins are characterized by the presence of a protein-protein interaction BTB domain. BTB proteins have diverse functions, including transcriptional regulation, protein degradation, chromatin remodeling, and cytoskeletal regulation. However, little is known about this gene family in tomato (Solanum lycopersicum), the most important model plant for crop species. In this study, 38 BTB genes were identified based on tomato whole-genome sequence. Phylogenetic analysis of BTB proteins in tomato revealed that SlBTB proteins could be divided into at least 4 subfamilies. The SlBTB proteins contains 1-3 BTB domains, and several other types of functional domains, including KCTD (Potassium channel tetramerization domain-containing), the MATH (meprin and TRAF homology), ANK (Ankyrin repeats), NPR1 (nonexpressor of pathogenesis-related proteins1), NPH3 (Nonphototropic Hypocotyl 3), TAZ zinc finger, C-terminal Kelch, Skp1 and Arm (Armadillo/beta-catenin-like repeat) domains are also found in some tomato BTB proteins. Moreover, their expression patterns in tissues/stages, in response to different abiotic stress treatments and hormones were also investigated. This study provides the first comprehensive analysis of BTB gene family in the tomato genome. The data will undoubtedly be useful for better understanding the potential functions of BTB genes, and their possible roles in mediating hormone cross-talk and abiotic stress in tomato as well as in some other relative species.
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Affiliation(s)
- Jinhua Li
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education; College of Horticulture and Landscape Architechture, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, China
| | - Xiaoxing Su
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education; College of Horticulture and Landscape Architechture, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, China
| | - Yinlei Wang
- Institute of Vegetable Crops, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China
| | - Wei Yang
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education; College of Horticulture and Landscape Architechture, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, China
| | - Yu Pan
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education; College of Horticulture and Landscape Architechture, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, China
| | - Chenggang Su
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education; College of Horticulture and Landscape Architechture, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, China
| | - Xingguo Zhang
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education; College of Horticulture and Landscape Architechture, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, China.
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Silva D, Olsen KW, Bednarz MN, Droste A, Lenkeit CP, Chaharbakhshi E, Temple-Wood ER, Jemc JC. Regulation of Gonad Morphogenesis in Drosophila melanogaster by BTB Family Transcription Factors. PLoS One 2016; 11:e0167283. [PMID: 27898696 PMCID: PMC5127561 DOI: 10.1371/journal.pone.0167283] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 11/07/2016] [Indexed: 02/06/2023] Open
Abstract
During embryogenesis, primordial germ cells (PGCs) and somatic gonadal precursor cells (SGPs) migrate and coalesce to form the early gonad. A failure of the PGCs and SGPs to form a gonad with the proper architecture not only affects germ cell development, but can also lead to infertility. Therefore, it is critical to identify the molecular mechanisms that function within both the PGCs and SGPs to promote gonad morphogenesis. We have characterized the phenotypes of two genes, longitudinals lacking (lola) and ribbon (rib), that are required for the coalescence and compaction of the embryonic gonad in Drosophila melanogaster. rib and lola are expressed in the SGPs of the developing gonad, and genetic interaction analysis suggests these proteins cooperate to regulate gonad development. Both genes encode proteins with DNA binding motifs and a conserved protein-protein interaction domain, known as the Broad complex, Tramtrack, Bric-à-brac (BTB) domain. Through molecular modeling and yeast-two hybrid studies, we demonstrate that Rib and Lola homo- and heterodimerize via their BTB domains. In addition, analysis of the colocalization of Rib and Lola with marks of transcriptional activation and repression on polytene chromosomes reveals that Rib and Lola colocalize with both repressive and activating marks and with each other. While previous studies have identified Rib and Lola targets in other tissues, we find that Rib and Lola are likely to function via different downstream targets in the gonad. These results suggest that Rib and Lola act as dual-function transcription factors to cooperatively regulate embryonic gonad morphogenesis.
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Affiliation(s)
- Diane Silva
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Kenneth W. Olsen
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL, United States of America
| | - Magdalena N. Bednarz
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Andrew Droste
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | | | - Edwin Chaharbakhshi
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Emily R. Temple-Wood
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Jennifer C. Jemc
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
- * E-mail:
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Chaharbakhshi E, Jemc JC. Broad-complex, tramtrack, and bric-à-brac (BTB) proteins: Critical regulators of development. Genesis 2016; 54:505-518. [DOI: 10.1002/dvg.22964] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 08/08/2016] [Accepted: 08/11/2016] [Indexed: 01/21/2023]
Affiliation(s)
- Edwin Chaharbakhshi
- Department of Biology; Loyola University Chicago; Chicago IL
- Stritch School of Medicine; Loyola University Chicago; Maywood IL
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11
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Yuan M, Guo H, Li J, Sui C, Qin Y, Wang J, Khan YH, Ye L, Xie F, Wang H, Yuan L, Ye J. Slit2 and Robo1 induce opposing effects on metastasis of hepatocellular carcinoma Sk-hep-1 cells. Int J Oncol 2016; 49:305-15. [PMID: 27176045 DOI: 10.3892/ijo.2016.3506] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 03/28/2016] [Indexed: 11/05/2022] Open
Abstract
The neural guidance molecular, Slit2, and its cognate receptor, Robo1, play critical roles in the development of the nervous system, nevertheless, their functions are not limited to this system. Numerous studies have shown decreased Slit2 expression in a wide variety of cancers, highlighting its potential as a tumor suppressor. However, the Slit2/Robo1 signaling axis was reported to induce either suppressive or stimulatory effects on tumor growth and metastasis, depending on cellular context. There is a paucity of information on the effects of the Slit2/Robo1 signaling axis on the growth and metastasis of human hepatocellular carcinoma (HCC). Large-scale data mining of the Oncomine database has revealed heterogeneous expression of Slit2 in HCC. We screened the Sk-hep-1, a cell line showing a relatively high level of Slit2, and low level of Robo1 expression. After Slit2 knockdown and Robo1 overexpression in these cells, we found Slit2 and Robo1 exerted opposing effects on tumor growth and metastasis both in in vitro and in vivo models. Slit2 knockdown and Robo1 overexpression in Sk-hep-1 cells promoted tumor growth and metastasis, suggesting a negative and positive role for Slit2 and Robo1, respectively, in tumor progression. Robo1 overexpression upregulated matrix metalloproteinase (MMP)2, -9 and membrane-type1 MMP (MT1-MMP) expression, stimulated MMP2, but not MMP9 activation, and downregulated expression of TIMP1 and 2. The PI3K/Akt signaling pathway is of importance in regulating MMP2 expression in Sk-hep-1 cells, since Robo1 overexpression stimulated phosphorylation of Akt while the PI3K inhibitor LY294002, significantly inhibited the upregulation of MMP2 and also the enhanced cell invasion induced by Robo1 overexpression. We postulate that Robo1 promotes tumor invasion partly by the upregulation of MMP2 after activation of PI3K/Akt signaling pathway. Notably, Slit2 knockdown caused the upregulation of Robo1 expression both at the mRNA and protein levels. Thus, the stimulatory effects of Slit2 knockdown on tumor progression can be ascribed, at least in part, to the upregulation of Robo1 and its positive role in tumor progression.
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Affiliation(s)
- Mingjing Yuan
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China
| | - Hui Guo
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China
| | - Jing Li
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China
| | - Chengzhi Sui
- The First Affiliated Hospital of Xiamen University, Xiamen, Fujian, P.R. China
| | - Ying Qin
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China
| | - Jingjing Wang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China
| | - Yasir Hayat Khan
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China
| | - Liying Ye
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China
| | - Fuan Xie
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China
| | - Heng Wang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China
| | - Li Yuan
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China
| | - Jun Ye
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China
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12
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Basement Membranes in the Worm: A Dynamic Scaffolding that Instructs Cellular Behaviors and Shapes Tissues. CURRENT TOPICS IN MEMBRANES 2015; 76:337-71. [PMID: 26610919 DOI: 10.1016/bs.ctm.2015.08.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The nematode worm Caenorhabditis elegans has all the major basement membrane proteins found in vertebrates, usually with a smaller gene family encoding each component. With its powerful forward genetics, optical clarity, simple tissue organization, and the capability to functionally tag most basement membrane components with fluorescent proteins, C. elegans has facilitated novel insights into the assembly and function of basement membranes. Although basement membranes are generally thought of as static structures, studies in C. elegans have revealed their active properties and essential functions in tissue formation and maintenance. Here, we review discoveries from C. elegans development that highlight dynamic aspects of basement membrane assembly, function, and regulation during organ growth, tissue polarity, cell migration, cell invasion, and tissue attachment. These studies have helped transform our view of basement membranes from static support structures to dynamic scaffoldings that play broad roles in regulating tissue organization and cellular behavior that are essential for development and have important implications in human diseases.
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13
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Li J, Ye Y, Zhang R, Zhang L, Hu X, Han D, Chen J, He X, Wang G, Yang X, Wang L. Robo1/2 regulate follicle atresia through manipulating granulosa cell apoptosis in mice. Sci Rep 2015; 5:9720. [PMID: 25988316 PMCID: PMC4437031 DOI: 10.1038/srep09720] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 03/17/2015] [Indexed: 12/12/2022] Open
Abstract
Secreted Slit proteins and their Roundabout (Robo) receptors act as a repulsive cue to prevent axons from migrating to inappropriate locations during the development of the nervous system. Slit/Robo has also been implicated in reproductive system development, but the molecular mechanism of the Slit/Robo pathway in the reproductive system remains poorly understood. Using a transgenic mouse model, we investigated the function of the Slit/Robo pathway on ovarian follicle development and atresia. We first demonstrated that more offspring were born to mice with a partial knockout of the Robo1/2 genes in mice. We next showed that Robo1 and Robo2 are strongly expressed in ovarian granulosa cells. Apoptosis in granulosa cells was reduced when Robo1/2 were partially knocked out, and this observation was further verified by in vitro Robo1/2 knockout experiments in mouse and human granulosa cells. We also found that ovarian angiogenesis was enhanced by a partial lack of Robo1/2 genes. In summary, our data suggest that the Slit/Robo pathway can impact follicle development and atresia by influencing granulosa cell apoptosis.
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Affiliation(s)
- Jiangchao Li
- Institute of Vascular Biological Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Yuxiang Ye
- Institute of Vascular Biological Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Renli Zhang
- Reproductive Medicine Center, Guangdong General Hospital, Guangzhou 515006, China
| | - Lili Zhang
- Reproductive Medicine Center, Guangdong General Hospital, Guangzhou 515006, China
- Southern Medical University, Guangzhou 510515, China
| | - Xiwen Hu
- Institute of Vascular Biological Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Dong Han
- Reproductive Medicine Center, Guangdong General Hospital, Guangzhou 515006, China
| | - Jiayuan Chen
- Institute of Vascular Biological Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Xiaodong He
- Institute of Vascular Biological Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Guang Wang
- Key Laboratory for Regenerative Medicine of the Ministry of Education, Division of Histology & Embryology, Medical College, Jinan University, Guangzhou 510632, China
| | - Xuesong Yang
- Key Laboratory for Regenerative Medicine of the Ministry of Education, Division of Histology & Embryology, Medical College, Jinan University, Guangzhou 510632, China
| | - Lijing Wang
- Institute of Vascular Biological Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
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14
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Stine RR, Greenspan LJ, Ramachandran KV, Matunis EL. Coordinate regulation of stem cell competition by Slit-Robo and JAK-STAT signaling in the Drosophila testis. PLoS Genet 2014; 10:e1004713. [PMID: 25375180 PMCID: PMC4222695 DOI: 10.1371/journal.pgen.1004713] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 08/26/2014] [Indexed: 02/01/2023] Open
Abstract
Stem cells in tissues reside in and receive signals from local microenvironments called niches. Understanding how multiple signals within niches integrate to control stem cell function is challenging. The Drosophila testis stem cell niche consists of somatic hub cells that maintain both germline stem cells and somatic cyst stem cells (CySCs). Here, we show a role for the axon guidance pathway Slit-Roundabout (Robo) in the testis niche. The ligand Slit is expressed specifically in hub cells while its receptor, Roundabout 2 (Robo2), is required in CySCs in order for them to compete for occupancy in the niche. CySCs also require the Slit-Robo effector Abelson tyrosine kinase (Abl) to prevent over-adhesion of CySCs to the niche, and CySCs mutant for Abl outcompete wild type CySCs for niche occupancy. Both Robo2 and Abl phenotypes can be rescued through modulation of adherens junction components, suggesting that the two work together to balance CySC adhesion levels. Interestingly, expression of Robo2 requires JAK-STAT signaling, an important maintenance pathway for both germline and cyst stem cells in the testis. Our work indicates that Slit-Robo signaling affects stem cell function downstream of the JAK-STAT pathway by controlling the ability of stem cells to compete for occupancy in their niche.
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Affiliation(s)
- Rachel R. Stine
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Leah J. Greenspan
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Kapil V. Ramachandran
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Erika L. Matunis
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
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15
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Tripathy R, Kunwar PS, Sano H, Renault AD. Transcriptional regulation of Drosophila gonad formation. Dev Biol 2014; 392:193-208. [PMID: 24927896 DOI: 10.1016/j.ydbio.2014.05.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 05/22/2014] [Accepted: 05/26/2014] [Indexed: 01/08/2023]
Abstract
The formation of the Drosophila embryonic gonad, involving the fusion of clusters of somatic gonadal precursor cells (SGPs) and their ensheathment of germ cells, provides a simple and genetically tractable model for the interplay between cells during organ formation. In a screen for mutants affecting gonad formation we identified a SGP cell autonomous role for Midline (Mid) and Longitudinals lacking (Lola). These transcriptional factors are required for multiple aspects of SGP behaviour including SGP cluster fusion, germ cell ensheathment and gonad compaction. The lola locus encodes more than 25 differentially spliced isoforms and we have identified an isoform specific requirement for lola in the gonad which is distinct from that in nervous system development. Mid and Lola work in parallel in gonad formation and surprisingly Mid overexpression in a lola background leads to additional SGPs at the expense of fat body cells. Our findings support the idea that although the transcription factors required by SGPs can ostensibly be assigned to those being required for either SGP specification or behaviour, they can also interact to impinge on both processes.
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Affiliation(s)
- Ratna Tripathy
- Max Planck Institute for Developmental Biology, Spemannstr. 35, 72074 Tübingen, Germany
| | - Prabhat S Kunwar
- Division of Biology, California Institute of Technology, Pasadena, CA, USA
| | - Hiroko Sano
- Department of Molecular Genetics, Institute of Life Sciences, Kurume University, Kurume, Fukuoka, Japan
| | - Andrew D Renault
- Max Planck Institute for Developmental Biology, Spemannstr. 35, 72074 Tübingen, Germany.
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16
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Functional analysis of the Drosophila embryonic germ cell transcriptome by RNA interference. PLoS One 2014; 9:e98579. [PMID: 24896584 PMCID: PMC4045815 DOI: 10.1371/journal.pone.0098579] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 05/05/2014] [Indexed: 11/19/2022] Open
Abstract
In Drosophila melanogaster, primordial germ cells are specified at the posterior pole of the very early embryo. This process is regulated by the posterior localized germ plasm that contains a large number of RNAs of maternal origin. Transcription in the primordial germ cells is actively down-regulated until germ cell fate is established. Bulk expression of the zygotic genes commences concomitantly with the degradation of the maternal transcripts. Thus, during embryogenesis, maternally provided and zygotically transcribed mRNAs determine germ cell development collectively. In an effort to identify novel genes involved in the regulation of germ cell behavior, we carried out a large-scale RNAi screen targeting both maternal and zygotic components of the embryonic germ line transcriptome. We identified 48 genes necessary for distinct stages in germ cell development. We found pebble and fascetto to be essential for germ cell migration and germ cell division, respectively. Our data uncover a previously unanticipated role of mei-P26 in maintenance of embryonic germ cell fate. We also performed systematic co-RNAi experiments, through which we found a low rate of functional redundancy among homologous gene pairs. As our data indicate a high degree of evolutionary conservation in genetic regulation of germ cell development, they are likely to provide valuable insights into the biology of the germ line in general.
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17
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Eliazer S, Palacios V, Wang Z, Kollipara RK, Kittler R, Buszczak M. Lsd1 restricts the number of germline stem cells by regulating multiple targets in escort cells. PLoS Genet 2014; 10:e1004200. [PMID: 24625679 PMCID: PMC3952827 DOI: 10.1371/journal.pgen.1004200] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 01/10/2014] [Indexed: 01/06/2023] Open
Abstract
Specialized microenvironments called niches regulate tissue homeostasis by controlling the balance between stem cell self-renewal and the differentiation of stem cell daughters. However the mechanisms that govern the formation, size and signaling of in vivo niches remain poorly understood. Loss of the highly conserved histone demethylase Lsd1 in Drosophila escort cells results in increased BMP signaling outside the cap cell niche and an expanded germline stem cell (GSC) phenotype. Here we present evidence that loss of Lsd1 also results in gradual changes in escort cell morphology and their eventual death. To better characterize the function of Lsd1 in different cell populations within the ovary, we performed Chromatin immunoprecipitation coupled with massive parallel sequencing (ChIP-seq). This analysis shows that Lsd1 associates with a surprisingly limited number of sites in escort cells and fewer, and often, different sites in cap cells. These findings indicate that Lsd1 exhibits highly selective binding that depends greatly on specific cellular contexts. Lsd1 does not directly target the dpp locus in escort cells. Instead, Lsd1 regulates engrailed expression and disruption of engrailed and its putative downstream target hedgehog suppress the Lsd1 mutant phenotype. Interestingly, over-expression of engrailed, but not hedgehog, results in an expansion of GSC cells, marked by the expansion of BMP signaling. Knockdown of other potential direct Lsd1 target genes, not obviously linked to BMP signaling, also partially suppresses the Lsd1 mutant phenotype. These results suggest that Lsd1 restricts the number of GSC-like cells by regulating a diverse group of genes and provide further evidence that escort cell function must be carefully controlled during development and adulthood to ensure proper germline differentiation. The mechanisms that govern the formation, size and signaling output of in vivo niches remain poorly understood. Studies of Drosophila germline stem cells (GSCs) have suggested that chromatin programming greatly influences the behavior of these cells and their progeny. Previous work has shown that loss of the highly conserved histone demethylase Lsd1 results in ectopic niche signaling and an expanded GSC phenotype. To determine direct regulatory targets of Lsd1, we employed chromatin immunoprecipitation coupled with massive parallel sequencing (ChIP-seq) using specific cell populations inside and outside of the GSC niche. These experiments revealed that Lsd1 exhibits highly enriched binding to over one hundred genomic sites within a specific cell population. Furthermore, mis-regulation of some of these direct targets contributes to the expanded stem cell phenotype observed in Lsd1 mutants. These results provide insights into how Lsd1 directly restricts the size of the GSC microenvironment and establish a platform for understanding and exploring chromatin programming inside and outside an in vivo stem cell niche.
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Affiliation(s)
- Susan Eliazer
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Victor Palacios
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Zhaohui Wang
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Rahul K. Kollipara
- McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Ralf Kittler
- McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Michael Buszczak
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
- * E-mail:
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18
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Formesyn EM, Cardoen D, Ernst UR, Danneels EL, Van Vaerenbergh M, De Koker D, Verleyen P, Wenseleers T, Schoofs L, de Graaf DC. Reproduction of honeybee workers is regulated by epidermal growth factor receptor signaling. Gen Comp Endocrinol 2014; 197:1-4. [PMID: 24333651 DOI: 10.1016/j.ygcen.2013.12.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 11/28/2013] [Accepted: 12/03/2013] [Indexed: 11/19/2022]
Abstract
Eusocial insect societies display a remarkable reproductive division of labor between a single fertile queen and thousands of largely sterile workers. In most species, however, the workers retain the capacity to reproduce, particularly in queenless colonies where typically many workers lay eggs. As yet, the molecular determinants that initiate this shift in worker fertility are still poorly documented. By using RNA interference we here demonstrate that the knockdown of epidermal growth factor receptor, a gene which was previously shown to be involved in queen-worker caste differentiation, also induces reproduction in worker honeybees (Apis mellifera). These data show that worker fertility and queen-worker caste determination partly rely on the same gene regulatory networks, thereby providing a major breakthrough in our understanding of the molecular determinants of the social insects' spectacular reproductive division of labor.
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Affiliation(s)
- Ellen M Formesyn
- Laboratory of Zoophysiology, Ghent University, B-9000 Ghent, Belgium
| | - Dries Cardoen
- Laboratory of Socio-ecology and Social Evolution, KU Leuven, B-3000 Leuven, Belgium
| | - Ulrich R Ernst
- Research Group of Functional Genomics and Proteomics, KU Leuven, B-3000 Leuven, Belgium
| | - Ellen L Danneels
- Laboratory of Zoophysiology, Ghent University, B-9000 Ghent, Belgium
| | | | - Dieter De Koker
- Laboratory of Zoophysiology, Ghent University, B-9000 Ghent, Belgium
| | - Peter Verleyen
- Research Group of Functional Genomics and Proteomics, KU Leuven, B-3000 Leuven, Belgium
| | - Tom Wenseleers
- Laboratory of Socio-ecology and Social Evolution, KU Leuven, B-3000 Leuven, Belgium
| | - Liliane Schoofs
- Research Group of Functional Genomics and Proteomics, KU Leuven, B-3000 Leuven, Belgium
| | - Dirk C de Graaf
- Laboratory of Zoophysiology, Ghent University, B-9000 Ghent, Belgium.
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19
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Rohrschneider MR, Nance J. The union of somatic gonad precursors and primordial germ cells during Caenorhabditis elegans embryogenesis. Dev Biol 2013; 379:139-51. [PMID: 23562590 DOI: 10.1016/j.ydbio.2013.03.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 03/12/2013] [Accepted: 03/26/2013] [Indexed: 11/17/2022]
Abstract
Somatic gonadal niche cells control the survival, differentiation, and proliferation of germline stem cells. The establishment of this niche-stem cell relationship is critical, and yet the precursors to these two cell types are often born at a distance from one another. The simple Caenorhabditis elegans gonadal primordium, which contains two somatic gonad precursors (SGPs) and two primordial germ cells (PGCs), provides an accessible model for determining how stem cell and niche cell precursors first assemble during development. To visualize the morphogenetic events that lead to formation of the gonadal primordium, we generated transgenic strains to label the cell membranes of the SGPs and PGCs and captured time-lapse movies as the gonadal primordium formed. We identify three distinct phases of SGP behavior: posterior migration along the endoderm towards the PGCs, extension of a single long projection around the adjacent PGC, and a dramatic wrapping over the PGC surfaces. We show that the endoderm and PGCs are dispensable for SGP posterior migration and initiation of projections. However, both tissues are required for the final positioning of the SGPs and the morphology of their projections, and PGCs are absolutely required for SGP wrapping behaviors. Finally, we demonstrate that the basement membrane component laminin, which localizes adjacent to the developing gonadal primordium, is required to prevent the SGPs from over-extending past the PGCs. Our findings provide a foundation for understanding the cellular and molecular regulation of the establishment of a niche-stem cell relationship.
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Affiliation(s)
- Monica R Rohrschneider
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York, NY 10016, USA
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20
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Sano H, Kunwar PS, Renault AD, Barbosa V, Clark IBN, Ishihara S, Sugimura K, Lehmann R. The Drosophila actin regulator ENABLED regulates cell shape and orientation during gonad morphogenesis. PLoS One 2012; 7:e52649. [PMID: 23300733 PMCID: PMC3530444 DOI: 10.1371/journal.pone.0052649] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 11/16/2012] [Indexed: 12/27/2022] Open
Abstract
Organs develop distinctive morphologies to fulfill their unique functions. We used Drosophila embryonic gonads as a model to study how two different cell lineages, primordial germ cells (PGCs) and somatic gonadal precursors (SGPs), combine to form one organ. We developed a membrane GFP marker to image SGP behaviors live. These studies show that a combination of SGP cell shape changes and inward movement of anterior and posterior SGPs leads to the compaction of the spherical gonad. This process is disrupted in mutants of the actin regulator, enabled (ena). We show that Ena coordinates these cell shape changes and the inward movement of the SGPs, and Ena affects the intracellular localization of DE-cadherin (DE-cad). Mathematical simulation based on these observations suggests that changes in DE-cad localization can generate the forces needed to compact an elongated structure into a sphere. We propose that Ena regulates force balance in the SGPs by sequestering DE-cad, leading to the morphogenetic movement required for gonad compaction.
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Affiliation(s)
- Hiroko Sano
- HHMI and Developmental Genetics Program, Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University Medical Center, New York, New York, United States of America.
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21
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Sinden D, Badgett M, Fry J, Jones T, Palmen R, Sheng X, Simmons A, Matunis E, Wawersik M. Jak-STAT regulation of cyst stem cell development in the Drosophila testis. Dev Biol 2012; 372:5-16. [PMID: 23010510 DOI: 10.1016/j.ydbio.2012.09.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 09/15/2012] [Accepted: 09/16/2012] [Indexed: 10/27/2022]
Abstract
Establishment and maintenance of functional stem cells is critical for organ development and tissue homeostasis. Little is known about the mechanisms underlying stem establishment during organogenesis. Drosophila testes are among the most thoroughly characterized systems for studying stem cell behavior, with germline stem cells (GSCs) and somatic cyst stem cells (CySCs) cohabiting a discrete stem cell niche at the testis apex. GSCs and CySCs are arrayed around hub cells that also comprise the niche and communication between hub cells, GSCs, and CySCs regulates the balance between stem cell maintenance and differentiation. Recent data has shown that functional, asymmetrically dividing GSCs are first established at ∼23 h after egg laying during Drosophila testis morphogenesis (Sheng et al., 2009). This process correlates with coalescence of the hub, but development of CySCs from somatic gonadal precursors (SGPs) was not examined. Here, we show that functional CySCs are present at the time of GSC establishment, and that Jak-STAT signaling is necessary and sufficient for CySC maintenance shortly thereafter. Furthermore, hyper-activation of Jak in CySCs promotes expansion of the GSC population, while ectopic Jak activation in the germline induces GSC gene expression in GSC daughter cells but does not prevent spermatogenic differentiation. Together, these observations indicate that, similar to adult testes, Jak-STAT signaling from the hub acts on both GSCs and CySC to regulate their development and differentiation, and that additional signaling from CySCs to the GSCs play a dominant role in controlling GSC maintenance during niche formation.
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Affiliation(s)
- D Sinden
- College of William & Mary, Biology Department, Williamsburg, VA 23185, USA
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22
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Jemc JC, Milutinovich AB, Weyers JJ, Takeda Y, Van Doren M. raw Functions through JNK signaling and cadherin-based adhesion to regulate Drosophila gonad morphogenesis. Dev Biol 2012; 367:114-25. [PMID: 22575490 DOI: 10.1016/j.ydbio.2012.04.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2011] [Revised: 03/22/2012] [Accepted: 04/24/2012] [Indexed: 01/13/2023]
Abstract
To form a gonad, germ cells (GCs) and somatic gonadal precursor cells (SGPs) must migrate to the correct location in the developing embryo and establish the cell-cell interactions necessary to create proper gonad architecture. During gonad morphogenesis, SGPs send out cellular extensions to ensheath the individual GCs and promote their development. We have identified mutations in the raw gene that result in a failure of the SGPs to ensheath the GCs, leading to defects in GC development. Using genetic analysis and gene expression studies, we find that Raw negatively regulates JNK signaling during gonad morphogenesis, and increased JNK signaling is sufficient to cause ensheathment defects. In particular, Raw functions upstream of the Drosophila Jun-related transcription factor to regulate its subcellular localization. Since JNK signaling regulates cell adhesion during the morphogenesis of many tissues, we examined the relationship between raw and the genes encoding Drosophila E-cadherin and β-catenin, which function together in cell adhesion. We find that loss of DE-cadherin strongly enhances the raw mutant gonad phenotype, while increasing DE-cadherin function rescues this phenotype. Further, loss of raw results in mislocalization of β-catenin away from the cell surface. Therefore, cadherin-based cell adhesion, likely at the level of β-catenin, is a primary mechanism by which Raw regulates germline-soma interaction.
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Affiliation(s)
- Jennifer C Jemc
- Department of Biology, Johns Hopkins University, 3400 N Charles St, Baltimore, MD 21218, USA
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23
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Siddiqui NU, Li X, Luo H, Karaiskakis A, Hou H, Kislinger T, Westwood JT, Morris Q, Lipshitz HD. Genome-wide analysis of the maternal-to-zygotic transition in Drosophila primordial germ cells. Genome Biol 2012; 13:R11. [PMID: 22348290 PMCID: PMC3334568 DOI: 10.1186/gb-2012-13-2-r11] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 01/12/2012] [Accepted: 02/20/2012] [Indexed: 11/23/2022] Open
Abstract
Background During the maternal-to-zygotic transition (MZT) vast changes in the embryonic transcriptome are produced by a combination of two processes: elimination of maternally provided mRNAs and synthesis of new transcripts from the zygotic genome. Previous genome-wide analyses of the MZT have been restricted to whole embryos. Here we report the first such analysis for primordial germ cells (PGCs), the progenitors of the germ-line stem cells. Results We purified PGCs from Drosophila embryos, defined their proteome and transcriptome, and assessed the content, scale and dynamics of their MZT. Transcripts encoding proteins that implement particular types of biological functions group into nine distinct expression profiles, reflecting coordinate control at the transcriptional and posttranscriptional levels. mRNAs encoding germ-plasm components and cell-cell signaling molecules are rapidly degraded while new transcription produces mRNAs encoding the core transcriptional and protein synthetic machineries. The RNA-binding protein Smaug is essential for the PGC MZT, clearing transcripts encoding proteins that regulate stem cell behavior, transcriptional and posttranscriptional processes. Computational analyses suggest that Smaug and AU-rich element binding proteins function independently to control transcript elimination. Conclusions The scale of the MZT is similar in the soma and PGCs. However, the timing and content of their MZTs differ, reflecting the distinct developmental imperatives of these cell types. The PGC MZT is delayed relative to that in the soma, likely because relief of PGC-specific transcriptional silencing is required for zygotic genome activation as well as for efficient maternal transcript clearance.
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Affiliation(s)
- Najeeb U Siddiqui
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
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24
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Abstract
Cell-cell signaling and adhesion are critical for establishing tissue architecture during development and for maintaining tissue architecture and function in the adult. Defects in adhesion and signaling can result in mislocalization of cells, uncontrolled proliferation and improper differentiation, leading to tissue overgrowth, tumor formation, and cancer metastasis. An important example is found in the germline. Germ cells that are not incorporated into the gonad exhibit a greater propensity for forming germ cell tumors, and defects in germline development can reduce fertility. While much attention is given to germ cells, their development into functional gametes depends upon somatic gonadal cells. The study of model organisms has provided great insights into how somatic gonadal cells are specified, the molecular mechanisms that regulate gonad morphogenesis, and the role of germline-soma communication in the establishment and maintenance of the germline stem cell niche. This work will be discussed in the context of Drosophila melanogaster.
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Affiliation(s)
- Jennifer C Jemc
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA.
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