1
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Perillo M, Swartz SZ, Pieplow C, Wessel GM. Molecular mechanisms of tubulogenesis revealed in the sea star hydro-vascular organ. Nat Commun 2023; 14:2402. [PMID: 37160908 PMCID: PMC10170166 DOI: 10.1038/s41467-023-37947-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 04/06/2023] [Indexed: 05/11/2023] Open
Abstract
A fundamental goal in the organogenesis field is to understand how cells organize into tubular shapes. Toward this aim, we have established the hydro-vascular organ in the sea star Patiria miniata as a model for tubulogenesis. In this animal, bilateral tubes grow out from the tip of the developing gut, and precisely extend to specific sites in the larva. This growth involves cell migration coupled with mitosis in distinct zones. Cell proliferation requires FGF signaling, whereas the three-dimensional orientation of the organ depends on Wnt signaling. Specification and maintenance of tube cell fate requires Delta/Notch signaling. Moreover, we identify target genes of the FGF pathway that contribute to tube morphology, revealing molecular mechanisms for tube outgrowth. Finally, we report that FGF activates the Six1/2 transcription factor, which serves as an evolutionarily ancient regulator of branching morphogenesis. This study uncovers distinct mechanisms of tubulogenesis in vivo and we propose that cellular dynamics in the sea star hydro-vascular organ represents a key comparison for understanding the evolution of vertebrate organs.
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Affiliation(s)
- Margherita Perillo
- Department of Molecular, Cellular Biology and Biochemistry, BioMed Division, Brown University, 185 Meeting Street, Providence, RI, 02912, USA.
- Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA, 02543, USA.
| | - S Zachary Swartz
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA, 02142, USA
- Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA, 02543, USA
| | - Cosmo Pieplow
- Department of Molecular, Cellular Biology and Biochemistry, BioMed Division, Brown University, 185 Meeting Street, Providence, RI, 02912, USA
| | - Gary M Wessel
- Department of Molecular, Cellular Biology and Biochemistry, BioMed Division, Brown University, 185 Meeting Street, Providence, RI, 02912, USA.
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2
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Perillo M, Swartz SZ, Wessel GM. A conserved node in the regulation of Vasa between an induced and an inherited program of primordial germ cell specification. Dev Biol 2022; 482:28-33. [PMID: 34863708 PMCID: PMC8761175 DOI: 10.1016/j.ydbio.2021.11.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 11/05/2021] [Accepted: 11/28/2021] [Indexed: 02/03/2023]
Abstract
Primordial germ cells (PGCs) are specified by diverse mechanisms in early development. In some animals, PGCs are specified via inheritance of maternal determinants, while in others, in a process thought to represent the ancestral mode, PGC fate is induced by cell interactions. Although the terminal factors expressed in specified germ cells are widely conserved, the mechanisms by which these factors are regulated can be widely diverse. Here we show that a post-translational mechanism of germ cell specification is conserved between two echinoderm species thought to employ divergent germ line segregation strategies. Sea urchins segregate their germ line early by an inherited mechanism. The DEAD-box RNA - helicase Vasa, a conserved germline factor, becomes enriched in the PGCs by degradation in future somatic cells by the E3-ubiquitin-ligase Gustavus (Gustafson et al., 2011). This post-translational activity occurs early in development, substantially prior to gastrulation. Here we test this process in germ cell specification of sea star embryos, which use inductive signaling mechanisms after gastrulation for PGC fate determination. We find that Vasa-GFP protein becomes restricted to the PGCs in the sea star even though the injected mRNA is present throughout the embryo. Gustavus depletion, however, results in uniform accumulation of the protein. These data demonstrate that Gustavus-mediated Vasa turnover in somatic cells is conserved between species with otherwise divergent PGC specification mechanisms. Since Gustavus was originally identified in Drosophila melanogaster to have similar functions in Vasa regulation (Kugler et al., 2010), we conclude that this node of Vasa regulation in PGC formation is ancestral and evolutionarily transposable from the ancestral, induced PGC specification program to an inherited PGC specification mechanism.
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Affiliation(s)
- Margherita Perillo
- Department of Molecular, Cellular Biology and Biochemistry, BioMed Division, Brown University, 185 Meeting Street, Providence, RI, 02912, USA
| | - S Zachary Swartz
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA, 02142, USA
| | - Gary M Wessel
- Department of Molecular, Cellular Biology and Biochemistry, BioMed Division, Brown University, 185 Meeting Street, Providence, RI, 02912, USA.
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3
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Abstract
The early embryos of sea urchins and other echinoderms have served as experimental models for the study of cell division since the nineteenth century. Their rapid development, optical clarity, and ease of manipulation continue to offer advantages for studying spindle assembly and cytokinesis. In the absence of transgenic lines, alternative strategies must be employed to visualize microtubules and actin. Here, we describe methods to visualize actin and microtubule using either purified, recombinant proteins, or probes in in vitro-transcribed mRNAs.
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Affiliation(s)
- Debadrita Pal
- Department of Biology, New Mexico State University, Las Cruces, NM, USA
| | | | | | | | - Charles B Shuster
- Department of Biology, New Mexico State University, Las Cruces, NM, USA.
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4
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Swartz SZ, Tan TH, Perillo M, Fakhri N, Wessel GM, Wikramanayake AH, Cheeseman IM. Polarized Dishevelled dissolution and reassembly drives embryonic axis specification in sea star oocytes. Curr Biol 2021; 31:5633-5641.e4. [PMID: 34739818 PMCID: PMC8692449 DOI: 10.1016/j.cub.2021.10.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 08/20/2021] [Accepted: 10/08/2021] [Indexed: 11/22/2022]
Abstract
The organismal body axes that are formed during embryogenesis are intimately linked to intrinsic asymmetries established at the cellular scale in oocytes.1 However, the mechanisms that generate cellular asymmetries within the oocyte and then transduce that polarity to organismal scale body axes are poorly understood outside of select model organisms. Here, we report an axis-defining event in meiotic oocytes of the sea star Patiria miniata. Dishevelled (Dvl) is a cytoplasmic Wnt pathway effector required for axis development in diverse species,2-4 but the mechanisms governing its function and distribution remain poorly defined. Using time-lapse imaging, we find that Dvl localizes uniformly to puncta throughout the cell cortex in Prophase I-arrested oocytes but becomes enriched at the vegetal pole following meiotic resumption through a dissolution-reassembly mechanism. This process is driven by an initial disassembly phase of Dvl puncta, followed by selective reformation of Dvl assemblies at the vegetal pole. Rather than being driven by Wnt signaling, this localization behavior is coupled to meiotic cell cycle progression and influenced by Lamp1+ endosome association and Frizzled receptors pre-localized within the oocyte cortex. Our results reveal a cell cycle-linked mechanism by which maternal cellular polarity is transduced to the embryo through spatially regulated Dvl dynamics.
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Affiliation(s)
- S Zachary Swartz
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Embryology Course: Concepts and Techniques in Modern Developmental Biology, Marine Biological Laboratory, Woods Hole, MA 02543, USA.
| | - Tzer Han Tan
- Massachusetts Institute of Technology, Department of Physics, Cambridge, MA 02142, USA
| | | | - Nikta Fakhri
- Massachusetts Institute of Technology, Department of Physics, Cambridge, MA 02142, USA
| | - Gary M Wessel
- MCB Department, Brown University, Providence, RI 02912, USA
| | - Athula H Wikramanayake
- Department of Biology, University of Miami, Coral Gables, FL 33134, USA; Embryology Course: Concepts and Techniques in Modern Developmental Biology, Marine Biological Laboratory, Woods Hole, MA 02543, USA
| | - Iain M Cheeseman
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA.
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5
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Swartz SZ, Nguyen HT, McEwan BC, Adamo ME, Cheeseman IM, Kettenbach AN. Selective dephosphorylation by PP2A-B55 directs the meiosis I-meiosis II transition in oocytes. eLife 2021; 10:70588. [PMID: 34342579 PMCID: PMC8370769 DOI: 10.7554/elife.70588] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Accepted: 08/02/2021] [Indexed: 12/17/2022] Open
Abstract
Meiosis is a specialized cell cycle that requires sequential changes to the cell division machinery to facilitate changing functions. To define the mechanisms that enable the oocyte-to-embryo transition, we performed time-course proteomics in synchronized sea star oocytes from prophase I through the first embryonic cleavage. Although we found that protein levels were broadly stable, our analysis reveals that dynamic waves of phosphorylation underlie each meiotic stage. We found that the phosphatase PP2A-B55 is reactivated at the meiosis I/meiosis II (MI/MII) transition, resulting in the preferential dephosphorylation of threonine residues. Selective dephosphorylation is critical for directing the MI/MII transition as altering PP2A-B55 substrate preferences disrupts key cell cycle events after MI. In addition, threonine to serine substitution of a conserved phosphorylation site in the substrate INCENP prevents its relocalization at anaphase I. Thus, through its inherent phospho-threonine preference, PP2A-B55 imposes specific phosphoregulated behaviors that distinguish the two meiotic divisions.
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Affiliation(s)
- S Zachary Swartz
- Whitehead Institute for Biomedical Research, Cambridge, United States.,Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Hieu T Nguyen
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, United States
| | - Brennan C McEwan
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, United States
| | - Mark E Adamo
- Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, United States
| | - Iain M Cheeseman
- Whitehead Institute for Biomedical Research, Cambridge, United States.,Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Arminja N Kettenbach
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, United States.,Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, United States
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6
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Swartz SZ, McKay LS, Su KC, Bury L, Padeganeh A, Maddox PS, Knouse KA, Cheeseman IM. Quiescent Cells Actively Replenish CENP-A Nucleosomes to Maintain Centromere Identity and Proliferative Potential. Dev Cell 2019; 51:35-48.e7. [PMID: 31422918 PMCID: PMC6783363 DOI: 10.1016/j.devcel.2019.07.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Revised: 05/28/2019] [Accepted: 07/15/2019] [Indexed: 12/20/2022]
Abstract
Centromeres provide a robust model for epigenetic inheritance as they are specified by sequence-independent mechanisms involving the histone H3-variant centromere protein A (CENP-A). Prevailing models indicate that the high intrinsic stability of CENP-A nucleosomes maintains centromere identity indefinitely. Here, we demonstrate that CENP-A is not stable at centromeres but is instead gradually and continuously incorporated in quiescent cells including G0-arrested tissue culture cells and prophase I-arrested oocytes. Quiescent CENP-A incorporation involves the canonical CENP-A deposition machinery but displays distinct requirements from cell cycle-dependent deposition. We demonstrate that Plk1 is required specifically for G1 CENP-A deposition, whereas transcription promotes CENP-A incorporation in quiescent oocytes. Preventing CENP-A deposition during quiescence results in significantly reduced CENP-A levels and perturbs chromosome segregation following the resumption of cell division. In contrast to quiescent cells, terminally differentiated cells fail to maintain CENP-A levels. Our work reveals that quiescent cells actively maintain centromere identity providing an indicator of proliferative potential.
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Affiliation(s)
- S Zachary Swartz
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA
| | - Liliana S McKay
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA
| | - Kuan-Chung Su
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA
| | - Leah Bury
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA
| | - Abbas Padeganeh
- Biology Department, UNC Chapel Hill, 120 South Road, Chapel Hill, NC 27599-3280, USA
| | - Paul S Maddox
- Biology Department, UNC Chapel Hill, 120 South Road, Chapel Hill, NC 27599-3280, USA
| | - Kristin A Knouse
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA
| | - Iain M Cheeseman
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
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7
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Oulhen N, Swartz SZ, Wang L, Wikramanayake A, Wessel GM. Distinct transcriptional regulation of Nanos2 in the germ line and soma by the Wnt and delta/notch pathways. Dev Biol 2019; 452:34-42. [PMID: 31075220 PMCID: PMC6848975 DOI: 10.1016/j.ydbio.2019.04.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/19/2019] [Accepted: 04/21/2019] [Indexed: 12/23/2022]
Abstract
Specification of the primordial germ cells (PGCs) is essential for sexually reproducing animals. Although the mechanisms of PGC specification are diverse between organisms, the RNA binding protein Nanos is consistently required in the germ line in all species tested. How Nanos is selectively expressed in the germ line, however, remains largely elusive. We report that in sea urchin embryos, the early expression of Nanos2 in the PGCs requires the maternal Wnt pathway. During gastrulation, however, Nanos2 expression expands into adjacent somatic mesodermal cells and this secondary Nanos expression instead requires Delta/Notch signaling through the forkhead family member FoxY. Each of these transcriptional regulators were tested by chromatin immunoprecipitation analysis and found to directly interact with a DNA locus upstream of Nanos2. Given the conserved importance of Nanos in germ line specification, and the derived character of the micromeres and small micromeres in the sea urchin, we propose that the ancestral mechanism of Nanos2 expression in echinoderms was by induction in mesodermal cells during gastrulation.
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Affiliation(s)
- Nathalie Oulhen
- Department of Molecular and Cell Biology and Biochemistry, Brown University, 185 Meeting Street, Providence, RI, 02912, USA
| | - S Zachary Swartz
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA, 02142, USA
| | - Lingyu Wang
- Department of Biology and Center for Genomic and Computational Biology, Duke University, Durham, NC, USA
| | | | - Gary M Wessel
- Department of Molecular and Cell Biology and Biochemistry, Brown University, 185 Meeting Street, Providence, RI, 02912, USA.
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8
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Oulhen N, Swartz SZ, Laird J, Mascaro A, Wessel GM. Transient translational quiescence in primordial germ cells. Development 2017; 144:1201-1210. [PMID: 28235822 PMCID: PMC5399625 DOI: 10.1242/dev.144170] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Accepted: 02/01/2017] [Indexed: 01/07/2023]
Abstract
Stem cells in animals often exhibit a slow cell cycle and/or low transcriptional activity referred to as quiescence. Here, we report that the translational activity in the primordial germ cells (PGCs) of the sea urchin embryo (Strongylocentrotus purpuratus) is quiescent. We measured new protein synthesis with O-propargyl-puromycin and L-homopropargylglycine Click-iT technologies, and determined that these cells synthesize protein at only 6% the level of their adjacent somatic cells. Knockdown of translation of the RNA-binding protein Nanos2 by morpholino antisense oligonucleotides, or knockout of the Nanos2 gene by CRISPR/Cas9 resulted in a significant, but partial, increase (47%) in general translation specifically in the PGCs. We found that the mRNA of the translation factor eEF1A is excluded from the PGCs in a Nanos2-dependent manner, a consequence of a Nanos/Pumilio response element (PRE) in its 3'UTR. In addition to eEF1A, the cytoplasmic pH of the PGCs appears to repress translation and simply increasing the pH also significantly restores translation selectively in the PGCs. We conclude that the PGCs of this sea urchin institute parallel pathways to quiesce translation thoroughly but transiently.
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Affiliation(s)
- Nathalie Oulhen
- Department of Molecular and Cell Biology and Biochemistry, Brown University, 185 Meeting Street, Providence, RI 02912, USA
| | - S Zachary Swartz
- Department of Molecular and Cell Biology and Biochemistry, Brown University, 185 Meeting Street, Providence, RI 02912, USA
- Whitehead Institute for Biomedical Research, MIT, Nine Cambridge Center, Cambridge, MA 02142, USA
| | - Jessica Laird
- Department of Molecular and Cell Biology and Biochemistry, Brown University, 185 Meeting Street, Providence, RI 02912, USA
| | - Alexandra Mascaro
- Department of Molecular and Cell Biology and Biochemistry, Brown University, 185 Meeting Street, Providence, RI 02912, USA
| | - Gary M Wessel
- Department of Molecular and Cell Biology and Biochemistry, Brown University, 185 Meeting Street, Providence, RI 02912, USA
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9
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Fresques T, Swartz SZ, Juliano C, Morino Y, Kikuchi M, Akasaka K, Wada H, Yajima M, Wessel GM. The diversity of nanos expression in echinoderm embryos supports different mechanisms in germ cell specification. Evol Dev 2016; 18:267-78. [PMID: 27402572 PMCID: PMC4943673 DOI: 10.1111/ede.12197] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Specification of the germ cell lineage is required for sexual reproduction in all animals. However, the timing and mechanisms of germ cell specification is remarkably diverse in animal development. Echinoderms, such as sea urchins and sea stars, are excellent model systems to study the molecular and cellular mechanisms that contribute to germ cell specification. In several echinoderm embryos tested, the germ cell factor Vasa accumulates broadly during early development and is restricted after gastrulation to cells that contribute to the germ cell lineage. In the sea urchin, however, the germ cell factor Vasa is restricted to a specific lineage by the 32-cell stage. We therefore hypothesized that the germ cell specification program in the sea urchin/Euechinoid lineage has evolved to an earlier developmental time point. To test this hypothesis we determined the expression pattern of a second germ cell factor, Nanos, in four out of five extant echinoderm clades. Here we find that Nanos mRNA does not accumulate until the blastula stage or later during the development of all other echinoderm embryos except those that belong to the Echinoid lineage. Instead, Nanos is expressed in a restricted domain at the 32-128 cell stage in Echinoid embryos. Our results support the model that the germ cell specification program underwent a heterochronic shift in the Echinoid lineage. A comparison of Echinoid and non-Echinoid germ cell specification mechanisms will contribute to our understanding of how these mechanisms have changed during animal evolution.
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Affiliation(s)
- Tara Fresques
- Department of Molecular Biology, Cell Biology and Biochemistry, 185 Meeting Street, Brown University, Providence RI 02912
| | - S. Zachary Swartz
- Department of Molecular Biology, Cell Biology and Biochemistry, 185 Meeting Street, Brown University, Providence RI 02912
| | - Celina Juliano
- Department of Molecular Biology, Cell Biology and Biochemistry, 185 Meeting Street, Brown University, Providence RI 02912
- Department of Molecular and Cellular Biology, College of Biological Sciences, One Shields Avenue, University of California, Davis, Davis CA 95616
| | - Yoshiaki Morino
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan
| | - Mani Kikuchi
- Misaki Marine Biological Station, Graduate School of Science, University of Tokyo, Koajiro 1024, Misaki, Miura 238-0225, Japan
| | - Koji Akasaka
- Misaki Marine Biological Station, Graduate School of Science, University of Tokyo, Koajiro 1024, Misaki, Miura 238-0225, Japan
| | - Hiroshi Wada
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan
| | - Mamiko Yajima
- Department of Molecular Biology, Cell Biology and Biochemistry, 185 Meeting Street, Brown University, Providence RI 02912
| | - Gary M. Wessel
- Department of Molecular Biology, Cell Biology and Biochemistry, 185 Meeting Street, Brown University, Providence RI 02912
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10
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Affiliation(s)
- S Zachary Swartz
- Whitehead Institute for Biomedical Research, Cambridge MA, 02142
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11
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Abstract
With few exceptions, all animals acquire the ability to produce eggs or sperm at some point in their life cycle. Despite this near-universal requirement for sexual reproduction, there exists an incredible diversity in germ line development. For example, animals exhibit a vast range of differences in the timing at which the germ line, which retains reproductive potential, separates from the soma, or terminally differentiated, nonreproductive cells. This separation may occur during embryonic development, after gastrulation, or even in adults, depending on the organism. The molecular mechanisms of germ line segregation are also highly diverse, and intimately intertwined with the overall transition from a fertilized egg to an embryo. The earliest embryonic stages of many species are largely controlled by maternally supplied factors. Later in development, patterning control shifts to the embryonic genome and, concomitantly with this transition, the maternally supplied factors are broadly degraded. This chapter attempts to integrate these processes--germ line segregation, and how the divergence of germ line and soma may utilize the egg to embryo transitions differently. In some embryos, this difference is subtle or maybe lacking altogether, whereas in other embryos, this difference in utilization may be a key step in the divergence of the two lineages. Here, we will focus our discussion on the echinoderms, and in particular the sea urchins, in which recent studies have provided mechanistic understanding in germ line determination. We propose that the germ line in sea urchins requires an acquisition of maternal factors from the egg and, when compared to other members of the taxon, this appears to be a derived mechanism. The acquisition is early--at the 32-cell stage--and involves active protection of maternal mRNAs, which are instead degraded in somatic cells with the maternal-to-embryonic transition. We collectively refer to this model as the Time Capsule method for germ line determination.
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Affiliation(s)
- S Zachary Swartz
- Department of Molecular and Cellular Biology, Brown University, Providence, Rhode Island, USA
| | - Gary M Wessel
- Department of Molecular and Cellular Biology, Brown University, Providence, Rhode Island, USA.
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12
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Wessel GM, Swartz SZ. Earlier, but later than that, though not that early… Simplifying the many shades of gray in germ line determination. Mol Reprod Dev 2015; 82:Fmi. [PMID: 25868088 DOI: 10.1002/mrd.22484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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13
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Wessel GM, Brayboy L, Fresques T, Gustafson EA, Oulhen N, Ramos I, Reich A, Swartz SZ, Yajima M, Zazueta V. The biology of the germ line in echinoderms. Mol Reprod Dev 2014; 81:679-711. [PMID: 23900765 PMCID: PMC4102677 DOI: 10.1002/mrd.22223] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Accepted: 07/23/2013] [Indexed: 12/16/2022]
Abstract
The formation of the germ line in an embryo marks a fresh round of reproductive potential. The developmental stage and location within the embryo where the primordial germ cells (PGCs) form, however, differs markedly among species. In many animals, the germ line is formed by an inherited mechanism, in which molecules made and selectively partitioned within the oocyte drive the early development of cells that acquire this material to a germ-line fate. In contrast, the germ line of other animals is fated by an inductive mechanism that involves signaling between cells that directs this specialized fate. In this review, we explore the mechanisms of germ-line determination in echinoderms, an early-branching sister group to the chordates. One member of the phylum, sea urchins, appears to use an inherited mechanism of germ-line formation, whereas their relatives, the sea stars, appear to use an inductive mechanism. We first integrate the experimental results currently available for germ-line determination in the sea urchin, for which considerable new information is available, and then broaden the investigation to the lesser-known mechanisms in sea stars and other echinoderms. Even with this limited insight, it appears that sea stars, and perhaps the majority of the echinoderm taxon, rely on inductive mechanisms for germ-line fate determination. This enables a strongly contrasted picture for germ-line determination in this phylum, but one for which transitions between different modes of germ-line determination might now be experimentally addressed.
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Affiliation(s)
- Gary M. Wessel
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, Rhode Island
| | - Lynae Brayboy
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, Rhode Island
| | - Tara Fresques
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, Rhode Island
| | - Eric A. Gustafson
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, Rhode Island
| | - Nathalie Oulhen
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, Rhode Island
| | - Isabela Ramos
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, Rhode Island
| | - Adrian Reich
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, Rhode Island
| | - S. Zachary Swartz
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, Rhode Island
| | - Mamiko Yajima
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, Rhode Island
| | - Vanessa Zazueta
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, Rhode Island
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14
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Swartz SZ, Reich AM, Oulhen N, Raz T, Milos PM, Campanale JP, Hamdoun A, Wessel GM. Deadenylase depletion protects inherited mRNAs in primordial germ cells. Development 2014; 141:3134-42. [PMID: 25100654 PMCID: PMC4197533 DOI: 10.1242/dev.110395] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 06/22/2014] [Indexed: 12/12/2022]
Abstract
A crucial event in animal development is the specification of primordial germ cells (PGCs), which become the stem cells that create sperm and eggs. How PGCs are created provides a valuable paradigm for understanding stem cells in general. We find that the PGCs of the sea urchin Strongylocentrotus purpuratus exhibit broad transcriptional repression, yet enrichment for a set of inherited mRNAs. Enrichment of several germline determinants in the PGCs requires the RNA-binding protein Nanos to target the transcript that encodes CNOT6, a deadenylase, for degradation in the PGCs, thereby creating a stable environment for RNA. Misexpression of CNOT6 in the PGCs results in their failure to retain Seawi transcripts and Vasa protein. Conversely, broad knockdown of CNOT6 expands the domain of Seawi RNA as well as exogenous reporters. Thus, Nanos-dependent spatially restricted CNOT6 differential expression is used to selectively localize germline RNAs to the PGCs. Our findings support a 'time capsule' model of germline determination, whereby the PGCs are insulated from differentiation by retaining the molecular characteristics of the totipotent egg and early embryo.
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Affiliation(s)
- S Zachary Swartz
- Department of Molecular, Cellular Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Adrian M Reich
- Department of Molecular, Cellular Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Nathalie Oulhen
- Department of Molecular, Cellular Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Tal Raz
- Helicos BioSciences Corporation, One Kendall Square, Building 700, Cambridge, MA 02139, USA
| | - Patrice M Milos
- Helicos BioSciences Corporation, One Kendall Square, Building 700, Cambridge, MA 02139, USA
| | - Joseph P Campanale
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California at San Diego, 8750 Biological Grade Road, La Jolla, CA 92037, USA
| | - Amro Hamdoun
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California at San Diego, 8750 Biological Grade Road, La Jolla, CA 92037, USA
| | - Gary M Wessel
- Department of Molecular, Cellular Biology and Biochemistry, Brown University, Providence, RI 02912, USA
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15
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Abstract
Isolating cells based on specific gene expression enables a focused biochemical and molecular analysis. While cultured cells and hematopoietic cells, for example, are routinely isolated by fluorescence activated cell sorting (FACS), early embryonic cells are a relatively untapped source for FACS applications often because the embryos of many animals are quite limiting. Furthermore, many applications require genetic model organisms in which cells can be labeled by fluorescent transgenes, or antibodies against cell surface antigens. Here we define conditions in the sea urchin embryo for isolation of embryonic cells based on expression of specific proteins. We use the sea urchin embryo for which a nearly unlimited supply of embryonic cells is available and demonstrate the conditions for separation of the embryo into single cells, fixation of the cells for antibody penetration into the cells, and conditions for FACS of a rare cell type in the embryo. This protocol may be adapted for analysis of mRNA, chromatin, protein, or carbohydrates and depends only on the probe availability for the cell of interest. We anticipate that this protocol will be broadly applicable to embryos of other species.
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Affiliation(s)
- Celina Juliano
- Department of Molecular and Cellular Biology & Biochemistry, Brown University, Providence, RI, USA
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16
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Materna SC, Swartz SZ, Smith J. Notch and Nodal control forkhead factor expression in the specification of multipotent progenitors in sea urchin. Development 2013; 140:1796-806. [PMID: 23533178 PMCID: PMC3621494 DOI: 10.1242/dev.091157] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2013] [Indexed: 01/23/2023]
Abstract
Indirect development, in which embryogenesis gives rise to a larval form, requires that some cells retain developmental potency until they contribute to the different tissues in the adult, including the germ line, in a later, post-embryonic phase. In sea urchins, the coelomic pouches are the major contributor to the adult, but how coelomic pouch cells (CPCs) are specified during embryogenesis is unknown. Here we identify the key signaling inputs into the CPC specification network and show that the forkhead factor foxY is the first transcription factor specifically expressed in CPC progenitors. Through dissection of its cis-regulatory apparatus we determine that the foxY expression pattern is the result of two signaling inputs: first, Delta/Notch signaling activates foxY in CPC progenitors; second, Nodal signaling restricts its expression to the left side, where the adult rudiment will form, through direct repression by the Nodal target pitx2. A third signal, Hedgehog, is required for coelomic pouch morphogenesis and institution of laterality, but does not directly affect foxY transcription. Knockdown of foxY results in a failure to form coelomic pouches and disrupts the expression of virtually all transcription factors known to be expressed in this cell type. Our experiments place foxY at the top of the regulatory hierarchy underlying the specification of a cell type that maintains developmental potency.
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Affiliation(s)
- Stefan C. Materna
- California Institute of Technology, Division of Biology, m/c 156-29, Pasadena, CA 91125, USA
| | - S. Zachary Swartz
- Brown University, Department of Molecular Biology, Cell Biology and Biochemistry, 185 Meeting Street, Providence, RI 02912, USA
| | - Joel Smith
- California Institute of Technology, Division of Biology, m/c 156-29, Pasadena, CA 91125, USA
- Brown University, Department of Molecular Biology, Cell Biology and Biochemistry, 185 Meeting Street, Providence, RI 02912, USA
- Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543, USA
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17
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Abstract
The germline of multicellular animals is segregated from somatic tissues, which is an essential developmental process for the next generation. Although certain ecdysozoans and chordates segregate their germline during embryogenesis, animals from other taxa segregate their germline after embryogenesis from multipotent progenitor cells. An overlapping set of genes, including vasa, nanos and piwi, operate in both multipotent precursors and in the germline. As we propose here, this conservation implies the existence of an underlying germline multipotency program in these cell types that has a previously underappreciated and conserved function in maintaining multipotency.
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Affiliation(s)
- Celina E. Juliano
- Department of Molecular and Cellular Biology, Brown University, Providence, RI 02912, USA
| | - S. Zachary Swartz
- Department of Molecular and Cellular Biology, Brown University, Providence, RI 02912, USA
| | - Gary M. Wessel
- Department of Molecular and Cellular Biology, Brown University, Providence, RI 02912, USA
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18
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Swartz SZ, Juliano CE, Raz T, Lipson D, Milos P, Hamdoun A, Wessel GM. An ancient molecular circuit specifying multipotency. Dev Biol 2010. [DOI: 10.1016/j.ydbio.2010.05.368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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19
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Swartz SZ, Chan XY, Lambert JD. Localization of Vasa mRNA during early cleavage of the snail Ilyanassa. Dev Genes Evol 2008; 218:107-13. [DOI: 10.1007/s00427-008-0203-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Accepted: 12/28/2007] [Indexed: 10/22/2022]
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