Essential roles of G 12/13 signaling in distinct cell behaviors driving zebrafish convergence and extension gastrulation movements

Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
The Journal of Cell Biology (Impact Factor: 9.83). 07/2005; 169(5):777-87. DOI: 10.1083/jcb.200501104
Source: PubMed


Galpha(12/13) have been implicated in numerous cellular processes, however, their roles in vertebrate gastrulation are largely unknown. Here, we show that during zebrafish gastrulation, suppression of both Galpha(12) and Galpha(13) signaling by overexpressing dominant negative proteins and application of antisense morpholino-modified oligonucleotide translation interference disrupted convergence and extension without changing embryonic patterning. Analyses of mesodermal cell behaviors revealed that Galpha(12/13) are required for cell elongation and efficient dorsalward migration during convergence independent of noncanonical Wnt signaling. Furthermore, Galpha(12/13) function cell-autonomously to mediate mediolateral cell elongation underlying intercalation during notochord extension, likely acting in parallel to noncanonical Wnt signaling. These findings provide the first evidence that Galpha(12) and Galpha(13) have overlapping and essential roles in distinct cell behaviors that drive vertebrate gastrulation.

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Available from: Fang Lin, Oct 10, 2015
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    • "The previously validated MOs targeting the following genes were injected into embryos at 1-cell stage: gna13a and gna13b (2-3 ng each) (Lin et al., 2005), s1pr2/mil (15 ng) (Kawahara et al., 2009) and sox32 (4 ng) (Wong et al., 2012). "
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    ABSTRACT: Coordination between the endoderm and adjacent cardiac mesoderm is crucial for heart development. We previously showed that myocardial migration is promoted by convergent movement of the endoderm, which itself is controlled by the S1pr2/Gα13 signaling pathway, but it remains unclear how the movements of the two tissues is coordinated. Here, we image live and fixed embryos to follow these movements, revealing previously unappreciated details of strikingly complex and dynamic associations between the endoderm and myocardial precursors. We found that during segmentation the endoderm underwent three distinct phases of movement relative to the midline: rapid convergence, little convergence and slight expansion. During these periods, the myocardial cells exhibited different stage-dependent migratory modes: co-migration with the endoderm, movement from the dorsal to the ventral side of the endoderm (subduction) and migration independent of endoderm convergence. We also found that defects in S1pr2/Gα13-mediated endodermal convergence affected all three modes of myocardial cell migration, probably due to the disruption of fibronectin assembly around the myocardial cells and consequent disorganization of the myocardial epithelium. Moreover, we found that additional cell types within the anterior lateral plate mesoderm (ALPM) also underwent subduction, and that this movement likewise depended on endoderm convergence. Our study delineates for the first time the details of the intricate interplay between the endoderm and ALPM during embryogenesis, highlighting why endoderm movement is essential for heart development, and thus potential underpinnings of congenital heart disease. © 2015. Published by The Company of Biologists Ltd.
    Development 09/2015; 142(17). DOI:10.1242/dev.113944 · 6.46 Impact Factor
    • "2516 RESEARCH ARTICLE Development (2015) 142, 2508-2520 doi:10.1242/dev.119032 DEVELOPMENT Gα 12/13 acting in a cell-autonomous manner and likely in parallel to Wnt/PCP (Lin et al., 2005), and Rok2 affecting cell shape cellautonomously but ML cell alignment in a non-cell-autonomous manner acting downstream of Wnt/PCP (Lin et al., 2005; Marlow et al., 2002). Although a link between the cytoskeleton and Wnt/PCP has been established, stage/domain-specific signals instructing such cytoskeletal regulators remain to be clarified. "
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    ABSTRACT: During vertebrate gastrulation, convergence and extension movements elongate embryonic tissues anteroposteriorly and narrow them mediolaterally. Planar Cell Polarity (PCP) signaling is essential for mediolateral cell elongation underlying these movements, but how this polarity arises is poorly understood. We analyzed cell elongation, orientation, and migration behaviors of lateral mesodermal cells undergoing convergence and extension movements in wild-type embryos and mutants for the Wnt/PCP core component Trilobite/Vangl2. We demonstrate that Vangl2 function is required at the time when cells transition to a highly elongated and mediolaterally aligned body. We show that tri/vangl2 mutant cells fail to undergo this transition and to migrate along a straight path and high net speed towards the dorsal midline. Instead, tri/vangl2 mutant cells exhibit an anterior/animal pole bias in their cell body alignment and movement direction, suggesting that PCP signaling promotes effective dorsal migration in part by suppressing anterior/animalward cell polarity and movement. Endogenous Vangl2 protein accumulates at the plasma membrane of mesenchymal converging cells at the time its function is required for mediolaterally polarized cell behavior. Heterochronic cell transplantations demonstrated that Vangl2 cell membrane accumulation is stage dependent, and regulated by both intrinsic factors and an extracellular signal, which is distinct from PCP signaling or other gastrulation regulators, including BMP and Nodals. Moreover, mosaic expression of fusion proteins revealed enrichment of Vangl2 at the anterior cell edges of highly mediolaterally elongated cells, consistent with the PCP pathway core components' asymmetric distribution in Drosophila and vertebrate epithelia. © 2015. Published by The Company of Biologists Ltd.
    Development 06/2015; 142(14). DOI:10.1242/dev.119032 · 6.46 Impact Factor
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    • "The Wnt-PCP pathway requires finely balanced regulation to elicit polarize cell movement as either gain or loss-of-function of Wnt-PCP components results in severe gastrulation defects [68–75]. RhoA is controlled by several additional regulators during zebrafish gastrulation including the non-receptor tyrosine kinases Fyn and Yes [76,77], which signal along with tyrosine phosphatases Shp2 [78], RPTPα and PTPε [79,80] In addition pathways dependent on Gα12 and Gα13 [81], AKAP12 (Gravin) [29,82] Adhesion-associated GAPs [83] and several Rho-GEFs [84–87] control RhoA signaling and disruption of any of these regulators causes severe gastrulation and body axis elongation defects. Critical targets of RhoA during gastrulation include formins [88], which control actin polymerization, and the Rho-dependent kinase Rock [30,89] and myosin phosphatase [9], which control actomyosin contractility [20]. "
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    ABSTRACT: The myosin phosphatase is a highly conserved regulator of actomyosin contractility. Zebrafish has emerged as an ideal model system to study the in vivo role of myosin phosphatase in controlling cell contractility, cell movement and epithelial biology. Most work in zebrafish has focused on the regulatory subunit of the myosin phosphatase called Mypt1. In this work, we examined the critical role of Protein Phosphatase 1, PP1, the catalytic subunit of the myosin phosphatase. We observed that in zebrafish two paralogous genes encoding PP1β, called ppp1cba and ppp1cbb, are both broadly expressed during early development. Furthermore, we found that both gene products interact with Mypt1 and assemble an active myosin phosphatase complex. In addition, expression of this complex results in dephosphorylation of the myosin regulatory light chain and large scale rearrangements of the actin cytoskeleton. Morpholino knock-down of ppp1cba and ppp1cbb results in severe defects in morphogenetic cell movements during gastrulation through loss of myosin phosphatase function. Our work demonstrates that zebrafish have two genes encoding PP1β, both of which can interact with Mypt1 and assemble an active myosin phosphatase. In addition, both genes are required for convergence and extension during gastrulation and correct dosage of the protein products is required.
    PLoS ONE 09/2013; 8(9):e75766. DOI:10.1371/journal.pone.0075766 · 3.23 Impact Factor
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