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Cellular and molecular mechanisms regulating limb position in vertebrates
S114
Abstracts
the suppression of natal down could be due to different molecular and cellular mechanisms in budgerigars whose chicks are also naked.
doi:10.1016/j.mod.2017.04.303
PS3.98 Antagonistic BMP-cWNT signaling in the cnidarian Nematostella vectensis: Implications for the evolution of mesoderm Naveen Wijesenaa, David Simmonsb, Mark Martindaleb a
Rajarata University of Sri Lanka, Mihintale, Sri Lanka Whitney Lab, University of Florida, Saint Augustine, United States
b
Gastrulation was arguably the key evolutionary innovation that enabled metazoan diversification, leading to the formation of distinct germ layers and specialized tissues. Differential gene expression specifying cell fate is governed by the inputs of intracellular and/or extracellular signals. Beta-catenin/Tcf and the TGF-beta Bone Morphogenetic Protein (BMP) provide critical molecular signaling inputs during germ layer specification in bilaterian metazoans but there has beenno direct experimental evidence for a specific role for BMP signaling during endomesoderm specification in the early branching metazoan Nematostella vectensis (ananthozoan cnidarian),. Using forward transcriptomics, we show that Betacatenin/Tcf signaling and BMP2/4 signaling provide differential inputs into the cnidarian endomesodermal gene regulatory network at the onset of gastrulation (24hpf) inNematostella vectensis. Surprisingly, Beta-catenin/Tcf signaling and BMP2/4 signaling regulate a subset of common downstream target genes in the GRN in opposite ways, leading to the spatial and temporal differentiation of fields of cells in the developing embryo. Thus, we show that regulatory interactions between Beta-catenin/Tcf signaling and BMP2/4 signaling are required for the specification and determination of different embryonic regions and the patterning of the oralaboral axis in Nematostella. We also show functionally that the conserved “kernel” of the bilaterian heart mesoderm GRN is operational in Nematostella vectensis, which reinforces the hypothesis that the endoderm and mesoderm in triploblastic bilaterians evolved from the bifunctional endomesoderm (gastrodermis) of a diploblastic ancestor, and that slow rhythmic contractions might have been one of the earliest functions of mesoderm.
doi:10.1016/j.mod.2017.04.304
PS3.99 Cellular and molecular mechanisms regulating limb position in vertebrates Chloe Moreaua,b,c, Nicolas Denansd, Olivier Pourquiée, Jerome Grosa,b a
Institut Pasteur, Paris, France URA2578, CNRS, France c Cellule Pasteur UPMC, Paris, France d Stanford School of Medicine, United States e Harvard Medical School, Boston, United States b
During vertebrate development, limbs emerge from the trunk of the embryo as buds that progressively elongate into fully developed
appendages. Whereas the molecular and genetic interactions underlying limb initiation, outgrowth and patterning have been greatly elucidated, how limbs reproducibly form at specific locations along the body axis still remains unclear. The position of limbs is very consistent within one species but is highly variable among vertebrates. Interestingly, a number of studies have shown that this variation is associated with variations in the expression pattern of Hox genes. Because of their role in patterning embryonic axes, these genes have long remained good candidates in regulating the position of the limbs. Here, we hypothesize that the positional information of limb progenitor cells is acquired during the early steps of gastrulation and we explore the role of Hox genes in this process. Combining classical embryology techniques with molecular and live imaging approaches in the chick embryo, we aim at characterizing the cellular and molecular events underlying the formation of the Lateral Plate Mesoderm (LPM, i.e. the mesodermal compartment giving rise to limbs) and in particular the role of Hox genes in patterning the LPM into limb-forming and non-limb-forming domains, during the gastrulation process.
doi:10.1016/j.mod.2017.04.305
PS3.100 Single-cell RNA-seq unveils divergent modes of chemoresistance in squamous cell carcinoma Ankur Sharmaa, Vibhor Kumara, Elaine Yiqun Caob, Hui Sun Leongb, Muhammad Hakimullaha, Neeraja Ramakrishnana, Xiaoqian Zhanga, Fui Teen Chongb, Shumei Chiaa, Matan Thangavelu Thangavelua, Angeline Mei Lin Wonga, Xue Lin Kwangb, Daniel Shao-Weng Tanb, Giridharan Periyasamya, N. Gopalakrishna Iyerb, Ramanuj DasGuptaa a
Genome Institute of, Singapore National Cancer Centre, Singapore
b
Intra-tumor heterogeneity (ITH) generates distinct cellular populations that contribute to tumor maintenance, progression, and drug-resistance. However, the contribution of individual cells to chemotherapy-resistance remains poorly understood. We generated single-cell mRNA sequencing profile of cisplatin-resistant squamous cell carcinoma (SCC) cells. Here we demonstrate that retention of native cellular-states is the principle mode of drug-resistance, a phenomenon we term ‘cellular inertia’. Interestingly, in comparison to other cancers ‘cellular-plasticity’ manifesting as epithelial-tomesenchymal transition (EMT) was observed to be a minor source of drug-resistance. These observations were also corroborated in cisplatin treated oral SCC patients. Importantly, gene expression signature from cellular plasticity-induced drug-resistant models correlated with poor survival. Synthetic lethal screens revealed a critical function of chromatin remodelers in EMT-associated acquired drug resistance. Specifically, we demonstrate the role of BRD4mediated H3K27 acetylation as an adaptive response to chemotherapy, which could be reversed by JQ1. In summary, our study provides critical insights into the divergent modes of drug resistance, and paves the way for therapeutic modalities involving epigenetic targeting of tumor evolution and ITH.
doi:10.1016/j.mod.2017.04.306
Abstracts
the suppression of natal down could be due to different molecular and cellular mechanisms in budgerigars whose chicks are also naked.
doi:10.1016/j.mod.2017.04.303
PS3.98 Antagonistic BMP-cWNT signaling in the cnidarian Nematostella vectensis: Implications for the evolution of mesoderm Naveen Wijesenaa, David Simmonsb, Mark Martindaleb a
Rajarata University of Sri Lanka, Mihintale, Sri Lanka Whitney Lab, University of Florida, Saint Augustine, United States
b
Gastrulation was arguably the key evolutionary innovation that enabled metazoan diversification, leading to the formation of distinct germ layers and specialized tissues. Differential gene expression specifying cell fate is governed by the inputs of intracellular and/or extracellular signals. Beta-catenin/Tcf and the TGF-beta Bone Morphogenetic Protein (BMP) provide critical molecular signaling inputs during germ layer specification in bilaterian metazoans but there has beenno direct experimental evidence for a specific role for BMP signaling during endomesoderm specification in the early branching metazoan Nematostella vectensis (ananthozoan cnidarian),. Using forward transcriptomics, we show that Betacatenin/Tcf signaling and BMP2/4 signaling provide differential inputs into the cnidarian endomesodermal gene regulatory network at the onset of gastrulation (24hpf) inNematostella vectensis. Surprisingly, Beta-catenin/Tcf signaling and BMP2/4 signaling regulate a subset of common downstream target genes in the GRN in opposite ways, leading to the spatial and temporal differentiation of fields of cells in the developing embryo. Thus, we show that regulatory interactions between Beta-catenin/Tcf signaling and BMP2/4 signaling are required for the specification and determination of different embryonic regions and the patterning of the oralaboral axis in Nematostella. We also show functionally that the conserved “kernel” of the bilaterian heart mesoderm GRN is operational in Nematostella vectensis, which reinforces the hypothesis that the endoderm and mesoderm in triploblastic bilaterians evolved from the bifunctional endomesoderm (gastrodermis) of a diploblastic ancestor, and that slow rhythmic contractions might have been one of the earliest functions of mesoderm.
doi:10.1016/j.mod.2017.04.304
PS3.99 Cellular and molecular mechanisms regulating limb position in vertebrates Chloe Moreaua,b,c, Nicolas Denansd, Olivier Pourquiée, Jerome Grosa,b a
Institut Pasteur, Paris, France URA2578, CNRS, France c Cellule Pasteur UPMC, Paris, France d Stanford School of Medicine, United States e Harvard Medical School, Boston, United States b
During vertebrate development, limbs emerge from the trunk of the embryo as buds that progressively elongate into fully developed
appendages. Whereas the molecular and genetic interactions underlying limb initiation, outgrowth and patterning have been greatly elucidated, how limbs reproducibly form at specific locations along the body axis still remains unclear. The position of limbs is very consistent within one species but is highly variable among vertebrates. Interestingly, a number of studies have shown that this variation is associated with variations in the expression pattern of Hox genes. Because of their role in patterning embryonic axes, these genes have long remained good candidates in regulating the position of the limbs. Here, we hypothesize that the positional information of limb progenitor cells is acquired during the early steps of gastrulation and we explore the role of Hox genes in this process. Combining classical embryology techniques with molecular and live imaging approaches in the chick embryo, we aim at characterizing the cellular and molecular events underlying the formation of the Lateral Plate Mesoderm (LPM, i.e. the mesodermal compartment giving rise to limbs) and in particular the role of Hox genes in patterning the LPM into limb-forming and non-limb-forming domains, during the gastrulation process.
doi:10.1016/j.mod.2017.04.305
PS3.100 Single-cell RNA-seq unveils divergent modes of chemoresistance in squamous cell carcinoma Ankur Sharmaa, Vibhor Kumara, Elaine Yiqun Caob, Hui Sun Leongb, Muhammad Hakimullaha, Neeraja Ramakrishnana, Xiaoqian Zhanga, Fui Teen Chongb, Shumei Chiaa, Matan Thangavelu Thangavelua, Angeline Mei Lin Wonga, Xue Lin Kwangb, Daniel Shao-Weng Tanb, Giridharan Periyasamya, N. Gopalakrishna Iyerb, Ramanuj DasGuptaa a
Genome Institute of, Singapore National Cancer Centre, Singapore
b
Intra-tumor heterogeneity (ITH) generates distinct cellular populations that contribute to tumor maintenance, progression, and drug-resistance. However, the contribution of individual cells to chemotherapy-resistance remains poorly understood. We generated single-cell mRNA sequencing profile of cisplatin-resistant squamous cell carcinoma (SCC) cells. Here we demonstrate that retention of native cellular-states is the principle mode of drug-resistance, a phenomenon we term ‘cellular inertia’. Interestingly, in comparison to other cancers ‘cellular-plasticity’ manifesting as epithelial-tomesenchymal transition (EMT) was observed to be a minor source of drug-resistance. These observations were also corroborated in cisplatin treated oral SCC patients. Importantly, gene expression signature from cellular plasticity-induced drug-resistant models correlated with poor survival. Synthetic lethal screens revealed a critical function of chromatin remodelers in EMT-associated acquired drug resistance. Specifically, we demonstrate the role of BRD4mediated H3K27 acetylation as an adaptive response to chemotherapy, which could be reversed by JQ1. In summary, our study provides critical insights into the divergent modes of drug resistance, and paves the way for therapeutic modalities involving epigenetic targeting of tumor evolution and ITH.
doi:10.1016/j.mod.2017.04.306