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Werner E G Muller - One of the best experts on this subject based on the ideXlab platform.
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Evolution of Metazoan Cell Junction Proteins: The Scaffold Protein MAGI and the Transmembrane Receptor Tetraspanin in the Demosponge Suberites domuncula
Journal of Molecular Evolution, 2004Co-Authors: Teresa Adell, Isabel M. Müller, Matthias Wiens, Vera Gamulin, Michael Korzhev, Sanja Perović-ottstadt, Werner E G MullerAbstract:Until recently the positioning of the sponges (phylum Porifera) within the metazoan systematics was hampered by the lack of molecular evidence for the existence of junctional structures in the surface cell layers. In this study two genes related to the tight junctions are characterized from the demosponge Suberites domuncula : tetraspanin ( SDTM4SF ), a cell surface receptor, and MAGI ( SDMAGI ), a MAGUK (membrane-associated guanylate kinase homologue) protein. Especially the MAGI protein is known in other metazoan animal phyla to exist exclusively in tight junctions. The characteristic domains of MAGI proteins (six PDZ domains, two WW domains, and a truncated guanylate kinase motif) are conserved in the sponge protein. The functional analysis of SDMAGI done by in situ hybridization shows its expression in the surface epithelial layers (exoPinacoderm and endoPinacoderm). Northern blot studies reveal that expression of SDMAGI and SDTM4SF increases after formation of the Pinacoderm layer in the animals as well as in primmorphs. These results support earlier notions that sponges contain junctional structures. We conclude that sponges contain epithelia whose cells are organized by cell junctions.
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a 1 3 β d glucan recognition protein from the sponge suberites domuncula
FEBS Journal, 2004Co-Authors: Sanja Perovicottstadt, Isabel M. Müller, Matthias Wiens, Vera Gamulin, Peter Proksch, Michael Korzhev, Teresa Adell, Werner E G MullerAbstract:Sponges (phylum Porifera) live in a symbiotic relationship with microorganisms, primarily bacteria. Until now, molecular proof for the capacity of sponges to recognize fungi in the surrounding aqueous milieu has not been available. Here we demonstrate, for the demosponge Suberites domuncula (Porifera, Demospongiae, Hadromerida), a cell surface receptor that recognizes (13)-β-d-glucans, e.g. curdlan or laminarin. This receptor, the (13)-β-d-glucan-binding protein, was identified and its cDNA analysed. The gene coding for the 45 kDa protein was found to be upregulated in tissue after incubation with carbohydrate. Simultaneously with the increased expression of this gene, two further genes showed an elevated steady state level of expression; one codes for a fibrinogen-like protein and the other for the epidermal growth factor precursor. Expression of the (13)-β-d-glucan-binding protein and the fibrinogen-like protein occurred in cells on the sponge surface, in the Pinacoderm. By Western blotting, the product of the fibrinogen-like protein gene was identified, the recombinant protein isolated, and antibodies raised to this protein. Their application revealed that a 5 kDa factor is produced, which is apparently processed from the 77 kDa epidermal growth factor precursor. Finally, we provided evidence that a tyrosine kinase pathway is initiated in response to exposure to d-glucan; its phosphorylation activity could be blocked by aeroplysinin. In turn, the increased expression of the downstream genes was suppressed. We conclude that sponges possess a molecular mechanism for recognizing fungi via the d-glucan carbohydrates on their surfaces.
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differentiation capacity of epithelial cells in the sponge suberites domuncula
Cell and Tissue Research, 2004Co-Authors: Heinz C Schroder, Renato Batel, Isabel M. Müller, Matthias Wiens, Sanja Perovicottstadt, Werner E G MullerAbstract:Sponges (phylum Porifera) represent the oldest metazoans. Their characteristic metazoan adhesion molecules and transcription factors enable them to establish a complex "Bauplan"; three major differentiated cell types (epithelial cells, skeletal cells/sclerocytes, and contractile cells) can be distinguished. Since no molecular markers are as yet available to distinguish these somatic cells or the corresponding embryonic cells from which they originate, we have selected the following three genes for their characterization: noggin (a signaling molecule in development), a caspase that encodes an apoptotic molecule, and silicatein. Silicatein is an enzyme that is involved in the synthesis of siliceous spicules and can hence be considered as a marker for scleroblasts. We have used the demosponge Suberites domuncula as a model system. During the hatching of the gemmules (asexual reproduction bodies) of S. domuncula, the expression of both noggin and caspase increases, whereas no transcripts for silicatein can be detected, irrespective of the presence of silicate or ferric iron (Fe3+) in the medium. In contrast, in adult specimens, silicate/Fe3+ cause an increased expression of these genes. In situ analysis has revealed that the first cells that express noggin, caspase, and silicatein lie in the epithelial layer of the Pinacoderm. In a later phase, the noggin- and silicatein-positive cells migrate into the mesohyl, where they are found in association with spicules. Thus, the Pinacoderm of sponges contains cells that have a differentiating capacity and from which somatic cells, such as skeletal cells/sclerocytes, derive.
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polarity factor frizzled in the demosponge suberites domuncula identification expression and localization of the receptor in the epithelium Pinacoderm 1
FEBS Letters, 2003Co-Authors: Teresa Adell, Isabelle Nefkens, Werner E G MullerAbstract:Until recently, it was assumed that polarity and axis formation have evolved only in metazoan phyla higher than Cnidaria. One key molecule involved in the signal transduction causing tissue polarity is Frizzled, a seven-transmembrane receptor that is activated by the Wnt family of secreted proteins. We report the isolation and characterization of a Frizzled gene from the demosponge Suberites domuncula (Sd-Fz). The deduced polypeptide comprises all characteristic domains known from Frizzled receptors of higher metazoans. In situ hybridization studies show that Sd-Fz is expressed in cells close to the surface of the sponges and in the pinacocytes of some canals. Northern blot analysis demonstrates its upregulation during the formation of three-dimensional sponge cell aggregates in culture. These data provide for the first time experimental evidence that already in the lowest metazoan phylum (Porifera) genes are present which are very likely involved in tissue polarity.
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primmorphs generated from dissociated cells of the sponge suberites domuncula a model system for studies of cell proliferation and cell death
Mechanisms of Ageing and Development, 1998Co-Authors: Marcio R Custodio, Franz Brümmer, Renate Steffen, Radovan Borojevic, Michael Nickel, Claudia Koziol, Ivo Prokic, Werner E G MullerAbstract:Sponges (Porifera) represent the lowest metazoan phylum; they have been shown to be provided with the characteristic metazoan structural and functional molecules. One autapomorphic character of sponges is the presence of high levels of telomerase activity in all cells (or almost all cells, including somatic cells). In spite of this fact previous attempts to cultivate sponge cells remained unsuccessful. It was found that dissociated sponge cells do not replicate DNA and lose their telomerase activity. In addition, no nutrients or metabolites have been detected that would stimulate sponge cells to divide. In the present study we report the culture conditions required for the formation of multicellular aggregates from dissociated single cells of Suberites domuncula, termed primmorphs. These primmorphs are formed in seawater without addition of further supplements, and have an organised tissue-like structure; they have been cultured for more than 5 months. Cross-sections revealed a distinct external layer covered by a continuous Pinacoderm, and a central zone composed primarily of spherulous cells. After their association into primmorphs, the cells turn from the telomerase-negative state into the telomerase-positive state; a telomerase level of 4.7 total product generated (TPG) units/5 x 10(3) cell equivalents has been determined. Moreover, a major fraction of the cells in the primmorphs undergoes DNA synthesis and hence has the capacity to grow. Applying the BrdU-labelling and detection assay it is demonstrated that up to 33.8% of the cells in the primmorphs are labelled with BrdU after an incubation period of 12 h. It is proposed that the primmorph system described here is a powerful novel model system to study basic mechanisms of cell proliferation and cell interaction, as well as of morphogenesis, ageing and apoptosis.
Diego Gilagudelo - One of the best experts on this subject based on the ideXlab platform.
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posibles mecanismos quimicos y biologicos para el control de la epibiosis de las esponjas aplysina insularis y aplysina lacunosa demospongiae verongida
Acta Biológica Colombiana, 2007Co-Authors: Jennyfer Andrea Mora Cristancho, Diego GilagudeloAbstract:Las esponjas Aplysina insularis (con epitelio libre de epibiontes), y Aplysina lacunosa (con epitelio recubierto por epibiontes) fueron escogidas como modelo para estudiar algunos de los mecanismos quimicos y bacterianos que podrian determinar su grado de epibiosis. A traves de la tecnica molecular de electroforesis en gel con gradiente desnaturalizante (DGGE), se determino que la comunidad de epibiontes bacterianos varia entre individuos, pero en general es muy similar entre especies de esponja, sin ninguna relacion con el grado de epibiosis. Para las dos especies, se detectaron diferencias en la presencia/ausencia de compuestos bromados bioactivos en las fracciones quimicas del extracto crudo. Todas las fracciones quimicas con compuestos bromados inhibieron el crecimiento de todas las cepas bacterianas aisladas de biopeliculas asociadas a diferentes superficies (Pinacodermo externo de A. insularis y A. lacunosa, Pinacodermo del pseudoatrio de A. lacunosa, y una superficie inerte, la concha del bivalvo Donax sp.). Tres fracciones quimicas de A. lacunosa y dos de A. insularis presentaron los niveles de actividad antibacteriana mas altos. La susceptibilidad in vitro a las fracciones con compuestos bromados de las bacterias aisladas de las superficies limpias fue menor que aquellas aisladas de superficies con mayor grado de epibiosis. Asumiendo que los compuestos bromados son exudados, ellos podrian controlar el crecimiento de algunas poblaciones bacterianas in situ. Se sugiere que las sinuosidades morfologicas de la superficie de A. lacunosa restringen la exudacion de compuestos bromados hacia las depresiones inhalantes, las cuales se mantienen limpias, mientras que esto permite que las crestas sean colonizadas, quiza para camuflarse. Las cepas bacterianas aisladas del Pinacodermo externo y limpio de A. insularis presentaron una frecuencia alta de interacciones antagonicas in vitro con bacterias aisladas de la misma superficie, sugiriendo que las interacciones antagonicas pueden prevenir la epibiosis a traves de la regulacion del crecimiento bacteriano. Se discuten varios mecanismos por los cuales la epibiosis puede ser controlada.
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posibles mecanismos quimicos y biologicos para el control de la epibiosis de las esponjas aplysina insularis y aplysina lacunosa demospongiae verongida
Acta Biológica Colombiana, 2007Co-Authors: Jennyfer Andrea Mora Cristancho, Diego GilagudeloAbstract:Las esponjas Aplysina insularis (con epitelio libre de epibiontes), y Aplysina lacunosa (con epitelio recubierto por epibiontes) fueron escogidas como modelo para estudiar algunos de los mecanismos quimicos y bacterianos que podrian determinar su grado de epibiosis. A traves de la tecnica molecular de electroforesis en gel con gradiente desnaturalizante (DGGE), se determino que la comunidad de epibiontes bacterianos varia entre individuos, pero en general es muy similar entre especies de esponja, sin ninguna relacion con el grado de epibiosis. Para las dos especies, se detectaron diferencias en la presencia/ausencia de compuestos bromados bioactivos en las fracciones quimicas del extracto crudo. Todas las fracciones quimicas con compuestos bromados inhibieron el crecimiento de todas las cepas bacterianas aisladas de biopeliculas asociadas a diferentes superficies (Pinacodermo externo de A. insularis y A. lacunosa, Pinacodermo del pseudoatrio de A. lacunosa, y una superficie inerte, la concha del bivalvo Donax sp.). Tres fracciones quimicas de A. lacunosa y dos de A. insularis presentaron los niveles de actividad antibacteriana mas altos. La susceptibilidad in vitro a las fracciones con compuestos bromados de las bacterias aisladas de las superficies limpias fue menor que aquellas aisladas de superficies con mayor grado de epibiosis. Asumiendo que los compuestos bromados son exudados, ellos podrian controlar el crecimiento de algunas poblaciones bacterianas in situ. Se sugiere que las sinuosidades morfologicas de la superficie de A. lacunosa restringen la exudacion de compuestos bromados hacia las depresiones inhalantes, las cuales se mantienen limpias, mientras que esto permite que las crestas sean colonizadas, quiza para camuflarse. Las cepas bacterianas aisladas del Pinacodermo externo y limpio de A. insularis presentaron una frecuencia alta de interacciones antagonicas in vitro con bacterias aisladas de la misma superficie, sugiriendo que las interacciones antagonicas pueden prevenir la epibiosis a traves de la regulacion del crecimiento bacteriano. Se discuten varios mecanismos por los cuales la epibiosis puede ser controlada.
Jennyfer Andrea Mora Cristancho - One of the best experts on this subject based on the ideXlab platform.
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posibles mecanismos quimicos y biologicos para el control de la epibiosis de las esponjas aplysina insularis y aplysina lacunosa demospongiae verongida
Acta Biológica Colombiana, 2007Co-Authors: Jennyfer Andrea Mora Cristancho, Diego GilagudeloAbstract:Las esponjas Aplysina insularis (con epitelio libre de epibiontes), y Aplysina lacunosa (con epitelio recubierto por epibiontes) fueron escogidas como modelo para estudiar algunos de los mecanismos quimicos y bacterianos que podrian determinar su grado de epibiosis. A traves de la tecnica molecular de electroforesis en gel con gradiente desnaturalizante (DGGE), se determino que la comunidad de epibiontes bacterianos varia entre individuos, pero en general es muy similar entre especies de esponja, sin ninguna relacion con el grado de epibiosis. Para las dos especies, se detectaron diferencias en la presencia/ausencia de compuestos bromados bioactivos en las fracciones quimicas del extracto crudo. Todas las fracciones quimicas con compuestos bromados inhibieron el crecimiento de todas las cepas bacterianas aisladas de biopeliculas asociadas a diferentes superficies (Pinacodermo externo de A. insularis y A. lacunosa, Pinacodermo del pseudoatrio de A. lacunosa, y una superficie inerte, la concha del bivalvo Donax sp.). Tres fracciones quimicas de A. lacunosa y dos de A. insularis presentaron los niveles de actividad antibacteriana mas altos. La susceptibilidad in vitro a las fracciones con compuestos bromados de las bacterias aisladas de las superficies limpias fue menor que aquellas aisladas de superficies con mayor grado de epibiosis. Asumiendo que los compuestos bromados son exudados, ellos podrian controlar el crecimiento de algunas poblaciones bacterianas in situ. Se sugiere que las sinuosidades morfologicas de la superficie de A. lacunosa restringen la exudacion de compuestos bromados hacia las depresiones inhalantes, las cuales se mantienen limpias, mientras que esto permite que las crestas sean colonizadas, quiza para camuflarse. Las cepas bacterianas aisladas del Pinacodermo externo y limpio de A. insularis presentaron una frecuencia alta de interacciones antagonicas in vitro con bacterias aisladas de la misma superficie, sugiriendo que las interacciones antagonicas pueden prevenir la epibiosis a traves de la regulacion del crecimiento bacteriano. Se discuten varios mecanismos por los cuales la epibiosis puede ser controlada.
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posibles mecanismos quimicos y biologicos para el control de la epibiosis de las esponjas aplysina insularis y aplysina lacunosa demospongiae verongida
Acta Biológica Colombiana, 2007Co-Authors: Jennyfer Andrea Mora Cristancho, Diego GilagudeloAbstract:Las esponjas Aplysina insularis (con epitelio libre de epibiontes), y Aplysina lacunosa (con epitelio recubierto por epibiontes) fueron escogidas como modelo para estudiar algunos de los mecanismos quimicos y bacterianos que podrian determinar su grado de epibiosis. A traves de la tecnica molecular de electroforesis en gel con gradiente desnaturalizante (DGGE), se determino que la comunidad de epibiontes bacterianos varia entre individuos, pero en general es muy similar entre especies de esponja, sin ninguna relacion con el grado de epibiosis. Para las dos especies, se detectaron diferencias en la presencia/ausencia de compuestos bromados bioactivos en las fracciones quimicas del extracto crudo. Todas las fracciones quimicas con compuestos bromados inhibieron el crecimiento de todas las cepas bacterianas aisladas de biopeliculas asociadas a diferentes superficies (Pinacodermo externo de A. insularis y A. lacunosa, Pinacodermo del pseudoatrio de A. lacunosa, y una superficie inerte, la concha del bivalvo Donax sp.). Tres fracciones quimicas de A. lacunosa y dos de A. insularis presentaron los niveles de actividad antibacteriana mas altos. La susceptibilidad in vitro a las fracciones con compuestos bromados de las bacterias aisladas de las superficies limpias fue menor que aquellas aisladas de superficies con mayor grado de epibiosis. Asumiendo que los compuestos bromados son exudados, ellos podrian controlar el crecimiento de algunas poblaciones bacterianas in situ. Se sugiere que las sinuosidades morfologicas de la superficie de A. lacunosa restringen la exudacion de compuestos bromados hacia las depresiones inhalantes, las cuales se mantienen limpias, mientras que esto permite que las crestas sean colonizadas, quiza para camuflarse. Las cepas bacterianas aisladas del Pinacodermo externo y limpio de A. insularis presentaron una frecuencia alta de interacciones antagonicas in vitro con bacterias aisladas de la misma superficie, sugiriendo que las interacciones antagonicas pueden prevenir la epibiosis a traves de la regulacion del crecimiento bacteriano. Se discuten varios mecanismos por los cuales la epibiosis puede ser controlada.
Michael Nickel - One of the best experts on this subject based on the ideXlab platform.
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the contractile sponge epithelium sensu lato body contraction of the demosponge tethya wilhelma is mediated by the Pinacoderm
The Journal of Experimental Biology, 2011Co-Authors: Michael Nickel, Corina Scheer, Jorg U Hammel, Julia Herzen, Felix BeckmannAbstract:SUMMARY Sponges constitute one of the two metazoan phyla that are able to contract their bodies despite a complete lack of muscle cells. Two competing hypotheses on the mechanisms behind this have been postulated to date: (1) mesohyl-mediated contraction originating from fusiform smooth muscle-like actinocytes (‘myocytes’) and (2) epidermal contraction originating in pinacocytes. No direct support exists for either hypothesis. The question of agonist–antagonist interaction in sponge contraction seems to have been completely neglected so far. In the present study we addressed this by studying sponge contraction kinetics. We also tested both hypotheses by carrying out volumetric studies of 3D synchrotron radiation-based x-ray microtomography data obtained from contracted and expanded specimens of Tethya wilhelma . Our results support the Pinacoderm contraction hypothesis. Should mesohyl contraction be present, it is likely to be part of the antagonist system. We conclude that epithelial contraction plays a major role in sponges. Contractile epithelia sensu lato may be regarded as part of the ground pattern of the Metazoa.
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kinetics and rhythm of body contractions in the sponge tethya wilhelma porifera demospongiae
The Journal of Experimental Biology, 2004Co-Authors: Michael NickelAbstract:SUMMARY Sponges of the species Tethya wilhelma display rhythmic body contractions, which were analyzed by digital timelapse imaging and semi-automated image analysis. For the first time, differential, quantitative data on sponge behaviour could be obtained. The sponges are able to reduce their body volume by up to 73.3% during regular contractions. Each contraction cycle follows a characteristic pattern of four phases, permitting analysis of the kinetics of contraction and expansion. Long-term observations (for >7 days) reveal that the sponge contractions display a day-night periodicity in which contraction cycles are significantly longer during the dark hours. The contractions seem to be mediated by the Pinacoderm; they are triggered locally and spread over the sponge surface at 12.5 μm s -1 . If two individuals of a clone are fused, the individual contraction rhythm of both sponges persists for several days, until a single new individual sponge is formed with a synchronized rhythm. The reported results and techniques establish T. wilhelma as a model organism for research on the development of aneural signal transduction and integration during early Metazoan evolution.
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primmorphs generated from dissociated cells of the sponge suberites domuncula a model system for studies of cell proliferation and cell death
Mechanisms of Ageing and Development, 1998Co-Authors: Marcio R Custodio, Franz Brümmer, Renate Steffen, Radovan Borojevic, Michael Nickel, Claudia Koziol, Ivo Prokic, Werner E G MullerAbstract:Sponges (Porifera) represent the lowest metazoan phylum; they have been shown to be provided with the characteristic metazoan structural and functional molecules. One autapomorphic character of sponges is the presence of high levels of telomerase activity in all cells (or almost all cells, including somatic cells). In spite of this fact previous attempts to cultivate sponge cells remained unsuccessful. It was found that dissociated sponge cells do not replicate DNA and lose their telomerase activity. In addition, no nutrients or metabolites have been detected that would stimulate sponge cells to divide. In the present study we report the culture conditions required for the formation of multicellular aggregates from dissociated single cells of Suberites domuncula, termed primmorphs. These primmorphs are formed in seawater without addition of further supplements, and have an organised tissue-like structure; they have been cultured for more than 5 months. Cross-sections revealed a distinct external layer covered by a continuous Pinacoderm, and a central zone composed primarily of spherulous cells. After their association into primmorphs, the cells turn from the telomerase-negative state into the telomerase-positive state; a telomerase level of 4.7 total product generated (TPG) units/5 x 10(3) cell equivalents has been determined. Moreover, a major fraction of the cells in the primmorphs undergoes DNA synthesis and hence has the capacity to grow. Applying the BrdU-labelling and detection assay it is demonstrated that up to 33.8% of the cells in the primmorphs are labelled with BrdU after an incubation period of 12 h. It is proposed that the primmorph system described here is a powerful novel model system to study basic mechanisms of cell proliferation and cell interaction, as well as of morphogenesis, ageing and apoptosis.
Teresa Adell - One of the best experts on this subject based on the ideXlab platform.
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Evolution of Metazoan Cell Junction Proteins: The Scaffold Protein MAGI and the Transmembrane Receptor Tetraspanin in the Demosponge Suberites domuncula
Journal of Molecular Evolution, 2004Co-Authors: Teresa Adell, Isabel M. Müller, Matthias Wiens, Vera Gamulin, Michael Korzhev, Sanja Perović-ottstadt, Werner E G MullerAbstract:Until recently the positioning of the sponges (phylum Porifera) within the metazoan systematics was hampered by the lack of molecular evidence for the existence of junctional structures in the surface cell layers. In this study two genes related to the tight junctions are characterized from the demosponge Suberites domuncula : tetraspanin ( SDTM4SF ), a cell surface receptor, and MAGI ( SDMAGI ), a MAGUK (membrane-associated guanylate kinase homologue) protein. Especially the MAGI protein is known in other metazoan animal phyla to exist exclusively in tight junctions. The characteristic domains of MAGI proteins (six PDZ domains, two WW domains, and a truncated guanylate kinase motif) are conserved in the sponge protein. The functional analysis of SDMAGI done by in situ hybridization shows its expression in the surface epithelial layers (exoPinacoderm and endoPinacoderm). Northern blot studies reveal that expression of SDMAGI and SDTM4SF increases after formation of the Pinacoderm layer in the animals as well as in primmorphs. These results support earlier notions that sponges contain junctional structures. We conclude that sponges contain epithelia whose cells are organized by cell junctions.
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a 1 3 β d glucan recognition protein from the sponge suberites domuncula
FEBS Journal, 2004Co-Authors: Sanja Perovicottstadt, Isabel M. Müller, Matthias Wiens, Vera Gamulin, Peter Proksch, Michael Korzhev, Teresa Adell, Werner E G MullerAbstract:Sponges (phylum Porifera) live in a symbiotic relationship with microorganisms, primarily bacteria. Until now, molecular proof for the capacity of sponges to recognize fungi in the surrounding aqueous milieu has not been available. Here we demonstrate, for the demosponge Suberites domuncula (Porifera, Demospongiae, Hadromerida), a cell surface receptor that recognizes (13)-β-d-glucans, e.g. curdlan or laminarin. This receptor, the (13)-β-d-glucan-binding protein, was identified and its cDNA analysed. The gene coding for the 45 kDa protein was found to be upregulated in tissue after incubation with carbohydrate. Simultaneously with the increased expression of this gene, two further genes showed an elevated steady state level of expression; one codes for a fibrinogen-like protein and the other for the epidermal growth factor precursor. Expression of the (13)-β-d-glucan-binding protein and the fibrinogen-like protein occurred in cells on the sponge surface, in the Pinacoderm. By Western blotting, the product of the fibrinogen-like protein gene was identified, the recombinant protein isolated, and antibodies raised to this protein. Their application revealed that a 5 kDa factor is produced, which is apparently processed from the 77 kDa epidermal growth factor precursor. Finally, we provided evidence that a tyrosine kinase pathway is initiated in response to exposure to d-glucan; its phosphorylation activity could be blocked by aeroplysinin. In turn, the increased expression of the downstream genes was suppressed. We conclude that sponges possess a molecular mechanism for recognizing fungi via the d-glucan carbohydrates on their surfaces.
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polarity factor frizzled in the demosponge suberites domuncula identification expression and localization of the receptor in the epithelium Pinacoderm 1
FEBS Letters, 2003Co-Authors: Teresa Adell, Isabelle Nefkens, Werner E G MullerAbstract:Until recently, it was assumed that polarity and axis formation have evolved only in metazoan phyla higher than Cnidaria. One key molecule involved in the signal transduction causing tissue polarity is Frizzled, a seven-transmembrane receptor that is activated by the Wnt family of secreted proteins. We report the isolation and characterization of a Frizzled gene from the demosponge Suberites domuncula (Sd-Fz). The deduced polypeptide comprises all characteristic domains known from Frizzled receptors of higher metazoans. In situ hybridization studies show that Sd-Fz is expressed in cells close to the surface of the sponges and in the pinacocytes of some canals. Northern blot analysis demonstrates its upregulation during the formation of three-dimensional sponge cell aggregates in culture. These data provide for the first time experimental evidence that already in the lowest metazoan phylum (Porifera) genes are present which are very likely involved in tissue polarity.