Role of phospholipase A2 in the stimulation of sponge cell proliferation by homologous lectin

Gramzow, Monika; Schröder, Heinz C.; Fritsche, U.; Kurelec, Branko; Robitzki, Andrea A.; Zimmermann, Herbert; Friese, Klaus; Kreuter, Matthias; Müller, Wernér E.G.

doi:10.1016/0092-8674(89)90616-8

Cited by 40 publications

(15 citation statements)

References 45 publications

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“…A sponge 68-kDa protein also bound to CS and HA [122]. The AF from G. cydonium is tightly associated with glycosyltransferases [131,132], lectins [88,133,134], and a series of different glycoproteins [121,135]. Polyclonal antibodies raised against purified AF from G. cydonium inhibited cell aggregation of homologous cells but not of heterologous Tethya lyncurium cells CMLS, Cell.…”

Section: General Structure Of Afsmentioning

confidence: 99%

Circular proteoglycans from sponges: first members of the spongican family

Fernàndez‐Busquets

Burger

2003

Cellular and Molecular Life Sciences (CMLS)

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Species-specific cell adhesion in marine sponges is mediated by a new family of modular proteoglycans whose general supramolecular structure resembles that of hyalectans. However, neither their protein nor their glycan moieties have significant sequence homology to other proteoglycans, despite having protein subunits equivalent to link proteins and to proteoglycan monomer core proteins, and glycan subunits equivalent to hyaluronan and to the glycosaminoglycans of hyalectans. In some species, these molecular components are assembled into a structure with a circular core formed by the link protein- and hyaluronan-like subunits. Besides their involvement in cell adhesion, these sponge proteoglycans, for which we propose the term spongicans, participate in signal transduction processes and are suspected to play a role in sponge self-nonself recognition. Their in vivo roles and the mild methods used to purify large amounts of functionally active spongicans make them ideal models to study the functions and possible new applications of proteoglycans in biomedical research.

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Section: General Structure Of Afsmentioning

confidence: 99%

Circular proteoglycans from sponges: first members of the spongican family

Fernàndez‐Busquets

Burger

2003

Cellular and Molecular Life Sciences (CMLS)

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“…The assay mixture for determination of phospholipase A2 activity (substrate: l-acyl-2-[l-'4C]arachidonylglycerophosphoethanolamine) was composed as described previously [34]. The released fatty acid was extracted and quantitated as described [35].…”

Section: Enzyme Assaysmentioning

confidence: 99%

Purification and characterization of a pore‐forming protein from the marine sponge Tethya lyncurium

Mangel

Leitão

Batel³

et al. 1992

European Journal of Biochemistry

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A pore-forming protein was detected and purified for the first time from a marine sponge (Tethyu lyncurium). The purified protein has a polypeptide molecular mass of 21 kDa and a pf of 6.4. Tethyu pore-forming protein (also called Tethya hemolysin) rapidly lysed erythrocytes from a variety of organisms. After binding to target membranes, the hemolysin resisted elution with EDTA, salt or solutions of low ionic strength and hence resembled an integral membrane protein. Erythrocytes could be protected from hemolysis induced by Tethya hemolysin by addition of 30 mM dextran 4 (4-6 kDa; cquivalent hydrodynamic diffusion radius, 1.75 -2.3 nm) to the extracellular medium, but not by addition of uncharged molecules of smaller size [sucrose, raffinose and poly(ethy1ene glycol) 1550; equivalent hydrodynamic diffusion radii, 0.46,0.57 and 1.2 nm, respectively]. This result indicates that hemolysin is able to form stable transmembrane pores with an effective diameter of about 2-3 nm. Treatment of osmotically protected erythrocytes with Tethya hemolysin caused a rapid efflux of intracellular K f and ATP, and a rapid influx of extracellularly added CaZ+ and sucrose. In negative-staining electron microscopy, target erythrocyte membranes exposed to purified Tethya hemolysin displayed ultrastructural lesions but without visible pores.

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“…This fact touches upon some interesting evolutionary aspects. While previous studies revealed that G. cydonium contains cDNA for insulin [3] and calpactin ( [42] and unpublished results) with a high similarity to the corresponding cDNA from human (similarity > 60%) the high degree of similarity of sponge ras to D. discoideum ras was surprising. This finding again raises the question of the positioning of the Dictyostelidae within the subclass of Acrasiomycetes and in particular the relation of them to the Mesozoa [43].…”

Section: Resultsmentioning

confidence: 80%

Regulated expression and phosphorylation of the 23–26‐kDa ras protein in the sponge Geodia cydonium

Robitzki¹,

Schröder²,

Ugarković³

et al. 1990

European Journal of Biochemistry

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We have cloned, sequenced and examined the sponge Geodia cydonium cDNA encoding a protein homologous to ras proteins. The sponge ras protein has a more conserved N-terminal region and a less conserved Cterminal region, especially in comparison to Dictyostelium discoideum; the similarity to human c-Ha-ras-I and to Saccharomyces cerevisiae is less pronounced. The sponge ras cDNA comprises five TAG triplets; at the translational level these UAG termination codons are suppressed by a Gln-tRNA. The sponge ras protein was isolated and partially purified (23 -26 kDa) and found to undergo phosphorylation at a threonine moiety, when dissociated cells were incubated in the presence of a homologous aggregation factor and insulin. Insulin-mediated phosphorylation of the ras protein resulted in a decrease in its Kd with GTP from 2 FM to 80 nM. The activated ras protein displayed high GTPase activity if the partially purified protein was incubated with homologous lectin and lectin receptor molecules. These results suggest that in the sponge, ras is activated by the insulin/insulin(insulin-like)-receptor system. This transition enables the ras protein to interact with the lectin-receptor/lectin complex, a process which may ultimately lead to an initiation of an intracellular signal-transduction chain.Sponges are the lowest multicellular eukaryotic organisms. Due to the relatively low specialization and concomitantly to the high differentiation and dedifferentiation potency of the cells, the sponge cell system has proven to be a useful model for studying the mechanism of cell-cell adhesion on molecular level. Results of detailed biochemical and cell biological studies with the main cell-adhesion molecules, the aggregation factor and the aggregation receptor, led to the formulation of the modulation theory of cell adhesion [I].The events of cell adhesion are contingent on a multiplicity of precisely coordinated intracellular signal-transduction pathways. Using the marine sponge Geodia cydonium we showed [2] that during the initial phase of cell-cell contact the aggregation factor causes a rapid stimulation of the phosphatidylinositol pathway, resulting in an activation of protein kinase C and subsequent phosphorylation of DNA topoisomerase 11. As one consequence of these processes, the cells undergo a phase of high-level DNA synthesis. However, at later stages, the aggregation factor loses its mitogenic activity; this function is then taken over by the matrix lectin. During this switch, the lectin receptor associates in the plasma membrane with the ras protooncogene product.In the present study we report that the recently discovered insulin and its receptor molecules in sponges [3] augment the level of phosphorylation of the ras protein, resulting in an increase in its intrinsic GTPase activity in response to an

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Role of phospholipase A2 in the stimulation of sponge cell proliferation by homologous lectin

Cited by 40 publications

References 45 publications

Circular proteoglycans from sponges: first members of the spongican family

Circular proteoglycans from sponges: first members of the spongican family

Purification and characterization of a pore‐forming protein from the marine sponge Tethya lyncurium

Regulated expression and phosphorylation of the 23–26‐kDa ras protein in the sponge Geodia cydonium

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