Galectins in the Phylogenetically Oldest Metazoa, the Sponges (Porifera).

Müller, Werner; Blumbach, Barbara; Wagner-Hülsmann, Claudia; Lessel, Uta

doi:10.4052/tigg.9.123

Cited by 31 publications

(15 citation statements)

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“…It is important for the understanding of the silicatein function that S. domuncula galectin-2 is able to self-associate in the presence of Ca 2ϩ ; this property already has been described earlier for the G. cydonium galectin (41). Also in G. cydonium, galectin is a dominant protein in the mesohyl (41,43), which forms in the presence of Ca 2ϩ ions three-dimensional self-associates, with sizes of Ͼ1 m. Because the native S. domuncula galectin-2 is a glycoprotein, we assume that this self-association is due to the binding of the galactose-binding domain to the carbohydrate side chains within galectin-2, as shown for the G. cydonium galectin. The second molecule expressed in S. domuncula after exposure to silicate is collagen.…”

Section: Discussionmentioning

confidence: 67%

Co-expression and Functional Interaction of Silicatein with Galectin

Schröder

Boreiko

Korzhev

et al. 2006

Journal of Biological Chemistry

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128

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Sponges (phylum Porifera) of the class of Demospongiae are stabilized by a siliceous skeleton. It is composed of silica needles (spicules), which provide the morphogenetic scaffold of these metazoans. In the center of the spicules there is an axial filament that consists predominantly of silicatein, an enzyme that catalyzes the synthesis of biosilica. By differential display of transcripts we identified additional proteins involved in silica formation. Two genes were isolated from the marine demosponge Suberites domuncula; one codes for a galectin and the other for a fibrillar collagen. The galectin forms aggregates to which silicatein molecules bind. The extent of the silicatein-mediated silica formation strongly increased if associated with the galectin. By applying a new and mild extraction procedure that avoids hydrogen fluoride treatment, native axial filaments were extracted from spicules of S. domuncula. These filaments contained, in addition to silicatein, the galectin and a few other proteins. Immunogold electron microscopic studies underscored the role of these additional proteins, in particular that of galectin, in spiculogenesis. Galectin, in addition to silicatein, presumably forms in the axial canal as well as on the surface of the spicules an organized net-like matrix. In the extraspicular space most of these complexes are arranged concentrically around the spicules. Taken together, these additional proteins, working together with silicatein, may also be relevant for potential (nano)-biotechnological applications of silicatein in the formation of surface coatings. Finally, we propose a scheme that outlines the matrix (galectin/silicatein)-guided appositional growth of spicules through centripetal and centrifugal synthesis and deposition of biosilica.The members of the phylum Porifera (sponges) are grouped according to their mineral skeleton into three classes: Hexactinellida and Demospongiae, which comprise a siliceous skeleton, and Calcarea, with calcareous skeletal materials (1). The elements constituting these skeletons are termed spicules; they are used as systematic characters for a given sponge species (2). Given the comprehensive studies of Bütschli (3) and Minchin (4), a descriptive view of the formation of the siliceous spicules has been well established. In demosponges, where most studies have been performed with Suberites domuncula, spicules are initially formed within specialized cells called sclerocytes (5). S. domuncula has the advantage of containing only macroscleres (tylostyles/oxeas), whereas most other sponges, e.g. Tethya aurantium, contain macroscleres (oxeas) as well as microscleres (spherasters) (6). Spicules have in their center a 1-2-m-wide axial canal (7), which contains the axial filament. In demosponges first siliceous deposits are arranged around this axial filament. When spicules reach lengths of about 10 m they are extruded from the cells. The spicules are completed extracellularly in the mesohyl (8), where they reach final sizes of 10 m (microscleres) and 200 m (mac...

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Section: Discussionmentioning

confidence: 67%

Co-expression and Functional Interaction of Silicatein with Galectin

Schröder

Boreiko

Korzhev

et al. 2006

Journal of Biological Chemistry

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128

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“…The cDNAs of two isoforms of the galectins from G. cydonium were cloned (Pfeifer et al, 1993;Wagner-Hü lsmann et al, 1996). The predicted proteins deduced from the complete sequences display high similarity with the corresponding molecules from vertebrates and Caenorhabditis elegans (Hirabayashi and Kasai, 1993;Mü ller et al, 1997). The deduced aa sequences of the two isoforms feature the characteristic carbohydrate-recognition domain at LHFNPR-G-V-N-W-E-R[H]-PF (the amino acids [aa] given in bold are those directly involved in binding to the carbohydrate); this domain is conserved from sponge to human (Pfeifer et al, 1993) (Fig.…”

Section: Cell-cell Adhesion Moleculesmentioning

confidence: 99%

Towards an understanding of the molecular basis of immune responses in sponges: The marine demospongeGeodia cydonium as a model

Müller

Koziol

Müller

et al. 1999

Microsc. Res. Tech.

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The phylogenetic position of the phylum Porifera (sponges) is near the base of the kingdom Metazoa. During the last few years, not only rRNA sequences but, more importantly, cDNA/genes that code for proteins have been isolated and characterized from sponges, in particular from the marine demosponge Geodia cydonium. The analysis of the deduced amino acid sequences of these proteins allowed a molecular biological approach to the question of the monophyly of the Metazoa. Molecules of the extracellular matrix/basal lamina, with the integrin receptor, fibronectin, and galectin as prominent examples, and of cell‐surface receptors (tyrosine kinase receptor), elements of sensory systems (crystallin, metabotropic glutamate receptor) as well as homologs/modules of an immune system (immunoglobulin‐like molecules, scavenger receptor cysteine‐rich [SRCR]‐ and short consensus repeats [SCR]‐repeats), classify the Porifera as true Metazoa. As living fossils, provided with simple, primordial molecules allowing cell‐cell and cell‐matrix adhesion as well as processes of signal transduction as known in a more complex manner from higher Metazoa, sponges also show pecularities not known in later phyla. In this paper, the adhesion molecules presumably involved in the sponge immune system are reviewed; these are the basic adhesion molecules (galectin, integrin, fibronectin, and collagen) and especially the highly polymorphic adhesion molecules, the receptor tyrosine kinase as well as the polypeptides comprising scavenger receptor cysteine‐rich (SRCR) and short consensus repeats (SCR) modules. In addition, it is reported that in the model sponge system of G. cydonium, allogeneic rejection involves an upregulation of phenylalanine hydroxylase, an enzyme initiating the pathway to melanin synthesis. Microsc. Res. Tech. 44:218–236, 1999. © 1999 Wiley‐Liss, Inc.

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“…The extraspicular environment is relatively poor in cells but rich in bulky extracellular matrix proteins, consisting of galectins as the dominant adhesion molecules. Galectin molecules form a gel‐like scaffold in the presence of Ca 2+ [62], and this in turn provides a fluid/stable dynamic matrix for the highly mobile ‘wandering cells’. Therefore, the environment of the spicules is highly suitable as a platform for cells transporting metabolites and also water.…”

Section: Hardening Of Biosilica – An Essential Step During Spicule Fomentioning

confidence: 99%

Silicateins, silicatein interactors and cellular interplay in sponge skeletogenesis: formation of glass fiber‐like spicules

et al. 2012

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Biomineralization processes are characterized by controlled deposition of inorganic polymers ⁄ minerals mediated by functional groups linked to organic templates. One metazoan taxon, the siliceous sponges, has utilized these principles and even gained the ability to form these polymers ⁄ minerals by an enzymatic mechanism using silicateins. Silicateins are the dominant protein species present in the axial canal of the skeletal elements of the siliceous sponges, the spicules, where they form the axial filament. Silicateins also represent a major part of the organic components of the silica lamellae, which are cylindrically arranged around the axial canal. With the demosponge Suberites domuncula as a model, quantitative enzymatic studies revealed that both the native and the recombinant enzyme display in vitro the same biosilica-forming activity as the enzyme involved in spicule formation in vivo. Monomeric silicatein molecules assemble into filaments via fractal intermediates, which are stabilized by the silicatein-interacting protein silintaphin-1. Besides the silicateins, a silica-degrading enzyme silicase acting as a catabolic enzyme has been identified. Growth of spicules proceeds in vivo in two directions: first, by axial growth, a process that is controlled by evagination of cell protrusions and mediated by the axial filament-associated silicateins; and second, by appositional growth, which is driven by the extraspicular silicateins, a process that provides the spicules with their final size and morphology. This radial layer-by-layer accretion is directed by organic cylinders that are formed around the growing spicule and consist of galectin and silicatein. The cellular interplay that controls the morphogenetic processes during spiculogenesis is outlined.

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Galectins in the Phylogenetically Oldest Metazoa, the Sponges (Porifera).

Cited by 31 publications

References 0 publications

Co-expression and Functional Interaction of Silicatein with Galectin

Co-expression and Functional Interaction of Silicatein with Galectin

Towards an understanding of the molecular basis of immune responses in sponges: The marine demospongeGeodia cydonium as a model

Silicateins, silicatein interactors and cellular interplay in sponge skeletogenesis: formation of glass fiber‐like spicules

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