A six‐armed, tenascin‐like protein extracted from the Porifera Oscarella tuberculata (Homosclerophorida)

Abstract

A six-armed complex could be extracted from the marine sponge Osccrrellu tuberculuta by a two-step incubation, first in Tris-buffered saline containing EDTA, then in Tris-buffered saline containing urea. The crude extracts contained, in addition, collagen fibrils with surface filaments, individual filaments resembling collagen molecules, and laminidnidogen-like complexes. The extracts were subsequently purified by gel-filtration chromatography and low-pressure ion-exchange chromatography on DEAE-cellulose, then analyzed by SDS/PAGE and iinmunoblotting methods. A glycoprotein of high molecular mass was isolated, and reduced to subunits of 230 kDa. After transfer to nitrocellulose, both the complex and its subunits were faintly stained by antibodies against amphibian tenascin. Electron microscopy of the purified extracts demonstrated the presence of a large population of tenascin-like molecules and complexes of several molecules interacting with each other by their central globule.Tenascin (also known as hexabrachion, cytotactin, J1, myotendinous antigen) is a large extracellular-matrix glycoprotein containing six similar disulfide-linked subunits which give the protein a characteristic six-armed structure when visualized by electron microscopy ([l-31 for review). It has a distinctive tissue distribution during development [4, 51 and several reports described both its adhesive and anti-adhesive properties (reviewed in [6, 71). Recent studies indicate that the promoter of the tenascin gene contains target regions responding to homeodomain proteins, suggesting that tenascin could be a morphoregulatory molecule 18, 91. However, the crucial role of tenascin during development has been questioned by recent data. Homologous recombination experiments produced mutant mice in which tenascin gene expression was disrupted, but the homozygous null-mutant mice had apparently no defect [lo], at least under resting conditions.Tenascin has been characterized in several vertebrate groups, including Amphibians [ll]. Its presence has been also demonstrated in leech, where it promotes neurite outgrowth [12, 131. Tenascin-like proteins have been localized in sea-urchin embryos [14], and two genes related to tenascin have been detected in Drusophilu: Ten' [15] and Ten"' (Baumgartner, S . , unpublished results).In the course of our research program on the evolution of the extracellular matrix, we have investigated the presence of basement-membrane molecules in Porifera. The Porifera constitute the most primitive phylum of multicellular animals. They possess an extended extracellular matrix [16] containing at least two types of collagen [17-191, However, a group of marine sponges, the Homosclerophorida, possess laminae underlying their epithelia which resemble basement membranes [23]. These sponges have a simplified organization which is sometimes considered as a result of an evolutionary process [24]. Pieces of Oscurellu where treated in order to extract laminin, an adhesive glycoprotein of basement membranes, according to an efficie...

Molecular evolution of integrins: Genes encoding integrin β subunits from a coral and a sponge

“…There have been suggestions of integrin-like proteins in the cnidarian Hydra, based on immunological data and inhibition studies using Arg-Gly-Asp (RGD) peptides (17)(18)(19). In the most primitive metazoan phylum, the Porifera (sponges), there have been no good experimental suggestions of integrins, but some extracellular matrix proteins similar to those from vertebrates have been identified, including collagens and a tenascin-like molecule (20)(21)(22)(23)(24). With these facts in mind, we set out to identify genes encoding integrin-related proteins from primitive metazoans.…”

Characterization of the Bovine Tenascin-X

“…These proteins are widely encountered in the animal kingdom (1,2). In invertebrates, tenascin-like molecules were demonstrated in leech (3) and in Porifera, the most primitive phylum of multicellular organism (4). In Drosophila, two molecules related to tenascins, coded by the genes ten a and ten m , were characterized (5,6).…”

Self-nonself recognition: genomic and transcriptomic insights from the sponge aggregation factors

“…To the best of my knowledge, the presence of AFs and cellular reaggregation functionality has not been investigated in homoscleromorph sponges to date. Humbert-David and Garrone (1993) reported the presence in O. tuberculata of a circular molecule closely resembling the circular core AF structure; however, it is unknown whether this represents a true AF, and if so, whether the underlying protein sequence is similar to that in C. prolifera and other characterised species.…”

“…AFs are sponge specific (Srivastava et al 2010) extracellular proteoglycans (Fernàndez-Busquets and Burger 2003), that are linear in Halichondria bowerbankii, H. (Humphreys et al 1977;Müller et al 1978a;Jarchow et al 2000), but which exhibit a novel 'sunburst'-like confirmation in C. prolifera (), Clathria parthena, Geodia cydonium and Oscarella tuberculata (Cauldwell et al 1973;Henkart et al 1973;Müller and Zahn 1973;Humphreys et al 1975;1977;Humbert-David and Garrone 1993;Jarchow et al 2000) ( arms, respectively, of each ring (Jarchow et al 2000). Attached glycan subunits are an integral mediator of AF binding (Misevic and Finne 1987;Misevic and Burger 1990a;1990b;, although some binding ability also appears to reside in the AF protein backbone (Jarchow et al 2000).…”

“…AFs from Halichondria panicea (Jarchow et al 2000), Halichondria bowerbankii (Humphreys et al 1977), Haliclona oculata (Humphreys et al 1977), Suberites domuncula (Müller et al 1978a), Suberites (formerly Ficulina) ficus (Jarchow et al 2000) and Terpios zeteki (Humphreys et al 1977) are linear, and very similar in appearance to other classical proteoglycans (Fernàndez-Busquets and Burger 2003). Conversely, AFs from Clathria (formerly Microciona) prolifera (CpAFs) (Humphreys et al 1975;1977;Jarchow et al 2000), Clathria parthena , Geodia cydonium (Müller and Zahn 1973), and Oscarella tuberculata (Humbert-David and Garrone 1993) display a sunburst-like morphology with a circularised backbone that is otherwise very similar to the linear form. The circular, sunburst-like proteoglycan form appears to be unique to sponges (Fernàndez-Busquets and Burger 2003) and therefore is either a convergent trait, the result of secondary loss in a number of species whose ancestor possessed both forms, or it represents the ancestral AF form that was subsequently linearised in several demosponge clades.…”