Cloning and expression of new receptors belonging to the immunoglobulin superfamily from the marine sponge Geodia cydonium

Abstract

A cDNA encoding a receptor tyrosine kinase (RTK) was previously cloned and expressed from the marine sponge (Porifera) Geodia cydonium. In addition to the two intracellular regions characteristic for RTKs, two immunoglobulin (Ig)-like domains are found in the extracellular part of the sponge RTK. In the present study it is shown that no further Ig-like domain is present in the upstream region of the cDNA as well as of the gene hitherto known from the sponge RTK. Two different full-length cDNAs have been isolated and characterized in the present study, which possess two Ig-like domains, one transmembrane segment, and only a short intracellular part, without a TK domain. The two deduced polypeptides were preliminarily termed sponge adhesion molecules (SAM). The longer form of the SAM, GCSAML, encodes a deduced aa sequence, GCSAML, which comprises in the open reading frame 505 amino acids (aa) and has a calculated Mr of 53911. The short form, GCSAMS, has 313 aa residues and an Mr of 33987. The two Ig-like domains in GCSAML and GCSAMS are highly similar to the corresponding Ig-like domains in the RTKs from G. cydonium; the substitutions on both the aa and nt level are restricted to a few sites. Phylogenetic analyses revealed that the Ig-like domain 1 is similar to the human Ig lambda chain variable region, while the Ig-like domain 2 is related more closely to the human Ig heavy chain variable region. Transplantation experiments (autografting) were performed to demonstrate that the level of expression of the two new genes, GCSAML and GCSAMS, is upregulated during the self/self fusion process. Immunohistochemical analyses using antibodies raised against the two Ig-like domains demonstrate a strong expression in the fusion zone between graft and host. This finding has been supported by northern blotting experiments that revealed that especially GCSAML is strongly upregulated after autografting (up to 12-fold); the expression of GCSAMS reaches a value of 5-fold if compared with the controls. The results presented here demonstrate that the expression of the new molecules described, comprising two Ig-like domains, is upregulated during the process of autograft fusion.

Increased expression of the potential proapoptotic molecule DD2 and increased synthesis of leukotriene B4 during allograft rejection in a marine sponge

“…After this period the allografts show necrotic alterations ( Figure 1D) and are completely rejected after 10 days. 24,44,45 …”

50 million years of chordate evolution: Seeking the origins of adaptive immunity

“…Ig and TCR molecules feature a structural motif comprised of ␤-pleated sheets, known as the ''Ig fold,'' whose archtypical presence in receptors and adhesion molecules through phylum Chordata and even in invertebrates (13,14) dates it before the entrance of RAG. Many investigations have approached the hypothesized primordial receptor by searching for relics of Ig-type molecules in classes of organisms that diverged before agnathans.…”

“…Many investigations have approached the hypothesized primordial receptor by searching for relics of Ig-type molecules in classes of organisms that diverged before agnathans. Sequences isolated from hagfish (15,16), tunicate (17), and sponge (14,18) aligned with canonical Ig domains produce a similarity score that falls into the ''twilight zone'' of questionable See companion article on page 7417. † To whom reprint requests should be addressed.…”

“…Apart from shared general features that support their candidacy as primitive allorecognition receptors, the NITR and PIRtypes of receptor genes are not obviously related, and data acquired to date suggest it is unlikely they are located in syntenic chromosomal regions (G. W. Litman, personal communication). In the ongoing search for non-rearranging Ig-like allorecognition receptors that may predate the TCR and Ig receptors, it is interesting to note the upregulation of two Ig-like receptor molecules at the interface of sponge autografts (14).…”

Cyclosporin A Suspends Transplantation Reactions in the Marine SpongeMicrociona prolifera

“…These include molecules containing scavenger receptor cysteine-rich domains (9), TLRs (10), the 2Ј,5Ј-oligoadenylate synthetase (11), cytokine-like molecules (12), and also factors similar to those produced by cytokine-responsive macrophage molecules such as the allograft inflammatory factor 1 (13). In addition, hallmarks of adaptive immune systems such as Ig-like domains have been identified in sponges (14,15), in some cases exhibiting intraspecific polymorphism (16,17).…”