Stimulation of protein (collagen) synthesis in sponge cells by a cardiac myotrophin‐related molecule from Suberites domuncula

Abstract

The body wall of sponges (Porifera), the lowest metazoan phylum, is formed by two epithelial cell layers of exopinacocytes and endopinacocytes, both of which are associated with collagen fibrils. Here we show that a myotrophin-like polypeptide from the sponge Suberites domuncula causes the expression of collagen in cells from the same sponge in vitro. The cDNA of the sponge myotrophin was isolated; the potential open reading frame of 360 nt encodes a 120 aa long protein (Mr of 12,837). The sequence SUBDOMYOL shares high similarity with the known metazoan myotrophin sequences. The expression of SUBDOMYOL is low in single cells but high after formation of primmorph aggregates as well as in intact animals. Recombinant myotrophin was found to stimulate protein synthesis by fivefold, as analyzed by incorporation studies using [3H] lysine. In addition, it is shown that after incubation of single cells with myotrophin, the primmorphs show an unusual elongated, oval-shaped appearance. It is demonstrated that in the presence of recombinant myotrophin, the cells up-regulate the expression of the collagen gene. The cDNA for S. domuncula collagen was isolated; the deduced aa sequence shows that the collagenous internal domain is rather short, with only 24 G-x-y collagen triplets. We conclude that the sponge myotrophin causes in homologous cells the same/similar effect as the cardiac myotrophin in mammalian cells, where it is involved in initiation of cardial ventricular hypertrophy. We assume that an understanding of sponge molecular cell biology will also contribute to a further elucidation of human diseases, here of the cardiovascular system.

Molecular Mechanism of Spicule Formation in the Demosponge Suberites domuncula: Silicatein-Collagen-Myotrophin

“…The data presented above demonstrate that at suitable concentrations silicate induces the genes encoding collagen, silicatein and myotrophin. However, the gene induction of silicatein appears to be a complex process, since the morphogen myotrophin induces only the collagen, but not the silicatein gene Schröder et al 2000). This finding supports earlier observations indicating that the formation of collagen fibrils can proceed independently of spicule formation as well as closely connected with this process (reviewed in: Simpson 1984).…”

Co-expression and Functional Interaction of Silicatein with Galectin

“…Three segments can be distinguished: (i) the N-terminal non-collagen region (aa 1 to aa 26 ); (ii) the region comprising the characteristic G-X-Y collagen triple helix repeats (in COLL3_SUBDO 37 triples; aa 27-136 ); and finally (iii) the non-collagen C-terminal part (aa ). This arrangement has been described also for the other collagen proteins from S. domuncula (15,37). Data bank searches revealed that COLL3_SUBDO shares highest sequence similarity to the fibrillar collagen from Haliotis discus (BAA75668 (38)) with E ϭ 8e Ϫ39 and from…”

“…Until now, only genes encoding non-fibrillar collagens had been described in sponges, e.g. as for Ephydatia muelleri (40) or S. domuncula (37). The newly discovered S. domuncula collagen displays the typical structure for fibrillar collagens: the N-peptide, the triple helix segment, and the C-peptide.…”

Sponge Bcl-2 homologous protein (BHP2-GC) confers distinct stress resistance to human HEK-293 cells

“…This cDNA was used for expression in Escherichia coli as described. 53,69 The cDNA was inserted into the bacterial oligohistidine expression vector pQE-32 (Quiagen). E. coli (XL1-blue) were transformed with this plasmid and expression of fusion protein was induced with isopropyl 1-thio-b-Dgalactopyranoside (IPTG).…”