Mouse Ten-m/Odz Is a New Family of Dimeric Type II Transmembrane Proteins Expressed in Many Tissues

Abstract

The Drosophila gene ten-m/odz is the only pair rule gene identified to date which is not a transcription factor. In an attempt to analyze the structure and the function of ten-m/odz in mouse, we isolated four murine ten-m cDNAs which code for proteins of 2,700–2,800 amino acids. All four proteins (Ten-m1–4) lack signal peptides at the NH2 terminus, but contain a short hydrophobic domain characteristic of transmembrane proteins, 300–400 amino acids after the NH2 terminus. About 200 amino acids COOH-terminal to this hydrophobic region are eight consecutive EGF-like domains.Cell transfection, biochemical, and electronmicroscopic studies suggest that Ten-m1 is a dimeric type II transmembrane protein. Expression of fusion proteins composed of the NH2-terminal and hydrophobic domain of ten-m1 attached to the alkaline phosphatase reporter gene resulted in membrane-associated staining of the alkaline phosphatase. Electronmicroscopic and electrophoretic analysis of a secreted form of the extracellular domain of Ten-m1 showed that Ten-m1 is a disulfide-linked dimer and that the dimerization is mediated by EGF-like modules 2 and 5 which contain an odd number of cysteines.Northern blot and immunohistochemical analyses revealed widespread expression of mouse ten-m genes, with most prominent expression in brain. All four ten-m genes can be expressed in variously spliced mRNA isoforms. The extracellular domain of Ten-m1 fused to an alkaline phosphatase reporter bound to specific regions in many tissues which were partially overlapping with the Ten-m1 immunostaining. Far Western assays and electronmicroscopy demonstrated that Ten-m1 can bind to itself.

Drosophila odz gene is required for multiple cell types in the compound retina

“…Unlike our model, type II models for Odz/Tenm proteins have also been proposed by other groups (Oohashi et al, 1999;Rubin et al, 1999). They model a short N terminal portion of the protein as intracellular, followed by a highly hydrophobic region considered a transmembrane domain (as opposed to a signal peptide region by our analysis) and a large, C-terminal extracellular, globular portion (Oohashi et al, 1999).…”

“…They model a short N terminal portion of the protein as intracellular, followed by a highly hydrophobic region considered a transmembrane domain (as opposed to a signal peptide region by our analysis) and a large, C-terminal extracellular, globular portion (Oohashi et al, 1999). According to this model, it is possible to expect a failure of necessary dimerization mediated by extracellular domains (Feng et al, 2002) in the large C-terminal truncation we carried out.…”

“…odz is the archetype of a family of genes found in all metazoans (e.g., Wilson et al, 1994;Wang et al, 1998;Oohashi et al, 1999;Otaki and Firestein, 1999;Rubin et al, 1999;Mieda et al, 1999;Brandau et al, 1999;Ben-Zur et al, 2000), also implicated in pattern formation in development. The first non-Drosophilan Odz/Tenm mutations, mouse Odz4 alleles that lead to failure in gastrulation and somite formation, and a small deletion of the Caenorhabditis elegans ortholog that leads to embryo arrest among early defects (Lossie et al, 2005;Drabikowski et al, 2005), support this family's necessity for proper metazoan patterning.…”

Untitled

“…The Ten M family is a new protein family that was first discovered in Drosophila 1 and later also in many other animals such as C. elegans 2 , chicken 3 , mouse 4 , rat 5 , zebrafish 3 , and human 6 . Ten M proteins are about 2500-3000 amino acids in length.…”

“…In the type II proteins, the Cterminus is the extracellular part and, in the Ten M family, it consists of three specific domains, namely tenascin-type EGF-like repeats, a cysteine rich domain called CC-domain, and several repetitive motifs of tyrosine and aspartic acid residues, called YD-repeats. The intracellular N-terminal part contains about 150-400 amino acids 4,7 . The sequences of Ten M proteins show high homology to the extracellular matrix molecule tenascin, a major vertebrate extracellular matrix glycoprotein.…”