Human membrane cofactor protein (MCP, CD46) has been suggested, although no convincing evidence has been proposed, to be a fertilization-associated protein, in addition to its primary functions as a complement regulator and a measles virus receptor. We have cloned a cDNA encoding the murine homologue of MCP. This cDNA showed 45% identity in deduced protein sequence and 62% identity in nucleotide sequence with human MCP. Its ectodomains were four short consensus repeats and a serine/threonine-rich domain, and it appeared to be a type 1 membrane protein with a 23-amino acid transmembrane domain and a short cytoplasmic tail. The protein expressed on Chinese hamster ovary cell transfectants was 47 kDa on SDS/PAGE immunoblotting, approximately 6 kDa larger than the murine testis MCP. It served as a cofactor for factor I-mediated inactivation of the complement protein C3b in a homologous system and, to a lesser extent, in a human system. Strikingly, the major message of murine MCP was 1.5 kb and was expressed predominantly in the testis. It was not detected in mice defective in spermatogenesis or with immature germ cells (until 23 days old). Thus, murine MCP may be a sperm-dominant protein the message of which is expressed selectively in spermatids during germ-cell differentiation.

AGEs may be factors associated with diabetic periodontitis and may be useful as biomarkers that reflect such deterioration.

Toll-like receptors (TLR) in the innate immune system have not been identified in non-mammalian vertebrates. Two types of TLR were cloned from a chicken bursa cDNA library using degenerate primers based on the consensus sequences of mouse and Drosophila Toll and designated as chicken TLR (chTLR) type 1 and type 2. Of the nine human TLRs reported to date, these chTLRs showed the highest homology to human TLR2. The extracellular regions of type 1 and type 2 contained a distinct ϳ200-amino acid stretch and were 45.3 and 46.3% homologous to that of human TLR2. The intracellular Toll/interleukin-1R homology domain of type 1 and type 2 was perfectly identical to each other and highly homologous (80.7%) to that of human TLR2. Both types were widely detected by reverse transcriptase-polymerase chain reaction and immunoblotting in various chicken organs, especially those rich in connective tissue. Both genes were mapped to chromosome 4q1.1, suggesting that they arose by gene duplication. By reporter gene assay, type 2 and to a lesser extent type 1, selectively signaled the presence of mycoplasma macrophage-activating lipopeptide-2/M161Ag in the human embryonic kidney 293 cell system. Cotransfection of type 2 and human CD14 or MD-2 into human embryonic kidney 293 cells allowed the response to Escherichia coli lipopolysaccharide (LPS), whereas type 1 did not signal LPS or any other microbial components tested. These results indicated that chTLR type 2 covers two major microbe patterns, lipoproteins and LPS, which are regulated by TLR2 and TLR4 in mammals. In oviparous animals, the duplicated TLRs in the pattern-recognition system may function for host-pathogen discrimination in a manner that is distinct from that in mammals.

Human membrane cofactor protein (MCP, CD46) is a ubiquitously expressed protein known to protect cells from complement attack. Interestingly, when we examined the expression of mouse CD46, which we recently cloned, the message was found only in testis and the protein was found on the inner acrosomal membrane of sperm. In order to elucidate the function of CD46, we produced mice carrying a null mutation in the CD46 gene by using homologous recombination. Despite the absence of CD46, the mice were healthy and both sexes were fertile. However, to our surprise, the fertilizing ability of males appeared to be facilitated by disruption of the CD46 gene, as the average number of pups born from CD46 ؊/؊ males was significantly greater than that of wild-type males. It was also revealed that the incidence of the spontaneous acrosome reaction doubled in CD46 ؊/؊ sperm compared to that in wild-type sperm. It was assumed that this increase caused the heightened fertilizing ability found in CD46 ؊/؊ sperm. These data suggest that CD46 may have some role in regulating sperm acrosome reaction.

We studied the MRI appearances of the brain in 159 patients with diabetes mellitus (DM) and 2566 age-matched individuals without DM (controls). The images were reviewed for cerebral infarcts, hemorrhage, atrophy and subcortical arteriosclerotic encephalopathy. Cerebral atrophy was significantly more frequent in patients with DM than in controls (P > 0.005) from the sixth to the eighth decade. The frequency of atrophy was 41.2% in the 6th decade, 60.0% in the 7th and 92.3% in the 8th decade in DM, and 19.8%, 38.9% and 56.8% respectively in controls. Unexpectedly, there was no statistically significant difference in the incidences of cerebrovascular diseases at any age.

Rae1 alpha, Rae1 beta, and Rae1 gamma cDNAs isolated from retinoic acid-treated mouse embryonal carcinoma F9 cells encode cell surface proteins sharing partial homology with MHC class I molecules, and mRNAs corresponding to these cDNAs were detected exclusively in early mouse embryos, especially in the head region. To initiate studies on their roles, the rae1 alpha gene and the genomic DNAs covering the complete coding regions of the rae1 beta and rae1 gamma genes were isolated and their structures were analyzed. Although the coding regions of the three rae1 genes were highly homologous, the restriction map of the 5'-end region of the rae1 alpha gene differed from that of the rae1 beta and rae1 gamma genes. The rae1 family members were mapped by FISH on mouse chromosome 10A4 region. Genomic DNAs hybridizable with a Rae1 cDNA were not detected in rat and human. Rae1 genes were preferentially expressed in early mouse embryos, preferentially in the brain, and RAE1 proteins were anchored on the cell surface by a glycosyl phosphatidylinositol (GPI)-tail, a feature shared by important cell surface ligands.

No abstract

Rae-1 cDNA is one of the retinoic acid (RA) inducible cDNA clones in mouse embryonal carcinoma F9 cells. Rae-1 mRNAs were detected in mouse early embryos, but not in various tissues of adult mice. RAE-1 protein apparently consists of 253 amino acids and is likely to be a glycoprotein consisting of a leader sequence, an extracellular domain, a serine, threonine, proline-rich domain, and a transmembrane domain. Interestingly, it has a weak, but significant homology with major histocompatibility complex (MHC) class I molecules and was immunocytochemically identified as a cell surface protein. By determining partial nucleotide sequences of 17 Rae-1 cDNAs isolated from the RA-induced F9 cells, at least three different kinds of Rae-1 cDNAs were identified and were named Rae-1 alpha, Rae-1 beta, and Rae-1 gamma cDNAs, respectively. As the overall nucleotide sequence homology among these three cDNAs was about 98%, they constitute a novel gene family which is likely to be involved in early mammalian embryogenesis.