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A number of members belonging to a disintegrin and metalloprotease (ADAM) family of cell surface proteins, including ADAM21, are expressed specifically or predominantly in the mammalian testis. Here, we investigated the transcriptional characteristics of the Adam21 gene. We found that Adam21 produces two types of transcripts with different developmental stages and cellular localizations. One type comprises germ cell-specific transcripts with both exons 1 and 2, while the other type corresponds to exon 2 and is expressed in testicular somatic cells. Further, regulatory and promoter regions responsible for the expression of Adam21 in testicular somatic cells were investigated using an in silico sequence analysis and an in vitro transient transfection assay. We identified an essential promoter and mapped regulatory regions that repress the transcription of Adam21. Finally, we confirmed the expression of Adam21 at the protein level in testicular somatic cells in which the promoter of the gene was found to be active. This is the first study to provide information regarding transcriptional regulation of a testicular ADAM family member, which will aid in elucidation of the transcriptional mechanisms of other testicular Adam genes., (Copyright 2010 Elsevier B.V. All rights reserved.)

Recurrent spontaneous abortion occurs in approximately 3% of women with diagnosed pregnancies. The etiology in approximately 40% of recurrent spontaneous abortion is unexplained. To elucidate unexplained recurrent spontaneous abortion at the molecular level, we systemically identified differentially expressed genes during implantation window period in unexplained recurrent spontaneous abortion and characterized their functions in a human endometrial cell line. Expression levels of implantation-related genes selected from previously reported, various microarray data were determined to identify differentially expressed genes between normal fertile and unexplained recurrent spontaneous abortion subjects by real-time quantitative RT-PCR. Of 29 implantation-related genes, the transcript levels of cellular retinoic acid binding protein 2 and olfactomedin 1 were higher, whereas that of complement component 4 binding protein alpha was lower in subjects with unexplained recurrent spontaneous abortion, compared to normal fertile subjects. A correlation was evident between the transcript and protein levels of complement component 4 binding protein alpha and cellular retinoic acid binding protein 2. Expression of cellular retinoic acid binding protein 2 was positively correlated with retinoic acid-related genes in normal fertile subjects, but no significant association was observed in unexplained recurrent spontaneous abortion subjects. In relation to complement component 4 binding protein alpha, C5a receptor protein level was significantly higher in subjects with unexplained recurrent spontaneous abortion. Stable expression of cellular retinoic acid binding protein 2 and olfactomedin 1 in a human endometrial cell line inhibited cell growth and induced cell accumulation in the S and G(2)-M phase fractions, but did not trigger apoptosis. This study represents the first systematic identification of differentially expressed genes in unexplained recurrent spontaneous abortion. Defective cell growth by the differentially expressed genes suggests their implication in implantation failure in women with unexplained recurrent spontaneous abortion.