CCAAT/enhancer binding protein beta regulates expression of the cystatin-related epididymal spermatogenic (Cres) gene

Structural characterization and expression analysis of a novel cysteine protease inhibitor from Haliotis discus hannai Ino

The sequence of the cysteine protease inhibitor gene of Haliotis discus hannai (designated HdCpi) was determined using the RACE method. The full-length HdCpi cDNA is 1049 bp long, and contains an open reading frame of 813 bp, encoding a 271-amino-acid protein with a calculated molecular mass of 29.83 kDa and an isoelectric point of 8.57. The deduced amino acid sequence of HdCpi contains two cystatin-like domains, and each has the structural features of the cystatin family, including three evolutionarily conserved motifs known to interact with the active sites of cysteine peptidases: the Gly residue at the N-terminus (Gly(65) and Gly(160)), the Gln-X-Val-X-Gly motif (Q(106)IVSG(110) and Q(202)VVAG(206)), and the less conserved motif at the C-terminus (S(136)W(137) and A(254)W(255)). Many putative transcription-factor-binding sites involved in the immune system and cancer occur in the promoter region of HdCpi. Quantitative real-time RT-PCR detected HdCpi expression in all the tissues examined and in the gills of abalone challenged with the bacterium Vibrio anguillarum. HdCpi transcripts were expressed in the mantle, gill, digestive tract, hemocytes, and muscle, and increased HdCpi expression was observed after bacterial stimulation. These results suggest that HdCpi is a biologically active protease inhibitor that is likely to be involved in the antibacterial response of the abalone.

Recapitulation of germ cell- and pituitary-specific expression with 1.6 kb of the cystatin-related epididymal spermatogenic (Cres) gene promoter in transgenic mice

The Cres (cystatin-related epididymal spermatogenic) gene encodes the defining member of a new subgroup within the family 2 cystatins of cysteine protease inhibitors. Cres expression is highly tissue- and cell-specific, with messenger RNA (mRNA) present in the testicular round/elongating spermatids, proximal caput epididymal epithelium, gonadotroph cells in the anterior pituitary gland, and corpus luteum of the ovary. To begin to elucidate the molecular mechanisms controlling the tissue- and cell-specific expression of the Cres gene, transgenic mice were generated containing 1.6 kilobases (kb) of the mouse Cres promoter linked to the bacterial chloramphenicol acetyltransferase (CAT) reporter gene. A CAT enzyme-linked immunosorbent assay detected CAT protein in the testis, epididymis, isolated cauda epididymal spermatozoa, and anterior pituitary gland from mice heterozygous and homozygous for the transgene. However, reverse transcription (RT)-PCR did not detect CAT mRNA in any regions of the epididymis, suggesting that the CAT protein detected in the epididymis was from spermatozoa. RT-PCR also did not detect CAT mRNA in the ovary. RT-PCR analysis of the testes from mice of different postnatal ages showed CAT mRNA first detected at day 22, which correlated with the first appearance of Cres mRNA and with the presence of round spermatids. These studies demonstrate that 1.6 kb of Cres promoter contains the DNA elements necessary for germ cell and pituitary gland-specific expression but lacks critical sequences necessary for expression in the epididymis and ovary.

Characterization of Epididymal Epithelial Cell-Specific Gene Promoters by In Vivo Electroporation1

The mammalian epididymis plays a critical role in sperm maturation, a function dependent on testicular androgens. However, the function of the initial segment, the most proximal part of the epididymis, is also dependent on luminal factors of testicular origin. Efferent duct ligation (EDL), which prevents luminal testicular fluid from reaching the epididymis, results in changes in gene expression within this region. Cystatin-related epididymal spermatogenic (cres) gene and gamma-glutamyl transpeptidase (GGT) mRNA IV are highly expressed in the initial segment and are regulated by luminal testicular factors. EDL results in decreased expression of both genes. To evaluate these promoters in the context of their native physiological state, an in vivo electroporation procedure was used. Significant differences were observed in vivo compared to previous in vitro results. Whereas two C/EBP sites were necessary for transcriptional activity from a 135-base-pair (bp) cres promoter in vitro, only the 5' site displayed functional activity in the in vivo system. A 135-bp GGT promoter IV construct was sufficient for reporter gene expression in vitro. However, in vivo, substantial expression was not observed until the construct was extended to 530 bp. Three polyoma enhancer activator 3 (PEA3) sites were found to be necessary for in vivo reporter gene expression from this construct. A cis-acting negative regulatory element between -530 and -681 bp was also identified that was not previously recognized in the in vitro studies. These studies demonstrate the utility of in vivo electroporation for elucidating promoter elements that may not be identified when traditional in vitro methods are used.

Immortalization of epididymal epithelium in transgenic mice expressing simian virus 40 T antigen: characterization of cell lines and regulation of the polyoma enhancer activator 3

In the present study epididymal epithelium was immortalized in transgenic mice by expressing simian virus 40 T antigen under a 5.0-kb mouse glutathione peroxidase 5 promoter (GPX5-Tag1). Epididymal tumorigenesis was associated with an increase in c-Myc expression, and a marked decrease in B-Myc expression, with a 500-fold lower level in the GPX5-Tag1 caput epididymis compared with wild-type caput. Furthermore, B-Myc was undetectable in the immortalized corpus and cauda epididymis. Hence, it is possible that the normally high B-Myc expression in the epididymis is one of the factors contributing to the highly resistant nature of epididymis toward immortalization. Morphologically different epithelial cell lines were generated from the immortalized epididymides, and the cells expressed several genes typical for epididymal epithelium, such as mouse epididymal 1, mouse epididymal protein 9, androgen and estrogen receptors, anion exchangers 2 and 4, retinoic acid receptor alpha, and polyoma enhancer activator 3 (PEA3). This indicated the differentiated status of the cells and their usefulness for analyzing epididymal gene expression in vitro. As PEA3 is considered to be one of the transcription factors responsible for epididymal gene expression, we further studied its regulation in epididymal cells in vitro. The data showed that PEA3 mRNA expression is regulated in the epididymis via protein kinase A and ERK signaling cascades. Inhibiting protein kinase A resulted in up-regulation and inhibiting ERK resulted in down-regulation of PEA3 mRNA, whereas no significant effect on PEA3 expression was found by modulating the protein kinase C, stress-activated p38, phosphoinositol 3-kinase and p70 S6 kinase cascades.

Gene and protein expression in the epididymis of infertile c-ros receptor tyrosine kinase-deficient mice

Transgenic male mice bearing inactive mutations of the receptor tyrosine kinase c-ros lack the initial segment of the epididymis and are infertile. Several techniques were applied to determine differences in gene expression in the epididymal caput of heterozygous fertile (HET) and infertile homozygous knockout (KO) males that may explain the infertility. Complementary DNA arrays, gene chips, Northern and Western blots, and immunohistochemistry indicated that some proteins were downregulated, including the initial segment/proximal caput-specific genes c-ros, cystatin-related epididymal-spermatogenic (CRES), and lipocalin mouse epididymal protein 17 (MEP17), whereas other caput-enriched genes (glutathione peroxidase 5, a disintegrin and metalloproteinase [ADAM7], bone morphogenetic proteins 7 and 8a, A-raf, CCAAT/enhancer binding protein beta, PEA3) were unchanged. Genes normally absent from the initial segment (gamma-glutamyltranspeptidase, prostaglandin D2 synthetase, alkaline phosphatase) were expressed in the undifferentiated proximal caput of the KO. More distally, lipocalin 2 (24p3), CRISP1 (formerly MEP7), PEBP (MEP9), and mE-RABP (MEP10) were unchanged in expression. Immunohistochemistry and Western blots confirmed the absence of CRES in epididymal tissue and fluid and the continued presence of CRES in spermatozoa of the KO mouse. The glutamate transporters EAAC1 (EAAT3) and EAAT5 were downregulated and upregulated, respectively. The genes of over 70 transporters, channels, and pores were detected in the caput epididymidis, but in the KO, only three were downregulated and six upregulated. The changes in these genes could affect sperm function by modifying the composition of epididymal fluid and explain the infertility of the KO males. These genes may be targets for a posttesticular contraceptive.

Cystatin 11: a new member of the cystatin type 2 family

Cystatin (CST)11, a novel member of the CST type 2 family of cysteine protease inhibitors, was identified in Macaca mulatta epididymis by subtractive hybridization cloning. The human CST11 gene on chromosome 20p11.2 is located near three other CST genes expressed predominantly in the male reproductive tract. The CST11 gene spans three exons, a structure similar to that of other CST family 2 genes. An exon 2-deleted alternative transcript (CST11Delta2) was also identified. CST11 mRNA is expressed only in the epididymis as judged by Northern blot hybridization and is androgen regulated. The protein is most abundant in the initial segment, but is detected throughout the epididymis and on ejaculated human sperm. The calculated tertiary structure of CST11 reveals that the three regions corresponding to the protease inhibitory wedge of CST3 are similarly juxtaposed in CST11, consistent with protease inhibitor function. Intact and exon 2-deleted CST11 recombinant proteins were tested for antibacterial activity. After a 2-h incubation of Escherichia coli with 50 microg/ml recombinant CST11 or CST11Delta2, bacterial colony-forming units were reduced to 30% of control, indicating that both forms have antimicrobial activity.