Epididymal lipocalin-type prostaglandin D2 synthase: identification using mass spectrometry, messenger RNA localization, and immunodetection in mouse, rat, hamster, and monkey

Cloning and primary characterizations of rLcn9, a new member of epididymal lipocalins in rat

Lipocalins are a structurally conserved and diversely functional family of proteins that are of potential importance in epididymis functions. The rat Lcn9 gene was cloned by in silico methods and genome walking based on homology to the rhesus monkey epididymal ESC513 and its polyclonal antisera were prepared. The rat Lcn9 gene is located on chromosome 3p13 spanning 7 exons, contains 2.3 kb and encodes 179 amino acids with a 17-amino acid signal peptide. Northern blot, western blot, and immunohistochemical staining analysis revealed that rat Lcn9 was a novel epididymis-specific gene, expressed selectively in the proximal caput region, influenced by luminal fluid testicular factors. Moreover, Lcn9 protein was modified by N-glycosylation and bound on the postacrosomal domain of caput sperm. In conclusion, the rat Lcn9 exhibited tissue-, region-, and temporal-specific expression patterns and its expression was regulated by luminal testicular factors. Its potential roles in sperm maturation are discussed.

Isolation of lipocalin-type protein from rainbow trout seminal plasma and its localisation in the reproductive system

The lipocalin protein family is a large and diverse group of small extracellular proteins characterised by their ability to bind hydrophobic molecules. In the present study, we describe the isolation procedure for rainbow trout seminal plasma protein, characterised by a moderate migration rate during polyacrylamide gel electrophoresis, providing information regarding its basic features and immunohistochemical localisation. This protein was identified as a lipocalin-type protein (LTP). The molecular mass of LTP was found to be 18 848 Da and it was found to lack any carbohydrate components. Only a few Salmoniformes contain LTP in their seminal plasma. The abundance of LTP in the Sertoli and Leydig cells of the testes of the rainbow trout, as well as in secretory cells of the efferent duct, suggests that this protein is specific for rainbow trout milt, where it acts as a lipophilic carrier protein. Moreover, the specific localisation of LTP in the flagella of the spermatozoa suggests a role for LTP in sperm motility. Further experiments are necessary to identify the endogenous ligands for LTP in rainbow trout seminal plasma and to characterise the binding properties of this protein.

Epididymis-specific lipocalin promoters

Our goal is to decipher which DNA sequences are required for tissue-specific expression of epididymal genes. At least 6 epididymis-specific lipocalin genes are known. These are differently regulated and regionalized in the epididymis. Lipocalin 5 (Lcn5 or mE-RABP) and Lipocalin 8 (Lcn8 or mEP17) are homologous genes belonging to the epididymis-specific lipocalin gene cluster. Both the 5 kb promoter fragment of the Lcn5 gene and the 5.3 kb promoter fragment of the Lcn8 gene can direct transgene expression in the epididymis (Lcn5 to the distal caput and Lcn8 to the initial segment), indicating that these promoter fragments contain important cis-regulatory element(s) for epididymis-specific gene expression. To define further the fragments regulating gene expression, the Lcn5 promoter was examined in transgenic mice and immortalized epididymal cell lines. After serial deletion, the 1.8 kb promoter fragment of the Lcn5 gene was sufficient for tissue-specific and region-specific gene expression in transgenic mice. Transient transfection analysis revealed that a transcription factor forkhead box A2 (Foxa2) interacts with androgen receptor and binds to the 100 bp fragment of the Lcn5 promoter between 1.2 kb and 1.3 kb and that Foxa2 expression inhibits androgen-dependent induction of the Lcn5 promoter activity. Immunohistochemistry indicated a restricted expression of Foxa2 in the epididymis where endogenous Lcn5 gene expression is suppressed and that the Foxa2 inhibition of the Lcn5 promoter is consistent with the lack of expression of Lcn5 in the corpus and cauda. Our approach provides a basic strategy for further analysis of the epididymal lipocalin gene regulation and flexible control of epididymal function.

Differential Gene Expression among the Proximal Segments of the Rat Epididymis Is Lost after Efferent Duct Ligation1

The epididymis has traditionally been divided into the caput, corpus, and cauda regions, which are further organized into intraregional segments. In the rat and mouse, these segments have high degrees of transcriptional differentiation, and what has traditionally been called the initial segment of the rat epididymis actually consists of three transcriptionally different intraregional segments. These segments are regulated by endocrine, lumicrine, and paracrine factors, whose relative importance remains a topic of investigation. In the present study, 15-day unilateral efferent duct ligation (EDL) was used to deprive ipsilateral rat epididymides of lumicrine regulation. Segments 1-4 of EDL epididymides and contralateral, sham-operated tissues were collected individually. Microarray analysis of gene expression was used to determine the effect of lumicrine factor deprivation on the transcriptome-wide gene expression of each segment studied. More than 11 000 genes were detected as being expressed in each of the four segments examined. More than 2000 genes responded significantly to EDL in segment 1, although this number of genes declined in each succeeding segment. Segments 1 and 2 of control tissues were the most different transcriptionally and the most affected by EDL. In the absence of lumicrine factors, the four segments regressed to a transcriptionally undifferentiated state, which was consistent with the less-differentiated histology seen after EDL. Interestingly, for an individual gene, lumicrine factor deprivation could stimulate expression in some segments and suppress expression in other segments. These results reveal a higher complexity to the regulation of rat epididymal segments than heretofore appreciated.

Epididymis-specific promoter-driven gene targeting: a transcription factor which regulates epididymis-specific gene expression

Mammalian spermatozoa undergo several modification and finally acquire the ability to fertilize during epididymal transit. One of the distinct features of the epididymis is that it displays a highly regionalized pattern of gene expression. This tissue-, region-, and cell-specific pattern of gene expression is critical for the maintenance of a fully functional epididymis. One would hypothesize that disrupting this process provides an ideal approach to male contraception, since it would not interfere with testicular endocrine output or sperm production. To achieve this purpose, we studied a cluster of epididymis-specific lipocalin genes for understanding the specific mechanisms involved in the control of gene expression in the epididymis. We have identified six epididymis-specific lipocalin genes that are differently regulated and regionalized in the epididymis. Lipocalin 5 [Lcn5 or epididymal retinoic acid-binding protein (E-RABP)] is a member of this epididymis-specific lipocalin gene cluster, which binds hydrophobic molecules such as retinoic acid. We have previously shown that the 5kb promoter fragment of the Lcn5 gene confers both androgen-dependent regulation and epididymis-specific gene expression in transgenic mice whereas 0.6 kb promoter fragment does not. To further narrow down the important cis-regulatory elements that regulate gene expression in the epididymis, we studied the Lcn5 promoter in both transgenic mice and immortalized epididymal cells. We have found that 1.8kb promoter fragment of the Lcn5 gene was sufficient for tissue- and region-specific expression in transgenic mice, and that a transcription factor Forkhead box A2 (Foxa2) interacts with the androgen receptor and binds to the 100 bp fragment of the Lcn5 promoter between 1.2 and 1.3 kb. Our finding provides a framework for further analysis of the epididymal lipocalin gene regulation and modulated control of epididymis-specific expression.

Molecular cloning and tissue distribution of microsomal-1 and cytosolic prostaglandin E synthases in macaque

Prostaglandins derived from arachidonic acid are involved in a wide variety of physiological and pathological processes. The primary enzymes involved in the production of PGE2 from arachidonic acid are cyclooxygenases and prostaglandin E synthases. These enzymes have been identified in human, but only partially in the monkey where microsomal PGES-1 and cytosolic PGES have not been characterized. The present study was undertaken to clone these enzymes and to study their tissue distribution, along with mPGES-2. The coding sequence of Macaque mPGES-1 is 98% homologous to human mPGES-1 at the nucleic acid level and the deduced amino acid sequence has 98% homology with the human protein. The Macaque cPGES cDNA is more than 99% homologous to the human and the deduced amino acids sequence is identical to that of the human cPGES. By Northern blot analysis, we found that mPGES-2 and cPGES mRNA were expressed in the endometrium, myometrium, ovary and oviduct, albeit at different levels, while mPGES-1 mRNA was detected at a weak level, mainly in the oviduct. Western Blot analysis revealed that mPGES-2, mPGES-1 and cPGES proteins were present in all tissues tested. These results suggest that production of PGE2 in Macaque may involve more than one PGES and that further studies will be needed to fully understand the conditions under which each PGES contributes to PGE2 production.

Molecular evolution of epididymal lipocalin genes localized on mouse chromosome 2

We previously identified two murine secretory proteins, mE-RABP(Lcn5) and mEP17(Lcn8), belonging to the lipocalin family and specifically expressed in the epididymis. The genes are contiguous and localized on mouse chromosome 2. We now show that five other related lipocalin genes, Lcn9, Lcn10, Lcn11, Lcn12, and Lcn13, that evolved by in situ tandem duplication are present on the same locus. Lcn9, Lcn10, Lcn12, and Lcn13 genes, like Lcn5 and Lcn8 genes, are specifically expressed in the mouse epididymis. However, each gene has a distinct spatial expression within the epididymis and different regulation. Analysis of the human genome sequence shows the presence of genes encoding lipocalins with genomic organization, chromosomal arrangement, and orientation similar to that of the corresponding murine genes, indicating that the epididymal cluster is evolutionary conserved. A phylogenetic analysis of the new epididymal proteins reveals their spread position in the lipocalin protein family tree. This suggests the preservation of the regulatory sequences, while protein sequences have greatly diverged, reflecting functional diversity and possibly multifunctionality. In terms of the cluster ancestry, epididymal expression possibly appeared in a PGDS-like lipocalin in amniotes, and the duplications generating the cluster occurred at least in the common ancestor of rodents and primates. The presence and conservation of a cluster of five genes encoding epididymal lipocalins, differently regulated and regionalized in the epididymis, strongly suggests that these proteins may play an important role for male fertility.

Expression and Regulation of Lipocalin-Type Prostaglandin D Synthase in Rat Testis and Epididymis1

Lipocalin-type prostaglandin D synthase (L-PGDS), a bifunctional protein, is expressed in the male reproductive organs of many species. However, the expression and regulation of L-PGDS in rat are still uncertain. The present study investigated the regionalization and regulation of L-PGDS expression in rat testis and epididymis by in situ hybridization and immunohistochemistry under the conditions of sexual maturation, castration, and ethylene dimethane sulfonate (EDS) treatments. In sexually mature rats, L-PGDS mRNA was weakly expressed only in the testicular peritubular cells, whereas L-PGDS immunostaining was highly detected in the Leydig cells by Day 70 postpartum. During sexual maturation, L-PGDS mRNA expression was highly detected in the caput, corpus, and cauda of the epididymis 70 days after birth. Compared with normal L-PGDS expression in adult epididymis, both L-PGDS mRNA expression and protein immunostaining were significantly reduced in the caput, corpus, and cauda epididymis after castration. Testosterone propionate treatment induced a significant increase of L-PGDS expression in the epididymis of castrated rats. Compared with adult rat epididymis, L-PGDS mRNA and protein expression was down-regulated after EDS treatment. Testosterone propionate treatment could induce an increase of L-PGDS mRNA and protein expression in the epididymis of EDS-treated rats. In conclusion, both castration and EDS treatments caused a significant decrease of L-PGDS expression in the epididymis, whereas testosterone propionate treatment could induce an increase of L-PGDS expression in the epididymis of both castrated and EDS-treated rats, indicating that L-PGDS expression in the rat epididymis can be up-regulated by testosterone.

Protein Profiling in Brain Tumors Using Mass Spectrometry

PURPOSE

The purpose of this research was to perform a preliminary assessment of protein patterns in primary brain tumors using a direct-tissue mass spectrometric technique to profile and map biomolecules.

EXPERIMENTAL DESIGN

We examined 20 prospectively collected, snap-frozen normal brain and brain tumor specimens using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS), and compared peptide and protein expression in primary brain tumor and nontumor brain tissues.

RESULTS

MS can be used to identify protein expression patterns in human brain tissue and tumor specimens. The mass spectral patterns can reliably identify glial neoplasms of similar histological grade and differentiate them from tumors of different histological grades as well as from nontumor brain tissues. Initial bioinformatics cluster analysis algorithms classified tumor and nontumor tissues into similar groups comparable with their histological grade.

CONCLUSIONS

We describe a novel tool for the analysis of protein expression patterns in human glial neoplasms. Initial results demonstrate that MALDI-MS technology can significantly aid in the process of unraveling and understanding the molecular complexities of gliomas. MALDI-MS accurately and reliably identified normal and neoplastic tissues, and could be used to discriminate between tumors of increasing grades.

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.