What makes the spermatogonial stem cells (SSCs) self-renew or differentiate to produce spermatozo... more What makes the spermatogonial stem cells (SSCs) self-renew or differentiate to produce spermatozoa is barely understood, in particular in nonmammalian species. Our research explores possible regulations of the SSC niche in teleost, locally by paracrine factors and peripherally by hormonal regulation. In the present study, we focus on the Gdnf-Gfra1 pathway that plays a major role in the regulation of SSC self-renewal in mammals. We describe a complex evolution of the genes encoding for Gdnf and Gfra1 proteins in trout with the emergence of three gdnf and two gfra1 paralogs. Using quantitative PCR measurements in isolated testicular cell populations, the gdnfb paralog was found expressed in A-spermatogonia and probably in another testicular cell type. In contrast, the transcript of gfra1a, the Gdnf receptor, was preferentially expressed in a population of undifferentiated A-spermatogonia (und A-Spg) separated by centrifugal elutriation. These und A-Spg also demonstrated high stemness...
The Journal of steroid biochemistry and molecular biology, Jan 31, 2000
Androgens and especially 11-oxygenated androgens are known to be potent masculinizing steroids in... more Androgens and especially 11-oxygenated androgens are known to be potent masculinizing steroids in fish. As a first step to study their physiological implication in gonadal sex differentiation in fish, we cloned a testicular cytochrome P450(11beta) (11beta-hydroxylase) cDNA in the rainbow trout, Oncorhynchus mykiss. We isolated a 1882 bp P450(11beta) cDNA (rt11betaH2, AF217273) which contains an open reading frame encoding a 552 putative amino acids protein. This sequence was highly homologous (98% in nucleotides and 96.5% in amino acids) to another rainbow trout P450(11beta) sequence (AF179894) and also to a Japanese eel P450(11beta) (68% in amino acids). Northern blot analysis detected a single transcript of 2 kb which was highly expressed in the testis (stage II) and to a lesser degree in the anterior kidney (containing the interrenal tissue). No signal was detected in the posterior kidney, brain, liver, skin, intestine and heart. In the testis this transcript was highly expressed...
Journal of reproduction and fertility. Supplement, 1998
Two glutathione peroxidase genes (gpx5 and gpx3) were found to be expressed in the mouse epididym... more Two glutathione peroxidase genes (gpx5 and gpx3) were found to be expressed in the mouse epididymis. Gpx5 was shown to be epididymis specific and restricted to the caput epididymidis, while gpx3 was found to be expressed in a wide array of tissues including the caput, corpus and cauda epididymides. Both single copy genes are regulated by androgens as well as being developmentally regulated during postnatal ontogenesis of the epididymis. In this report data collected to date concerning the mechanisms by which these genes are regulated in the mouse epididymis are summarized. The putative roles of these antioxidant enzymes in the sperm maturation process are discussed.
Journal of reproduction and fertility. Supplement, 1998
Vitamin A is required to maintain the epididymal epithelium. In this report, the characterization... more Vitamin A is required to maintain the epididymal epithelium. In this report, the characterization and putative functions of a murine epididymal retinoic acid-binding protein (mE-RABP) that is secreted into the lumen from the mid-/distal caput epididymidis are discussed. The amino acid sequence analysis of the mE-RABP preprotein shows that mE-RABP is the mouse orthologue of the rat epididymal secretory protein I (ESPI). These proteins belong to the lipocalin superfamily and bind to active retinoids but not to retinol. Therefore, we propose that mE-RABP may function as an extracellular retinoid carrier-protein involved in the paracrine regulation of epididymal function by retinoids.
The murine epididymal retinoic acid-binding protein (mE-RABP) is specifically synthesized in the ... more The murine epididymal retinoic acid-binding protein (mE-RABP) is specifically synthesized in the mouse mid/distal caput epididymidis and secreted in the lumen. In this report, we have demonstrated by Southern blot analysis of genomic DNA that mE-RABP is encoded by a single-copy gene. A mouse 129/SvJ genomic bacterial artificial chromosome (BAC) library was screened using a cDNA encoding the minor form of mE-RABP. One positive BAC clone was characterized and sequenced to determine the nucleotide sequence of the entire mE-RABP gene. The molecular cloning of the mE-RABP gene completes the characterization of the 20.5-kDa-predicted preprotein leading to the minor and major forms of mE-RABP. Comparison of the DNA sequence of the promoter and coding regions with that of the rat epididymal secretory protein I (ESP I) gene showed that the mE-RABP gene is the orthologue of the ESP I gene that encodes a rat epididymal retinoic acid-binding protein. Several regulatory elements, including a put...
We have reported earlier the cloning and the chromosomal localization of 2 GPX-encoding sequences... more We have reported earlier the cloning and the chromosomal localization of 2 GPX-encoding sequences expressed differentially within the mouse epididymis, gpx5 and gpx3. Here, we have mapped on the mouse chromosomes the third known murine GPX-encoding gene, the cytosolic GPX or gpx1. We have compared the degree of identity of the 3 GPX proteins, the respective organization of the 3 corresponding single copy genes and, using degenerated oligonucleotides designed in highly conserved domains of the proteins, we have analyzed the expression of GPX-encoding genes in the mouse epididymis as well as in control tissues known to express GPX proteins (the liver for GPX1 and the kidney for GPX3). The 3 genes characterized to date were found expressed in each of the tissues tested but in a highly tissue-restricted manner. Nucleotidic sequences comparisons were carried out on GPX-encoding sequences from various species and were used to draw a dendrogram. Phylogenetic evaluation of the sequence info...
We have shown in earlier studies, using a mouse model, that the expression of the glutathione per... more We have shown in earlier studies, using a mouse model, that the expression of the glutathione peroxidase 5 protein (GPX5) is restricted to the epididymis and that the accumulation of its corresponding mRNA is hormonally, spatially and temporally regulated throughout postnatal development. We report here, using run-on assays, transient expression experiments as well as gel-shift and footprinting analyses on the findings that at least part of the androgenic control of the GPX5 expression is exerted at the transcriptional level via an androgen response element localized in the distal promoter region of the GPX5 gene. The gpx5 androgen response element (ARE) is found to be consistent with the consensus palindromic steroid-receptor target sequence 5'-AGWACWnnnTGTYCT-3' but exhibits a quite weak conservation in the left half site. The data presented here further expand the diversity of sequence able to confer androgen responsiveness.
The gonadotropin releasing hormone (GnRH) has long been considered as a neuropeptide involved in ... more The gonadotropin releasing hormone (GnRH) has long been considered as a neuropeptide involved in the control of the reproductive cycle. However, the presence of GnRH and its receptors in various tissues, including ovary and testis, suggests a role as autocrine/paracrine factor. In the present study, we report the expression of the sGnRH-1 and sGnRH-2 genes encoding salmon GnRH in rainbow trout testis throughout testicular development and spermatogenesis. We demonstrate that both sGnRH mRNA are expressed prior of sexual differentiation. In adult, northern blot analysis indicates that sGnRH-2 transcripts are expressed in the testis at higher levels than sGnRH-1 messengers. Moreover, we observed that the expression of sGnRH-2, and not sGnRH-1, messengers was stage-dependent. sGnRH-2 mRNA expression decreases at the onset and progressively rebounds at the end of spermatogenesis. In addition, we demonstrate that a complex stage-dependent and differential splicing of the sGnRH-2 messengers occurs throughout spermatogenesis. We isolated five transcripts corresponding to sGnRH-2 messengers. Two of them may encode a novel and shortened GnRH-associated peptide containing 18 residues instead of 46. Our data provide new insight in the putative role of GnRH and GAP peptides as autocrine/paracrine factors of spermatogenesis.
This report presents data that suggest that the tissue-restricted polyoma enhancer activator prot... more This report presents data that suggest that the tissue-restricted polyoma enhancer activator protein (PEA3) of the Ets oncogene family of DNA-binding proteins is a putative modulator of the epididymis-specific glutathione peroxidase 5 gene gpx5. Northern and polymerase chain reactions on reverse-transcribed epididymal RNAs were used to show that the PEA3 factor is spatially and temporally expressed within the mouse epididymis in a manner consistent with gpx5 characteristics of expression. Then, using contransfection experiments carried out in heterologous tissue-culture cells with various deletions of the gpx5 promoter driving a CAT reporter gene, we have shown that the transcriptional activity of the gpx5 promoter is modulated by the presence of the PEA3 protein. Subsequently, we have shown using gel-shift assays that DNA sequences located within the 5' flanking region of the gpx5 gene have the ability to bind specifically to the PEA3 protein. Finally, using Northern assays we present data that suggest that PEA3 mRNA accumulation in the mouse caput epididymidis is controlled by androgens and testicular factors. Altogether, these results strongly suggest that the PEA3 factor might participate in the transcriptional control of the murine epididymis caput-specific gpx5 gene.
It is well admitted that thyroid hormones (TH) play a role in the development of vertebrates. The... more It is well admitted that thyroid hormones (TH) play a role in the development of vertebrates. The major secretory product of the thyroid is a pro-hormone, T(4), which is activated in peripheral tissues by outer ring deiodination to T(3). We have isolated from rainbow trout testis, a full length cDNA encoding type II iodothyronine deiodinase (rtD2). The cDNA was 2410 nucleotides long and coded for a polypeptide of 264 amino acids including a selenocysteine residue. The predicted molecular weight of rtD2 was 29.3 kDa and the isoelectric point 8.71. The deduced amino acids sequence showed 80% identity with Fundulus heteroclitus D2 (fhD2) but only 68-69% identity with rat, mouse, and human D2. The 3' UTR contained a putative selenocysteine insertion sequence (SECIS) similar to that described in human cDNA. The rtD2 gene was isolated and the gene structure was similar to that described in human with two exons separated by a large intron. We studied rtD2 gene expression by Northern blot analysis using total RNA extracted from testis, ovary, and other tissues. We found a high expression of a 3 kb transcript in liver and in gonads. A lower expression was also detected in posterior kidney. In testis, rtD2 mRNA expression was dependent on spermatogenic stages: it increased at the onset of spermatogenesis. Our results show that the structural characteristics of the D2 protein and gene have been highly conserved during evolution. The rtD2 mRNA expression in the gonads suggests that rtD2 may be a key factor regulating local supply of active T(3) during rainbow trout gametogenesis.
The general rules established from mammalian species for the regulation of spermatogenesis by gon... more The general rules established from mammalian species for the regulation of spermatogenesis by gonadotropins may not be fully relevant in fish. Particularly, Fsh is as potent as Lh to stimulate steroidogenesis and the Fsh receptor is expressed in Leydig cells. In seasonal breeders, Fsh is likely the major gonadotropin involved in spermatogenesis onset and Lh is required to support spermatogenesis progression and gamete release. However, the genes that relay the action of Fsh and Lh have been poorly investigated in fish. The present study was aimed at identifying gonadotropin-dependent genes expressed in the testis during fish puberty. We cultured pubertal trout testicular explants for 96 h, with or without gonadotropin, and analyzed transcriptome variations using microarrays. Fsh and Lh had similar effects on a large group of genes while other genes were preferentially regulated by one or the other gonadotropin. We showed that most of the responsive genes were expressed in somatic ce...
In vertebrates, gonadotropins (GTHs) (FSH and LH) are two circulating pituitary glycoprotein horm... more In vertebrates, gonadotropins (GTHs) (FSH and LH) are two circulating pituitary glycoprotein hormones that play a major role in the regulation of gonadal functions, including gonadal cell proliferation/differentiation and steroidogenesis. In mammals, it is well known that their biological effects are mediated by highly specific membrane-bound receptors expressed preferentially on the somatic cells of the gonads. However, in fish, binding and functional studies have shown that cross-reactivity may occur in GTH receptors depending on the species. To understand the molecular mechanisms involved in GTH actions, functional characterization of trout GTH receptors and their gonadal gene expression pattern has been carried out. The present study describes the presence of two distinct GTH receptors in trout showing similarities with those of higher vertebrates but also differences in their structural determinants. In vitro functional studies demonstrate that rtLH specifically activates its c...
A complementary DNA encoding the mouse epididymal secretory protein MEP 10 (mouse epididymal prot... more A complementary DNA encoding the mouse epididymal secretory protein MEP 10 (mouse epididymal protein 10) was cloned and is now renamed murine epididymal retinoic acid binding protein (mE-RABP). The analysis of the predicted primary amino acid sequence showed that mE-RABP has a 75% identity with rat ESP I (epididymal secretory protein I), another epididymal retinoic acid-binding protein. The homology strongly suggests that mE-RABP is the mouse orthologue of rat ESP I. A computer analysis of the predicted three-dimensional structure confirmed that mE-RABP can accommodate retinoic acid as ligand. In the rat, ESP I messenger RNA (mRNA) is expressed in the efferent ducts and in the entire caput epididymidis. However, in the mouse, the expression of a 950-bp mE-RABP mRNA was detected only in principal cells of the mid/distal caput epididymidis, suggesting that the regulation of region-specific expression is different in rat and mouse. Northern blot analyses showed that mE-RABP gene expres...
What makes the spermatogonial stem cells (SSCs) self-renew or differentiate to produce spermatozo... more What makes the spermatogonial stem cells (SSCs) self-renew or differentiate to produce spermatozoa is barely understood, in particular in nonmammalian species. Our research explores possible regulations of the SSC niche in teleost, locally by paracrine factors and peripherally by hormonal regulation. In the present study, we focus on the Gdnf-Gfra1 pathway that plays a major role in the regulation of SSC self-renewal in mammals. We describe a complex evolution of the genes encoding for Gdnf and Gfra1 proteins in trout with the emergence of three gdnf and two gfra1 paralogs. Using quantitative PCR measurements in isolated testicular cell populations, the gdnfb paralog was found expressed in A-spermatogonia and probably in another testicular cell type. In contrast, the transcript of gfra1a, the Gdnf receptor, was preferentially expressed in a population of undifferentiated A-spermatogonia (und A-Spg) separated by centrifugal elutriation. These und A-Spg also demonstrated high stemness...
The Journal of steroid biochemistry and molecular biology, Jan 31, 2000
Androgens and especially 11-oxygenated androgens are known to be potent masculinizing steroids in... more Androgens and especially 11-oxygenated androgens are known to be potent masculinizing steroids in fish. As a first step to study their physiological implication in gonadal sex differentiation in fish, we cloned a testicular cytochrome P450(11beta) (11beta-hydroxylase) cDNA in the rainbow trout, Oncorhynchus mykiss. We isolated a 1882 bp P450(11beta) cDNA (rt11betaH2, AF217273) which contains an open reading frame encoding a 552 putative amino acids protein. This sequence was highly homologous (98% in nucleotides and 96.5% in amino acids) to another rainbow trout P450(11beta) sequence (AF179894) and also to a Japanese eel P450(11beta) (68% in amino acids). Northern blot analysis detected a single transcript of 2 kb which was highly expressed in the testis (stage II) and to a lesser degree in the anterior kidney (containing the interrenal tissue). No signal was detected in the posterior kidney, brain, liver, skin, intestine and heart. In the testis this transcript was highly expressed...
Journal of reproduction and fertility. Supplement, 1998
Two glutathione peroxidase genes (gpx5 and gpx3) were found to be expressed in the mouse epididym... more Two glutathione peroxidase genes (gpx5 and gpx3) were found to be expressed in the mouse epididymis. Gpx5 was shown to be epididymis specific and restricted to the caput epididymidis, while gpx3 was found to be expressed in a wide array of tissues including the caput, corpus and cauda epididymides. Both single copy genes are regulated by androgens as well as being developmentally regulated during postnatal ontogenesis of the epididymis. In this report data collected to date concerning the mechanisms by which these genes are regulated in the mouse epididymis are summarized. The putative roles of these antioxidant enzymes in the sperm maturation process are discussed.
Journal of reproduction and fertility. Supplement, 1998
Vitamin A is required to maintain the epididymal epithelium. In this report, the characterization... more Vitamin A is required to maintain the epididymal epithelium. In this report, the characterization and putative functions of a murine epididymal retinoic acid-binding protein (mE-RABP) that is secreted into the lumen from the mid-/distal caput epididymidis are discussed. The amino acid sequence analysis of the mE-RABP preprotein shows that mE-RABP is the mouse orthologue of the rat epididymal secretory protein I (ESPI). These proteins belong to the lipocalin superfamily and bind to active retinoids but not to retinol. Therefore, we propose that mE-RABP may function as an extracellular retinoid carrier-protein involved in the paracrine regulation of epididymal function by retinoids.
The murine epididymal retinoic acid-binding protein (mE-RABP) is specifically synthesized in the ... more The murine epididymal retinoic acid-binding protein (mE-RABP) is specifically synthesized in the mouse mid/distal caput epididymidis and secreted in the lumen. In this report, we have demonstrated by Southern blot analysis of genomic DNA that mE-RABP is encoded by a single-copy gene. A mouse 129/SvJ genomic bacterial artificial chromosome (BAC) library was screened using a cDNA encoding the minor form of mE-RABP. One positive BAC clone was characterized and sequenced to determine the nucleotide sequence of the entire mE-RABP gene. The molecular cloning of the mE-RABP gene completes the characterization of the 20.5-kDa-predicted preprotein leading to the minor and major forms of mE-RABP. Comparison of the DNA sequence of the promoter and coding regions with that of the rat epididymal secretory protein I (ESP I) gene showed that the mE-RABP gene is the orthologue of the ESP I gene that encodes a rat epididymal retinoic acid-binding protein. Several regulatory elements, including a put...
We have reported earlier the cloning and the chromosomal localization of 2 GPX-encoding sequences... more We have reported earlier the cloning and the chromosomal localization of 2 GPX-encoding sequences expressed differentially within the mouse epididymis, gpx5 and gpx3. Here, we have mapped on the mouse chromosomes the third known murine GPX-encoding gene, the cytosolic GPX or gpx1. We have compared the degree of identity of the 3 GPX proteins, the respective organization of the 3 corresponding single copy genes and, using degenerated oligonucleotides designed in highly conserved domains of the proteins, we have analyzed the expression of GPX-encoding genes in the mouse epididymis as well as in control tissues known to express GPX proteins (the liver for GPX1 and the kidney for GPX3). The 3 genes characterized to date were found expressed in each of the tissues tested but in a highly tissue-restricted manner. Nucleotidic sequences comparisons were carried out on GPX-encoding sequences from various species and were used to draw a dendrogram. Phylogenetic evaluation of the sequence info...
We have shown in earlier studies, using a mouse model, that the expression of the glutathione per... more We have shown in earlier studies, using a mouse model, that the expression of the glutathione peroxidase 5 protein (GPX5) is restricted to the epididymis and that the accumulation of its corresponding mRNA is hormonally, spatially and temporally regulated throughout postnatal development. We report here, using run-on assays, transient expression experiments as well as gel-shift and footprinting analyses on the findings that at least part of the androgenic control of the GPX5 expression is exerted at the transcriptional level via an androgen response element localized in the distal promoter region of the GPX5 gene. The gpx5 androgen response element (ARE) is found to be consistent with the consensus palindromic steroid-receptor target sequence 5'-AGWACWnnnTGTYCT-3' but exhibits a quite weak conservation in the left half site. The data presented here further expand the diversity of sequence able to confer androgen responsiveness.
The gonadotropin releasing hormone (GnRH) has long been considered as a neuropeptide involved in ... more The gonadotropin releasing hormone (GnRH) has long been considered as a neuropeptide involved in the control of the reproductive cycle. However, the presence of GnRH and its receptors in various tissues, including ovary and testis, suggests a role as autocrine/paracrine factor. In the present study, we report the expression of the sGnRH-1 and sGnRH-2 genes encoding salmon GnRH in rainbow trout testis throughout testicular development and spermatogenesis. We demonstrate that both sGnRH mRNA are expressed prior of sexual differentiation. In adult, northern blot analysis indicates that sGnRH-2 transcripts are expressed in the testis at higher levels than sGnRH-1 messengers. Moreover, we observed that the expression of sGnRH-2, and not sGnRH-1, messengers was stage-dependent. sGnRH-2 mRNA expression decreases at the onset and progressively rebounds at the end of spermatogenesis. In addition, we demonstrate that a complex stage-dependent and differential splicing of the sGnRH-2 messengers occurs throughout spermatogenesis. We isolated five transcripts corresponding to sGnRH-2 messengers. Two of them may encode a novel and shortened GnRH-associated peptide containing 18 residues instead of 46. Our data provide new insight in the putative role of GnRH and GAP peptides as autocrine/paracrine factors of spermatogenesis.
This report presents data that suggest that the tissue-restricted polyoma enhancer activator prot... more This report presents data that suggest that the tissue-restricted polyoma enhancer activator protein (PEA3) of the Ets oncogene family of DNA-binding proteins is a putative modulator of the epididymis-specific glutathione peroxidase 5 gene gpx5. Northern and polymerase chain reactions on reverse-transcribed epididymal RNAs were used to show that the PEA3 factor is spatially and temporally expressed within the mouse epididymis in a manner consistent with gpx5 characteristics of expression. Then, using contransfection experiments carried out in heterologous tissue-culture cells with various deletions of the gpx5 promoter driving a CAT reporter gene, we have shown that the transcriptional activity of the gpx5 promoter is modulated by the presence of the PEA3 protein. Subsequently, we have shown using gel-shift assays that DNA sequences located within the 5' flanking region of the gpx5 gene have the ability to bind specifically to the PEA3 protein. Finally, using Northern assays we present data that suggest that PEA3 mRNA accumulation in the mouse caput epididymidis is controlled by androgens and testicular factors. Altogether, these results strongly suggest that the PEA3 factor might participate in the transcriptional control of the murine epididymis caput-specific gpx5 gene.
It is well admitted that thyroid hormones (TH) play a role in the development of vertebrates. The... more It is well admitted that thyroid hormones (TH) play a role in the development of vertebrates. The major secretory product of the thyroid is a pro-hormone, T(4), which is activated in peripheral tissues by outer ring deiodination to T(3). We have isolated from rainbow trout testis, a full length cDNA encoding type II iodothyronine deiodinase (rtD2). The cDNA was 2410 nucleotides long and coded for a polypeptide of 264 amino acids including a selenocysteine residue. The predicted molecular weight of rtD2 was 29.3 kDa and the isoelectric point 8.71. The deduced amino acids sequence showed 80% identity with Fundulus heteroclitus D2 (fhD2) but only 68-69% identity with rat, mouse, and human D2. The 3' UTR contained a putative selenocysteine insertion sequence (SECIS) similar to that described in human cDNA. The rtD2 gene was isolated and the gene structure was similar to that described in human with two exons separated by a large intron. We studied rtD2 gene expression by Northern blot analysis using total RNA extracted from testis, ovary, and other tissues. We found a high expression of a 3 kb transcript in liver and in gonads. A lower expression was also detected in posterior kidney. In testis, rtD2 mRNA expression was dependent on spermatogenic stages: it increased at the onset of spermatogenesis. Our results show that the structural characteristics of the D2 protein and gene have been highly conserved during evolution. The rtD2 mRNA expression in the gonads suggests that rtD2 may be a key factor regulating local supply of active T(3) during rainbow trout gametogenesis.
The general rules established from mammalian species for the regulation of spermatogenesis by gon... more The general rules established from mammalian species for the regulation of spermatogenesis by gonadotropins may not be fully relevant in fish. Particularly, Fsh is as potent as Lh to stimulate steroidogenesis and the Fsh receptor is expressed in Leydig cells. In seasonal breeders, Fsh is likely the major gonadotropin involved in spermatogenesis onset and Lh is required to support spermatogenesis progression and gamete release. However, the genes that relay the action of Fsh and Lh have been poorly investigated in fish. The present study was aimed at identifying gonadotropin-dependent genes expressed in the testis during fish puberty. We cultured pubertal trout testicular explants for 96 h, with or without gonadotropin, and analyzed transcriptome variations using microarrays. Fsh and Lh had similar effects on a large group of genes while other genes were preferentially regulated by one or the other gonadotropin. We showed that most of the responsive genes were expressed in somatic ce...
In vertebrates, gonadotropins (GTHs) (FSH and LH) are two circulating pituitary glycoprotein horm... more In vertebrates, gonadotropins (GTHs) (FSH and LH) are two circulating pituitary glycoprotein hormones that play a major role in the regulation of gonadal functions, including gonadal cell proliferation/differentiation and steroidogenesis. In mammals, it is well known that their biological effects are mediated by highly specific membrane-bound receptors expressed preferentially on the somatic cells of the gonads. However, in fish, binding and functional studies have shown that cross-reactivity may occur in GTH receptors depending on the species. To understand the molecular mechanisms involved in GTH actions, functional characterization of trout GTH receptors and their gonadal gene expression pattern has been carried out. The present study describes the presence of two distinct GTH receptors in trout showing similarities with those of higher vertebrates but also differences in their structural determinants. In vitro functional studies demonstrate that rtLH specifically activates its c...
A complementary DNA encoding the mouse epididymal secretory protein MEP 10 (mouse epididymal prot... more A complementary DNA encoding the mouse epididymal secretory protein MEP 10 (mouse epididymal protein 10) was cloned and is now renamed murine epididymal retinoic acid binding protein (mE-RABP). The analysis of the predicted primary amino acid sequence showed that mE-RABP has a 75% identity with rat ESP I (epididymal secretory protein I), another epididymal retinoic acid-binding protein. The homology strongly suggests that mE-RABP is the mouse orthologue of rat ESP I. A computer analysis of the predicted three-dimensional structure confirmed that mE-RABP can accommodate retinoic acid as ligand. In the rat, ESP I messenger RNA (mRNA) is expressed in the efferent ducts and in the entire caput epididymidis. However, in the mouse, the expression of a 950-bp mE-RABP mRNA was detected only in principal cells of the mid/distal caput epididymidis, suggesting that the regulation of region-specific expression is different in rat and mouse. Northern blot analyses showed that mE-RABP gene expres...
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