Biomedical subjects

J A Jury

Publications and source records attributed to J A Jury.

9 recordsLinked to original sources

PubMed1999

Transcripts encoding the sperm surface protein tMDC II are non-functional in the human.

Five members of the MDC (metalloproteinase-like,disintegrin-like cysteine-rich domain) family of proteins (fertilin alpha, fertilin beta, tMDC I, tMDC II and tMDC III) are expressed on the surface of macaque (Macaca fascicularis) sperm, where they have been proposed to play a role in sperm-egg binding via an interaction between their disintegrin-like domain and one or more integrins on the egg plasma membrane. Of these, two (fertilin alpha and tMDC I) have recently been shown to be non-functional in the human. Here we report the existence of multiple isoforms of human tMDC II transcripts in the human, all of which are also non-functional owing to the presence of deletions and in-frame termination codons, when compared with the macaque orthologue, a finding which is further supported by the lack of immunoreactivity on Western blots of human testis and sperm extracts probed with a macaque anti-tMDC II polyclonal antiserum. These results are discussed in the context of our proposed model for multiple proteins implicated in sperm-egg interactions.

ADAM Proteins↗

PubMed1999

Identification, sequence analysis and expression of transcripts encoding a putative metalloproteinase, eMDC II, in human and macaque epididymis.

The metalloproteinase-like, disintegrin-like, cysteine-rich (MDC) family is a large group of sequence-related proteins, first characterized in the male reproductive tract, but subsequently also identified in non-reproductive tissues. Their primary translation products are of approximately 90 kDa and each can be divided into distinct domains which show remarkable homology to reprolysins; snake venom haemorrhagic components possessing metalloproteinase and/or disintegrin domains. Several MDC proteins are abundantly-expressed in the male reproductive tract, suggesting functions in fertility. We now describe the cloning, sequence determination and characterization of transcripts encoding the human and macaque (Macaca fascicularis) orthologues of a novel member of the MDC family (eMDC II) which is abundantly-expressed in the epididymis. Unlike many MDC proteins expressed in the reproductive tract, eMDC II possesses the extended 'catalytic centre' consensus sequence characteristic of a reprolysin-like metalloproteinase. This suggests that eMDC II has proteolytic activity.

ADAM Proteins↗

PubMed1998

The majority of human glutathione peroxidase type 5 (GPX5) transcripts are incorrectly spliced: implications for the role of GPX5 in the male reproductive tract.

An epididymis-specific, secretory glutathione peroxidase (GPX5) has been proposed previously to play a role in protecting mammalian sperm membranes from the deleterious effects of lipid peroxidation, which, if not contained, can lead to reduced fertilizing capacity. Here we report the cDNA cloning of human GPX5 and show that the majority of transcripts contain a 118 nt frame-shifting deletion, arising, most likely, from inappropriate excision of exon 3 during processing. Antisera raised against recombinant human GPX5 cross-reacted with rat and macaque (Macaca fascicularis) epididymal proteins of the size expected for full-length, active GPX5. However, no similar reactivity could be demonstrated in any of the human samples tested.

ATP-Binding Cassette Transporters↗

PubMed1998

Sequence analysis of a variety of primate fertilin alpha genes: evidence for non-functional genes in the gorilla and man.

The sperm surface fertilin complex was first described in the guinea pig where it was found as a heterodimer of alpha and beta subunits, both of which were proposed to play a role in sperm-oolemma recognition and plasma membrane fusion during fertilisation. Whilst the beta subunit is apparently testis-specific, the finding of low levels of fertilin alpha in nonreproductive tissues has cast some doubt on a unique role in fertilisation. Moreover, the absence of a functional fertilin alpha gene in the human would imply that this gene product is not absolutely essential for fertilisation, although it could play a facilitatory role. We now describe the organisation and sequence of the fertilin alpha genes in a range of primates, including the great apes, and find that the gorilla gene, like that of the human, is non-functional.

ADAM Proteins↗

PubMed1998

Macaque MDC family of proteins: sequence analysis, tissue distribution and processing in the male reproductive tract.

A large number of sequence-related, cysteine-rich membrane proteins containing metalloproteinase-like and disintegrin-like domains (the MDC protein family) have been identified in mammalian tissues from a variety of species. Previous studies in the macaque (Macaca fascicularis) have led to the cDNA cloning and sequence analysis of a number of MDC proteins which are abundantly expressed in the male reproductive tract. We now describe the distribution of seven of these macaque MDC transcripts in a range of different tissues. This description includes a novel macaque testis-derived MDC, tMDC III, whose full-length sequence is reported for the first time. In addition, polyclonal antisera have been used to localize a number of these MDC proteins to spermatogenic cells in testis sections, and to demonstrate their processing on the sperm surface during epididymal transit.

ADAM Proteins↗

PubMed1998

The MDC family of proteins and their processing during epididymal transit.

All members of the MDC family of integral membrane proteins contain a metalloproteinase-like domain, a disintegrin-like domain and a cysteine-rich domain. They have been identified in a wide range of mammalian tissues and many are abundantly expressed in the male reproductive tract. We have previously cloned and sequenced several MDC transcripts expressed in the testes of the macaque (Macaca fascicularis). Using polyclonal antisera we have localized a number of these MDC proteins (fertilin alpha, fertilin beta, tMDC I, tMDC II and tMDC III) to spermatogenic cells and demonstrated that they are processed as spermatozoa pass through the epididymis, yielding proteins that retain their disintegrin domain on mature, fertilization-competent cauda spermatozoa. In rodents, two of these MDC proteins (fertilin beta and tMDC I) have been implicated in egg recognition, mediated by a disintegrin-integrin interaction. It is possible that the additional MDC proteins expressed on macaque spermatozoa may also be involved in this process.

Animals↗

PubMed1997

The human fertilin alpha gene is non-functional: implications for its proposed role in fertilization.

In the guinea-pig, the alpha subunit of the fertilin complex, a heterodimeric surface membrane glycoprotein found on the head region of spermatozoa, has previously been proposed to mediate membrane fusion with the oolemma plasma membrane during fertilization. Here we describe experiments which indicate that the only fertilin alpha-like gene in humans is an expressed, but nonfunctional, pseudogene, possibly derived by genetic recombination between the two fertilin alpha genes found in some primates. This finding clearly raises questions about the importance and/or role of fertilin alpha in mammalian fertilization.

ADAM Proteins↗

PubMed1997

Rat MDC family of proteins: sequence analysis, tissue distribution, and expression in prepubertal and adult rat testis.

Increasing number of sequence-related cysteine-rich membrane proteins containing metalloproteinase-like and disintegrin-like domains (the MDC protein family) have been identified in mammalian tissues. Here, we report the cloning and sequence analysis of cDNAs encoding several rat orthologues of this protein family, some of which are found to be expressed exclusively in the male reproductive tract, others exhibiting a broader tissue distribution. We also examine their expression in prepubertal an adult rat testis, which, in conjunction with the data on tissue distribution, form a necessary prelude to further studies aimed at establishing their individual functions.

ADAM Proteins↗

PubMed1997

Cloning and sequence analysis of rat fertilin alpha and beta--developmental expression, processing and immunolocalization.

Fertilin alpha and beta are members of the MDC (metalloproteinase-like, disintegrin-like, cysteine-rich) protein family and are expressed on the sperm surface where they have been proposed to play a role in mammalian fertilization. Inhibition of sperm-oocyte binding and sperm-oocyte fusion make fertilin an attractive target for the development of an immunocontraceptive vaccine. Full-length cDNAs encoding alpha and beta fertilin subunits were isolated from a rat testis cDNA library and sequenced. Using reverse transcription-polymerase chain reaction (RT-PCR), the developmental expression of fertilin alpha and beta was determined in pre-pubertal and mature rat testes. Fertilin alpha mRNA was present at all stages of development, suggesting that it is not exclusively expressed in post-meiotic germ cells. In contrast, fertilin beta mRNA was first identified in day 19 testes, coincident with the presence of pachytene spermatocytes. Polyclonal antisera raised against a 28-residue peptide (corresponding to part of the disintegrin domain) and two recombinant fusion proteins identified a 90 kDa protein in testicular sperm extracts and a 60 kDa protein in caput and cauda epididymidal sperm extracts, the predicted sizes for rat fertilin beta precursor and mature protein respectively. Indirect immunofluorescence using the anti-peptide antisera stained the acrosomal cap of permeabilized testicular, caput and caudal spermatozoa and elongating spermatids in testicular sections.

ADAM Proteins↗