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The MDC family of proteins and their processing during epididymal transit
J Frayne1, J A Jury, H L Barker
1Department of Biochemistry, University of Bristol, School of Medical Sciences, UK.
Abstract:
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.
Insights
Metalloproteinase-like domain-containing (MDC) proteins in macaque sperm are processed during epididymal transit. Mature sperm retain disintegrin domains, suggesting a role in fertilization, similar to rodent counterparts.
Area of Science:
- Reproductive Biology
- Molecular Biology
- Proteomics
Background:
- Metalloproteinase-like domain-containing (MDC) proteins are integral membrane proteins with conserved domains.
- These proteins are found in various mammalian tissues, notably the male reproductive tract.
- Previous studies cloned and sequenced MDC transcripts from macaque testes.
Purpose of the Study:
- To localize MDC proteins (fertilin alpha, fertilin beta, tMDC I, tMDC II, tMDC III) in macaque reproductive tissues.
- To investigate the processing and localization of these MDC proteins during sperm maturation.
- To explore the potential role of macaque sperm MDC proteins in fertilization.
Main Methods:
- Cloning and sequencing of MDC transcripts from macaque testes.
- Immunolocalization using polyclonal antisera to identify protein locations.
- Analysis of protein processing during sperm passage through the epididymis.
Main Results:
- Several MDC proteins were localized to spermatogenic cells in macaque testes.
- MDC proteins undergo processing as spermatozoa move through the epididymis.
- Mature macaque spermatozoa retain the disintegrin domain of specific MDC proteins.
Conclusions:
- MDC proteins are expressed and processed in the macaque male reproductive tract.
- The retention of disintegrin domains on mature sperm suggests a role in fertilization.
- Macaque sperm MDC proteins may mediate egg recognition via disintegrin-integrin interactions, similar to rodent models.