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Epididymosomes: a heterogeneous population of microvesicles with multiple functions in sperm maturation and storage

Extracellular microvesicles present in the epididymal fluid have been named epididymosomes. Many epididymosome-associated proteins are transferred to spermatozoa during their maturation in the excurrent duct. Epididymosomes are heterogeneous, with their size varying between 50 and 250 nm. Two distin...

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Autor principal: Sullivan, Robert
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Medknow Publications & Media Pvt Ltd 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4577580/
https://www.ncbi.nlm.nih.gov/pubmed/26112475
http://dx.doi.org/10.4103/1008-682X.155255
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author Sullivan, Robert
author_facet Sullivan, Robert
author_sort Sullivan, Robert
collection PubMed
description Extracellular microvesicles present in the epididymal fluid have been named epididymosomes. Many epididymosome-associated proteins are transferred to spermatozoa during their maturation in the excurrent duct. Epididymosomes are heterogeneous, with their size varying between 50 and 250 nm. Two distinct population of epididymosomes characterized by different protein compositions and diameters have been isolated from the bovine epididymal fluid using different centrifugation protocols. One subpopulation of epididymosomes was characterized by CD9 and other tetraspanin partners. Transfer of proteins from these epididymosomes to maturing spermatozoa in co-incubation experiments was inhibited by antibodies against tetraspanin proteins. This suggests that this subpopulation of epididymosomes is involved in the acquisition of proteins involved in maturation by spermatozoa in the epididymis. The other population of epididymosomes was characterized by ELSPBP1 (epididymal sperm binding protein 1), known for its affinity for the phospholipid choline group. Flow cytometric analyses showed that ELSPBP1-positive epididymosomes only interacted with dying or dead epididymal spermatozoa in a Zn(2 +)-dependent manner. BLVRA (biliverdin reductase) was identified as a partner of ELSPBP1. This enzyme reduces biliverdin to bilirubin: two molecules with powerful anti-oxidant properties. We hypothesize that BLVRA is involved in an ROS-scavenging mechanism protecting live epididymal spermatozoa against detrimental molecules (ROS) released by dying cells. Therefore, it appears that there are at least two epididymosome population with distinct functions: targeting specific proteins to transiting spermatozoa by tetraspanin-mediated membrane fusion, and protection of epididymal spermatozoa against ROS released from dying cells. Further work is needed to understand functions of epididymosomes in epididymal physiology and sperm maturation and storage.
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spelling pubmed-45775802015-09-23 Epididymosomes: a heterogeneous population of microvesicles with multiple functions in sperm maturation and storage Sullivan, Robert Asian J Androl Invited Research Highlight Extracellular microvesicles present in the epididymal fluid have been named epididymosomes. Many epididymosome-associated proteins are transferred to spermatozoa during their maturation in the excurrent duct. Epididymosomes are heterogeneous, with their size varying between 50 and 250 nm. Two distinct population of epididymosomes characterized by different protein compositions and diameters have been isolated from the bovine epididymal fluid using different centrifugation protocols. One subpopulation of epididymosomes was characterized by CD9 and other tetraspanin partners. Transfer of proteins from these epididymosomes to maturing spermatozoa in co-incubation experiments was inhibited by antibodies against tetraspanin proteins. This suggests that this subpopulation of epididymosomes is involved in the acquisition of proteins involved in maturation by spermatozoa in the epididymis. The other population of epididymosomes was characterized by ELSPBP1 (epididymal sperm binding protein 1), known for its affinity for the phospholipid choline group. Flow cytometric analyses showed that ELSPBP1-positive epididymosomes only interacted with dying or dead epididymal spermatozoa in a Zn(2 +)-dependent manner. BLVRA (biliverdin reductase) was identified as a partner of ELSPBP1. This enzyme reduces biliverdin to bilirubin: two molecules with powerful anti-oxidant properties. We hypothesize that BLVRA is involved in an ROS-scavenging mechanism protecting live epididymal spermatozoa against detrimental molecules (ROS) released by dying cells. Therefore, it appears that there are at least two epididymosome population with distinct functions: targeting specific proteins to transiting spermatozoa by tetraspanin-mediated membrane fusion, and protection of epididymal spermatozoa against ROS released from dying cells. Further work is needed to understand functions of epididymosomes in epididymal physiology and sperm maturation and storage. Medknow Publications & Media Pvt Ltd 2015 2015-06-23 /pmc/articles/PMC4577580/ /pubmed/26112475 http://dx.doi.org/10.4103/1008-682X.155255 Text en Copyright: © Asian Journal of Andrology http://creativecommons.org/licenses/by-nc-sa/3.0 This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms
spellingShingle Invited Research Highlight
Sullivan, Robert
Epididymosomes: a heterogeneous population of microvesicles with multiple functions in sperm maturation and storage
title Epididymosomes: a heterogeneous population of microvesicles with multiple functions in sperm maturation and storage
title_full Epididymosomes: a heterogeneous population of microvesicles with multiple functions in sperm maturation and storage
title_fullStr Epididymosomes: a heterogeneous population of microvesicles with multiple functions in sperm maturation and storage
title_full_unstemmed Epididymosomes: a heterogeneous population of microvesicles with multiple functions in sperm maturation and storage
title_short Epididymosomes: a heterogeneous population of microvesicles with multiple functions in sperm maturation and storage
title_sort epididymosomes: a heterogeneous population of microvesicles with multiple functions in sperm maturation and storage
topic Invited Research Highlight
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4577580/
https://www.ncbi.nlm.nih.gov/pubmed/26112475
http://dx.doi.org/10.4103/1008-682X.155255
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