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RESEARCH ARTICLE

Spermatozoa from mice deficient in Niemann-Pick disease type C2 (NPC2) protein have defective cholesterol content and reduced in vitro fertilising ability

Dolores Busso A B E , María José Oñate-Alvarado B , Elisa Balboa A , Juan Castro A , Carlos Lizama B , Gabriela Morales A , Susana Vargas C , Steffen Härtel C , Ricardo D. Moreno B and Silvana Zanlungo A D E
+ Author Affiliations
- Author Affiliations

A Department of Gastroenterology, Faculty of Medicine, Pontificia Universidad Católica. Avda. Bernardo O’Higgins 340. 8331150 Santiago, Chile.

B Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica. Avda. Bernardo O’Higgins 340. 8331150 Santiago, Chile.

C Laboratory for Scientific Image Analysis (SCIAN-Lab), Program of Anatomy and Developmental Biology, Instituto de Ciencias Biomédicas ICBM, Faculty of Medicine, Universidad de Chile, Avda. Independencia 1027. 8389100 Santiago, Chile.

D FONDAP “Center for Genome Regulation”, Avenida Blanco Encalada 2085. 8370415 Santiago, Chile.

E Corresponding authors. Emails: dbusso@med.puc.cl; silvana@med.puc.cl

Reproduction, Fertility and Development 26(4) 609-621 https://doi.org/10.1071/RD12059
Submitted: 25 February 2012  Accepted: 3 April 2013   Published: 29 May 2013

Abstract

The cholesterol content of the sperm membrane is regulated during both maturation in the epididymis and capacitation in the female tract, two processes required for the spermatozoa to acquire their fertilising ability. Because Niemann-Pick disease, type C2 (NPC2) protein is one of the most abundant components of the epididymal fluid and contains a functional cholesterol-binding site that can transfer cholesterol between membranes, it has been suggested for years that NPC2 could be involved in the regulation of cholesterol levels in spermatozoa during epididymal maturation. In the present study, western blot and immunohistochemistry analyses demonstrated significant levels of NPC2 in the mouse epididymal epithelium. Epididymal spermatozoa obtained from NPC2–/– mice were morphologically normal and had normal motility parameters, but had a reduced cholesterol content compared with that of wild-type (WT) spermatozoa, as determined by both biochemical and by flow cytometry analyses. These results suggest that NPC2 could be involved in regulating cholesterol levels in spermatozoa during epididymal maturation. To understand the relevance of epididymal NPC2 for sperm function, the ability of spermatozoa to undergo events influenced by epididymal maturation, such as capacitation and fertilisation, were compared between WT and NPC2–/– mice. Capacitated NPC2–/– spermatozoa exhibited defective tyrosine phosphorylation patterns and a reduced ability to fertilise cumulus–oocyte complexes compared with WT spermatozoa, supporting the relevance of mouse epididymal NPC2 for male fertility.

Additional keywords: epididymis, fertilisation.


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