Characterization of lactoferrin receptor on human spermatozoa
Sources of Funding: None
Introduction
Lactoferrin (LF) is abundant in human seminal plasma and on sperm surfaces. However, lactoferrin receptor (LFR) on human spermatozoa has not yet been reported.
Methods
To study the expression, localization and characteristics of LFR on human spermatozoa, different experimental approaches were applied: LFR gene was amplified from a human testis cDNA library and recombinant LFR (rLFR) protein was produced in the expression vector Escherichia coli BL21 (DE3); human sperm membrane proteins were extracted and analysed via Western blot; the binding of LF to LFR was investigated by Far-Western blot, immunoprecipitation and autoradiography analysis and the localization of LFR on sperm surfaces was detected using immunofluorescence.
Results
LFR gene was amplified from a human testis cDNA library and the molecular weight of rLFR was 34 kDa. The native LFR on human spermatozoa was a 136-kDa tetramer which was anchored to the sperm head and mid-piece through glycophosphatidylinositol. LF could bind to LFR competitively in vitro.
Conclusions
As far as is known, this study has elucidated for the first time that LFR was expressed at the testis level, was anchored to the sperm membrane by glycophosphatidylinositol during spermatogenesis. LFR may play important roles through binding to and mediating LF. Â
Funding
None
Pengqi Wang
Bianjiang Liu
Xiaobin Niu
Shifeng Su
Wei Zhang