Presence, localization, and origin of clusterin in normal human spermatozoa

Abstract

Purpose Clusterin in mammalian semen is a secretory form of clusterin (sCLU) with the heterodimeric structure. It is secreted by the epididymis and seminal vesicle. It is generally agreed that clusterin mainly exists on the surface of abnormal spermatozoa and is implicated in decreased sperm motility, sperm aggregation and infertility. However, few studies observe clusterin in normal spermatozoa, which is presumed to be a novel form. Up to now, the systematical information about the presence, localization, origin and function of clusterin in normal human spermatozoa has yet not been established. The aim of our current study is to systematically research clusterin in normal human spermatozoa.Methods We detected the presence of clusterin via western blot, explored the localization of clusterin using immunofluorescence, and investigated the origin and distribution of clusterin in human testis by western blot and immunohistochemistry. Results We found native clusterin in the inner plasma membrane of normal human spermatozoa. It was derived from the testis and showed similar molecular weight and heterodimeric structure compared with sCLU in semen and on the surface of abnormal spermatozoa. Conclusion Clusterin in normal spermatozoa should be self-synthesized during the later stage of spermatogenesis. The different localization and origin suggested that the clusterin observed by us may be a novel form compared with conventional sCLU on the surface of abnormal spermatozoa.

Toward the identification of a subset of unexplained infertility: a sperm proteomic approach

“…Increased CLU expression also has been associated with increased sperm DNA fragmentation (40). Additionally, CLU has been reported in normal spermatozoa, but the different localization and origin of this CLU suggest it to be a novel form compared with the conventional CLU (46). Further investigation is vital to elucidate what role CLU has in normozoospermia and how CLU expression in sperm can potentially (if at all) contribute to the future developmental potential of the embryo.…”

Characterization of seminal plasma proteomic alterations associated with the IVF and rescue‐ICSI pregnancy in assisted reproduction

“…Among them, the seminal vesicles, prostate, testes, and epididymides are the major secretory origins and account for approximately 65%, 25%, and 10%, respectively, of the semen volume (Drabovich et al, 2014). Some seminal proteins have tissue specificity: Seminal vesicles mainly secrete semenogelins and fibronectin (Lilja et al, 1987), the epididymis secretes clusterin (Han et al, 2012), the prostate secretes kallikreins (Verze et al, 2016), and the bulbourethral glands secrete mucinous proteins (Boursnell et al, 1970).…”

Relative abundance of heat shock proteins and clusterin transcripts in spermatozoa collected from boar routinely utilised in an artificial insemination centre: preliminary results

“…No correlation between HSP70 and semen quality was found (Turba et al 2007) while HSP90 was investigated only in relation to the quality of cryopreserved semen (Wang et al 2014;Zhang et al 2015). Clusterin (CLU), a pleiotropic glycoprotein mainly present in seminal plasma has also been found to be associated with spermatozoa in various species (Sylvester et al 1991;Ibrahim et al 1999;Ibrahim et al 2001;Han et al 2012). In human and bull sperm, clusterin mainly exists on the surface of immature, low motile or morphologically abnormal spermatozoa and therefore its presence has been proposed as a marker of poor sperm quality (O'Bryan et al 1994;Ibrahim et al 2000;Muciaccia et al 2010).…”