Sperm nuclear proteome and its epigenetic potential

Abstract

SUMMARYThe main function of the sperm cell is to transmit the paternal genetic message and epigenetic information to the embryo. Importantly, the majority of the genes in the sperm chromatin are highly condensed by protamines, whereas genes potentially needed in the initial stages of development are associated with histones, representing a form of epigenetic marking. However, so far little attention has been devoted to other sperm chromatin-associated proteins that, in addition to histones and protamines, may also have an epigenetic role. Therefore, with the goal of contributing to cover this subject we have compiled, reviewed and report a list of 581 chromatin or nuclear proteins described in the human sperm cell. Furthermore, we have analysed their Gene Ontology Biological Process enriched terms and have grouped them into different functional categories. Remarkably, we show that 56% of the sperm nuclear proteins have a potential epigenetic activity, being involved in at least one of the following functions: chromosome organization, chromatin organization, protein-DNA complex assembly, DNA packaging, gene expression, transcription, chromatin modification and histone modification. In addition, we have also included and compared the sperm cell proteomes of different model species, demonstrating the existence of common trends in the chromatin composition in the mammalian mature male gamete. Taken together, our analyses suggest that the mammalian sperm cell delivers to the offspring a rich combination of histone variants, transcription factors, chromatin-associated and chromatin-modifying proteins which have the potential to encode and transmit an extremely complex epigenetic information.

Histone retention, protein carbonylation, and lipid peroxidation in spermatozoa: Possible role in recurrent pregnancy loss

“…Moreover, since the intermediate spermatozoa outnumber the normal spermatozoa in RPL patients, their chance of being able to fertilize an oocyte is more than the darkly stained spermatozoa. Extensive work has been done to characterize the levels of histone retention needed for fertilization success, with recent work targeted in unravelling the PTMs in histones for epigenetic significance [Brunner et al 2014;Castillo et al 2014;Krejci et al 2015]. Persistence of abnormal and random histones can contribute in disrupting embryo viability and normal embryo development .…”

“…In fact, a positive correlation was found between poor protamination and higher levels of ROS production and subsequent DNA fragmentation in individuals with abnormal semen parameters [Kiani-Esfahani et al 2013]. Besides, the retention of histone is not random and is known to have epigenetic significance making it one of the important parameters to be studied in sperm of RPL [Brunner et al 2014;Castillo et al 2014]. Moreover, it is well-known that spermatozoa themselves contain negligible levels of antioxidants, and thus render the cells particularly reliant to their immediate seminal plasma for protection [O'Flaherty 2014].…”

Protein biomarkers for male artificial insemination subfertility in bovine spermatozoa

“…In the nuclei, most of the core histones are substituted transiently by the transition proteins and finally by the protamines 63. Many reviews previously have described the details of the relationship between male infertility and epigenetics at the histones and protamines of male germ cells 64, 65, 66, 67, 68. In this section, information is introduced on bovine sperm protamines and their relationship with bull AI subfertility.…”

The effect of tetrabromobisphenol A on protamine content and DNA integrity in mouse spermatozoa

“…This is especially relevant as sperm genome integrity seems to be necessary to accomplish fertilization (Tomsu et al, 2002;Simon et al, 2011). However, protamines may also be involved in paternal genome imprinting during spermatogenesis and in the constitution of epigenetic marks potentially transmitted to the oocyte upon fertilization (Oliva & Dixon, 1991;Oliva, 2006;Carrell et al, 2008;Hammoud et al, 2011;Castillo et al, 2014). Despite all the above studies correlating TBBPA with male reproductive effects and the links between altered protamination, DNA fragmentation and male infertility, to our knowledge, there are no studies measuring the effect of TBBPA on protamination of the sperm cell and DNA integrity.…”