Human sperm chromatin epigenetic potential: genomics, proteomics, and male infertility
Judit Castillo1, Josep Maria Estanyol2, Josep Lluis Ballescą3, Rafael Oliva1
1 Human Genetics Research Group, IDIBAPS, Faculty of Medicine, University of Barcelona, Casanova 143; Biochemistry and Molecular Genetics Service, Biomedical Diagnostic Centre, Hospital Clinic, Villarroel 170, 08036 Barcelona, Spain
2 Proteomics Unit, Scientific and Technological Centres of the University of Barcelona (CCiTUB), Casanova 143, 08036, Barcelona, Spain
3 Clinic Institute of Gynaecology, Obstetrics and Neonatology, Hospital Clinic, Villarroel 170, 08036 Barcelona, Spain
Human Genetics Research Group, IDIBAPS, Faculty of Medicine, University of Barcelona, Casanova 143; Biochemistry and Molecular Genetics Service, Biomedical Diagnostic Centre, Hospital Clinic, Villarroel 170, 08036 Barcelona
Source of Support: None, Conflict of Interest: None
The classical idea about the function of the mammalian sperm chromatin is that it serves to transmit a highly protected and transcriptionally inactive paternal genome, largely condensed by protamines, to the next generation. In addition, recent sperm chromatin genome-wide dissection studies indicate the presence of a differential distribution of the genes and repetitive sequences in the protamine-condensed and histone-condensed sperm chromatin domains, which could be potentially involved in regulatory roles after fertilization. Interestingly, recent proteomic studies have shown that sperm chromatin contains many additional proteins, in addition to the abundant histones and protamines, with specific modifications and chromatin affinity features which are also delivered to the oocyte. Both gene and protein signatures seem to be altered in infertile patients and, as such, are consistent with the potential involvement of the sperm chromatin landscape in early embryo development. This present work reviews the available information on the composition of the human sperm chromatin and its epigenetic potential, with a particular focus on recent results derived from high-throughput genomic and proteomic studies. As a complement, we provide experimental evidence for the detection of phosphorylations and acetylations in human protamine 1 using a mass spectrometry approach. The available data indicate that the sperm chromatin is much more complex than what it was previously thought, raising the possibility that it could also serve to transmit crucial paternal epigenetic information to the embryo.