Genetics: Disturbances of nuclear condensation in human spermatozoa: search for mutations in the genes for protamine 1, protamine 2 and transition protein 1

Abstract

During spermiogenesis, the successive replacement of the somatic histones by basic proteins, the transition proteins and protamines, allows normal sperm nuclear condensation. It was suggested that disturbances in nuclear condensation may result in male infertility. Here we report the first molecular analysis of the structure of three genes which code for germ cell-specific nuclear proteins, namely protamine 1 (PRM1), protamine 2 (PRM2) and transition protein 1 (TNP1) in infertile men with disturbed sperm chromatin condensation. In 36 infertile men whose spermatozoa showed a positive reaction with aniline blue, which is an indication for the presence of histones in the nuclei, the complete nucleotide sequences of the coding regions and 5' and 3' untranslated regions of the three genes were evaluated. In addition, 10 infertile patients with oligoasthenoteratozoospermia were studied in the same way, as well as nine infertile patients whose spermatozoa showed a reduction of the protamine 2 content. We did not detect any mutation in the three genes in any of the patients. We assume that the disturbances in the sperm chromatin condensation of our patients, and those described in the literature, are not primarily due to mutations in the genes for PRM1, PRM2 and TNP1.

Identification of Genetic Variation in the 5′ and 3′ Non-coding Regions of the Protamine Genes in Patients with Protamine Deregulation

“…Indeed, many investigators have attempted to identify any significant mutations in the protamine coding regions [de Yebra and Oliva 1993;Schlicker et al 1994;Aoki et al 2006a]. However, Tanaka, et al in 2003 identified one azoospermic patient with a premature stop codon in P2 [Tanaka et al 2003].…”

“…Several groups evaluated the coding sequences of protamine 1, 2 and transition protein 1, 2 to identify specifically relevant alterations that may possibly explain the cause of protamine deregulation [de Yebra and Oliva 1993;Schlicker et al 1994;Tanaka et al 2003;Miyagawa et al 2005;Aoki et al 2006a;Iguchi et al 2006]. Generally, there was no correlation between the absence of protamines and mutations within the coding regions of the protamine genes or transition protein genes.…”

Sperm Chromatin Structure Assay: Its Clinical Use for Detecting Sperm DNA Fragmentation in Male Infertility and Comparisons With Other Techniques

“…A fertile man with an influenza-induced fever (39.9ЊC; Figure 2) also expressed an unprocessed P2 precursor coincident with an increased histone:protamine ratio, decreased free -sulfhydryl groups, and increased DNA stainability . The presence of an unprocessed P2 precursor (de Yebra et al, 1998) combined with evidence that genes encoding P1, P2, and transition proteins are normal (Schlicker et al, 1994) indicates that incomplete protein processing of P2 can lead to chromatin abnormalities. The role of abnormal P2 in infertility is substantiated by the importance of P2 in the formation of zinc-finger structures (Bianchi et al, 1994) and intermolecular and intramolecular disulfide bonds, which are necessary for chromatin stabilization (Calvin and Bedford, 1971;Bedford and Calvin, 1974;Evenson et al, 1980b).…”

Raman spectroscopy of DNA packaging in individual human sperm cells distinguishes normal from abnormal cells

“…Sperm head morphology has been established by the World Health Organization (WHO) as the most important criterion to assess the fertility of males. There is, however, evidence and growing concern that not all sperm with normal shape are fully functional and may contain DNA that is improperly packaged [15][16][17]. Fertilization events involving abnormal sperm could have adverse effects on early embryo development or lead to genetic disease.…”