title: TSSK6 is required for γH2AX formation and the histone-to-protamine transition during spermiogenesis.
abstract: Spermiogenesis includes transcriptional silencing, chromatin condensation and extensive morphological changes as spermatids transform into sperm. Chromatin condensation involves histone hyperacetylation, transitory DNA breaks, histone H2AX (also known as H2AFX) phosphorylation at Ser139 (γH2AX), and replacement of histones by protamines. Previously, we have reported that the spermatid protein kinase TSSK6 is essential for fertility in mice, but its specific role in spermiogenesis is unknown. Here, we show that TSSK6 expression is spatiotemporally coincident with γH2AX formation in the nuclei of developing mouse spermatids. RNA-sequencing analysis demonstrates that genetic ablation ofTssk6does not impact gene expression or silencing in spermatids. However, loss of TSSK6 blocks γH2AX formation, even though the timing and level of the transient DNA breaks is unaltered. Further,Tssk6-knockout sperm contained increased levels of histones H3 and H4, and protamine 2 precursor and intermediate(s) indicative of a defective histone-to-protamine transition. These results demonstrate that TSSK6 is required for γH2AX formation during spermiogenesis, and also link γH2AX to the histone-to-protamine transition and male fertility.
authors.affiliation: Division of Biotechnology Review and Research IV, Office of Biotechnology Products, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA kula.jha@fda.hhs.gov gibbes.johnson@fda.hhs.gov.
authors.forename: Kula N
authors.identifier: 0000-0002-2218-1864
authors.initials: KN
authors.lastname: Jha
authors.affiliation: Division of Biotechnology Review and Research IV, Office of Biotechnology Products, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA.
authors.forename: Swamy K
authors.initials: SK
authors.lastname: Tripurani
authors.affiliation: Division of Biotechnology Review and Research IV, Office of Biotechnology Products, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA kula.jha@fda.hhs.gov gibbes.johnson@fda.hhs.gov.
authors.forename: Gibbes R
authors.initials: GR
authors.lastname: Johnson
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D017353:Gene Deletion; D006657:Histones / Q000378:metabolism*; D008297:Male; D018345:Mice, Knockout; D011479:Protamines / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D013087:Spermatids / Q000378:metabolism; D013091:Spermatogenesis; D013997:Time Factors; D059467:Transcriptome / Q000235:genetics
chemical_list: D006657:Histones; D011479:Protamines; C475961:gamma-H2AX protein, mouse; C068621:protamine 2; D017346:Protein Serine-Threonine Kinases; C501083:Tssk6 protein, mouse
keywords: Chromatin condensation; Protamine; Spermatid; Spermiogenesis; TSSK6; γH2AX