Acetylation of histone H4 in complex structural transitions of spermiogenic chromatin

✍ Scribed by Kathryn Kurtz; Fina Martínez-Soler; Juan Ausió; Manel Chiva

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 388 KB
• Volume: 102
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/jcb.21365

✦ Synopsis

Abstract

In spermiogenic nuclei of the cephalopod mollusc Sepia officinalis histones are replaced by a precursor‐protamine molecule, which is later converted into protamine. Simultaneously, spermiogenic chromatin undergoes a complex structural change. Somatic‐like chromatin belonging to the earliest spermatid is progressively reorganized into: (a) granules of 20 nm diameter, (b) fibres of 30–35 nm, and (c) fibres of 40–50 nm. In the final phases of spermiogenesis these fibres of 40–50 nm join to form larger structures of condensed chromatin, and lastly, the uniformly packed chromatin in the sperm nucleus. Using specific antibodies for mono‐ and hyperacetylated forms of histone H4, in this work we show that the first structural remodelling of chromatin (from somatic‐like organization into 20 nm granules) is given concomitantly with a massive mono‐acetylation of H4 (acetylation in lysine 12), whereas the structural remodelling from 30–35 to 40–50 nm fibres is produced simultaneously with hyperacetylation of H4 and the nuclear removal of histones. J. Cell. Biochem. 102: 1432–1441, 2007. © 2007 Wiley‐Liss, Inc.