tailieunhanh - Báo cáo khoa học: From meiosis to postmeiotic events: The secrets of histone disappearance

One of the most obscure phenomena in modern biology is the near genome-wide displacement of histones that occurs during the postmeiotic phases of spermatogenesis in many species. Here we review the literature to show that, during spermatogenic differentiation, three major molecular mechanisms come together to ‘prepare’ the nucleosomes for facilitated disassembly and histone removal. | ỊFEBS Journal MINIREVIEW From meiosis to postmeiotic events The secrets of histone disappearance Jonathan Gaucher Nicolas Reynoird Emilie Montellier Faycal Boussouar Sophie Rousseaux and Saadi Khochbin INSERM U823 Université Joseph Fourier Institut Albert Bonniot Grenoble France Keywords acetylation chromatin epigenetics histone variants nucleosomes protamines protease sperm transition proteins Correspondence S. Khochbin INSERM U823 Universite Joseph Fourier Institut Albert Bonniot Grenoble F-38700 France Fax 33 4 76 54 95 95 Tel 33 4 76 54 95 83 E-mail khochbin@ Received 20 July 2009 accepted 20 October 2009 doi One of the most obscure phenomena in modern biology is the near genome-wide displacement of histones that occurs during the postmeiotic phases of spermatogenesis in many species. Here we review the literature to show that during spermatogenic differentiation three major molecular mechanisms come together to prepare the nucleosomes for facilitated disassembly and histone removal. Introduction One of the last completely unknown biological processes is the molecular basis of postmeiotic haploid genome reprogramming. Our lack of knowledge of this phenomenon includes sporulation in lower eukaryotes and pollen formation in plants as well as spermatogenesis all directing a large-scale genome compaction. Simple and fundamental questions regarding the molecular basis of genome compaction and reorganization are completely unanswered. Additional questions concern the assembly of new DNA-packaging proteins including specific histone variants and nonhistone small basic proteins such as transition proteins TPs and protamines Prms 1-4 . For about 30 years these questions have inspired various types of investigation without providing any insights into the molecular mechanisms involved. These studies have however suggested that an essen- Abbreviations Prm protamine TP transition protein. tial element in histone replacement .

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