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Chromosoma. 2017 Jun;126(3):399-415. doi: 10.1007/s00412-016-0598-1. Epub 2016 May 10.

The enigmatic meiotic dense body and its newly discovered component, SCML1, are dispensable for fertility and gametogenesis in mice.

Author information

1
Institute of Physiological Chemistry, Medical Faculty of TU Dresden, Fiedlerstrasse 42, 01307, Dresden, Germany.
2
Biotechnology Center of the TU Dresden, Tatzberg 47/49, 01307, Dresden, Germany.
3
Department of Human Genetics, Radboud University Medical Center, Geert Grooteplein 10, 6525 GA, Nijmegen, The Netherlands.
4
DFG Center for Regenerative Therapies, Dresden (CRTD), Technische Universit├Ąt Dresden, Dresden, 01307, Germany.
5
Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria.
6
Max Planck Institute of Biochemistry, Martinsried, Germany.
7
Wellcome Trust Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK.
8
Institute of Physiological Chemistry, Medical Faculty of TU Dresden, Fiedlerstrasse 42, 01307, Dresden, Germany. attila.toth@mailbox.tu-dresden.de.

Abstract

Meiosis is a critical phase in the life cycle of sexually reproducing organisms. Chromosome numbers are halved during meiosis, which requires meiosis-specific modification of chromosome behaviour. Furthermore, suppression of transposons is particularly important during meiosis to allow the transmission of undamaged genomic information between generations. Correspondingly, specialized genome defence mechanisms and nuclear structures characterize the germ line during meiosis. Survival of mammalian spermatocytes requires that the sex chromosomes form a distinct silenced chromatin domain, called the sex body. An enigmatic spherical DNA-negative structure, called the meiotic dense body, forms in association with the sex body. The dense body contains small non-coding RNAs including microRNAs and PIWI-associated RNAs. These observations gave rise to speculations that the dense body may be involved in sex body formation and or small non-coding RNA functions, e.g. the silencing of transposons. Nevertheless, the function of the dense body has remained mysterious because no protein essential for dense body formation has been reported yet. We discovered that the polycomb-related sex comb on midleg-like 1 (SCML1) is a meiosis-specific protein and is an essential component of the meiotic dense body. Despite abolished dense body formation, Scml1-deficient mice are fertile and proficient in sex body formation, transposon silencing and in timely progression through meiosis and gametogenesis. Thus, we conclude that dense body formation is not an essential component of the gametogenetic program in the mammalian germ line.

KEYWORDS:

Dense body; Meiosis; Polycomb; Transposon; piRNA

PMID:
27165042
DOI:
10.1007/s00412-016-0598-1
[Indexed for MEDLINE]

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