Dynamics of Sex Chromosome Activity During Gametogenesis
Conference Recording Apr 17, 2013
About the Speaker
Willy Baarends received her PhD from Erasmus University Rotterdam in 1995, where she cloned the anti-müllerian hormone type II receptor, and studied its gonadal expression . Subsequently, she worked as a post-doc, in the Erasmus MC Department of Reproduction and Development. At present, she holds a tenured position as associate professor at this department. Her current work focuses on regulation of chromatin structure in relation to DNA repair in the germ line, impacting on fertility and early development.
During meiotic prophase all chromosomes have to find their homologous partner. A special enzyme, named SPO11, generates numerous DNA double-strand breaks (DSBs) when meiotic prophase initiates, and the specialized process that repairs these breaks aids in bringing the homologous chromosomes together to form pairs. During spermatogenesis in mammals, the heterologous sex chromosomes pair only in the short pseudoautosomal regions, whereas the autosomes pair along the whole length. This is associated with meiotic sex chromosome inactivation (MSCI), a phenomenon that affects also the postmeiotic regulation of sex chromosome activity and may even influence paternal X-chromosome activity in the early embryo. MSCI leads to the formation of the socalled XY body, which consists of the chromatin of the X and Y chromosome, is marked by specific histone modifications, and usually localizes in the periphery of the nucleus. We are interested in the mechanism of MSCI initiation, how it is maintained, and what the biological relevance of the process is. Our results suggest a link between DSB repair and the initiation of the silencing process. Furthermore, a DSB repair protein that affects histone modifications is involved in the maintenance of MSCI. Finally, analyses of MSCI in different species provide more insight in the possible biological relevance of MSCI.