Articulo
Methylation of the <i>Gpat2</i> promoter regulates transient expression during mouse spermatogenesis
Autor
García Fabiani, María Belén
Montanaro, Mauro Aldo
Lacunza, Ezequiel
Cattaneo, Elizabeth Renee
Coleman, Rosalind A.
Pellón Maisón, Magalí
González Baró, María del Rosario
Institución
Resumen
Spermatogenesis is a highly regulated process that involves both mitotic and meiotic divisions, as well as cellular differentiation to yield mature spermatozoa from undifferentiated germinal stem cells. Although <i>Gpat2</i> was originally annotated as a glycerol-3-phospate acyltransferase by sequence homology to <i>Gpat1</i>, GPAT2 is highly expressed in testis but not in lipogenic tissues and is not up-regulated during adipocyte differentiation. New data show that GPAT2 is required for the synthesis of piRNAs, a group of small RNAs that protect the germ cell genome from retrotransposable elements. In order to understand the relationship between GPAT2 and its role in the testis, we focused on <i>Gpat2</i> expression during the first wave of mouse spermatogenesis. <i>Gpat2</i> expression was analyzed by qPCR, <i>in situ</i> hybridization, immunohistochemistry and Western blot. <i>Gpat2</i> mRNA content and protein expression were maximal at 15 dpp and restricted to pachytene spermatocytes. To achieve this transient expression, both epigenetic mechanisms and <i>trans</i>-acting factors are involved. <i>In vitro</i> assays showed that <i>Gpat2</i> expression correlates with DNA demethylation and histone acetylation and that it is up-regulated by retinoic acid. Epigenetic regulation by DNA methylation was confirmed <i>in vivo</i> in germ cells by bisulfite sequencing of the <i>Gpat2</i> promoter. Consistent with the initiation of meiosis at 11 dpp, methylation decreased dramatically. Thus, <i>Gpat2</i> is expressed at a specific stage of spermatogenesis, consistent with piRNA synthesis and meiosis I prophase, and its on-off expression pattern responds predominantly to epigenetic modifications. Facultad de Ciencias Médicas Instituto de Investigaciones Bioquímicas de La Plata Centro de Investigaciones Inmunológicas Básicas y Aplicadas