Methylation of the Gpat2 promoter regulates transient expression during mouse spermatogenesis.
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 Gpat2 was originally annotated as encoding a glycerol-3-phosphate acyltransferase by sequence homology to Gpat1, 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 (piwi-interacting RNAs), 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 Gpat2 expression during the first wave of mouse spermatogenesis. Gpat2 expression was analysed by qPCR (quantitative real-time PCR), in situ hybridization, immunohistochemistry and Western blotting. Gpat2 mRNA content and protein expression were maximal at 15 dpp (days post-partum) and were restricted to pachytene spermatocytes. To achieve this transient expression, both epigenetic mechanisms and trans-acting factors are involved. In vitro assays showed that Gpat2 expression correlates with DNA demethylation and histone acetylation and that it is up-regulated by retinoic acid. Epigenetic regulation by DNA methylation was confirmed in vivo in germ cells by bisulfite sequencing of the Gpat2 promoter. Consistent with the initiation of meiosis at 11 dpp, methylation decreased dramatically. Thus, Gpat2 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.
Instituto de Investigaciones Bioquímicas de La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata 1900, Argentina.
Maria B
MB
Garcia-Fabiani
Instituto de Investigaciones Bioquímicas de La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata 1900, Argentina.
Mauro A
MA
Montanaro
Centro de Investigaciones Inmunológicas Básicas y Aplicadas, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata 1900, Argentina.
Ezequiel
E
Lacunza
Instituto de Investigaciones Bioquímicas de La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata 1900, Argentina.
Elizabeth R
ER
Cattaneo
Department of Nutrition, University of North Carolina, Chapel Hill, NC 27599, U.S.A.
Rosalind A
RA
Coleman
Instituto de Investigaciones Bioquímicas de La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata 1900, Argentina.
Magali
M
Pellon-Maison
Instituto de Investigaciones Bioquímicas de La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata 1900, Argentina mgbaro@med.unlp.edu.ar.
Maria R
MR
Gonzalez-Baro
D000818:Animals; D019175:DNA Methylation / Q000502:physiology*; D044127:Epigenesis, Genetic / Q000502:physiology*; D005992:Glycerol-3-Phosphate O-Acyltransferase / Q000235:genetics / Q000378:metabolism*; D008297:Male; D049469:Meiotic Prophase I / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D049471:Pachytene Stage / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D013090:Spermatocytes / Q000166:cytology / Q000378:metabolism*; D013091:Spermatogenesis / Q000502:physiology*
D012333:RNA, Messenger; D034741:RNA, Small Interfering; D005992:Glycerol-3-Phosphate O-Acyltransferase; C571223:glycerol-3-phosphate acyltransferase 2, mouse
GPAT2; epigenetic regulation; meiosis; retinoic acid