Epigenetic regulation of oogenesis and germ stem cell maintenance by the Drosophila histone methyltransferase Eggless/dSetDB1.
The Drosophila melanogaster histone lysine methyltransferase (HKMT) Eggless (Egg/dSETDB1) catalyzes methylation of Histone H3 lysine 9 (H3K9), a signature of repressive heterochromatin. Our previous studies showed that H3K9 methylation by Egg is required for oogenesis. Here we analyze a set of EMS-induced mutations in the egg gene, identify the molecular lesions of these mutations, and compare the effects on oogenesis of both strong loss-of-function and weak hypomorphic alleles. These studies show that H3K9 methylation by Egg is required for multiple stages of oogenesis. Mosaic expression experiments show that the egg gene is not required intrinsically in the germ cells for their early differentiation, but is required in the germ cells for their survival past stage 5 of oogenesis. egg is also required in germ stem cells for their maintenance, since egg- germ stem cells initially survive but are not maintained as females age. Mosaic analysis also reveals that the early egg chamber budding defects in egg- ovaries are due to an intrinsic requirement for egg in follicle stem cells and their descendents, and that egg plays a non-autonomous role in somatic cells in the germarium to influence the differentiation of early germ cells.
Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
Emily
E
Clough
Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
Thomas
T
Tedeschi
Department of Biological Sciences, Columbia University, New York, NY 10027, USA. Electronic address: tih1@columbia.edu.
Tulle
T
Hazelrigg
D000483:Alleles; D000818:Animals; D002454:Cell Differentiation; D019175:DNA Methylation; D029721:Drosophila Proteins / Q000235:genetics*; D004331:Drosophila melanogaster; D044127:Epigenesis, Genetic; D005854:Germ Cells / Q000166:cytology*; D011495:Histone-Lysine N-Methyltransferase; D009030:Mosaicism; D009866:Oogenesis / Q000235:genetics*; D013234:Stem Cells / Q000166:cytology*
D029721:Drosophila Proteins; D011495:Histone-Lysine N-Methyltransferase; C519551:egg protein, Drosophila
Epigenetics; Heterochromatin; Methylation; Oogenesis; Stem cells