dSETDB1 and SU(VAR)3-9 sequentially function during germline-stem cell differentiation in Drosophila melanogaster.
Germline-stem cells (GSCs) produce gametes and are thus true "immortal stem cells". In Drosophila ovaries, GSCs divide asymmetrically to produce daughter GSCs and cystoblasts, and the latter differentiate into germline cysts. Here we show that the histone-lysine methyltransferase dSETDB1, located in pericentric heterochromatin, catalyzes H3-K9 trimethylation in GSCs and their immediate descendants. As germline cysts differentiate into egg chambers, the dSETDB1 function is gradually taken over by another H3-K9-specific methyltransferase, SU(VAR)3-9. Loss-of-function mutations in dsetdb1 or Su(var)3-9 abolish both H3K9me3 and heterochromatin protein-1 (HP1) signals from the anterior germarium and the developing egg chambers, respectively, and cause localization of H3K9me3 away from DNA-dense regions in most posterior germarium cells. These results indicate that dSETDB1 and SU(VAR)3-9 act together with distinct roles during oogenesis, with dsetdb1 being of particular importance due to its GSC-specific function and more severe mutant phenotype.
Yoon
Jeongheon
J
Center for Regenerative Medicine, Korean Research Institute of Bioscience and Biotechnology, Daejeon, Korea.
Lee
Kyu-Sun
KS
Park
Jung Sun
JS
Yu
Kweon
K
Paik
Sang-Gi
SG
Kang
Yong-Kook
YK
D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004331:Drosophila melanogaster / Q000166:cytology / Q000235:genetics*; D005260:Female; D005854:Germ Cells; D011495:Histone-Lysine N-Methyltransferase; D008297:Male; D009154:Mutation; D010053:Ovary / Q000166:cytology / Q000378:metabolism; D012097:Repressor Proteins / Q000502:physiology*; D013234:Stem Cells / Q000166:cytology*
D029721:Drosophila Proteins; D012097:Repressor Proteins; C089148:Su(var)3-9 protein, Drosophila; D011495:Histone-Lysine N-Methyltransferase; C519551:egg protein, Drosophila