The telomere-specific non-LTR retrotransposons SART1 and TRAS1 are suppressed by Piwi subfamily proteins in the silkworm, Bombyx mori.
The telomere structures in Bombyx mori are thought to be maintained mainly by the transposition of the specialized telomeric retroelements SART and TRAS. The silkworm genome has telomeric TTAGG repeats and telomerase, but this telomerase displays little or no activity. Here, we report that the transcription of the telomeric retroelements SART1 and TRAS1 is suppressed by the silkworm Piwi subfamily proteins BmAgo3 and Siwi. The silkworm Piwi subfamily was found to be expressed predominantly in the gonads and early embryo, as in other model organisms, but in BmN4 cultured cells, these proteins formed granules that were separate from the nuage, which is a different behaviour pattern. The expression of TRAS1 was increased in BmN4 cells when BmAgo3 or Siwi were silenced by RNAi. Our results suggest that B. mori Piwi proteins are involved in regulating the transposition of telomeric retroelements, and that the functional piRNA pathway is conserved in BmN4 cultured cells.
Tatsuke
Tsuneyuki
T
Laboratory of Silkworm Science, Kyushu University Graduate School of Bioresource and Bioenvironmental Sciences, Hakozaki 6-10-1, Fukuoka, 812-8581, Japan.
Sakashita
Kosuke
K
Masaki
Yuki
Y
Lee
Jae Man
JM
Kawaguchi
Yutaka
Y
Kusakabe
Takahiro
T
D000818:Animals; D012831:Bombyx / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D034622:RNA Interference; D034743:RNA-Induced Silencing Complex / Q000235:genetics / Q000378:metabolism*; D018626:Retroelements; D016615:Telomere / Q000737:chemistry*; D020079:Terminal Repeat Sequences
D034743:RNA-Induced Silencing Complex; D018626:Retroelements