Loss of l(3)mbt leads to acquisition of the ping-pong cycle in Drosophila ovarian somatic cells

Abstract

In Drosophila germ cells, PIWI-interacting RNAs (piRNAs) are amplified through a PIWI slicer-dependent feed-forward loop termed the ping-pong cycle, yielding secondary piRNAs. However, the detailed mechanism remains poorly understood, largely because an ex vivo model system amenable to biochemical analyses has not been available. Here, we show that CRISPR-mediated loss of function of lethal (3) malignant brain tumor [l(3)mbt] leads to ectopic activation of the germ-specific pingpong cycle in ovarian somatic cells. Perinuclear foci resembling nuage, the ping-pong center, appeared following l(3)mbt mutation. This activation of the ping-pong machinery in cultured cells will greatly facilitate elucidation of the mechanism underlying secondary piRNA biogenesis in Drosophila.

Domestic chickens activate a piRNA defense against avian leukosis virus

“…We then compared expression of piRNA pathway genes in White Leghorn and Red Jungle Fowl (Figure 3E). RNA silencing pathway genes, including CIWI , CILI , A-MYB (Li et al, 2013), DDX4 (Kuramochi-Miyagawa et al, 2010), MAEL (Soper et al, 2008), L3MBTL4 (Fagegaltier et al, 2016; Sumiyoshi et al, 2016), MOV10l1 (Frost et al, 2010; Zheng et al, 2010), TDRD1 (Chen et al, 2009; Kojima et al, 2009; Reuter et al, 2009; Wang et al, 2009), TDRKH (TDRD2) (Saxe et al, 2013), TDRD3 , TDRD5 (Yabuta et al, 2011), TDRD7 (Tanaka et al, 2011), TDRD9 (Aravin et al, 2009; Shoji et al, 2009), and TDRD12 (Aravin et al, 2009; Shoji et al, 2009), exhibited a median abundance of 164 fpkm in White Leghorn testis, which was not significantly different from expression in Red Jungle Fowl (median abundance of 167 fpkm, p=0.63). This expression of TE piRNAs and piRNA processing genes at approximately the same levels in Red Jungle Fowl and White Leghorn suggests that the activation of piRNAs in White Leghorn is specific to ALVE.…”

Drosophila PAF1 Modulates PIWI/piRNA Silencing Capacity

“…We tested known Piwi-pathway factors such as: 1) PIWI-associated factors MAELSTROM (MAEL), ASTERIX (ARX/GTSF1), and PANORAMIX/SILENCIO (PANX/SILE); 2) piRNA biogenesis factors ARMITAGE (ARMI) and ZUCCHINI (ZUCC); and 3) four Tudor-domain-containing germline-specific factors expressed in OSC/OSS cells: SPINDLE-E (SPN-E), KRIMPER (KRIMP), QIN, and TUDOR (TUD) [18]. Although OSS cells only generate primary piRNAs, they ectopically express Tudor-domain factors implicated in secondary piRNA biogenesis [19–22].…”

“…Greater fold change for endogenous TEs could be due to a much smaller denominator of very low steady-state expression enforced by additional silencing mechanisms acting well on chromosomes but poorly on reporters [6, 8]. Future goals will be to stably integrate reporters and test additional Piwi pathway-expressing Drosophila cell lines, such as the male-derived WRR-1 cells that contrast the female-derived OSC/OSS cells [39], and the OSC-delta-l(3)mbt cells which express secondary ping-pong piRNAs [18]. …”

Human germ/stem cell-specific gene TEX19 influences cancer cell proliferation and cancer prognosis

“…This is supported by the finding that tumours in Drosophila melanogaster activate a large cohort of germline genes during oncogenesis and that some of these are essential for tumour progression [7–9]. Analysis of gene expression in human tumours indicates that a similar pattern of germline gene activation is also apparent, inferring a possible functional requirement [3].…”