Regulatory relationship among piwi, pumilio, and bag-of-marbles in Drosophila germline stem cell self-renewal and differentiation
Regulatory relationship among piwi, pumilio, and bag-of-marbles in Drosophila germline stem cell self-renewal and differentiation
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DOI：
10.1016/j.cub.2005.01.005
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发表时间：
2005-01-26
期刊：
影响因子：
9.2
通讯作者：
Lin, HF
中科院分区：
文献类型：
--
作者：
Szakmary, A;Cox, DN;Lin, HF
果蝇卵巢生殖系干细胞（GSC）向其分化的子细胞（成囊细胞）的转化受生态位信号和内在因素的控制。piwi和pumilio（pum）是GSC自我更新所必需的，而bag-of-marbles（bam）是成囊细胞分化所必需的[1-8]。我们证明，Piwi和Barn蛋白的表达相互独立，在GSC和成囊细胞的相互模式。然而，在这些细胞中，任何一种的过度表达都会拮抗另一种。此外，piwi;bam双突变体表型复制谷仓突变体。这种上位性反映了piwi的生态位信号传导功能，因为在barn突变体卵巢中从生态位细胞中去除piwi也表现为模仿bam突变体。因此，bam对生态位Piwi是上位性的，但不是生殖系Piwi功能。尽管如此，缺乏生殖系Piwi的bam（-）卵巢含有的生殖细胞比bam-卵巢少约4倍，这与生殖系Piwi促进GSC有丝分裂4倍的作用一致[3]。最后，pum对bam是上位性的，表明生态位Piwi不通过Pum调节Bam-C。我们认为，小生境Piwi通过抑制GSC中的bam表达来维持GSC，从而阻止Barn下调Pum/Nos抑制分化基因翻译的功能和生殖系Piwi促进生殖细胞分裂的功能。
The transition from a Drosophila ovarian germline stem cell (GSC) to its differentiated daughter cell, the cystoblast, is controlled by both niche signals and intrinsic factors. piwi and pumilio (pum) are essential for GSC self-renewal, whereas bag-of-marbles (bam) is required for cystoblast differentiation [1-8]. We demonstrate that Piwi and Barn proteins are expressed independently of each other in reciprocal patterns in GSCs and cystoblasts. However, overexpression of either one antagonizes the other in these cells. Furthermore, piwi;bam double mutants phenocopy the barn mutant. This epistasis reflects the niche signaling function of piwi because depleting piwi from niche cells in barn mutant ovaries also phenocopies bam mutants. Thus, bam is epistatic to niche Piwi, but not germline Piwi function. Despite this, bam(-) ovaries lacking germline Piwi contain approximately 4-fold fewer germ cells than bam- ovaries, consistent with the role of germline Piwi in promoting GSC mitosis by 4-fold [3]. Finally, pum is epistatic to bam, indicating that niche Piwi does not regulate Bam-C through Pum. We propose that niche Piwi maintains GSCs by repressing bam expression in GSCs, which consequently prevents Barn from downregulating Pum/Nos function in repressing the translation of differentiation genes and germline Piwi function in promoting germ cell division.