Rab11 maintains connections between germline stem cells and niche cells in the Drosophila ovary
Rab11 maintains connections between germline stem cells and niche cells in the Drosophila ovary
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DOI：
10.1242/dev.008466
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发表时间：
2007-10-01
期刊：
影响因子：
4.6
通讯作者：
Cohen, Robert S.
中科院分区：
文献类型：
--
作者：
Bogard, Nicholas;Lan, Lan;Cohen, Robert S.
所有干细胞都有能力平衡其自我更新和分化的子代细胞的产生。果蝇卵巢的生殖系干细胞(GSCs)通过物理上附着于前壁龛帽子细胞和刻板细胞分裂来维持这种平衡，即只有一个女儿附着在壁龛上。GSC通过贴壁连接附着在帽细胞上，贴壁连接似乎也通过捕获纺锤体来定向GSC的分裂，Fusome是有丝分裂纺锤体的生殖系特异性组织者。在这里，我们表明，在卵巢中需要Rab11 GTP酶来维持GSC-帽细胞的连接，并将融合体锚定到GSC的前皮层。因此，Rab11缺失的GSC从NICE帽细胞中分离出来，含有移位的融合体并经历异常的细胞分裂，导致GSC分化早期停止。这些缺陷可能反映了Rab11在E-cadherin运输中的作用，因为E-cadherin在Rab11阳性循环内体(RES)中积累，E-cadherin和Armadillo(β-catenin)都在Rab11缺失的GSCs表面发现数量减少。E-钙粘附素转运所通过的Rab11阳性RE与融合体密切相关。我们认为，这种联系极化了Rab11对E-钙粘蛋白和其他物质向GSC前皮质的运输，从而同时加强了GSC-壁龛连接、Fusome定位和不对称细胞分裂。这些研究突出了膜转运在干细胞生物学中的重要作用。
All stem cells have the ability to balance their production of self- renewing and differentiating daughter cells. The germline stem cells (GSCs) of the Drosophila ovary maintain such balance through physical attachment to anterior niche cap cells and stereotypic cell division, whereby only one daughter remains attached to the niche. GSCs are attached to cap cells via adherens junctions, which also appear to orient GSC division through capture of the fusome, a germline- specific organizer of mitotic spindles. Here we show that the Rab11 GTPase is required in the ovary to maintain GSC- cap cell junctions and to anchor the fusome to the anterior cortex of the GSC. Thus, rab11- null GSCs detach from niche cap cells, contain displaced fusomes and undergo abnormal cell division, leading to an early arrest of GSC differentiation. Such defects are likely to reflect a role for Rab11 in E- cadherin trafficking as E- cadherin accumulates in Rab11- positive recycling endosomes ( REs) and E- cadherin and Armadillo ( beta- catenin) are both found in reduced amounts on the surface of rab11- null GSCs. The Rab11- positive REs through which E- cadherin transits are tightly associated with the fusome. We propose that this association polarizes the trafficking by Rab11 of E- cadherin and other cargoes toward the anterior cortex of the GSC, thus simultaneously fortifying GSC- niche junctions, fusome localization and asymmetric cell division. These studies bring into focus the important role of membrane trafficking in stem cell biology.