https://scholars.lib.ntu.edu.tw/handle/123456789/140061
Title: | 線蟲ced-2/crkII與ced-10/rac在凋亡細胞吞噬機制中具有先前未知的負向調節作用 ced-2/crkII and ced-10/rac have previously unassigned negative roles in engulfment of apoptotic cells in C. elegans |
Authors: | 黃騰緯 Huang, Teng-Wei |
Keywords: | 線蟲;凋亡細胞;吞噬機制;ced-2;ced-10;engulfment | Issue Date: | 2008 | Abstract: | 在C. elegans中,兩條平行且部分重複的訊息傳遞途徑作用於凋亡細胞的吞噬機制中,至少有八個基因(ced-1, ced-6, ced-7, dyn-1 and ced-2, ced-5, ced-10, ced-12)參與其中。這些基因一旦發生突變,就會造成吞噬功能的缺陷,並產生存留的細胞屍體。CED-2是一個帶有SH2 domain和 SH3 domain的adapter protein,它可能會與CED-5/CED-12形成的heterodimeric guanine nucleotide exchange factor結合,共同活化CED-10(small Rac GTPase),造成細胞骨架的重組,使吞噬細胞能夠吞噬凋亡細胞。我們意外的發現ced-10(n3246) mutation顯著降低ced-5 mutants中的細胞屍體數目。在使用4D顯微攝影,分析AB cell lineage和MS cell lineage中最早的14個細胞死亡過程後,結果發現ced-10(n3246)部分抑制了ced-5 mutant中的吞噬缺陷。這些結果顯示在吞噬凋亡細胞的過程中,ced-10可能具有負向調節的作用。有趣的是,ced-10(n3246)並不會減低ced-12 single mutant或ced-12; ced-5 double mutants中的細胞屍體數目,顯示ced-10的負向調節作用需要ced-12。我們也發現ced-2(n1994)可以減少ced-10(n3246)中的細胞屍體數目,而ced-2(e1752)則否;細胞屍體數目減少的原因是吞噬缺陷受到部分抑制。這些發現意味著CED-2可能透過N-terminal SH3 domain進行對吞噬機制的抑制作用。進一步的遺傳分析顯示ced-2的負向調節作用需要ced-12而不需ced-5。總括來說,透過遺傳和性狀分析,我們的研究顯示ced-2和ced-10在細胞凋亡過程中,對吞噬機制具有先前未知的負向調節作用。 In Caenorhabditis elegans, two partially redundant pathways containing at least eight genes (ced-1, ced-6, ced-7, dyn-1 and ced-2, ced-5, ced-10, ced-12) function in the engulfment of apoptotic cells. Mutations in any of these genes cause engulfment defects and hence result in the persistence of cell corpses. CED-2, a SH2 and SH3 containing adapter protein, may bind to the CED-5/CED-12 heterodimeric guanine nucleotide exchange factor complex to activate CED-10, a small Rac GTPase, leading to cytoskeletal reorganization during engulfment of apoptotic cells. Surprisingly, we found ced-10(n3246) significantly reduced cell corpse number in ced-5 mutants. Using four-dimensional microscopic recording, we analyzed the first 14 cell deaths in the AB and MS cell lineages and found that ced-10(n3246) partially suppressed the engulfment defect of ced-5 mutants. These results reveal a possible negative role of ced-10 in cell-corpse engulfment. Interestingly, ced-10(n3246) did not reduce cell corpse number of ced-12 single or ced-12; ced-5 double mutants, indicating that the negative role of ced-10 may require ced-12. We also found that ced-2(n1994), but not ced-2(e1752), mutation reduced cell corpse number in the ced-10(n3246) background; the reduction was caused by a partial suppression of the Ced-10 engulfment defect. These findings suggest that CED-2 may exert an inhibitory function through its N-terminal SH3 domain. Further genetic analyses showed that the negative role of ced-2 required ced-12 but not ced-5. In summary, our genetic and phenotypic analyses reveal novel roles of ced-2 and ced-10 in negative regulation of cell-corpse engulfment during programmed cell death. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/184691 |
Appears in Collections: | 分子與細胞生物學研究所 |
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ntu-97-R94b43033-1.pdf | 23.32 kB | Adobe PDF | View/Open |
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