Opposite effects of Rho family GTPases on engulfment of apoptotic cells by macrophages
Opposite effects of Rho family GTPases on engulfment of apoptotic cells by macrophages
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DOI：
10.1074/jbc.m510972200
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发表时间：
2006-03-31
影响因子：
4.8
通讯作者：
Nagata, S
中科院分区：
文献类型：
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作者：
Nakaya, M;Tanaka, M;Nagata, S
专职或非专职吞噬细胞对凋亡细胞的有效吞噬对维持哺乳动物体内平衡至关重要。为了鉴定参与凋亡细胞吞噬的分子，我们建立了一个基于逆转录病毒的表达克隆系统，结合吞噬试验。通过筛选小鼠巨噬细胞系的cDNA文库，我们确定了两个小的GTdR家族成员（RhoG和Rab5），增强了凋亡细胞的吞噬。通过检查其他小的GTfl家族成员，我们发现Rac1增强了凋亡细胞的吞噬，而RhoA抑制了这一过程。因此，在原代巨噬细胞培养物中显性阴性形式的RhoG或Rac 1的表达严重降低了巨噬细胞吞噬凋亡细胞的能力，而显性阴性形式的RhoA增强了该过程。这些结果表明，凋亡细胞的有效吞噬需要小的GTdR家族成员的协同作用。我们先前证明，表达α（v）β（3）整合素的NIH3T3细胞在乳脂球表皮生长因子8存在下通过磷脂酰丝氨酸依赖性机制有效地吞噬凋亡细胞。RhoG或Rac1的显性负性形式抑制了这一过程，这表明RhoG和Rac1也参与了整合素介导的吞噬。
The efficient engulfment of apoptotic cells by professional or nonprofessional phagocytes is critical to maintain mammalian homeostasis. To identify molecules involved in the engulfment of apoptotic cells, we established a retrovirus-based expression cloning system coupled with the engulfment assay. By screening a cDNA library of a mouse macrophage cell line, we identified two small GTPase family members (RhoG and Rab5) that enhanced the engulfment of apoptotic cells. By examining other small GTPase family members, we found that Rac1 enhanced the engulfment of apoptotic cells, whereas RhoA inhibited the process. Accordingly, the expression of a dominant-negative form of RhoG or Rac1 in primary macrophage cultures severely reduced the ability of the macrophages to engulf apoptotic cells, and a dominant-negative form of RhoA enhanced the process. These results indicated that the efficient engulfment of apoptotic cells requires the concerted action of small GTPase family members. We demonstrated previously that NIH3T3 cells expressing the alpha(v)beta(3) integrin efficiently engulf apoptotic cells in the presence of milk fat globule epidermal growth factor 8 via a phosphatidylserine-dependent mechanism. The dominant-negative form of RhoG or Rac1 inhibited this process, which suggested RhoG and Rac1 are also involved in the integrin-mediated engulfment.