Caenorhabditis elegans transthyretin-like protein TTR-52 mediates recognition of apoptotic cells by the CED-1 phagocyte receptor.
During apoptosis, dying cells are swiftly removed by phagocytes. It is not fully understood how apoptotic cells are recognized by phagocytes. Here we report the identification and characterization of the Caenorhabditis elegans ttr-52 gene, which encodes a transthyretin-like protein and is required for efficient cell corpse engulfment. The TTR-52 protein is expressed in, and secreted from, C. elegans endoderm and clusters around apoptotic cells. Genetic analysis indicates that TTR-52 acts in the cell corpse engulfment pathway mediated by CED-1, CED-6 and CED-7 and affects clustering of the phagocyte receptor CED-1 around apoptotic cells. TTR-52 recognizes surface-exposed phosphatidylserine (PtdSer) in vivo and binds to both PtdSer and the extracellular domain of CED-1 in vitro. TTR-52 is therefore the first bridging molecule identified in C. elegans that mediates recognition of apoptotic cells by crosslinking the PtdSer 'eat me' signal with the phagocyte receptor CED-1.
Wang
Xiaochen
X
Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA. wangxiaochen@nibs.ac.cn
Li
Weida
W
Zhao
Dongfeng
D
Liu
Bin
B
Shi
Yong
Y
Chen
Baohui
B
Yang
Hengwen
H
Guo
Pengfei
P
Geng
Xin
X
Shang
Zhihong
Z
Peden
Erin
E
Kage-Nakadai
Eriko
E
Mitani
Shohei
S
Xue
Ding
D
D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000502:physiology; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological
C479695:CED-2 protein, C elegans; D029742:Caenorhabditis elegans Proteins; D008565:Membrane Proteins; C422043:ced-1 protein, C elegans