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.
Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA. wangxiaochen@nibs.ac.cn
Xiaochen
X
Wang
Weida
W
Li
Dongfeng
D
Zhao
Bin
B
Liu
Yong
Y
Shi
Baohui
B
Chen
Hengwen
H
Yang
Pengfei
P
Guo
Xin
X
Geng
Zhihong
Z
Shang
Erin
E
Peden
Eriko
E
Kage-Nakadai
Shohei
S
Mitani
Ding
D
Xue
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