TY - JOUR
T1 - Identification of two signaling submodules within the CrkII/ELMO/Dock180 pathway regulating engulfment of apoptotic cells
AU - Tosello-Trampont, A. C.
AU - Kinchen, J. M.
AU - Brugnera, E.
AU - Haney, L. B.
AU - Hengartner, M. O.
AU - Ravichandran, K. S.
N1 - Funding Information:
Acknowledgements. We thank Dr. Ray Birge for kindly providing us GFP-CrkII plasmids, Jan Redick and Christie Davis of the Advanced Microscopy Core Facility at University of Virginia for help and advice on confocal microscopy, and Costi Sifri, Gari Stergiou, Cheng-Wen Su, Cynthia Grimsley and members of the Ravichandran lab for helpful discussions. This work was supported by NIH grants to KSR and grants from the EU APOCLEAR, the Ernst Hadorn Foundation, and the Swiss National Science Fund to MOH. JMK is a recipient of an Arthritis Foundation Postdoctoral Fellowship.
PY - 2007/5
Y1 - 2007/5
N2 - Removal of apoptotic cells is a dynamic process coordinated by ligands on apoptotic cells, and receptors and other signaling proteins on the phagocyte. One of the fundamental challenges is to understand how different phagocyte proteins form specific and functional complexes to orchestrate the recognition/removal of apoptotic cells. One evolutionarily conserved pathway involves the proteins cell death abnormal (CED)-2/chicken tumor virus no. 10 (CT10) regulator of kinase (Crk)II, CED-5/180kDa protein downstream of chicken tumor virus no. 10 (Crk) (Dock180), CED-12/engulfment and migration (ELMO) and MIG-2/RhoG, leading to activation of the small GTPase CED-10/Rac and cytoskeletal remodeling to promote corpse uptake. Although the role of ELMO:Dock180 in regulating Rac activation has been well defined, the function of CED-2/CrkII in this complex is less well understood. Here, using functional studies in cell lines, we observe that a direct interaction between CrkII and Dock180 is not required for efficient removal of apoptotic cells. Similarly, mutants of CED-5 lacking the CED-2 interaction motifs could rescue engulfment and migration defects in CED-5 deficient worms. Mutants of CrkII and Dock180 that could not biochemically interact could colocalize in membrane ruffles. Finally, we identify MIG-2/RhoG (which functions upstream of Dock180:ELMO) as a possible point of crosstalk between these two signaling modules. Taken together, these data suggest that Dock180/ELMO and CrkII act as two evolutionarily conserved signaling submodules that coordinately regulate engulfment.
AB - Removal of apoptotic cells is a dynamic process coordinated by ligands on apoptotic cells, and receptors and other signaling proteins on the phagocyte. One of the fundamental challenges is to understand how different phagocyte proteins form specific and functional complexes to orchestrate the recognition/removal of apoptotic cells. One evolutionarily conserved pathway involves the proteins cell death abnormal (CED)-2/chicken tumor virus no. 10 (CT10) regulator of kinase (Crk)II, CED-5/180kDa protein downstream of chicken tumor virus no. 10 (Crk) (Dock180), CED-12/engulfment and migration (ELMO) and MIG-2/RhoG, leading to activation of the small GTPase CED-10/Rac and cytoskeletal remodeling to promote corpse uptake. Although the role of ELMO:Dock180 in regulating Rac activation has been well defined, the function of CED-2/CrkII in this complex is less well understood. Here, using functional studies in cell lines, we observe that a direct interaction between CrkII and Dock180 is not required for efficient removal of apoptotic cells. Similarly, mutants of CED-5 lacking the CED-2 interaction motifs could rescue engulfment and migration defects in CED-5 deficient worms. Mutants of CrkII and Dock180 that could not biochemically interact could colocalize in membrane ruffles. Finally, we identify MIG-2/RhoG (which functions upstream of Dock180:ELMO) as a possible point of crosstalk between these two signaling modules. Taken together, these data suggest that Dock180/ELMO and CrkII act as two evolutionarily conserved signaling submodules that coordinately regulate engulfment.
UR - http://www.scopus.com/inward/record.url?scp=34247530036&partnerID=8YFLogxK
U2 - 10.1038/sj.cdd.4402094
DO - 10.1038/sj.cdd.4402094
M3 - Article
C2 - 17304244
AN - SCOPUS:34247530036
SN - 1350-9047
VL - 14
SP - 963
EP - 972
JO - Cell Death and Differentiation
JF - Cell Death and Differentiation
IS - 5
ER -