TY - JOUR
T1 - Identification of calreticulin as a marker for phagocytosis of apoptotic cells in Drosophila
AU - Kuraishi, Takayuki
AU - Manaka, Junko
AU - Kono, Mari
AU - Ishii, Hidenari
AU - Yamamoto, Naoko
AU - Koizumi, Keita
AU - Shiratsuchi, Akiko
AU - Lee, Bok Luel
AU - Higashida, Haruhiro
AU - Nakanishi, Yoshinobu
N1 - Funding Information:
We thank Dr. S. Gamo, Dr. S. Nagata, Dr. S. Natori, the Bloomington Drosophila Stock Center, and the Developmental Studies Hybridoma Bank for the materials. We are also grateful to Drs. P. Henson and T. Awasaki for advice. This work was supported by the Grant-in-Aid for Scientific Research (no. 18–268) and the 21st Century COE Program from the Japan Society for the Promotion of Science, and in part by the Grant-in-Aid for Scientific Research (no. 16570112 and no. 18570123) from the Japan Society for the Promotion of Science. T.K. is a recipient of the predoctoral fellowship from the Japan Society for the Promotion of Science.
PY - 2007/2/1
Y1 - 2007/2/1
N2 - Apoptotic cell phagocytosis is initiated through the specific interaction between markers for phagocytosis present at the surface of targets and their receptors of phagocytes. Although many molecules have been proposed to be phagocytosis markers and receptors in mammals, information as to the identity of those molecules is limited for invertebrate animals. Calreticulin, a molecular chaperone that functions in the lumen of the endoplasmic reticulum, was recently reported to be the second general marker, the membrane phospholipid phosphatidylserine being the first, for mammalian apoptotic cells to be recognized by phagocytes. We here asked whether or not calreticulin serves as a marker for phagocytosis in Drosophila. Phagocytosis of apoptotic S2 cells by Drosophila hemocyte-derived l(2)mbn cells, which we previously showed to occur independent of phosphatidylserine, was inhibited by the addition of anti-calreticulin antibody. This inhibition was observed when the target cells, but not phagocytes, were pre-incubated with the antibody. In addition, RNA interference-mediated reduction of calreticulin expression in apoptotic S2 cells, but not in l(2)mbn cells, reduced the level of phagocytosis. An immunocytochemical analysis revealed that calreticulin is widely distributed at the surface of viable S2 cells. After the induction of apoptosis, cell surface calreticulin seemed to form aggregates, with no change in its amount. Furthermore, in embryos of a mutant Drosophila strain that expresses calreticulin at a reduced level, the level of phagocytosis of apoptotic cells was about a half of that observed in embryos of a wild-type strain. These results collectively indicate that calreticulin is the first molecule to be identified as a marker for phagocytosis of apoptotic cells by Drosophila phagocytes.
AB - Apoptotic cell phagocytosis is initiated through the specific interaction between markers for phagocytosis present at the surface of targets and their receptors of phagocytes. Although many molecules have been proposed to be phagocytosis markers and receptors in mammals, information as to the identity of those molecules is limited for invertebrate animals. Calreticulin, a molecular chaperone that functions in the lumen of the endoplasmic reticulum, was recently reported to be the second general marker, the membrane phospholipid phosphatidylserine being the first, for mammalian apoptotic cells to be recognized by phagocytes. We here asked whether or not calreticulin serves as a marker for phagocytosis in Drosophila. Phagocytosis of apoptotic S2 cells by Drosophila hemocyte-derived l(2)mbn cells, which we previously showed to occur independent of phosphatidylserine, was inhibited by the addition of anti-calreticulin antibody. This inhibition was observed when the target cells, but not phagocytes, were pre-incubated with the antibody. In addition, RNA interference-mediated reduction of calreticulin expression in apoptotic S2 cells, but not in l(2)mbn cells, reduced the level of phagocytosis. An immunocytochemical analysis revealed that calreticulin is widely distributed at the surface of viable S2 cells. After the induction of apoptosis, cell surface calreticulin seemed to form aggregates, with no change in its amount. Furthermore, in embryos of a mutant Drosophila strain that expresses calreticulin at a reduced level, the level of phagocytosis of apoptotic cells was about a half of that observed in embryos of a wild-type strain. These results collectively indicate that calreticulin is the first molecule to be identified as a marker for phagocytosis of apoptotic cells by Drosophila phagocytes.
KW - Apoptosis
KW - Calreticulin
KW - Drosophila
KW - Phagocytosis
KW - RNAi
UR - http://www.scopus.com/inward/record.url?scp=33846833738&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33846833738&partnerID=8YFLogxK
U2 - 10.1016/j.yexcr.2006.10.027
DO - 10.1016/j.yexcr.2006.10.027
M3 - Article
C2 - 17137576
AN - SCOPUS:33846833738
VL - 313
SP - 500
EP - 510
JO - Experimental Cell Research
JF - Experimental Cell Research
SN - 0014-4827
IS - 3
ER -