Activation of protein kinase C beta II by the stereo-specific phosphatidylserine receptor is required for phagocytosis of apoptotic thymocytes by resident murine tissue macrophages.
We showed previously that protein kinase C (PKC) is required for phagocytosis of apoptotic leukocytes by murine alveolar (AMø) and peritoneal macrophages (PMø) and that such phagocytosis is markedly lower in AMø compared with PMø. In this study, we examined the roles of individual PKC isoforms in phagocytosis of apoptotic thymocytes by these two Mø populations. By immunoblotting, AMø expressed equivalent PKC eta but lower amounts of other isoforms (alpha, betaI, betaII, delta, epsilon, mu, and zeta), with the greatest difference in betaII expression. A requirement for PKC betaII for phagocytosis was demonstrated collectively by phorbol 12-myristate 13-acetate-induced depletion of PKC betaII, by dose-response to PKC inhibitor Ro-32-0432, and by use of PKC betaII myristoylated peptide as a blocker. Exposure of PMø to phosphatidylserine (PS) liposomes specifically induced translocation of PKC betaII and other isoforms to membranes and cytoskeleton. Both AMø and PMø expressed functional PS receptor, blockade of which inhibited PKC betaII translocation. Our results indicate that murine tissue Mø require PKC betaII for phagocytosis of apoptotic cells, which differs from the PKC isoform requirement previously described in Mø phagocytosis of other particles, and imply that a crucial action of the PS receptor in this process is PKC betaII activation.
Todt
Jill C
JC
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Health Care System, Department of Veterans Affairs Care System, Ann Arbor, Michigan 48105-2303, USA.
Hu
Bin
B
Punturieri
Antonello
A
Sonstein
Joanne
J
Polak
Timothy
T
Curtis
Jeffrey L
JL
D000098:Acetophenones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D001578:Benzopyrans / Q000494:pharmacology; D015153:Blotting, Western; D002448:Cell Adhesion; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D005260:Female; D005434:Flow Cytometry; D015151:Immunoblotting; D007211:Indoles / Q000494:pharmacology; D020128:Inhibitory Concentration 50; D007527:Isoenzymes / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D019814:Myristic Acid / Q000494:pharmacology; D010587:Phagocytosis; D020033:Protein Isoforms; D011493:Protein Kinase C / Q000737:chemistry / Q000378:metabolism*; D064546:Protein Kinase C beta; D021381:Protein Transport; D011758:Pyrroles / Q000494:pharmacology; D012313:RNA / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013950:Thymus Gland / Q000166:cytology*; D013997:Time Factors
D000098:Acetophenones; D001578:Benzopyrans; D007211:Indoles; D007527:Isoenzymes; D008081:Liposomes; D020033:Protein Isoforms; C498708:Ptdsr protein, mouse; D011758:Pyrroles; D011956:Receptors, Cell Surface; C408123:phosphatidylserine receptor; D019814:Myristic Acid; C085989:Ro 32-0432; D012313:RNA; C085746:rottlerin; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D013755:Tetradecanoylphorbol Acetate