Generation of diacylglycerol and ceramide during homologous complement activation.

Abstract

Formation of sublytic terminal complement complexes (TCC) on nucleated cells produces transient increase in [Ca2+]i and activates protein kinase C. The present study is to evaluate whether TCC can generate endogenous signal messengers other than Ca2+ that regulate cell activities by measuring mass-levels of sn-1,2-diacylglycerol (DAG) and ceramide. As targets, lymphoblastoid human B cell lines JY25 and its mutant JY5 were used. JY5, cells deficient in glycosylphosphatidylinositol-anchored proteins with higher lytic susceptibility to human complement, are four times more efficient in forming C5b-9. When cells sensitized with limited anti-class II IgG were exposed to human serum to generate sublytic TCC, a sustained increase in DAG and ceramide was observed with a maximum 3.6-fold DAG increase over basal level in JY25 and 2.8-fold in JY5, and 6.3-fold ceramide increase in JY25 and 2.8-fold in JY5. The effect of TCC was evaluated with C7-deficient human serum (C7D) +/- C7 and also with C5b6, C7, C8, and C9 proteins. The DAG and ceramide increase by C7D + C7 over C7D control were 1.6- and 1.8-fold, respectively, in JY25, and 2.3-, and two-fold in JY5. TCC activation also induced an increased hydrolysis of sphyingomyelin and phosphatidylcholine. In addition, DAG increase by TCC was primarily achieved by C5b-7 and preincubation of cells with pertussis toxininhibited DAG increase, suggesting an involvement of a pertussis toxin-sensitive GTP-binding protein. As important signal transduction molecules, DAG and ceramide generated in response to TCC assembly, could participate in cell activation during inflammation and repair.

• Authors: F Niculescu, H Rus, S Shin, T Lang, M L Shin
• Journal: Journal of immunology (Baltimore, Md. : 1950) (J Immunol) Vol. 150 Issue 1 Pg. 214-24 (Jan 01 1993) ISSN: 0022-1767 [Print] United States
• PMID: 8417124 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Ceramides
• Complement C9
• Diglycerides
• Phosphatidylcholines
• Virulence Factors, Bordetella
• Pertussis Toxin
• Protein Kinase C

Topics

• Animals
• Cell Line, Transformed
• Ceramides (biosynthesis)
• Complement Activation
• Complement C9 (metabolism)
• Diglycerides (biosynthesis)
• Humans
• Mice
• Molecular Weight
• Pertussis Toxin
• Phosphatidylcholines (metabolism)
• Phosphorylation (drug effects)
• Protein Kinase C (metabolism)
• Substrate Specificity
• Virulence Factors, Bordetella (pharmacology)