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Infect Immun. 1992 January; 60(1): 231-236

Roles of protein kinase C and G proteins in activation of murine resting B lymphocytes by endotoxin-associated protein.

Department of Microbiology and Immunology, State University of New York, Brooklyn 11203.

ABSTRACT

Endotoxin-associated protein (EP) from the outer membrane of gram-negative bacteria is a potent immunomodulator. To examine the mechanism of EP stimulation, the protein kinase C inhibitors H7 and staurosporine were used. Both DNA and RNA synthesis of EP-stimulated murine resting B cells were completely inhibited when inhibitors were added at 0 h, whereas 55 to 76% inhibition of DNA synthesis was observed when H7 was added after 12 h of stimulation. In contrast, HA 1004, which blocks protein kinase A and protein kinase G activity, was relatively ineffective even at high concentrations, suggesting that the activity of protein kinase C is a primary mechanism of EP-induced murine B-cell proliferation. To examine the role of G proteins in EP-induced DNA synthesis in B cells, the effects of pertussis toxin (PT), which inactivates certain G proteins, and the B oligomer of PT (PTB), which does not, were also examined. PT was found to inhibit EP-induced DNA synthesis in a dose-dependent manner. However, PTB also caused equivalent inhibition, suggesting that PTB may be responsible for most of the inhibitory effect seen with the holotoxin. These results serve to question whether G proteins are involved in the signal transduction that occurs during EP-induced DNA synthesis in murine B cells.

This article has been cited by other articles:

• Manthey, C.L., Vogel, S.N. (1994). Elimination of trace endotoxin protein from rough chemotype LPS. Innate Immunity 1: 84-91 [Abstract]