Protein Kinase Inhibitor H7 Blocks the Induction of Immediate-Early Geneszif268and c-fosby a Mechanism Unrelated to Inhibition of Protein Kinase C but Possibly Related to Inhibition of Phosphorylation of RNA Polymerase II

T-lymphocyte activation via the antigen receptor complex (TCR) results in accumulation of p21ras in the active GTP-bound state. Stimulation of protein kinase C (PKC) can also activate p21ras, and it has been proposed that the TCR effect on p21ras occurs as a consequence of TCR regulation of PKC. To test the role of PKC in TCR regulation of p21ras, a permeabilized cell system was used to examine TCR regulation of p21ras under conditions in which TCR activation of PKC was blocked, first by using a PKC pseudosubstrate peptide inhibitor and second by using ionic conditions that prevent phosphatidyl inositol hydrolysis and hence diacylglycerol production and PKC stimulation. The data show that TCR-induced p21ras activation is not mediated exclusively by PKC. Thus, in the absence of PKC stimulation, the TCR was still able to induce accumulation of p21ras-GTP complexes, and this stimulation correlated with an inactivation of p21ras GTPase-activating proteins. The protein tyrosine kinase inhibitor herbimycin could prevent the non-PKC-mediated, TCR-induced stimulation of p21ras. These data indicate that two mechanisms for p21ras regulation coexist in T cells: one PKC mediated and one not. The TCR can apparently couple to p21ras via a non-PKC-controlled route that may involve tyrosine kinases.

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The protein kinase C inhibitor H-7 activates human neutrophils: effect on shape, actin polymerization, fluid pinocytosis and locomotion

Journal of Cell Science ◽

10.1242/jcs.96.1.99 ◽

1990 ◽

Vol 96 (1) ◽

pp. 99-106

Author(s):

H.U. Keller ◽

V. Niggli ◽

A. Zimmermann ◽

R. Portmann

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Actin Polymerization ◽

Kinase Inhibitor ◽

Human Neutrophils ◽

Kinase C ◽

Chemotactic Peptides ◽

Protein Kinase C Inhibitor ◽

Shape Changes ◽

Stimulation Of

The present study demonstrates new properties of H-7. The protein kinase inhibitor H-7 is a potent activator of several neutrophil functions. Stimulation of initially spherical nonmotile neutrophils elicits vigorous shape changes within a few seconds, increases in cytoskeletal actin, altered F-actin distribution, increased adhesiveness and a relatively small increase in pinocytic activity. H-7 has also chemokinetic activities. Depending on the experimental condition, H-7 may elicit or inhibit neutrophil locomotion. It failed to induce chemotaxis. Thus, the response pattern elicited by H-7 is different from that of other leukocyte activators such as chemotactic peptides, PMA or diacylglycerols. The finding that H-7 can elicit shape changes, actin polymerization and pinocytosis suggests that these events can occur without activation of protein kinase C (PKC). PMA-induced shape changes and stimulation of pinocytosis were not inhibited by H-7.

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