Selective effects of the PKC inhibitors Ro 31-8220 and CGP 41 251 on PMN locomotion, cell polarity, and pinocytosis

Abstract

Using two newly synthesized inhibitors, Ro 31-8220 and CGP 41 251, of protein kinase C (PKC), we analyzed: (1) how distinct PMN functions (shape changes, locomotion, pinocytosis) are regulated, and (2) the role of protein phosphorylation and PKC in this process. We were able to transform: (1) resting PMNs into locomoting cells using fNLPNTL, (2) locomoting cells into non-locomoting highly pinocytic cells using PMA, and (3) PMA-stimulated cells showing marked pinocytosis into locomoting or into resting cells using Ro 31-8220. It is thus possible to selectively manipulate PMN function (resting state, locomotion, marked pinocytosis), indicating that there are different regulatory pathways. It was not possible to induce locomotion and marked pinocytosis simultaneously, indicating crosstalk between pathways. Ro 31-8220 inhibited PMA-induced shape changes (nonpolar cells) and pinocytosis, but not fNLPNTL-induced shape changes (polarity) and pinocytosis. At higher concentrations, Ro 31-8220 alone elicited cell polarity and chemokinesis, indicating that a constitutively active protein kinase is involved in maintaining the spherical shape of resting PMNs. Functional effects of another PKC inhibitor, CGP 41 251, on neutrophil function were strikingly different. CGP 41 251 selectively inhibited fNLPNTL-induced polarity and locomotion (but not colchicine or Ro 31-8220-induced polarity), and it failed to inhibit PMA-induced, stimulated pinocytosis and shape changes. Although the effects of Ro 31-8220 vs. CGP 41 251 on PMN function were strikingly different, the inhibition of profiles for constitutive and for fNLPNTL- or PMA-induced protein phosphorylation in intact PMNs showed only small differences, which could not yet be conclusively related to cell function.