Phenylarsine Oxide and H2O2 Plus Vanadate Induce Reverse Translocation of Phorbol-Ester-Activated PKC.BETA.II

Abstract

ABSTRACT. The intracellular localization of protein kinase C (PKC) is important for the regulation of its biological activity. Recently, it was reported that, whereas phorbol esters such as PMA induce prolonged translocation of PKC to the plasma membrane, with physiological stimuli, the translocation of PKC is transient and followed by rapid return to the cytoplasm. In addition, this membrane dissociation of PKC was shown to require both the kinase activity of PKC and the phosphorylation of its carboxyl terminus autophosphorylation sites. However, the detailed molecular mechanism of PKC reverse translocation remains obscure. We demonstrated that in porcine polymorphonuclear leucocytes (PMNs), phenylarsine oxide (PAO), a putative protein tyrosine phosphatase

Mechanism of membrane redistribution of protein kinase C by its ATP-competitive inhibitors

“…It is well known that ATP-competitive inhibitors prolong the plasma-membrane translocation of cPKC in response to receptor stimulation or to the cell-permeable DAG analogue DiC8 (1,2-dioctanoyl-sn-glycerol) [18][19][20]. Our previous study [21] and that of Signorelli et al [22] showed that pervanadateor ceramide-induced PKC reverse translocation to the cytosol was prevented by treatment with ATP-competitive inhibitors. In addition, surprisingly, Hu and Exton [23] reported that treatment with the staurosporine analogues Ro-31-8220 and GF 109203X alone apparently induces translocation of PKCα to the membrane fraction.…”

“…Therefore it is possible that this concept also applies to other type PKC inhibitors. To date, a number of studies, including a previous one of our own, have shown that ATP-competitive inhibitors prevent membrane dissociation or re-localization of PKC after initial translocation in response to various stimuli [18][19][20][21][22][23][24]. From results using the inhibitors, some of those studies have concluded that the kinase activity of PKC (to phosphorylate the putative substrate) is required for those events.…”

“…Therefore, these inhibitors have been widely used to investigate the involvement of the kinase activity of PKC in cellular processes. However, recent evidence indicates that these staurosporine-related compounds (described as 'ATPcompetitive inhibitors') not only inhibit the kinase activity of PKC, but also affect its redistribution after initial translocation [18][19][20][21][22][23][24]. It is well known that ATP-competitive inhibitors prolong the plasma-membrane translocation of cPKC in response to receptor stimulation or to the cell-permeable DAG analogue DiC8 (1,2-dioctanoyl-sn-glycerol) [18][19][20].…”

The Life and Death of Protein Kinase C

“…Tyrosine phosphorylation may also serve an additional role in localization of PKC. Treatment of cells with tyrosine phosphatase inhibitors reverses the membrane translocation of PKC βII in phorbol ester-treated cells [55]. …”

“…Further studies investigating the molecular mechanism of this reverse translocation show that the C1 and C2 domains drive the membrane translocation and the catalytic activity of PKC is required for this process; it has been proposed that PKC must maintain its priming autophosphorylations at the C-terminus in order to disengage from the membrane [72, 73]. In phorbol ester-treated cells, tyrosine phosphorylation may also serve a role in facilitating the reverse translocation process [55]. Thus, PKC is responsible for regulating its own dynamic membrane trafficking with autophosphorylation serving as a priming step to initiate the signal termination process.…”