Activation of cellular protein kinase C and mode of inhibitory action of phospholipid-interacting compounds

Phospholipid/Calcium-Dependent Protein Kinase Activity in Human Cortisol-Hypersecreting Adrenocortical Adenoma

“…Vilgrain et al [5] also showed an increase in C-kinase activity in the cytosolic fraction, with an accompanying decrease in that in the particulate fraction in p 1-24 ACTH-stimulated bovine adrenocortical cells. These observations are in contrast with those for other cell types such as pancreatic acinar cells [1], platelets [2], pituitary cells [3] and neutrophils [4], in which C-kinase activity was translocated from the cytosol to the particulate fraction by the different types of agonists. However, Averdunk and Gunther [7] recently reported that upon stimulation of rat thymocytes with concanavalin A C-kinase activity was increased in the cytosolic fraction and decreased in the particulate fraction.…”

“…It is generally documented that C-kinase plays an important role in mediating functional responses in various cell types such as pancreatic acinar cells [1], platelets [2], pituitary cells [3], and neutrophils [4]. Recently, vilgrain et al [5] presented evidence showing that cytosolic C-kinase activity in isolated bovine adrenocortical cells was increased by stimulation with ,l 1-24 ACTH.…”

Phospholipid/Ca2+-dependent Protein Kinase Activity in Human Parathyroid Adenoma.

“…Cytosolic protein kinase C activity of parathyroid adenoma undergoing hypersecretion of PTH was lower than that of atrophic parathyroid tissue with repressed secretion, whereas membrane-associated protein kinase C activity was higher in the adenoma than in atrophic tissue. Recently, substantial evidence has shown that stimulation with TPA or other stimulants induces translocation of protein kinase C from cytosol fraction to membrane fraction in many cell types such as GH4Cl cells (Fearon and Tashjian, 1985), human platelets (Uratsuji et al, 1985) and pancreatic acinar cells (Noguchi et al, 1985). However, no report was available on the translocation of protein kinase C in hormoneproducing adenoma cells showing changes in secretion from the patient.…”

Phorbol diesters and transferrin modulate lymphoblastoid cell transferrin receptor expression by two different mechanisms

“…However, other data suggest that if C-kinase activation is necessary for TfR downregulation, it is not by itself sufficient (Kreutter et al, 1985). Although the precise biochemical mechanism of the phorbol diester-induced process in lymphoblastoid T-cells is not known, its rapid reversal by chlorpromazine, a lipid interactive agent (Uratsuji et al, 1985), suggests that T f R conformational changes resulting from intercalation of phorbol diesters or chlorpromazine into the cell membrane may produce rapid TfR down-or upregulation. Alternatively, it is possible that phorbol diester-induced downregulation may be due to reversible internalization in peripheral cytoplasmic vacuoles (Hopkins, 1983;Buys et al, 1984).…”