Down-regulation of Phospolipase D by Protein Kinase A in a Cell Free System of Human Neutrophils = 사람 호중구에서 phospholipase D 의 활성에 대한protein kinase A 의 억제에 대한 연구

다국어 초록 (Multilingual Abstract)

Agents which elevate cellular cAMP are known to inhibit the activation of phospholipase D (PLD) in human neutrophils. The PLD activity of human neutrophils requires protein factors in both membrane and cytosolic fractions. We have studied the regulation of PLD by the catalytic subunit of protein kinase A (cPKA) in a cell-free system cPKA significantly inhibited GTPyS-stimulated PLD activity but had no effect on phorbol ester-activated PLD Pretreatment of plasma membrane with cPKA and ATP unhibited PLD activation by added cytosol or 50-kDa cytosolic factor, but PLD activity of the cytosolic fraction was not affected by cPKA Affinity-purified brain PLD1 was phosphorylated by cPKA but its activity in the presence of GTPys, ADP-ribosylation factor (ARF), and phosphatidylinositol 4,5-bisphosphate was not affected RhoA, an activator of PLD, has been reported to be phosphorylated by PKA. The PKA-phosphorylated form of RhoA, an activator of PLD, has been reported to be phosphorylated by PKA. The PKA-phosphorylated form of RhoA was more easily extracted from membranes by RhoGDI than the unphosphorylated form, but the GTPyS-dependent translocation of RhoA from cytosolic RhoA-RhoGDI complexes to the plasma membrane was not affected significantly by cPKA These results suggest that inhibition of neutrophil PLD by PKA may be due to inhibition of the interaction between PLD and RhoA on the plasma membrane

목차 (Table of Contents)

• ABSTRACT
• INTRODUCTION
• MATERIALS AND METHODS
• RESULTS
• DISUCSSION
• REFERENCES