Activation of ARF- But not RHO-dependent nuclear phospholipase D in murine peritoneal macrophages on ligation of cvM signaling receptor

Activation of phospholipase D (PLD) is a receptor-mediated event revolved m signal transduction, ntembrane trafficking, cell proliferation, and phagocytosis Phosphatidic acid (PA). the prmary lipid product of PLD, possesses growth factors-like properties and acts as a second messenger. PA hydrolysis produces I)AG whose nu clear accumulation may trigger translocation of PKC to the nucleus. PK(? has been implicated in nuclear events upon binding of agonists to cel[ surface receptors Both heterotrimeric and low molecular weight G proteins (AIIF and Rho A) have been implicated in PLD activation. Ligation of macrophage a2-macroglobulin signaling re(el tors (a2MSR) with receptor-recognized forms of a2M, c2-methylamine and receptor binding fragment (RBF) activates a signaling cascade, triggering tyrosine phospho rylation of PLC-I, raising cytosolic pl[ and stimulating protein and I)NA synthesis. To understand tile role of PLD in events elicited consequent to the binding of I{BI" to c 2MSR, we assayed the activity of PLD in nuclei. RBF stimulated nuclear t'l,l) activity in a dose-dependent manner, reaching a peak vahle (80%) at 100 pM ligand concentration. PLD activation was severely inhibited by saturosporin, down regu lated by PDBu, ge,wstein, actinomycin I), and by modulation of intracelhdar Ca2+ levels with BAPTA/AM and thapsigargin. GTPTS and ARF individually stmmlated RBF-induced nuclear PLI) activity only marginally but together they produced the maximal stimulation, which was inhibited by GDP3S. RhoA alone or m combination with GTPTS or ATP showed no potentiating effect on RBF-mduced PLD aclivity in macrophage nuclei.

Duke Scholars

Author Salvatore Vincent Pizzo Pathology

Author Uma Kant Misra Pathology