Complement C5b-9 complex activates phospholipases in glomerular epithelial cells

A. V. Cybulsky, D. J. Salant, R. J. Quigg, J. Badalamenti, J. V. Bonventre

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Abstract

In rat membranous nephropathy, formation of the C5b-9 membrane attack complex (MAC) leadss to proteinuria in association with glomerular visceral epithelial cell (GEC) injury. These alterations in GEC function and morphology might result from changes in intracellular free Ca2+ concentration ([Ca2+](i)) and activation of phospholipases. We demonstrate that in cultured rat GEC, antibody-directed formation of noncytolytic amounts of the MAC induced a rapid and sustained increase in [Ca2+](i) that was partly inhibited by ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'-tretraacetic acid (EGTA). The MAC elevated levels of inositol bis-(IP2) and trisphosphate (IP3), as well as 1,2-diacylglycerol (DAG) and phosphatidic acid (PA). In permeabilized GEC, IP3 released Ca2+ from intracellular stores. Cellular 45Ca2+ uptake was also increased by the MAC. Thus, in GEC, the MAC induced Ca2+ mobilization from intracellular stores secondary to activation of phospholipase C and production of IP3, as well as enhanced Ca2+ influx. In addition, C5b-9 stimulated release of arachidonic acid (AA), prostaglandin F(2α), and thromboxane A2. Indomethacin partially inhibited the increase in DAG levels observed with the MAC, whereas the prostaglandin H2/thromboxane A2 analogue U46619 elevated DAG, suggesting that an eicosanoid product of MAC-induced AA release may enhance the activation of phospholipase C. Activation of phospholipases by the MAC may lead to altered GEC function and thereby contribute to the pathophysiological changes that characterize complement-dependent rat membranous nephropathy.

Original languageEnglish (US)
Pages (from-to)26/5
JournalAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Volume257
Issue number5
StatePublished - Jan 1 1989

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Keywords

  • 1,2-diacylglycerol
  • arachidonic acid
  • inositol phosphates
  • intracellular free calcium concentration
  • phospholipase C

ASJC Scopus subject areas

  • Physiology

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