Protein Kinase C Controls Vesicular Transport and Secretion of Apolipoprotein E from Primary Human Macrophages

Denuja Karunakaran, Maaike Kockx, Dylan Owen, John R. Burnett, Wendy Jessup, Leonard Kritharides

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

Macrophage-specific apolipoprotein E (apoE) secretion plays an important protective role in atherosclerosis. However, the precise signaling mechanisms regulating apoE secretion from primary human monocyte-derived macrophages (HMDMs) remain unclear. Here we investigate the role of protein kinase C (PKC) in regulating basal and stimulated apoE secretion from HMDMs. Treatment of HMDMs with structurally distinct pan-PKC inhibitors (calphostin C, Ro-31-8220, Go6976) and a PKC inhibitory peptide all significantly decreased apoE secretion without significantly affecting apoE mRNA or apoE protein levels. The PKC activator phorbol 12-myristate 13-acetate (PMA) stimulated apoE secretion, and both PMA-induced and apoAI-induced apoE secretion were inhibited by PKC inhibitors. PKC regulation of apoE secretion was found to be independent of the ATP binding cassette transporter ABCA1. Live cell imaging demonstrated that PKC inhibitors inhibited vesicular transport of apoE to the plasma membrane. Pharmacological or peptide inhibitor and knockdown studies indicate that classical isoforms PKC alpha/beta and not PKC delta, -epsilon, -theta, or -iota/zeta isoforms regulate apoE secretion from HMDMs. The activity of myristoylated alanine-rich protein kinase C substrate (MARCKS) correlated with modulation of PKC activity in these cells, and direct peptide inhibition of MARCKS inhibited apoE secretion, implicating MARCKS as a downstream effector of PKC in apoE secretion. Comparison with other secreted proteins indicated that PKC similarly regulated secretion of matrix metalloproteinase 9 and chitinase-3-like-1 protein but differentially affected the secretion of other proteins. In conclusion, PKC regulates the secretion of apoE from primary human macrophages.
Original languageEnglish
Pages (from-to)5186-5197
Number of pages12
JournalJournal of Biological Chemistry
Volume288
Issue number7
DOIs
Publication statusPublished - 15 Feb 2013

Keywords

  • MONOCYTE-DERIVED MACROPHAGES
  • HIGH-DENSITY-LIPOPROTEIN
  • HUMAN SKIN FIBROBLASTS
  • CELLS IN-VITRO
  • A-I
  • PHORBOL ESTER
  • MOUSE MACROPHAGES
  • ACTIVATED MACROPHAGES
  • NEUROBLASTOMA-CELLS
  • CHOLESTEROL EFFLUX

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