Heme: a novel inducer of MCP-1 through HO-dependent and HO-independent mechanisms.

Published

Journal Article

This study examined the effect of hemin on the expression of heme oxygenase-1 (HO-1) and monocyte chemoattractant protein-1 (MCP-1) in immortalized rat proximal tubular epithelial cells (IRPTCs). Hemin elicited a dose- and time-dependent induction of HO-1 and MCP-1 mRNA. HO activity contributed to MCP-1 mRNA expression at early time points (4-6 h) because inhibition of HO activity by zinc protoporphyrin (ZnPP) prevented hemin-induced expression of MCP-1 mRNA. Catalytically active intracellular iron was markedly increased in hemin-treated IRPTCs and contributed to the induction of HO-1 and MCP-1 mRNA because an iron chelator blocked hemin-induced upregulation of both genes, whereas a cell-permeant form of iron directly induced these genes. N-acetylcysteine completely blocked hemin-induced expression of HO-1 and MCP-1 mRNA, thereby providing added evidence for redox regulation of expression of these genes. The redox-sensitive transcription factor NF-kappaB was recruited in hemin-induced upregulation of MCP-1 because two different compounds that abrogate the activation of NF-kappaB (TPCK and BAY 11-7082) completely blocked hemin-induced upregulation of MCP-1 mRNA. In contrast to this HO-mediated induction of MCP-1 through redox-sensitive, iron-dependent, and NF-kappaB-involved pathways observed after 4-6 h, hemin also elicited a delayed induction of MCP-1 at 18 h through HO-independent pathways. We conclude that hemin is a potent inducer of MCP-1 in IRPTCs: HO-dependent, heme-degrading pathways lead to an early, robust, and self-remitting induction of MCP-1, whereas HO-independent mechanisms lead to a delayed expression of MCP-1.

Full Text

Duke Authors

Cited Authors

  • Kanakiriya, SKR; Croatt, AJ; Haggard, JJ; Ingelfinger, JR; Tang, S-S; Alam, J; Nath, KA

Published Date

  • March 2003

Published In

Volume / Issue

  • 284 / 3

Start / End Page

  • F546 - F554

PubMed ID

  • 12556365

Pubmed Central ID

  • 12556365

International Standard Serial Number (ISSN)

  • 1931-857X

Digital Object Identifier (DOI)

  • 10.1152/ajprenal.00298.2002

Language

  • eng

Conference Location

  • United States