Protein kinase C-eta (PKC-eta) is required for the development of inducible nitric oxide synthase (iNOS) positive phenotype in human monocytic cells

Nitric Oxide. 2003 Nov;9(3):123-34. doi: 10.1016/j.niox.2003.09.006.


Several murine and human monocytic cell lines and monocyte-derived macrophages (MDM) from healthy volunteers were studied to compare their production of nitric oxide (NO) and induction of iNOS following endotoxin treatment. Although the human cells were sensitive to endotoxin and responded well by producing TNF-alpha and matrix metalloproteases (MMP), there was no induction of iNOS expression or NO production by any of these cells. Murine cells, however, produced large amounts of NO and expressed iNOS following similar endotoxin stimulation. We investigated the expression of PKC isotypes in all human and murine cell lines as well as in MDM, and found that the human cells lacked PKC-eta while the murine counterparts lacked PKC-beta1. Subsequently, human cells that were transfected with PKC-eta were found to make large quantities of NO following endotoxin exposure, an observation not seen in untransfected cells. We propose that PKC-eta is essential for the development of the iNOS positive phenotype in human monocytic cells, and may be responsible for the development of a number of inflammatory related conditions. As such it may be a suitable target for therapeutic intervention.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Humans
  • Isoenzymes / metabolism
  • Lipopolysaccharides / pharmacology
  • Macrophages / enzymology
  • Matrix Metalloproteinases / biosynthesis
  • Mice
  • Monocytes / drug effects
  • Monocytes / enzymology*
  • Nitric Oxide / biosynthesis*
  • Nitric Oxide Synthase / biosynthesis*
  • Nitric Oxide Synthase / genetics
  • Nitric Oxide Synthase Type II
  • Phenotype
  • Protein Kinase C / physiology*
  • Transcription, Genetic
  • Tumor Necrosis Factor-alpha / biosynthesis


  • Isoenzymes
  • Lipopolysaccharides
  • Tumor Necrosis Factor-alpha
  • Nitric Oxide
  • NOS2 protein, human
  • Nitric Oxide Synthase
  • Nitric Oxide Synthase Type II
  • Nos2 protein, mouse
  • protein kinase C eta
  • Protein Kinase C
  • Matrix Metalloproteinases