iNOS gene silencing prevents inflammatory cytokine-induced β-cell apoptosis

Feng Li, Ram I. Mahato

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Human islet transplantation has great potential as an effective means of treating insulin-dependent diabetes mellitus. Upregulation of inducible nitric oxide synthase (iNOS) and subsequent product of radical nitric oxide (NO) impair islet β-cell function. Therefore, we hypothesize that iNOS gene silencing will prevent β-cell death and improve the survival and function of islets. Small interfering RNA duplex (siRNA) inhibited rat iNOS gene expression and NO production in rat β-cell lines (INS-1E) in a dose- and sequence-dependent manner. iNOS gene silencing also protected these β-cells from inflammatory cytokine-induced apoptosis and increased their capacity to secret insulin. Three siRNA sequences against human iNOS were then designed and transfected into human islets. Although there was dose- and sequence-dependent iNOS gene silencing and NO production in human islets, the effect of iNOS gene silencing on apoptosis of islets was only moderate, as evidenced by 25-30% reduction in caspase 3 activity and in the percentage of apoptotic cells. Since an islet is a cluster of 200-1000 cells, the transfection efficiency of lipid/siRNA complexes into human islets was only 21-28%, compared to effective transfection efficiency (>90%) in β-cell lines. Nevertheless, these results suggest that siRNA may penetrate beyond the periphery into a larger percentage of an islet mass than previously thought.

Original languageEnglish (US)
Pages (from-to)407-417
Number of pages11
JournalMolecular Pharmaceutics
Issue number3
StatePublished - May 2008
Externally publishedYes


  • Apoptosis
  • Islet transplantation
  • iNOS
  • siRNA
  • β cells

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmaceutical Science
  • Drug Discovery


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