c-FLIPL regulates PKC via AP-2 to inhibit Bax-mediated apoptosis induced by HIV-1 gp120 in Jurkat cells

Mol Cell Biochem. 2009 Oct;330(1-2):23-9. doi: 10.1007/s11010-009-0096-3. Epub 2009 Apr 11.

Abstract

c-FLIPL, an inhibitor of caspase 8, is known to inhibit the Fas/caspase 8 apoptotic pathway; however, its involvement of Bax/mitochondrial apoptosis is not well understood. Using human cells, Jurkat cell line, induced with HIV-1 gp120, we studied the effects of c-FLIPL on Bax/mitochondrial apoptosis. We found that the induction of apoptosis by HIV-1 envelope protein, gp120, involved the activation of both Bax-dependent and death receptor-mediated pathways, and HIV-1 infection deceased c-FLIPL expression. Interestingly, c-FLIPL expression downregulated protein kinase C (PKC) expression at the transcript level involving activated protein-2 (AP-2). c-FLIPL expression reduced AP-2 protein levels required to promote PKC protein expression and PKC-associated inactive form of Bax, and inhibited Bax activation, suggesting that c-FLIPL inhibits Bax activation via modulating PKC expression at the transcriptional level involving AP-2 during gp120 treatment. Collectively, these findings further corroborate the concept that gp120 plays an important role, via involvement of molecules such as c-FLIPL, in apoptotic cell death due to HIV-1 infection.

MeSH terms

  • Apoptosis / drug effects*
  • CASP8 and FADD-Like Apoptosis Regulating Protein / physiology*
  • Gene Expression Regulation
  • HIV Envelope Protein gp120 / pharmacology*
  • HIV Infections / immunology
  • HIV Infections / pathology
  • Humans
  • Jurkat Cells
  • Protein Kinase C / metabolism*
  • Transcription Factor AP-2 / physiology*
  • bcl-2-Associated X Protein / antagonists & inhibitors*

Substances

  • CASP8 and FADD-Like Apoptosis Regulating Protein
  • CFLAR protein, human
  • HIV Envelope Protein gp120
  • Transcription Factor AP-2
  • bcl-2-Associated X Protein
  • Protein Kinase C