The role of antiapoptotic Bcl-2 family members in endothelial apoptosis elucidated with antisense oligonucleotides.
In this study, we utilized potent antisense oligonucleotides to examine the role of two Bcl-2 family members found in human umbilical vein endothelial cells (HUVEC). The first, A1, is thought to be a TNF-alpha-inducible cytoprotective gene, and the second, Bcl-XL, is constitutively expressed. Inhibition of the constitutive levels of Bcl-XL caused 10-25% of the cell population to undergo apoptosis and increased the susceptibility of cells to treatment with low concentrations of staurosporin or ceramide. The caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp(OMe)-CH2 prevented DNA fragmentation and DeltaYm loss caused by Bcl-XL inhibition or Bcl-XL inhibition combined with staurosporin. However, disruption of DeltaYm caused by Bcl-XL inhibition combined with ceramide treatment was not inhibited by benzyloxycarbonyl-Val-Ala-Asp(OMe)-CH2, although DNA fragmentation was completely prevented. Taken together, these results demonstrate a direct protective role for Bcl-XL under normal resting conditions and under low level apoptotic challenges to HUVEC. Furthermore, Bcl-XL protects cells from caspase-dependent and -independent mechanisms of DeltaYm disruption. In contrast to Bcl-XL, A1 inhibition did not show a marked effect on the susceptibility of HUVEC to undergo apoptosis in response to TNF-alpha, ceramide, or staurosporin. These results demonstrate that although A1 may be a cytoprotective gene induced by TNF-alpha, it is not primarily responsible for HUVEC resistance to this cytokine.
Ackermann
E J
EJ
Department of Molecular Pharmacology, Isis Pharmaceuticals, Carlsbad, California 92008, USA.
Taylor
J K
JK
Narayana
R
R
Bennett
C F
CF
D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001483:Base Sequence; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D002518:Ceramides / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D018398:Homeodomain Proteins; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D015778:Minor Histocompatibility Antigens; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000187:drug effects; D051818:Replication Protein C; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D019311:Staurosporine / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D051020:bcl-X Protein
C096816:BCL2-related protein A1; C494811:BCL2L1 protein, human; D002518:Ceramides; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; C096063:MATA1 protein, S cerevisiae; D015778:Minor Histocompatibility Antigens; D016376:Oligonucleotides, Antisense; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014409:Tumor Necrosis Factor-alpha; D051020:bcl-X Protein; D020169:Caspases; D051818:Replication Protein C; D019311:Staurosporine