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Macrophage apolipoprotein-E knockdown modulates caspase-3 activation without altering sensitivity to apoptosis

Journal Article


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Abstract


  • Apolipoprotein-E (apoE) expression may be associated with apoptosis resistance. Since macrophages constitutively synthesize apoE we speculated that this may contribute to apoptosis resistance. Using siRNA, human monocyte derived macrophage (hMDM) apoE mRNA and protein was reduced by 97% and 61%, respectively. ApoE knockdown increased staurosporine-induced caspase-3 activation by 78% without altering cell survival or apoptosis as assessed by TUNEL analysis and morphological changes. This result was confirmed using murine bone marrow derived macrophages (mBMDM) from apoE null and wild type mice. In these experiments, staurosporine-induced caspase-3 activation was increased by 49% in apoE null compared to wild type mBMDM and this was not associated with differences in TUNEL signal, annexin-V binding or DNA fragmentation. ApoE is also important for cholesterol transport and macrophage cholesterol can regulate apoptosis. Knockdown of hMDM apoE inhibited basal cholesterol efflux by 20% without altering apolipoprotein-AI mediated cholesterol efflux over 24 h. Similarly, in apoE null mBMDM a non significant trend for a 16% reduction in basal cholesterol efflux was observed as compared to wild type mBMDM. In conclusion, apoE expression modulates capase-3 activity, but this has no significant impact on sensitivity to apoptosis and only a moderate impact on basal cholesterol efflux. © 2007 Elsevier B.V. All rights reserved.

Authors


  •   Elliott, David A. (external author)
  •   Kim, Woojin S. (external author)
  •   Jans, D A (external author)
  •   Garner, Brett

Publication Date


  • 2008

Citation


  • Elliott, D., Kim, W., Jans, D. & Garner, B. (2008). Macrophage apolipoprotein-E knockdown modulates caspase-3 activation without altering sensitivity to apoptosis. Biochimica et Biophysica Acta - General Subjects, 1780 (2), 145-153.

Scopus Eid


  • 2-s2.0-38549102993

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1044&context=ihmri

Ro Metadata Url


  • http://ro.uow.edu.au/ihmri/29

Number Of Pages


  • 8

Start Page


  • 145

End Page


  • 153

Volume


  • 1780

Issue


  • 2

Abstract


  • Apolipoprotein-E (apoE) expression may be associated with apoptosis resistance. Since macrophages constitutively synthesize apoE we speculated that this may contribute to apoptosis resistance. Using siRNA, human monocyte derived macrophage (hMDM) apoE mRNA and protein was reduced by 97% and 61%, respectively. ApoE knockdown increased staurosporine-induced caspase-3 activation by 78% without altering cell survival or apoptosis as assessed by TUNEL analysis and morphological changes. This result was confirmed using murine bone marrow derived macrophages (mBMDM) from apoE null and wild type mice. In these experiments, staurosporine-induced caspase-3 activation was increased by 49% in apoE null compared to wild type mBMDM and this was not associated with differences in TUNEL signal, annexin-V binding or DNA fragmentation. ApoE is also important for cholesterol transport and macrophage cholesterol can regulate apoptosis. Knockdown of hMDM apoE inhibited basal cholesterol efflux by 20% without altering apolipoprotein-AI mediated cholesterol efflux over 24 h. Similarly, in apoE null mBMDM a non significant trend for a 16% reduction in basal cholesterol efflux was observed as compared to wild type mBMDM. In conclusion, apoE expression modulates capase-3 activity, but this has no significant impact on sensitivity to apoptosis and only a moderate impact on basal cholesterol efflux. © 2007 Elsevier B.V. All rights reserved.

Authors


  •   Elliott, David A. (external author)
  •   Kim, Woojin S. (external author)
  •   Jans, D A (external author)
  •   Garner, Brett

Publication Date


  • 2008

Citation


  • Elliott, D., Kim, W., Jans, D. & Garner, B. (2008). Macrophage apolipoprotein-E knockdown modulates caspase-3 activation without altering sensitivity to apoptosis. Biochimica et Biophysica Acta - General Subjects, 1780 (2), 145-153.

Scopus Eid


  • 2-s2.0-38549102993

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1044&context=ihmri

Ro Metadata Url


  • http://ro.uow.edu.au/ihmri/29

Number Of Pages


  • 8

Start Page


  • 145

End Page


  • 153

Volume


  • 1780

Issue


  • 2