Akt/protein kinase B activation by adenovirus vectors contributes to NFkappaB-dependent CXCL10 expression.
In gene therapy, the innate immune system is a significant barrier to the effective application of adenovirus (Ad) vectors. In kidney epithelium-derived (REC) cells, serotype 5 Ad vectors induce the expression of the chemokine CXCL10 (IP-10), a response that is dependent on NFkappaB. Compared to the parental vector AdLuc, transduction with the RGD-deleted vector AdL.PB resulted in reduced CXCL10 activation despite increasing titers, implying that RGD-alpha(V) integrin interactions contribute to adenovirus induction of inflammatory genes. Akt, a downstream effector of integrin signaling, was activated within 10 min of transduction with Ad vectors in a dose-dependent manner. Akt activation was not present following transduction with AdL.PB, confirming the importance of capsid-alpha(V) integrin interactions in Ad vector Akt activation. Inhibition of the phosphoinositide-3-OH kinase/Akt pathway by Wortmannin or Ly294002 compounds decreased Ad vector induction of CXCL10 mRNA. Similarly, adenovirus-mediated overexpression of the dominant negative AktAAA decreased CXCL10 mRNA expression compared to the reporter vector AdLacZ alone. The effect of Akt on CXCL10 mRNA expression occurred via NFkappaB-dependent transcriptional activation, since AktAAA overexpression and Ly294002 both inhibited CXCL10 and NFkappaB promoter activation in luciferase reporter experiments. These results show that Akt plays a role in the Ad vector activation of NFkappaB and CXCL10 expression. Understanding the mechanism underlying the regulation of host immunomodulatory genes by adenovirus vectors will lead to strategies that will improve the efficacy and safety of these agents for clinical use.
Liu
Qiang
Q
Department of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
White
Lindsay R
LR
Clark
Sharon A
SA
Heffner
Daniel J
DJ
Winston
Brent W
BW
Tibbles
Lee Anne
LA
Muruve
Daniel A
DA
D000256:Adenoviridae / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D054357:Chemokine CXCL10; D019743:Chemokines, CXC / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D005822:Genetic Vectors; D016328:NF-kappa B / Q000276:immunology / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D054357:Chemokine CXCL10; D019743:Chemokines, CXC; D016328:NF-kappa B; D051057:Proto-Oncogene Proteins c-akt