IKKβ regulates essential functions of the vascular endothelium through kinase-dependent and -independent pathways

Abstract

Vascular endothelium provides a selective barrier between the blood and tissues, participates in wound healing and angiogenesis, and regulates tissue recruitment of inflammatory cells. Nuclear factor (NF)-κB transcription factors are pivotal regulators of survival and inflammation, and have been suggested as potential therapeutic targets in cancer and inflammatory diseases. Here we show that mice lacking IKKβ, the primary kinase mediating NF-κB activation, are smaller than littermates and born at less than the expected Mendelian frequency in association with hypotrophic and hypovascular placentae. IKKβ-deleted endothelium manifests increased vascular permeability and reduced migration. Surprisingly, we find that these defects result from loss of kinase-independent effects of IKKβ on activation of the serine-threonine kinase, Akt. Together, these data demonstrate essential roles for IKKβ in regulating endothelial permeability and migration, as well as an unanticipated connection between IKKβ and Akt signalling.

Abstract

IKK kinases activate nuclear factor-κB, and the activated form of this transcription factor is found in endothelial cells in diseased tissue. In this study, mice lacking IKKβ in the endothelium are generated, and it is shown that defects in endothelial cell function are both IKK kinase activity dependent and independent.