Transcription factor Foxo-1 can be inactivated via Akt-mediated phosphorylation. Since shear stress activates Akt, we determined whether Foxo-1 and the Foxo-1-dependent, angiogenesis-related Ang-2/Tie2-system are influenced by shear stress in endothelial cells. Expression of Foxo-1 and its target genes p27Kip1 and Ang-2 was decreased under shear stress (6 dyn/cm 2 , 24 h), nuclear exclusion of Foxo-1 by phosphorylation increased. eNOS and Tie2 were upregulated. No effects on Ang-1 expression were detected. In conclusion, Foxo-1 and Ang-2/Tie2 are part of the molecular response to shear stress, which may regulate angiogenesis.
The present imaging spectroscopy approach allows detailed assessment of oxygen transport and other functional parameters at the microcirculatory level.
Microvessels respond to metabolic stimuli (e.g. pO2) and
hemodynamic forces (e.g. shear stress and wall stress) with
structural adaptations including angiogenesis, remodeling and
pruning. These responses could be mediated by differential gene
expression in endothelial and smooth muscle cells. Therefore, rat
mesenteric arteries and veins were excised by microsurgery, and
mRNA expression of four angioadaptation-related genes was
quantified by real time duplex RT-PCR in equal amounts of total
RNA, correlated to two different house keeping genes (ß-actin,
GAPDH). The results show higher expression of VEGFA, TIE2,
and ANG2 in arteries than in veins, but equal expression of
ADAMTS1. Higher availability of VEGFA mRNA in endothelial cells
of arteries shown here could contribute to the maintenance of
mechanically stressed blood vessels and counteract pressureinduced vasoconstriction.
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