[ off topic ]
MZ...... Looks like they're from Duke. Take a look at the CNCT thread.
Circ Res 1997 Oct;81(4):567-574
[MEDLINE record in process]
Tie2 expression and phosphorylation in angiogenic and quiescent adult
tissues.
Wong AL, Haroon ZA, Werner S, Dewhirst MW, Greenberg CS, Peters KG
Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA.
Angiogenesis, the process of new vessels sprouting from the existing vasculature, is a critical process during early development.
However, angiogenesis rarely occurs in the adult, except in response to cyclic hormonal stimulation in the ovary and uterus, in
response to injury, and in response to pathological conditions such as tumorigenesis and diabetes mellitus. Tie2 (also known as
Tek) is a novel endothelium-specific receptor tyrosine kinase, which has been demonstrated to be essential for the development
of the embryonic vasculature; Tie2 knockout mice die by embryonic day 10.5 with specific defects in the formation of
microvessels. Tie2 is downregulated later in embryogenesis, and its function in the adult has been relatively unexplored. To gain
insight into the potential functions of Tie2 in the adult vasculature, Tie2 expression was examined in adult tissues undergoing
angiogenesis and in quiescent tissues. Tie2 expression was localized by immunohistochemistry to the endothelium of neovessels
in rat tissues undergoing angiogenesis during hormonally stimulated follicular maturation and uterine development and in healing
skin wounds. Immunoprecipitation and RNase protection assay demonstrated upregulation of Tie2 protein and mRNA in rat
and mouse skin wounds, respectively. Moreover, Tie2 immunoprecipitated from skin wounds was tyrosine-phosphorylated,
indicating active downstream signaling. Surprisingly, Tie2 was also expressed in the entire spectrum of the quiescent vasculature
(arteries, veins, and capillaries) in a wide range of adult tissues, and Tie2 immunoprecipitated from quiescent adult tissues was
also tyrosine-phosphorylated. Together, these results suggest a dual function for Tie2 in adult tissues involving both angiogenesis
and vascular maintenance. |
