Original Ariticle Brain microvasculature and hypoxia-related proteins in Alzheimer’s disease
Paula Grammas, Debjani Tripathy, Alma Sanchez, Xiangling Yin, Jinhua Luo
Garrison Institute on Aging and Department of Neurology, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
Received May 13, 2011; accepted June 11; 2011; Epub June 18, 2011; published August 15;2011
Abstract: Alzheimer’s disease (AD) is a progressive, neurodegenerative disease of increasing incidence. The pathologic processes that underlie this disorder are incompletely understood, however, hypoperfusion/hypoxia is thought to contribute to disease pathogenesis. Hypoxia inducible factor 1-alpha (HIF-1α), a key regulator of cellular responses to hypoxia, is elevated in the microcirculation of AD patients. Cerebral hypoxia is a potent stimulus for vascular activation and angiogenesis. Microvessels isolated from the brains of AD patients express a large number of angiogenic proteins. Despite considerable data in human tissues regarding vascular expression of hypoxia-related angiogenic proteins, there is little information regarding these proteins in the brain vasculature of transgenic AD mice. The objectives of this study were to determine expression of HIF-1α, angiogenic proteins, angiopoietin-2 (Ang-2), and matrix metalloproteinase 2 (MMP2), and survival/apoptotic proteins (Bcl-xL, caspase 3) in the cerebromicrovasculature of AD transgenic mice and to determine the direct effect of hypoxia on cerebral endothelial expression of these proteins in vitro. Cultured brain endothelial cells were subjected to hypoxia for 4-6 h and analyzed by western blot and immunofluorescence. Our results demonstrated that HIF-1α is induced in cultured brain endothelial cells exposed to hypoxia and that expression of Ang-2, MMP2 and caspase 3 was elevated and the anti-apoptotic protein Bcl-xL decreased. Brain sections from AD and control mice showed that HIF-1α, Ang-2, MMP2 and caspase 3 are elevated and Bcl-xL decreased in the microvasculature of AD mice. These data suggest the cerebromicrovasculature is an important target for the effects of hypoxia in the AD brain. (IJCEP1105004)
Keywords: Hypoxia, brain microvessels, AD mice, angiogenesis, apoptosis
Address all correspondence to: Paula Grammas, PhD Garrison Institute on Aging Texas Tech University Health Sciences Center 3601 4th Street Stop 9424 Lubbock, TX 79430, USA. Tel: 806-743-3612, Fax: 806-743-3636 E-mail: paula.grammas@ttuhsc.edu