title: Hypoxia induces angiogenic factors in brain microvascular endothelial cells.
abstract: Hypoxia is increasingly recognized as an important contributing factor to the development of brain diseases such as Alzheimer's disease (AD). In the periphery, hypoxia is a powerful regulator of angiogenesis. However, vascular endothelial cells are remarkably heterogeneous and little is known about how brain endothelial cells respond to hypoxic challenge. The objective of this study is to characterize the effect of hypoxic challenge on the angiogenic response of cultured brain-derived microvascular endothelial cells. Brain endothelial cell cultures were initiated from isolated rat brain microvessels and subjected to hypoxia (1% O(2)) for various time periods. The results showed that hypoxia induced rapid (≤ 0.5h) expression of hypoxia-inducible factor 1α (HIF-1α) and that cell viability, assessed by MTT assay, was unaffected within the first 8h. Examination of brain endothelial cell cultures for pro- and anti-angiogenic proteins by western blot, RT-PCR and ELISA revealed that within 0.5 to 2h of hypoxia levels of vascular endothelial growth factor and endothelin-1 mRNA and protein were elevated. The expression of heme oxygenase-1 also increased but only after 8h of hypoxia. In contrast, similar hypoxia exposure evoked a decrease in endothelial nitric oxide synthase and thrombospondin-2 levels. Exposure of brain endothelial cell cultures to hypoxia resulted in a significant (p<0.001) decrease (94%) in tube length, an in vitro index of angiogenesis, compared to control cultures. The data indicate that, despite a shift toward a pro-angiogenic phenotype, hypoxia inhibited vessel formation in brain endothelial cells. These results suggest that in brain endothelial cells expression of angiogenic factors is not sufficient for the development of new vessels. Further work is needed to determine what factors/conditions prevent hypoxia-induced angiogenic changes from culminating in the formation of new brain blood vessels and what role this may play in the pathologic changes observed in AD and other diseases characterized by cerebral hypoxia.
authors.affiliation: Garrison Institute on Aging, Department of Neurology, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.
authors.forename: J
authors.initials: J
authors.lastname: Luo
authors.forename: J
authors.initials: J
authors.lastname: Martinez
authors.forename: X
authors.initials: X
authors.lastname: Yin
authors.forename: A
authors.initials: A
authors.lastname: Sanchez
authors.forename: D
authors.initials: D
authors.lastname: Tripathy
authors.forename: P
authors.initials: P
authors.lastname: Grammas
mesh_terms: D042501:Angiogenic Proteins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000098:blood supply*; D015687:Cell Hypoxia; D002470:Cell Survival; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism* / Q000473:pathology; D019332:Endothelin-1 / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation; D006419:Heme Oxygenase (Decyclizing) / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D055806:Microvessels / Q000378:metabolism* / Q000473:pathology; D018919:Neovascularization, Physiologic; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019699:Thrombospondins / Q000378:metabolism; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D000099262:Thrombospondin 2
chemical_list: D042501:Angiogenic Proteins; D019332:Endothelin-1; D006419:Heme Oxygenase (Decyclizing); D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D052250:Nitric Oxide Synthase Type III; D010100:Oxygen; D012333:RNA, Messenger; D019699:Thrombospondins; D042461:Vascular Endothelial Growth Factor A; D000099262:Thrombospondin 2; C497444:Hif1a protein, rat; C467498:vascular endothelial growth factor A, rat; C496316:Nos3 protein, rat; C491523:Hmox1 protein, rat
references.citation: Microvasc Res. 1998 Jan;55(1):65-76
references.pmid: 9473410
references.citation: Mol Cell Biol. 1992 Dec;12(12):5373-85
references.pmid: 1448072
references.citation: J Exp Med. 2000 May 15;191(10):1789-98
references.pmid: 10811871
references.citation: Front Biosci. 2003 Sep 01;8:s1199-209
references.pmid: 12957863
references.citation: J Alzheimers Dis. 2006 Mar;9(1):51-8
references.pmid: 16627934
references.citation: Neuroscience. 2009 Feb 18;158(4):1348-55
references.pmid: 19041930
references.citation: Cytokine. 2010 May;50(2):117-20
references.pmid: 20207160
references.citation: Oncogene. 1997 May 22;14(20):2475-83
references.pmid: 9188862
references.citation: Circ Res. 1995 Sep;77(3):638-43
references.pmid: 7641334
references.citation: Mol Cell Biol. 1996 Sep;16(9):4604-13
references.pmid: 8756616
references.citation: Neuropathol Appl Neurobiol. 2011 Feb;37(1):56-74
references.pmid: 20946471
references.citation: Ann N Y Acad Sci. 1997 Sep 26;826:7-24
references.pmid: 9329677
references.citation: Am J Physiol Regul Integr Comp Physiol. 2011 Jun;300(6):R1288-95
references.pmid: 21368267
references.citation: Neurology. 1996 Jan;46(1):154-9
references.pmid: 8559366
references.citation: Acta Neuropathol. 2009 Jul;118(1):103-13
references.pmid: 19319544
references.citation: Curr Top Microbiol Immunol. 2010;345:71-103
references.pmid: 20582529
references.citation: Neurobiol Aging. 2002 Mar-Apr;23(2):237-43
references.pmid: 11804709
references.citation: FASEB J. 1999 Jan;13(1):9-22
references.pmid: 9872925
references.citation: Nat Med. 2003 Jun;9(6):677-84
references.pmid: 12778166
references.citation: Free Radic Biol Med. 2007 Sep 1;43(5):844-52
references.pmid: 17664148
references.citation: J Neurochem. 2008 May;105(4):1080-90
references.pmid: 18182045
references.citation: J Biol Chem. 2000 Jan 28;275(4):2281-7
references.pmid: 10644676
references.citation: J Alzheimers Dis. 2006 Sep;10(1):111-8
references.pmid: 16988487
references.citation: J Cell Sci. 2009 Apr 15;122(Pt 8):1055-7
references.pmid: 19339544
references.citation: Atherosclerosis. 2006 Jul;187(1):26-30
references.pmid: 16620829
references.citation: Clin Cancer Res. 2000 Jul;6(7):2941-50
references.pmid: 10914744
references.citation: Ann N Y Acad Sci. 2000;924:136-52
references.pmid: 11193790
references.citation: J Biol Chem. 2000 May 5;275(18):13613-20
references.pmid: 10788478
references.citation: Tissue Cell. 1993 Dec;25(6):833-46
references.pmid: 8140579
references.citation: J Biol Chem. 2001 Apr 20;276(16):12645-53
references.pmid: 11278891
references.citation: Acta Neuropathol. 1994;87(5):469-80
references.pmid: 8059599
references.citation: Am J Physiol Cell Physiol. 2009 May;296(5):C1162-70
references.pmid: 19244479
references.citation: Neuron. 2008 Jan 24;57(2):178-201
references.pmid: 18215617
references.citation: Cell Tissue Res. 2009 Jan;335(1):205-22
references.pmid: 18677515
references.citation: Biochem Biophys Res Commun. 2003 Feb 28;302(1):138-43
references.pmid: 12593860
references.citation: Semin Thromb Hemost. 2010 Apr;36(3):246-64
references.pmid: 20490977
references.citation: J Biol Chem. 1999 May 28;274(22):15732-9
references.pmid: 10336473
references.citation: Crit Care Med. 2003 Apr;31(4 Suppl):S221-30
references.pmid: 12682444
references.citation: Nat Rev Neurosci. 2006 Jan;7(1):41-53
references.pmid: 16371949
references.citation: Med Hypotheses. 2011 Jun;76(6):847-54
references.pmid: 21398043
references.citation: Ann N Y Acad Sci. 1997 Sep 26;826:433-6
references.pmid: 9329718
references.citation: Proc Natl Acad Sci U S A. 2003 Sep 16;100(19):10623-8
references.pmid: 12963823
references.citation: Exp Gerontol. 2000 Sep;35(6-7):821-30
references.pmid: 11053673
references.citation: Nat Med. 2005 Sep;11(9):959-65
references.pmid: 16116430
references.citation: J Physiol Pharmacol. 2009 Oct;60 Suppl 4:95-104
references.pmid: 20083857
references.citation: Neurol Res. 2003 Sep;25(6):605-10
references.pmid: 14503014
references.citation: J Lab Clin Med. 1998 Dec;132(6):519-29
references.pmid: 9851743
references.citation: Expert Rev Mol Med. 2011 Jun 10;13:e19
references.pmid: 21676288
references.citation: EMBO J. 2002 Oct 1;21(19):5216-24
references.pmid: 12356737
references.citation: Neurosci Lett. 2011 Feb 4;489(2):84-8
references.pmid: 21134418
references.citation: Ann Neurol. 1977 May;1(5):409-17
references.pmid: 617259
references.citation: Brain Res Mol Brain Res. 1998 Nov 12;62(1):101-5
references.pmid: 9795165
references.citation: J Neuroinflammation. 2011 Mar 25;8:26
references.pmid: 21439035
references.citation: J Alzheimers Dis. 2010;21(3):887-96
references.pmid: 20634595
references.citation: Stroke. 2002 Sep;33(9):2254-60
references.pmid: 12215596
references.citation: J Neural Transm (Vienna). 2011 Mar;118(3):381-7
references.pmid: 20563825
references.citation: Neuroreport. 2004 Jun 28;15(9):1507-10
references.pmid: 15194884
references.citation: J Clin Invest. 1990 Feb;85(2):587-90
references.pmid: 2153712
references.citation: Biochem Biophys Res Commun. 1998 Apr 28;245(3):894-9
references.pmid: 9588211
references.citation: Nature. 2002 Jan 10;415(6868):234-9
references.pmid: 11805848
references.citation: Essays Biochem. 2007;43:153-64
references.pmid: 17705799
references.citation: J Neurochem. 2009 Jul;110(2):469-85
references.pmid: 19457088
references.citation: Am J Pathol. 2010 Apr;176(4):1600-6
references.pmid: 20150433
references.citation: Neurobiol Aging. 2001 Nov-Dec;22(6):837-42
references.pmid: 11754990
references.citation: Nat Med. 2003 Jun;9(6):669-76
references.pmid: 12778165
references.citation: Adv Exp Med Biol. 1999;474:23-45
references.pmid: 10634991
references.citation: Annu Rev Cell Dev Biol. 1999;15:551-78
references.pmid: 10611972
references.citation: J Neurosci. 2010 Aug 25;30(34):11251-8
references.pmid: 20739545
references.citation: Am J Pathol. 2002 May;160(5):1583-7
references.pmid: 12000710
references.citation: FASEB J. 2006 Feb;20(2):314-6
references.pmid: 16354719
references.citation: Am J Physiol. 1994 Nov;267(5 Pt 2):H1921-7
references.pmid: 7526714
references.citation: Curr Vasc Pharmacol. 2005 Oct;3(4):309-14
references.pmid: 16248773
references.citation: Cardiovasc J Afr. 2009 Sep-Oct;20(5):303-10
references.pmid: 19907806
references.citation: Neurobiol Aging. 2000 Mar-Apr;21(2):321-30
references.pmid: 10867217
references.citation: Ann N Y Acad Sci. 2009 Oct;1177:169-77
references.pmid: 19845619
references.citation: J Neurosci. 2002 Aug 1;22(15):6401-7
references.pmid: 12151519
references.citation: Curr Pharm Des. 2003;9(7):583-8
references.pmid: 12570805
references.citation: Cancer Cell. 2004 Nov;6(5):485-95
references.pmid: 15542432
references.citation: Expert Rev Mol Med. 2010 Apr 19;12:e12
references.pmid: 20398440
references.citation: J Clin Invest. 1991 Sep;88(3):1054-7
references.pmid: 1885767
references.citation: Circ Res. 2003 Oct 3;93(7):664-73
references.pmid: 12958144
references.citation: Curr Neurovasc Res. 2008 Feb;5(1):71-81
references.pmid: 18289024