Regulation of angiopoietin-2 mRNA levels in bovine microvascular endothelial cells by cytokines and hypoxia.
Angiopoietin-2 (Ang2) is a ligand for the endothelial cell tyrosine kinase receptor Tie2 and counteracts blood vessel maturation/stability mediated by angiopoietin-1 (Ang1), the other known ligand of Tie2. Using degenerate oligonucleotides and reverse transcriptase-polymerase chain reaction, we have screened bovine microvascular endothelial (BME), aortic, lymphatic, pulmonary artery, and transformed fetal aortic endothelial cells, as well as rat smooth muscle cells for Ang1 and Ang2 expression. Except for high Ang2 mRNA levels found in BME cells, none of the endothelial cell types studied expressed appreciable levels of Ang1 or Ang2 mRNAs, whereas smooth muscle cells expressed both Ang1 and Ang2. BME cell Ang2 mRNA levels were increased by vascular endothelial growth factor (1.9- to 2.9-fold), basic fibroblast growth factor (1.6- to 2-fold), both cytokines in combination (2.9- to 4-fold), and hypoxia (3.1- to 5.6-fold) and were decreased by Ang1 (31% to 70%) or transforming growth factor-ss1 (64% to 81%). Ang2 also decreased (60% to 82%) BME cell Ang2 mRNA. mRNA levels for the Tie1 or Tie2 receptors were only slightly modulated under the conditions described above. These findings suggest that the angiogenic effect of a number of regulators may be achieved in part through the regulation of an autocrine loop of Ang2 activity in microvascular endothelial cells.
Department of Morphology, University Medical Center, Geneva, Switzerland.
S J
SJ
Mandriota
M S
MS
Pepper
D000302:Adrenal Cortex / Q000166:cytology; D000595:Amino Acid Sequence; D042683:Angiopoietin-1; D042702:Angiopoietin-2; D000818:Animals; D001011:Aorta / Q000166:cytology; D001483:Base Sequence; D002417:Cattle; D015687:Cell Hypoxia / Q000502:physiology; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology*; D016228:Endothelial Growth Factors / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology; D004791:Enzyme Inhibitors / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005910:Glioma; D006801:Humans; D008222:Lymphokines / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000378:metabolism; D008969:Molecular Sequence Data; D018919:Neovascularization, Physiologic / Q000502:physiology; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D042683:Angiopoietin-1; D042702:Angiopoietin-2; C467629:Angpt1 protein, rat; D016207:Cytokines; D016228:Endothelial Growth Factors; D004791:Enzyme Inhibitors; D008222:Lymphokines; D008562:Membrane Glycoproteins; D011506:Proteins; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D016222:Fibroblast Growth Factor 2; D020794:Receptor Protein-Tyrosine Kinases