Published online before print September 12, 2002, doi: 10.1161/01.RES.0000036753.50601.E9
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Submitted on May 8, 2002
Revised on August 28, 2002
Accepted on August 28, 2002
Acidification Prevents Endothelial Cell Apoptosis by Axl Activation
Daniela D'Arcangelo *;
From the Laboratorio di Patologia Vascolare, Istituto Dermopatico dell'Immacolata, Istituto di Ricovero e Cura a Carattere Scientifico, Rome, Italy.
* To whom correspondence should be addressed. E-mail: d.darcangelo{at}idi.it.
Prior studies have shown that acidification due to hypercarbia protects endothelial cells from serum deprivation-induced apoptosis. However, the mechanism(s) responsible for the antiapoptotic effect of acidification is still unclear. cDNA array screening was performed on human umbilical vein endothelial cells cultured in a bicarbonate medium equilibrated either with 5% CO2 (pH 7.4) or with 20% CO2 (pH 7.0). Tyrosine kinase receptor Axl expression was 3.3-fold higher after 6 hours at pH 7.0 compared with pH 7.4; this modulation was confirmed by reverse transcriptase-polymerase chain reaction (3.0±0.9-fold, P<0.03; n=3), Northern blot (3.6±0.1-fold, P<0.0003; n=3), and Western blot (10±1.8-fold, P<0.004; n=3). In a time-course study, both Northern and Western blot analyses showed that the most marked difference in Axl expression between pH 7.4 and pH 7.0 occurred after 24 to 48 hours. Furthermore, Axl phosphorylation was enhanced at pH 7.0. Axl ligand, the survival factor growth arrest-specific gene 6 product (Gas6), was released into the conditioned medium, and by Western blot analysis, similar amounts of protein were found at pH 7.0 and 7.4. Full-length Axl cDNA overexpression reduced serum deprivation-induced apoptosis by 64.4±11.9% in human umbilical vein endothelial cells cultured at pH 7.4 compared with mock-transfected cells (P<0.0004). Furthermore, overexpression of either soluble Axl or antisense Gas6 mRNA partially reverted the protective effect of acidification, increasing 
2.5-fold the number of apoptotic cells at pH 7.0 (control 19.3±2.7%, soluble Axl 48.9±9.7%, P<0.001; antisense Gas6 49.3±14.3%, P<0.03). In conclusion, Gas6/Axl signaling may play an important role in endothelial cell survival during acidification. The full text of this article is available at http://www.circresaha.org.
Key words: acidosis • apoptosis • endothelium • ischemia • Gas6/Axl
This article has been cited by other articles:
 |
|
 |
|
  M. Tjwa, L. Bellido-Martin, Y. Lin, E. Lutgens, S. Plaisance, F. Bono, N. Delesque-Touchard, C. Herve, R. Moura, A. D. Billiau, et al. Gas6 promotes inflammation by enhancing interactions between endothelial cells, platelets, and leukocytes Blood, April 15, 2008; 111(8): 4096 - 4105. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Hutterer, P. Knyazev, A. Abate, M. Reschke, H. Maier, N. Stefanova, T. Knyazeva, V. Barbieri, M. Reindl, A. Muigg, et al. Axl and Growth Arrest Specific Gene 6 Are Frequently Overexpressed in Human Gliomas and Predict Poor Prognosis in Patients with Glioblastoma Multiforme Clin. Cancer Res., January 1, 2008; 14(1): 130 - 138. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Clauser, S. Peyrard, P. Gaussem, M. Crespin, J. Emmerich, M. Aiach, and D. Borgel Development of a Novel Immunoassay for the Assessment of Plasma Gas6 Concentrations and Their Variation with Hormonal Status Clin. Chem., October 1, 2007; 53(10): 1808 - 1813. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. D'Arcangelo, V. Ambrosino, M. Giannuzzo, C. Gaetano, and M. C. Capogrossi Axl receptor activation mediates laminar shear stress anti-apoptotic effects in human endothelial cells Cardiovasc Res, September 1, 2006; 71(4): 754 - 763. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Gallicchio, S. Mitola, D. Valdembri, R. Fantozzi, B. Varnum, G. C. Avanzi, and F. Bussolino Inhibition of vascular endothelial growth factor receptor 2-mediated endothelial cell activation by Axl tyrosine kinase receptor Blood, March 1, 2005; 105(5): 1970 - 1976. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. P. Kavanagh Therapeutic Hypercapnia: Careful Science, Better Trials Am. J. Respir. Crit. Care Med., January 15, 2005; 171(2): 96 - 97. [Full Text] [PDF]
|
|
|
|
|
|
J. D. Lang, M. Figueroa, K. D. Sanders, M. Aslan, Y. Liu, P. Chumley, and B. A. Freeman Hypercapnia via Reduced Rate and Tidal Volume Contributes to Lipopolysaccharide-induced Lung Injury Am. J. Respir. Crit. Care Med., January 15, 2005; 171(2): 147 - 157. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. Hasanbasic, J. Cuerquis, B. Varnum, and M. D. Blostein Intracellular signaling pathways involved in Gas6-Axl-mediated survival of endothelial cells Am J Physiol Heart Circ Physiol, September 1, 2004; 287(3): H1207 - H1213. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. S. Sun, J. Fujimoto, and T. Tamaya Coexpression of growth arrest-specific gene 6 and receptor tyrosine kinases Axl and Sky in human uterine endometrial cancers Ann. Onc., June 1, 2003; 14(6): 898 - 906. [Abstract] [Full Text] [PDF]
|
|