Sickle cell anemia (SCA)
is an autosomal-recessive hemoglobinopathy with a highly variable phenotype. Multiple
clinical complications are characteristic of SCA including inflammatory and
oxidant damage to both small and large blood vessels, hemolysis, vasoocclusion,
and premature mortality. The overall severity of SCA is affected by multiple
genetic modifier loci, including ARFGEF2,
a gene known to modify TNF-α receptor
release from human endothelial cells. In this report, we examine the effect of
siRNA mediated knockdown of ARFGEF2 inhuman pulmonary artery endothelial
cells and report that TNF-α induced
expression of ICAM1 and VCAM1, both important mediators of endo-thelial-leukocyte adhesion, is
significantly enhanced after ARFGEF2
knockdown. Levels of ICAM-1 protein are also increased in TNF-α treated endothelial cells after ARFGEF2 knockdown; the increased ICAM-1
appears to be localized in the cytoplasm. IL-1β stimulation of endothelial cells without ARFGEF2 produced enhanced ICAM1
expression only. Additionally, ARFGEF2
knockdown distinctly altered endothelial cell morphology. Large-vessel
pathology in SCA is believed to begin with endothelial activation by
inflammatory cytokines and adhesion of sickle erythrocytes and leukocytes, leading to a progressive
vasculopathy characterized by smooth muscle cell migration and proliferation. Understanding how variability in the
function of ARFGEF2 alters the response
of pulmonary vasculature to TNF-α might suggest new targets for SCA treatment.
Cite this paper
D. Dworkis, E. Klings, S. Shenouda, N. Solovieff, E. Melista, C. Giovannucci, S. Safaya, G. Li, J. Vita, M. Steinberg and C. Baldwin, "ARFGEF2 Knockdown Enhances TNF-α Induced Endothelial Expression of the Cell Adhesion Molecules VCAM1 and ICAM1," Open Journal of Blood Diseases, Vol. 3 No. 1, 2013, pp. 25-31. doi: 10.4236/ojbd.2013.31006.
 G. A. Barabino, M. O. Platt and D. K. Kaul, “Sickle Cell Biomechanics,” Annual Review of Biomedical Engineering, Vol. 12, 2010, pp. 345-367.
 R. P. Hebbel, “Beyond Hemoglobin Polymerization: The Red Blood Cell Membrane and Sickle Disease Pathophysiology,” Blood, Vol. 77, No. 2, 1991, pp. 214-237.
 P. Sebastiani, et al., “Genetic Modifiers of the Severity of Sickle Cell Anemia Identified through a Genome-Wide Association Study,” American Journal of Hematology, Vol. 85, No. 1, 2010, pp. 29-35.
 M. H. Steinberg, “Predicting Clinical Severity in Sickle Cell Anaemia,” British Journal of Haematology, Vol. 129, No. 4, 2005, pp. 465-481.
 E. S. Klings and H. W. Farber, “Pulmonary Hypertension as a Risk Factor for Death in Patients with Sickle Cell Disease.” The New England Journal of Medicine, Vol. 350, 2004, pp. 2521-2522.
 M. T. Gladwin and E. Vichinsky, “Pulmonary Complications of Sickle Cell Disease,” The New England Journal of Medicine, Vol. 359, 2008, pp. 2254-2265.
 D. A. Dworkis, et al., “Severe Sickle Cell Anemia Is Associated with Increased Plasma Levels of TNF-R1 and VCAM-1,” American Journal of Hematology, Vol. 86, No. 2, 2011, pp. 220-223. doi:10.1002/ajh.21928
 L. A. Madge and J. S. Pober, “Tnf Signaling in Vascular Endothelial Cells,” Experimental and Molecular Pathology, Vol. 70, No. 3, 2001, pp. 317-325.
 G. Molema, “Heterogeneity in Endothelial Responsiveness to Cytokines, Molecular Causes, and Pharmacological Consequences,” Seminars in Thrombosis and Hemostasis, Vol. 36, No. 3, 2010, pp. 246-264.
 G. Chen and D. V. Goeddel, “TNF-R1 Signaling: A Beautiful Pathway,” Science, Vol. 296, No. 5573, 2002, pp. 1634-1635. doi:10.1126/science.1071924
 K. Ley, C. Laudanna, M. I. Cybulsky and S. Nourshargh, “Getting to the Site of Inflammation: The Leukocyte Adhesion Cascade Updated,” Nature Reviews Immunology, Vol. 7, 2007, pp. 678-689. doi:10.1038/nri2156
 A. Turhan, L. A. Weiss, N. Mohandas, B. S. Coller and P. S. Frenette, “Primary Role for Adherent Leukocytes in Sickle Cell Vascular Occlusion: A New Paradigm,” Proceedings of the National Academy Sciences of the USA. Vol. 99, No. 5, 2002, pp. 3047-3051.
 M. Zeghouf, B. Guibert, J. C. Zeeh and J. Cherfils, “Arf, Sec7 and Brefeldin A: A Model towards the Therapeutic Inhibition of Guanine Nucleotide-Exchange Factors,” Biochemical Society Transactions, Vol. 33, 2005, pp. 12651268. doi:10.1042/BST20051265
 H. W. Shin, N. Morinaga, M. Noda and K. Nakayama, “Big2, a Guanine Nucleotide Exchange Factor for ADPRibosylation Factors: Its Localization to Recycling Endosomes and Implication in the Endosome Integrity,” Molecular Biology of the Cell, Vol. 15, No. 12, 2004, pp. 5283-5294. doi:10.1091/mbc.E04-05-0388
 F. Boal and D. J. Stephens, “Specific Functions of BIG1 and BIG2 in Endomembrane Organization,” PLoS One, Vol. 5, 2010, p. e9898. doi:10.1371/journal.pone.0009898
 N. Segev, “Coordination of Intracellular Transport Steps by Gtpases,” Seminars in Cell & Developmental Biology, Vol. 22, No. 1, 2011, pp. 33-38.
 A. Islam, X. Shen, T. Hiroi, J. Moss, M. Vaughan and S. J. Levine, “The Brefeldin A-Inhibited Guanine NucleotideExchange Protein, BIG2, Regulates the Constitutive Release of TNFR1 Exosome-Like Vesicles,” Journal of Biological Chemistry, Vol. 282, 2007, pp. 9591-9599.
 S. Safaya, E. S. Klings, A. Odhiambo, G. Li, H. W. Farber and M. H. Steinberg, “Effect of Sodium Butyrate on Lung Vascular TNFSF15 (TL1A) Expression: Differential Expression Patterns in Pulmonary Artery and Microvascular Endothelial Cells,” Cytokine, Vol. 46, No. 1, 2009, pp. 72-78. doi:10.1016/j.cyto.2008.12.013
 E. S. Klings, et al., “Differential Gene Expression in Pulmonary Artery Endothelial Cells Exposed to Sickle Cell Plasma,” Physiological Genomics, Vol. 21, No. 3, 2005, pp. 293-298. doi:10.1152/physiolgenomics.00246.2004
 K. J. Livak and T. D. Schmittgen, “Analysis of Relative Gene Expression Data Using Real-Time Quantitative PCR and the 2(-Delta Delta c(t)) Method,” Methods, Vol. 25, No. 4, 2001, pp. 402-408. doi:10.1006/meth.2001.1262
 Team RDC, “R: A Language and Environment for Statistical Computing,” 2009.
 S. Muro, C. Gajewski, M. Koval and V. R. Muzykantov, “Icam-1 Recycling in Endothelial Cells: A Novel Pathway for Sustained Intracellular Delivery and Prolonged Effects of Drugs,” Blood, Vol. 105, No. 2, 2005, pp. 650-658. doi:10.1182/blood-2004-05-1714
 M. T. Gladwin and E. Vichinsky, “Pulmonary Complications of Sickle Cell Disease,” New England Journal of Medicine, Vol. 359, 2008, pp. 2254-2265.
 O. S. Platt, “Preventing Stroke in Sickle Cell Anemia,” New England Journal of Medicine, Vol. 353, pp. 27432745. doi:10.1056/NEJMp058274