Plexin-B1 activates NF-κB and IL-8 to promote a pro-angiogenic response in endothelial cells.

Abstract

BACKGROUND:

The semaphorins and their receptors, the plexins, are proteins related to c-Met and the scatter factors that have been implicated in an expanding signal transduction network involving co-receptors, RhoA and Ras activation and deactivation, and phosphorylation events. Our previous work has demonstrated that Semaphorin 4D (Sema4D) acts through its receptor, Plexin-B1, on endothelial cells to promote angiogenesis in a RhoA and Akt-dependent manner. Since NF-κB has been linked to promotion of angiogenesis and can be activated by Akt in some contexts, we wanted to examine NF-κB in Sema4D treated cells to determine if there was biological significance for the pro-angiogenic phenotype observed in endothelium.

METHODS/PRINCIPAL FINDINGS:

Using RNA interference techniques, gel shifts and NF-κB reporter assays, we demonstrated NF-κB translocation to the nucleus in Sema4D treated endothelial cells occurring downstream of Plexin-B1. This response was necessary for endothelial cell migration and capillary tube formation and protected endothelial cells against apoptosis as well, but had no effect on cell proliferation. We dissected Plexin-B1 signaling with chimeric receptor constructs and discovered that the ability to activate NF-κB was dependent upon Plexin-B1 acting through Rho and Akt, but did not involve its role as a Ras inhibitor. Indeed, inhibition of Rho by C3 toxin and Akt by LY294002 blocked Sema4D-mediated endothelial cell migration and tubulogenesis. We also observed that Sema4D treatment of endothelial cells induced production of the NF-κB downstream target IL-8, a response necessary for angiogenesis. Finally, we could show through co-immunofluorescence for p65 and CD31 that Sema4D produced by tumor xenografts in nude mice activated NF-κB in vessels of the tumor stroma.

CONCLUSION/SIGNIFICANCE:

These findings provide evidence that Sema4D/Plexin-B1-mediated NF-κB activation and IL-8 production is critical in the generation a pro-angiogenic phenotype in endothelial cells and suggests a new therapeutic target for the anti-angiogenic treatment of some cancers.

• Authors: Ying-Hua Yang, Hua Zhou, Nada O Binmadi, Patrizia Proia, John R Basile
• Journal: PloS one (PLoS One) Vol. 6 Issue 10 Pg. e25826 ( 2011) ISSN: 1932-6203 [Electronic] United States
• PMID: 22028792 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Retracted Publication)

Chemical References

• Antigens, CD
• CD100 antigen
• Interleukin-8
• Nerve Tissue Proteins
• PLXNB1 protein, human
• Receptors, Cell Surface
• Semaphorins
• Transcription Factor RelA
• Proto-Oncogene Proteins c-akt
• rhoA GTP-Binding Protein

Topics

• Animals
• Antigens, CD (genetics, pharmacology)
• Apoptosis (drug effects)
• Capillaries (drug effects, metabolism)
• Cell Line, Tumor
• Cell Movement (drug effects)
• Cell Transformation, Neoplastic
• Endothelial Cells (cytology, drug effects, metabolism, pathology)
• Gene Expression Regulation, Neoplastic (drug effects)
• Human Umbilical Vein Endothelial Cells (cytology, drug effects, metabolism)
• Humans
• Interleukin-8 (metabolism)
• Mice
• Neovascularization, Pathologic (metabolism)
• Nerve Tissue Proteins (genetics, metabolism)
• Proto-Oncogene Proteins c-akt (metabolism)
• Receptors, Cell Surface (genetics, metabolism)
• Semaphorins (genetics, pharmacology)
• Signal Transduction (drug effects)
• Transcription Factor RelA (metabolism)
• rhoA GTP-Binding Protein (metabolism)