Possible Role of Efnb1 Protein, a Ligand of Eph Receptor Tyrosine Kinases, in Modulating Blood Pressure

• Published in: The Journal of biological chemistry Vol. 287; no. 19; pp. 15557 - 15569
• Main Authors: Wu, Zenghui, Luo, Hongyu, Thorin, Eric, Tremblay, Johanne, Peng, Junzheng, Lavoie, Julie L., Wang, Yujia, Qi, Shijie, Wu, Tao, Wu, Jiangping
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 04-05-2012; American Society for Biochemistry and Molecular Biology
• Subjects: Adaptor Proteins, Signal Transducing - genetics; Adaptor Proteins, Signal Transducing - metabolism; Animals; Blood Pressure; Calcium - metabolism; Calcium Signaling; Cell Biology; Cell Size; Cells, Cultured; Eph Kinases; Ephrin-B1 - genetics; Ephrin-B1 - metabolism; EphrinB1; Female; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; Immunoblotting; In Vitro Techniques; Ligands; Male; Mesenteric Arteries - cytology; Mesenteric Arteries - metabolism; Mesenteric Arteries - physiology; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Microscopy, Fluorescence; Muscle Contraction; Muscle, Smooth, Vascular - cytology; Muscle, Smooth, Vascular - metabolism; Muscle, Smooth, Vascular - physiology; Myocytes, Smooth Muscle - metabolism; Myocytes, Smooth Muscle - physiology; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Protein Kinases; Protein Phosphorylation; Receptors, Eph Family - metabolism; Reverse Signaling; Reverse Transcriptase Polymerase Chain Reaction; RhoA; RNA Interference; Vascular Smooth Muscle Cells; Vasoconstriction; Vessel Constriction; Blood Pressure; Vascular Smooth Muscle Cells; EphrinB1; Protein Kinases; Eph Kinases; Protein Phosphorylation; Vessel Constriction; Calcium Signaling; RhoA; Reverse Signaling
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M112.340869

Eph kinases constitute the largest receptor tyrosine kinase family, and their ligands, ephrins (Efns), are also cell surface molecules. Although they are ligands, Efns can transduce signals reversely into cells. We have no prior knowledge of the role played by any members of this family of kinases or their ligands in blood pressure (BP) regulation. In the present studies, we investigated the role of Efnb1 in vascular smooth muscle cell (VSMC) contractility and BP regulation. We revealed that reverse signaling through Efnb1 led to a reduction of RhoA activation and VSMC contractility in vitro. Consistent with this finding, ex vivo, there was an increase of RhoA activity accompanied by augmented myosin light chain phosphorylation in mesenteric arteries from mice with smooth muscle-specific conditional Efnb1 gene knock-out (KO). Small interfering RNA knockdown of Grip1, a molecule associated with the Efnb1 intracellular tail, partially eliminated the effect of Efnb1 on VSMC contractility and myosin light chain phosphorylation. In support of these in vitro and ex vivo results, Efnb1 KO mice on a high salt diet showed a statistically significant heightened increment of BP at multiple time points during stress compared with wild type littermates. Our results demonstrate that Efnb1 is a previously unknown negative regulator of VSMC contractility and BP and that it exerts such effects via reverse signaling through Grip1.
Background: Currently, there is no knowledge about the function of ephrins in vascular smooth muscle contraction and blood pressure regulation.
Results: Stimulating Efnb1 reduces vascular smooth muscle cell contraction. Efnb1 null mutation increases RhoA activation and heightens blood pressure in mice.
Conclusion: Efnb1 can regulate vessel tone and blood pressure.
Significance: We identified a new group of molecules capable of regulating blood pressure.