EphrinB1 interacts with CNK1 and promotes cell migration through c-Jun N-terminal kinase (JNK) activation.
The Eph receptors and their membrane-bound ligands, ephrins, play important roles in various biological processes such as cell adhesion and movement. The transmembrane ephrinBs transduce reverse signaling in a tyrosine phosphorylation-dependent or -independent, as well as PDZ-dependent manner. Here, we show that ephrinB1 interacts with Connector Enhancer of KSR1 (CNK1) in an EphB receptor-independent manner. In cultured cells, cotransfection of ephrinB1 with CNK1 increases JNK phosphorylation. EphrinB1/CNK1-mediated JNK activation is reduced by overexpression of dominant-negative RhoA. Overexpression of CNK1 alone is sufficient for activation of RhoA; however, both ephrinB1 and CNK1 are required for JNK phosphorylation. Co-immunoprecipitation data showed that ephrinB1 and CNK1 act as scaffold proteins that connect RhoA and JNK signaling components, such as p115RhoGEF and MKK4. Furthermore, adhesion to fibronectin or active Src overexpression increases ephrinB1/CNK1 binding, whereas blocking Src activity by a pharmacological inhibitor decreases not only ephrinB1/CNK1 binding, but also JNK activation. EphrinB1 overexpression increases cell motility, however, CNK1 depletion by siRNA abrogates ephrinB1-mediated cell migration and JNK activation. Moreover, Rho kinase inhibitor or JNK inhibitor treatment suppresses ephrinB1-mediated cell migration. Taken together, our findings suggest that CNK1 is required for ephrinB1-induced JNK activation and cell migration.
From the Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland 21702.
Hee Jun
HJ
Cho
From the Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland 21702.
Yoo-Seok
YS
Hwang
From the Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland 21702.
Kathleen
K
Mood
From the Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland 21702.
Yon Ju
YJ
Ji
From the Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland 21702.
Junghwa
J
Lim
From the Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland 21702.
Deborah K
DK
Morrison
From the Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland 21702 daar@ncifcrf.gov.
Ira O
IO
Daar
D002460:Cell Line; D045744:Cell Line, Tumor; D002465:Cell Movement; D004789:Enzyme Activation; D036387:Ephrin-B1 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism
C500833:CNKSR1 protein, human; C484288:EFNB1 protein, human; D036387:Ephrin-B1; D047908:Intracellular Signaling Peptides and Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D020742:rhoA GTP-Binding Protein
CNK1; Cell Migration; Eph; Ephrin; Ras Homolog Gene Family, Member A (RhoA); Scaffold Protein; Signal Transduction; c-Jun N-terminal Kinase (JNK)