Characterization of interactions of adapter protein RAPL/Nore1B with RAP GTPases and their role in T cell migration.
Using a model of integrin-triggered random migration of T cells, we show that stimulation of LFA-1 integrins leads to the activation of Rap1 and Rap2 small GTPases. We further show that Rap1 and Rap2 have distinct roles in adhesion and random migration of these cells and that an adapter protein from the Ras association domain family (Rassf), RAPL, has a role downstream of Rap2 in addition to its link to Rap1. Further characterization of the RAPL protein and its interactions with small GTPases from the Ras family shows that RAPL forms more stable complexes with Rap2 and classical Ras proteins compared with Rap1. The different interaction pattern of RAPL with Rap1 and Rap2 is not affected by the disruption of the C-terminal SARAH domain that we identified as the alpha-helical region responsible for RAPL dimerization in vitro and in cells. Based on mutagenesis and three-dimensional modeling, we propose that interaction surfaces in RAPL-Rap1 and RAPL-Rap2 complexes are different and that a single residue in the switch I region of Rap proteins (residue 39) contributes considerably to the different kinetics of these protein-protein interactions. Furthermore, the distinct role of Rap2 in migration of T cells is lost when this critical residue is converted to the residue present in Rap1. Together, these observations suggest a wider role for Rassf adapter protein RAPL and Rap GTPases in cell motility and show that subtle differences between highly similar Rap proteins could be reflected in distinct interactions with common effectors and their cellular function.
Miertzschke
Mandy
M
Cancer Research UK Centre for Cell and Molecular Biology, Chester Beatty Laboratories, The Institute of Cancer Research, Fulham Road, London SW3 6JB, United Kingdom.
Stanley
Paula
P
Bunney
Tom D
TD
Rodrigues-Lima
Fernando
F
Hogg
Nancy
N
Katan
Matilda
M
D048868:Adaptor Proteins, Signal Transducing; D019943:Amino Acid Substitution; D051017:Apoptosis Regulatory Proteins; D002448:Cell Adhesion / Q000502:physiology; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology*; D019281:Dimerization; D006801:Humans; D007700:Kinetics; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism; D008954:Models, Biological; D008958:Models, Molecular; D020559:Monomeric GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020125:Mutation, Missense; D011485:Protein Binding / Q000502:physiology; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013601:T-Lymphocytes / Q000378:metabolism*; D020668:rap GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020827:rap1 GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D016169:Lymphocyte Function-Associated Antigen-1; D046912:Multiprotein Complexes; C430803:RAP1A protein, human; C454042:RASSF5 protein, human; C116756:RAP2A protein, human; D020559:Monomeric GTP-Binding Proteins; D020668:rap GTP-Binding Proteins; D020827:rap1 GTP-Binding Proteins