HIV-1 Nef binds the DOCK2-ELMO1 complex to activate rac and inhibit lymphocyte chemotaxis.
The infectious cycle of primate lentiviruses is intimately linked to interactions between cells of the immune system. Nef, a potent virulence factor, alters cellular environments to increase lentiviral replication in the host, yet the mechanisms underlying these effects have remained elusive. Since Nef likely functions as an adaptor protein, we exploited a proteomic approach to directly identify molecules that Nef targets to subvert the signaling machinery in T cells. We purified to near homogeneity a major Nef-associated protein complex from T cells and identified by mass spectroscopy its subunits as DOCK2-ELMO1, a key activator of Rac in antigen- and chemokine-initiated signaling pathways, and Rac. We show that Nef activates Rac in T cell lines and in primary T cells following infection with HIV-1 in the absence of antigenic stimuli. Nef activates Rac by binding the DOCK2-ELMO1 complex, and this interaction is linked to the abilities of Nef to inhibit chemotaxis and promote T cell activation. Our data indicate that Nef targets a critical switch that regulates Rac GTPases downstream of chemokine- and antigen-initiated signaling pathways. This interaction enables Nef to influence multiple aspects of T cell function and thus provides an important mechanism by which Nef impacts pathogenesis by primate lentiviruses.
Janardhan
Ajit
A
Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA.
Swigut
Tomek
T
Hill
Brian
B
Myers
Michael P
MP
Skowronski
Jacek
J
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D018106:CD28 Antigens / Q000096:biosynthesis; D017252:CD3 Complex / Q000096:biosynthesis; D002465:Cell Movement; D002633:Chemotaxis; D000939:Epitopes / Q000737:chemistry; D020690:GTPase-Activating Proteins; D015693:Gene Products, nef / Q000378:metabolism / Q000502:physiology*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D015497:HIV-1 / Q000378:metabolism*; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism; D019169:Jurkat Cells; D016086:Lentivirus / Q000235:genetics; D008214:Lymphocytes / Q000166:cytology* / Q000821:virology*; D013058:Mass Spectrometry / Q000379:methods; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D040901:Proteomics / Q000379:methods; D015398:Signal Transduction; D054311:nef Gene Products, Human Immunodeficiency Virus; D020744:rac GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000737:chemistry; D000097766:RAC2 GTP-Binding Protein
D048868:Adaptor Proteins, Signal Transducing; D018106:CD28 Antigens; D017252:CD3 Complex; D000939:Epitopes; D020690:GTPase-Activating Proteins; D015693:Gene Products, nef; D020662:Guanine Nucleotide Exchange Factors; D007376:Interleukin-2; D054311:nef Gene Products, Human Immunodeficiency Virus; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D000097766:RAC2 GTP-Binding Protein; C402110:DOCK2 protein, human; C465214:ELMO1 protein, human