Activation of the PAK-related kinase by human immunodeficiency virus type 1 Nef in primary human peripheral blood lymphocytes and macrophages leads to phosphorylation of a PIX-p95 complex.
Human immunodeficiency virus type 1 (HIV-1) Nef enhances virus replication in both primary T lymphocytes and monocyte-derived macrophages. This enhancement phenotype has been linked to the ability of Nef to modulate the activity of cellular kinases. We find that despite the reported high-affinity interaction between Nef and the Src kinase Hck in vitro, a Nef-Hck interaction in the context of HIV-1-infected primary macrophages is not detectable. However, Nef binding and activation of the PAK-related kinase and phosphorylation of its substrate could be readily detected in both infected primary T lymphocytes and macrophages. Furthermore, we show that this substrate is a complex composed of the recently characterized PAK interacting partner PIX (PAK-interacting guanine nucleotide exchange factor) and its tightly associated p95 protein. PAK and PIX-p95 appear to be differentially activated and phosphorylated depending on the intracellular environment in which nef is expressed. These results identify the PIX-p95 complex as a novel effector of Nef in primary cells and suggest that the regulation of the PAK signaling pathway may differ in T cells and macrophages.
Brown
A
A
Aaron Diamond AIDS Research Center, The Rockefeller University, New York, New York 10016, USA.
Wang
X
X
Sawai
E
E
Cheng-Mayer
C
C
D002352:Carrier Proteins / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D004789:Enzyme Activation; D020690:GTPase-Activating Proteins; D015693:Gene Products, nef / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D015497:HIV-1; D006801:Humans; D008264:Macrophages / Q000201:enzymology / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051572:Proto-Oncogene Proteins c-hck; D064067:Rho Guanine Nucleotide Exchange Factors; D013379:Substrate Specificity; D013601:T-Lymphocytes / Q000201:enzymology / Q000378:metabolism*; D054311:nef Gene Products, Human Immunodeficiency Virus; D054462:p21-Activated Kinases
D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C430213:GIT2 protein, human; D020690:GTPase-Activating Proteins; D015693:Gene Products, nef; D020662:Guanine Nucleotide Exchange Factors; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D064067:Rho Guanine Nucleotide Exchange Factors; D054311:nef Gene Products, Human Immunodeficiency Virus; D011505:Protein-Tyrosine Kinases; C496631:HCK protein, human; D051572:Proto-Oncogene Proteins c-hck; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases