Activation of p21-activated kinase 2 and its association with Nef are conserved in murine cells but are not sufficient to induce an AIDS-like disease in CD4C/HIV transgenic mice.
A well conserved feature of human immunodeficiency virus, type 1 (HIV-1) and simian immunodeficiency virus (SIV) Nef is the interaction with and activation of the human p21-activated kinase 2 (PAK2). The conservation of this interaction in other species and its significance for Nef pathogenesis in vivo are poorly documented. In the present study, we measured these parameters in Nef-expressing thymocytes, macrophages, and dendritic cells of a transgenic (Tg) mouse model of AIDS (CD4C/HIV). We found that Nef binds to and activates PAK2, but not PAK1 and -3, in these three cell subsets. Nef associates with only a small fraction of PAK2. The Nef-PAK2 complex also comprises beta-PIX-COOL. The impact of the Nef-PAK2 association on disease development was also analyzed in Tg mice expressing 10 different Nef mutant alleles. CD4C/HIV Tg mice expressing Nef alleles defective in Nef-PAK2 association (P69A, P72A/P75A, R105A/R106A, Delta56-66, or G2A (myristoylation site)) failed to develop disease of the non-lymphoid organs (kidneys and lungs). Among these, only Tg mice expressing Nef(P69A) and Nef(G2A) showed some depletion of CD4(+) T cells, although a down-regulation of the CD4 surface protein was documented in all these Tg lines, except those expressing Nef(Delta56-66). Among other Tg mice expressing Nef mutants having conserved the Nef-PAK2 association (RD35AA, D174K, P147A/P150A, Delta8-17, and Delta25-65), only Tg mice expressing Nef(Delta8-17) develop kidney and lung diseases, but all showed partial CD4(+) T cell depletion despite some being defective for CD4 down-regulation (RD35AA and D174K). Therefore, Nef can activate murine PAK2 and associate with a small fraction of it, as in human cells. Such activation and binding of PAK2 is clearly not sufficient but may be required to induce a multiorgan AIDS-like disease in Tg mice.
Vincent
Patrick
P
Laboratory of Molecular Biology, Clinical Research Institute of Montreal, 110 Pine Avenue West, Montreal, Quebec H2W 1R7, Canada.
Priceputu
Elena
E
Kay
Denis
D
Saksela
Kalle
K
Jolicoeur
Paul
P
Hanna
Zaher
Z
D000483:Alleles; D020816:Amino Acid Motifs; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D015704:CD4 Antigens / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D002469:Cell Separation; D017931:DNA Primers / Q000737:chemistry; D004195:Disease Models, Animal; D005434:Flow Cytometry; D015693:Gene Products, nef / Q000378:metabolism*; D006678:HIV / Q000378:metabolism*; D006801:Humans; D016130:Immunophenotyping; D008198:Lymph Nodes / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D010641:Phenotype; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D013950:Thymus Gland / Q000378:metabolism; D019076:Transgenes; D054311:nef Gene Products, Human Immunodeficiency Virus; D054462:p21-Activated Kinases
D015704:CD4 Antigens; D017931:DNA Primers; D015693:Gene Products, nef; D054311:nef Gene Products, Human Immunodeficiency Virus; C515907:PAK2 protein, human; C515909:Pak2 protein, mouse; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases