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

J Biol Chem. 2006 Mar 17;281(11):6940-54. doi: 10.1074/jbc.M512710200. Epub 2005 Dec 28.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Amino Acid Motifs
  • Animals
  • Blotting, Northern
  • Blotting, Western
  • CD4 Antigens / metabolism
  • CD4-Positive T-Lymphocytes / metabolism
  • Cell Separation
  • DNA Primers / chemistry
  • Disease Models, Animal
  • Flow Cytometry
  • Gene Products, nef / metabolism*
  • HIV / metabolism*
  • Humans
  • Immunophenotyping
  • Lymph Nodes / metabolism
  • Macrophages / metabolism
  • Mice
  • Mice, Transgenic
  • Mutation
  • Phenotype
  • Protein Binding
  • Protein Structure, Tertiary
  • Protein-Serine-Threonine Kinases / metabolism*
  • Thymus Gland / metabolism
  • Transgenes
  • nef Gene Products, Human Immunodeficiency Virus
  • p21-Activated Kinases

Substances

  • CD4 Antigens
  • DNA Primers
  • Gene Products, nef
  • nef Gene Products, Human Immunodeficiency Virus
  • PAK2 protein, human
  • Pak2 protein, mouse
  • Protein-Serine-Threonine Kinases
  • p21-Activated Kinases