title: HIV-1 Tat neurotoxicity is prevented by matrix metalloproteinase inhibitors.
abstract: The release of potentially neurotoxic molecules by HIV-infected brain macrophages is accompanied by neuronal injury and death that results in the development of HIV-associated dementia (HAD). Among the potential neurotoxins implicated in the development of HAD is the HIV-1 transactivating protein, Tat. To investigate the mechanism by which Tat causes neurotoxicity, brain-derived Tat sequences from nondemented (Tat-ND) and demented (Tat-HAD) AIDS patients, which differed primarily in the augmenting region of Tat, were expressed in U937 monoblastoid cells and primary human macrophages. Cells expressing Tat-HAD protein exhibited elevated matrix metalloproteinase (MMP)-2 and -7 release and activation, but cells expressing Tat-ND did not exhibit enhanced MMP expression. Conditioned media from Tat-HAD-transfected cells caused significantly greater neuronal death (15.4 +/- 4.3%) than did Tat-ND (4.4 +/- 2.1%) or nontransfected (2.1 +/- 0.8%) cell-derived conditioned media. The neurotoxicity induced by Tat-HAD was inhibited by anti-MMP-2 or -7 antibodies (p < 0.005) but not by antibodies against MMP-9 or Tat. Similarly, scid/nod mice receiving striatal implants of Tat-HAD-transfected cells exhibited greater neurobehavioral abnormalities and neuronal loss (p < 0.005) than did animals receiving Tat-ND or nontransfected cells, which were reduced by treatment with the MMP inhibitor prinomastat (p < 0.005). These findings indicate that Tat causes neuronal death through an indirect mechanism that is Tat sequence dependent and involves the induction of MMPs.
authors.affiliation: Department of Clinical Neuroscience, University of Calgary, Canada.
authors.forename: J B
authors.initials: JB
authors.lastname: Johnston
authors.forename: K
authors.initials: K
authors.lastname: Zhang
authors.forename: C
authors.initials: C
authors.lastname: Silva
authors.forename: D R
authors.initials: DR
authors.lastname: Shalinsky
authors.forename: K
authors.initials: K
authors.lastname: Conant
authors.forename: W
authors.initials: W
authors.lastname: Ni
authors.forename: D
authors.initials: D
authors.lastname: Corbett
authors.forename: V W
authors.initials: VW
authors.lastname: Yong
authors.forename: C
authors.initials: C
authors.lastname: Power
mesh_terms: D015526:AIDS Dementia Complex / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D015696:Gene Products, tat / Q000633:toxicity*; D015497:HIV-1 / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D020783:Matrix Metalloproteinase 7 / Q000378:metabolism*; D061965:Matrix Metalloproteinase Inhibitors; D051379:Mice; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism; D010446:Peptide Fragments / Q000633:toxicity*; D016133:Polymerase Chain Reaction; D054322:tat Gene Products, Human Immunodeficiency Virus
chemical_list: D015696:Gene Products, tat; D061965:Matrix Metalloproteinase Inhibitors; D010446:Peptide Fragments; D054322:tat Gene Products, Human Immunodeficiency Virus; C415751:tat peptide (1-9), Human immunodeficiency virus 1; D020783:Matrix Metalloproteinase 7; D020778:Matrix Metalloproteinase 2