HIV-1 protein tat induces apoptosis of hippocampal neurons by a mechanism involving caspase activation, calcium overload, and oxidative stress

Inna I. Kruman, Avindra Nath, Mark P. Mattson

Research output: Contribution to journalArticle

Abstract

Patients infected with HIV-1 often exhibit cognitive deficits that are related to progressive neuronal degeneration and cell death. The protein Tat, which is released from HIV-1-infected cells, was recently shown to be toxic toward cultured neurons. We now report that Tat induces apoptosis in cultured embryonic rat hippocampal neurons. Tat induced caspase activation, and the caspase inhibitor zVAD-fmk prevented Tat-induced neuronal death. Tat induced a progressive elevation of cytoplasmic-free calcium levels, which was followed by mitochondrial calcium uptake and generation of mitochondrial- reactive oxygen species (ROS). The intracellular calcium chelator BAPTA-AM and the inhibitor of mitochondrial calcium uptake ruthenium red protected neurons against Tat-induced apoptosis. zVAD-fmk suppressed Tat-induced increases of cytoplasmic calcium levels and mitochondrial ROS accumulation, indicating roles for caspases in the perturbed calcium homeostasis and oxidative stress induced by Tat. An inhibitor of nitric oxide synthase, and the peroxynitrite scavenger uric acid, protected neurons against Tat-induced apoptosis, indicating requirements for nitric oxide production and peroxynitrite formation in the cell death process. Finally, Tat caused a delayed and progressive mitochondrial membrane depolarization, and cyclosporin A prevented Tat-induced apoptosis, suggesting an important role for mitochondrial membrane permeability transition in Tat-induced apoptosis. Collectively, our data demonstrate that Tat can induce neuronal apoptosis by a mechanism involving disruption of calcium homeostasis, caspase activation, and mitochondrial calcium uptake and ROS accumulation. Agents that interupt this apoptotic cascade may prove beneficial in preventing neuronal degeneration and associated dementia in AIDS patients.

Original languageEnglish (US)
Pages (from-to)276-288
Number of pages13
JournalExperimental Neurology
Volume154
Issue number2
DOIs
StatePublished - Dec 1998
Externally publishedYes

Fingerprint

Human Immunodeficiency Virus Proteins
Caspases
HIV-1
Oxidative Stress
Apoptosis
Calcium
Neurons
Reactive Oxygen Species
Peroxynitrous Acid
Mitochondrial Membranes
Homeostasis
Cell Death
tat Gene Products
Ruthenium Red
Caspase Inhibitors
Poisons
Uric Acid
Nitric Oxide Synthase
Cyclosporine
Dementia

Keywords

  • AIDS dementia
  • Caspase
  • Mitochondrial transmembrane potential
  • Nitric oxide
  • Oxidative stress
  • Peroxynitrite

ASJC Scopus subject areas

  • Neurology
  • Neuroscience(all)

Cite this

HIV-1 protein tat induces apoptosis of hippocampal neurons by a mechanism involving caspase activation, calcium overload, and oxidative stress. / Kruman, Inna I.; Nath, Avindra; Mattson, Mark P.

In: Experimental Neurology, Vol. 154, No. 2, 12.1998, p. 276-288.

Research output: Contribution to journalArticle

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