Induction of cystine-glutamate transporter Xc - by human immunodeficiency virus type 1 transactivator protein Tat in retinal pigment epithelium

Christy C. Bridges, Huankai Hu, Seiji Miyauchi, Umapathy N Siddaramappa, Malliga E. Ganapathy, Leszek Ignatowicz, Dennis M. Maddox, Sylvia B Smith, Vadivel Ganapathy

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

PURPOSE. The transactivator protein Tat encoded by the human immunodeficiency virus-1 (HIV-1) genome reduces glutathione levels in mammalian cells. Because the retina contains large amounts of glutathione, a study was undertaken to determine the influence of Tat on glutathione levels, γ-glutamyl transpeptidase activity, and the expression and activity of the cystine-glutamate transporter xc - in the human retinal pigment epithelial cell line ARPE-19 and in retina from Tat-transgenic mice. METHODS. The transport function of xc - was measured as glutamate uptake in the absence of Na+. mRNA levels for xCT and 4F2hc, the two subunits of system xc -, were monitored by RT-PCR and Northern blot and protein levels by Western blot. The expression pattern of xCT and 4F2hc in the mouse retina was analyzed by immunofluorescence. RESULTS. Expression of Tat in ARPE-19 cells led to a decrease in glutathione levels and an increase in γ-glutamyl transpeptidase activity. The transport function of xc - was upregulated, and this increase was accompanied by increases in the levels of mRNAs for xCT and 4F2hc and in corresponding protein levels. The influence of Tat on the expression of xc - was independent of the cellular status of glutathione. Most of these findings were confirmed in the retina of Tat-transgenic mice. CONCLUSIONS. Expression of HIV-1 Tat in the retina decreases glutathione levels and increases γ-glutamyl transpeptidase activity. Tat also upregulates the expression of system xc -. Glutathione levels may be decreased and the expression of xc - enhanced in the retina of patients with HIV-1 infection, leading to oxidative stress and excitotoxicity.

Original languageEnglish (US)
Pages (from-to)2906-2914
Number of pages9
JournalInvestigative Ophthalmology and Visual Science
Volume45
Issue number9
DOIs
StatePublished - Sep 1 2004

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tat Gene Products
Amino Acid Transport System X-AG
Trans-Activators
Cystine
Retinal Pigment Epithelium
Glutathione
HIV-1
Retina
gamma-Glutamyltransferase
Transgenic Mice
Messenger RNA
Retinal Pigments
Virus Diseases
Northern Blotting
Fluorescent Antibody Technique
Glutamic Acid
Proteins
Oxidative Stress
Up-Regulation
Western Blotting

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

Cite this

Induction of cystine-glutamate transporter Xc - by human immunodeficiency virus type 1 transactivator protein Tat in retinal pigment epithelium. / Bridges, Christy C.; Hu, Huankai; Miyauchi, Seiji; Siddaramappa, Umapathy N; Ganapathy, Malliga E.; Ignatowicz, Leszek; Maddox, Dennis M.; Smith, Sylvia B; Ganapathy, Vadivel.

In: Investigative Ophthalmology and Visual Science, Vol. 45, No. 9, 01.09.2004, p. 2906-2914.

Research output: Contribution to journalArticle

Bridges, Christy C. ; Hu, Huankai ; Miyauchi, Seiji ; Siddaramappa, Umapathy N ; Ganapathy, Malliga E. ; Ignatowicz, Leszek ; Maddox, Dennis M. ; Smith, Sylvia B ; Ganapathy, Vadivel. / Induction of cystine-glutamate transporter Xc - by human immunodeficiency virus type 1 transactivator protein Tat in retinal pigment epithelium. In: Investigative Ophthalmology and Visual Science. 2004 ; Vol. 45, No. 9. pp. 2906-2914.
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abstract = "PURPOSE. The transactivator protein Tat encoded by the human immunodeficiency virus-1 (HIV-1) genome reduces glutathione levels in mammalian cells. Because the retina contains large amounts of glutathione, a study was undertaken to determine the influence of Tat on glutathione levels, γ-glutamyl transpeptidase activity, and the expression and activity of the cystine-glutamate transporter xc - in the human retinal pigment epithelial cell line ARPE-19 and in retina from Tat-transgenic mice. METHODS. The transport function of xc - was measured as glutamate uptake in the absence of Na+. mRNA levels for xCT and 4F2hc, the two subunits of system xc -, were monitored by RT-PCR and Northern blot and protein levels by Western blot. The expression pattern of xCT and 4F2hc in the mouse retina was analyzed by immunofluorescence. RESULTS. Expression of Tat in ARPE-19 cells led to a decrease in glutathione levels and an increase in γ-glutamyl transpeptidase activity. The transport function of xc - was upregulated, and this increase was accompanied by increases in the levels of mRNAs for xCT and 4F2hc and in corresponding protein levels. The influence of Tat on the expression of xc - was independent of the cellular status of glutathione. Most of these findings were confirmed in the retina of Tat-transgenic mice. CONCLUSIONS. Expression of HIV-1 Tat in the retina decreases glutathione levels and increases γ-glutamyl transpeptidase activity. Tat also upregulates the expression of system xc -. Glutathione levels may be decreased and the expression of xc - enhanced in the retina of patients with HIV-1 infection, leading to oxidative stress and excitotoxicity.",
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T1 - Induction of cystine-glutamate transporter Xc - by human immunodeficiency virus type 1 transactivator protein Tat in retinal pigment epithelium

AU - Bridges, Christy C.

AU - Hu, Huankai

AU - Miyauchi, Seiji

AU - Siddaramappa, Umapathy N

AU - Ganapathy, Malliga E.

AU - Ignatowicz, Leszek

AU - Maddox, Dennis M.

AU - Smith, Sylvia B

AU - Ganapathy, Vadivel

PY - 2004/9/1

Y1 - 2004/9/1

N2 - PURPOSE. The transactivator protein Tat encoded by the human immunodeficiency virus-1 (HIV-1) genome reduces glutathione levels in mammalian cells. Because the retina contains large amounts of glutathione, a study was undertaken to determine the influence of Tat on glutathione levels, γ-glutamyl transpeptidase activity, and the expression and activity of the cystine-glutamate transporter xc - in the human retinal pigment epithelial cell line ARPE-19 and in retina from Tat-transgenic mice. METHODS. The transport function of xc - was measured as glutamate uptake in the absence of Na+. mRNA levels for xCT and 4F2hc, the two subunits of system xc -, were monitored by RT-PCR and Northern blot and protein levels by Western blot. The expression pattern of xCT and 4F2hc in the mouse retina was analyzed by immunofluorescence. RESULTS. Expression of Tat in ARPE-19 cells led to a decrease in glutathione levels and an increase in γ-glutamyl transpeptidase activity. The transport function of xc - was upregulated, and this increase was accompanied by increases in the levels of mRNAs for xCT and 4F2hc and in corresponding protein levels. The influence of Tat on the expression of xc - was independent of the cellular status of glutathione. Most of these findings were confirmed in the retina of Tat-transgenic mice. CONCLUSIONS. Expression of HIV-1 Tat in the retina decreases glutathione levels and increases γ-glutamyl transpeptidase activity. Tat also upregulates the expression of system xc -. Glutathione levels may be decreased and the expression of xc - enhanced in the retina of patients with HIV-1 infection, leading to oxidative stress and excitotoxicity.

AB - PURPOSE. The transactivator protein Tat encoded by the human immunodeficiency virus-1 (HIV-1) genome reduces glutathione levels in mammalian cells. Because the retina contains large amounts of glutathione, a study was undertaken to determine the influence of Tat on glutathione levels, γ-glutamyl transpeptidase activity, and the expression and activity of the cystine-glutamate transporter xc - in the human retinal pigment epithelial cell line ARPE-19 and in retina from Tat-transgenic mice. METHODS. The transport function of xc - was measured as glutamate uptake in the absence of Na+. mRNA levels for xCT and 4F2hc, the two subunits of system xc -, were monitored by RT-PCR and Northern blot and protein levels by Western blot. The expression pattern of xCT and 4F2hc in the mouse retina was analyzed by immunofluorescence. RESULTS. Expression of Tat in ARPE-19 cells led to a decrease in glutathione levels and an increase in γ-glutamyl transpeptidase activity. The transport function of xc - was upregulated, and this increase was accompanied by increases in the levels of mRNAs for xCT and 4F2hc and in corresponding protein levels. The influence of Tat on the expression of xc - was independent of the cellular status of glutathione. Most of these findings were confirmed in the retina of Tat-transgenic mice. CONCLUSIONS. Expression of HIV-1 Tat in the retina decreases glutathione levels and increases γ-glutamyl transpeptidase activity. Tat also upregulates the expression of system xc -. Glutathione levels may be decreased and the expression of xc - enhanced in the retina of patients with HIV-1 infection, leading to oxidative stress and excitotoxicity.

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M3 - Article

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