Levels of major selenoproteins in T cells decrease during HIV infection and low molecular mass selenium compounds increase

Levels of major selenoproteins in T cells decrease during HIV infection and low molecular mass selenium compounds increase

^*Department of Biochemistry, University of Nebraska, Lincoln, NE 68588-0664; ^†Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, ^‡Section on the Molecular Biology of Selenium, Basic Research Laboratory, National Cancer Institute, and ^¶Molecular Virology Section, Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892

Contributed by Thressa C. Stadtman

Abstract

It has been observed previously that plasma selenium and glutathione levels are subnormal in HIV-infected individuals, and plasma glutathione peroxidase activity is decreased. Under these conditions the survival rate of AIDS patients is reduced significantly. In the present study, using ⁷⁵Se-labeled human Jurkat T cells, we show that the levels of four ⁷⁵Se-containing proteins are lower in HIV-infected cell populations than in uninfected cells. These major selenoproteins migrated as 57-, 26-, 21-, and 15-kDa species on SDS/PAGE gels. In our earlier studies, the 57-kDa protein was purified from T cells and identified as a subunit of thioredoxin reductase. The 26- and 21-kDa proteins were identified in immunoblot assays as the glutathione peroxidase (cGPX or GPX1) subunit and phospholipid hydroperoxide glutathione peroxidase (PHGPX or GPX4), respectively. We recently purified the 15-kDa protein and characterized it as a selenoprotein of unknown function. In contrast to selenoproteins, low molecular mass [⁷⁵Se]compounds accumulated during HIV infection and migrated as a diffuse band near the front of SDS/PAGE gels.

Footnotes

↵ § To whom reprint requests should be addressed. e-mail: vng{at}unlinfo2.unl.edu.
ABBREVIATIONS:

GPX,

glutathione peroxidase;

GPX1,

glutathione peroxidase 1;

PHGPX or GPX4,

phospholipid hydroperoxide GPX;

GPDH,

glyceraldehyde-3-phosphate dehydrogenase;

SECIS,

selenocysteine insertion sequence