Tubular cell HIV-1 gp120 expression induces caspase 8 activation and apoptosis.
Renal biopsy data indicate that tubular epithelial cells serve as a reservoir for HIV-1 infection. We studied the effect of HIV-1 gp120 envelope gene expression on tubular cell apoptosis. HIV-1 gp120 was expressed in a lentiviral vector pHR-CMV-IRES2-EGFP-DeltaB. This plasmid construct was used to produce pseudotyped virus using VSV-G envelope to enhance the tropism for efficient viral transduction. Human proximal tubular (HK-2) cells were transduced and assayed for cellular injury by trypan blue exclusion, Hoechst and PI staining, TUNEL, and cell cycle staging. HIV-1 gp120-transduced HK-2 cells showed cellular injury in a time-dependent manner. Gp120-transduced cells showed 2.5-fold greater apoptosis when compared with vector-transduced cells. Cell cycle analysis did not reveal any alteration between gp120-transduced cells and vector-transduced cells. Gp120-transduced cells showed higher expression of both Fas and FasL, whereas pretreatment with anti-FasL antibody partially inhibited gp120-induced tubular cell apoptosis. Similarly, pretreatment with caspase-8 inhibitor attenuated gp120-induced HK2 cell apoptosis. Moreover, gp120-transduced cells showed activation of caspase 8. These results suggest that HIV-1 gp120 expression induces tubular cell apoptosis through the extrinsic pathway by enhancing Fas and FasL expression and activation of caspase-8.
Vashistha
Himanshu
H
Department of Medicine, Long Island Jewish Medical Center, New Hyde Park, and North Shore University Hospital, Manhasset, New York, USA.
Husain
Mohammed
M
Kumar
Dileep
D
Singhal
Pravin C
PC
D017209:Apoptosis / Q000502:physiology*; D053181:Caspase 8 / Q000502:physiology*; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000821:virology*; D015699:HIV Envelope Protein gp120 / Q000096:biosynthesis / Q000502:physiology*; D006801:Humans; D007684:Kidney Tubules / Q000166:cytology*
D015699:HIV Envelope Protein gp120; C514793:gp120 protein, Human immunodeficiency virus 1; D053181:Caspase 8