Limits...
Role of endolysosomes in HIV-1 Tat-induced neurotoxicity.

Hui L, Chen X, Haughey NJ, Geiger JD - ASN Neuro (2012)

Bottom Line: Combined anti-retroviral therapeutic drugs effectively increase the lifespan of HIV-1-infected individuals who then have a higher prevalence of HAND (HIV-1 associated neurocognitive disorder).As early as 24 h after HIV-1 Tat was applied to neurons, HIV-1 Tat accumulated in endolysosomes, endolysosome morphology was affected and their size increased, endolysosome membrane integrity was disrupted, endolysosome pH increased, specific activities of endolysosome enzymes decreased and autophagy was inhibited, as indicated by the significant changes in three markers for autophagy.In contrast, statistically significant levels of HIV-1 Tat-induced neuronal cell death were observed only after 48 h of HIV-1 Tat treatment.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58203, USA.

ABSTRACT
Combined anti-retroviral therapeutic drugs effectively increase the lifespan of HIV-1-infected individuals who then have a higher prevalence of HAND (HIV-1 associated neurocognitive disorder). Soluble factors including HIV-1 proteins released from HIV-1-infected cells have been implicated in the pathogenesis of HAND, and particular attention has been paid to the HIV-1 Tat (transactivator of transcription) protein because of its ability to directly excite neurons and cause neuronal cell death. Since HIV-1 Tat enters cells by receptor-mediated endocytosis and since endolysosomes play an important role in neuronal cell life and death, we tested here the hypothesis that HIV-1 Tat neurotoxicity is associated with changes in the endolysosome structure and function and also autophagy. Following the treatment of primary cultured rat hippocampal neurons with HIV-1 Tat or as controls mutant-Tat or PBS, neuronal viability was determined using a triple staining method. Preceding observations of HIV-1 Tat-induced neuronal cell death, we observed statistically significant changes in the structure and membrane integrity of endolysosomes, endolysosome pH and autophagy. As early as 24 h after HIV-1 Tat was applied to neurons, HIV-1 Tat accumulated in endolysosomes, endolysosome morphology was affected and their size increased, endolysosome membrane integrity was disrupted, endolysosome pH increased, specific activities of endolysosome enzymes decreased and autophagy was inhibited, as indicated by the significant changes in three markers for autophagy. In contrast, statistically significant levels of HIV-1 Tat-induced neuronal cell death were observed only after 48 h of HIV-1 Tat treatment. Our findings suggest that endolysosomes are involved in HIV-1 Tat-induced neurotoxicity and may represent a target for therapeutic intervention against HAND.

Show MeSH

Related in: MedlinePlus

HIV-1 Tat-disrupted endolysosome membrane integrityEndolysosome membrane integrity was evaluated by measuring the leakage of Lucifer Yellow dye. Control neurons displayed a discrete punctate fluorescent staining pattern in perinuclear regions with no fluorescence in cytoplasm (left panel), whereas neurons treated with HIV-1 Tat for 1 day displayed endolysosome membrane leakage as indicated by diffusion of fluorescence into cytoplasm (right panel, bar  = 10 μm).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3379000&req=5

Figure 5: HIV-1 Tat-disrupted endolysosome membrane integrityEndolysosome membrane integrity was evaluated by measuring the leakage of Lucifer Yellow dye. Control neurons displayed a discrete punctate fluorescent staining pattern in perinuclear regions with no fluorescence in cytoplasm (left panel), whereas neurons treated with HIV-1 Tat for 1 day displayed endolysosome membrane leakage as indicated by diffusion of fluorescence into cytoplasm (right panel, bar  = 10 μm).

Mentions: Endolysosome dysfunction has been implicated in initiating stress pathways that lead to cellular dysfunction and death (Roberg and Ollinger, 1998; Turk et al., 2002; Guicciardi et al., 2004; Kroemer and Jaattela, 2005; Kurz et al., 2008). Here, we determined the extent to which HIV-1 Tat-affected endolysosome membrane integrity using Lucifer Yellow dye (Yang et al., 1998). We found that while control neurons displayed a discrete punctate pattern of perinuclear fluorescent staining (Figure 5), HIV-1 Tat-treated neurons displayed increased endolysosome membrane leakage as evidenced by diffuse fluorescent staining (Figure 5) in the cytoplasm.


Role of endolysosomes in HIV-1 Tat-induced neurotoxicity.

Hui L, Chen X, Haughey NJ, Geiger JD - ASN Neuro (2012)

HIV-1 Tat-disrupted endolysosome membrane integrityEndolysosome membrane integrity was evaluated by measuring the leakage of Lucifer Yellow dye. Control neurons displayed a discrete punctate fluorescent staining pattern in perinuclear regions with no fluorescence in cytoplasm (left panel), whereas neurons treated with HIV-1 Tat for 1 day displayed endolysosome membrane leakage as indicated by diffusion of fluorescence into cytoplasm (right panel, bar  = 10 μm).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3379000&req=5

Figure 5: HIV-1 Tat-disrupted endolysosome membrane integrityEndolysosome membrane integrity was evaluated by measuring the leakage of Lucifer Yellow dye. Control neurons displayed a discrete punctate fluorescent staining pattern in perinuclear regions with no fluorescence in cytoplasm (left panel), whereas neurons treated with HIV-1 Tat for 1 day displayed endolysosome membrane leakage as indicated by diffusion of fluorescence into cytoplasm (right panel, bar  = 10 μm).
Mentions: Endolysosome dysfunction has been implicated in initiating stress pathways that lead to cellular dysfunction and death (Roberg and Ollinger, 1998; Turk et al., 2002; Guicciardi et al., 2004; Kroemer and Jaattela, 2005; Kurz et al., 2008). Here, we determined the extent to which HIV-1 Tat-affected endolysosome membrane integrity using Lucifer Yellow dye (Yang et al., 1998). We found that while control neurons displayed a discrete punctate pattern of perinuclear fluorescent staining (Figure 5), HIV-1 Tat-treated neurons displayed increased endolysosome membrane leakage as evidenced by diffuse fluorescent staining (Figure 5) in the cytoplasm.

Bottom Line: Combined anti-retroviral therapeutic drugs effectively increase the lifespan of HIV-1-infected individuals who then have a higher prevalence of HAND (HIV-1 associated neurocognitive disorder).As early as 24 h after HIV-1 Tat was applied to neurons, HIV-1 Tat accumulated in endolysosomes, endolysosome morphology was affected and their size increased, endolysosome membrane integrity was disrupted, endolysosome pH increased, specific activities of endolysosome enzymes decreased and autophagy was inhibited, as indicated by the significant changes in three markers for autophagy.In contrast, statistically significant levels of HIV-1 Tat-induced neuronal cell death were observed only after 48 h of HIV-1 Tat treatment.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58203, USA.

ABSTRACT
Combined anti-retroviral therapeutic drugs effectively increase the lifespan of HIV-1-infected individuals who then have a higher prevalence of HAND (HIV-1 associated neurocognitive disorder). Soluble factors including HIV-1 proteins released from HIV-1-infected cells have been implicated in the pathogenesis of HAND, and particular attention has been paid to the HIV-1 Tat (transactivator of transcription) protein because of its ability to directly excite neurons and cause neuronal cell death. Since HIV-1 Tat enters cells by receptor-mediated endocytosis and since endolysosomes play an important role in neuronal cell life and death, we tested here the hypothesis that HIV-1 Tat neurotoxicity is associated with changes in the endolysosome structure and function and also autophagy. Following the treatment of primary cultured rat hippocampal neurons with HIV-1 Tat or as controls mutant-Tat or PBS, neuronal viability was determined using a triple staining method. Preceding observations of HIV-1 Tat-induced neuronal cell death, we observed statistically significant changes in the structure and membrane integrity of endolysosomes, endolysosome pH and autophagy. As early as 24 h after HIV-1 Tat was applied to neurons, HIV-1 Tat accumulated in endolysosomes, endolysosome morphology was affected and their size increased, endolysosome membrane integrity was disrupted, endolysosome pH increased, specific activities of endolysosome enzymes decreased and autophagy was inhibited, as indicated by the significant changes in three markers for autophagy. In contrast, statistically significant levels of HIV-1 Tat-induced neuronal cell death were observed only after 48 h of HIV-1 Tat treatment. Our findings suggest that endolysosomes are involved in HIV-1 Tat-induced neurotoxicity and may represent a target for therapeutic intervention against HAND.

Show MeSH
Related in: MedlinePlus