Journal Article

Uptake of Biotinylated Spermine in Astrocytes: Effect of Cx43 siRNA, HIV-Tat Protein and Polyamine Transport Inhibitor on Polyamine Uptake

Veh, Rüdiger W., Eaton, Misty J., Malpica-Nieves, Christian J., Rivera, Yomarie, Rivera-Aponte, David E., Phanstiel, Otto, Skatchkov, Serguei N.

2021

Overview

Polyamines (PAs) are polycationic biomolecules containing multiple amino groups. Patients with HIV-associated neurocognitive disorder (HAND) have high concentrations of the polyamine N-acetylated spermine in their brain and cerebral spinal fluid (CSF) and have increased PA release from astrocytes. These effects are due to the exposure to HIV-Tat. In healthy adult brain, PAs are accumulated but not synthesized in astrocytes, suggesting that PAs must enter astrocytes to be N-acetylated and released. Therefore, we tested if Cx43 hemichannels (Cx43-HCs) are pathways for PA flux in control and HIV-Tat-treated astrocytes. We used biotinylated spermine (b-SPM) to examine polyamine uptake. We found that control astrocytes and those treated with siRNA-Cx43 took up b-SPM, similarly suggesting that PA uptake is via a transporter/channel other than Cx43-HCs. Surprisingly, astrocytes pretreated with both HIV-Tat and siRNA-Cx43 showed increased accumulation of b-SPM. Using a novel polyamine transport inhibitor (PTI), trimer 44NMe, we blocked b-SPM uptake, showing that PA uptake is via a PTI-sensitive transport mechanism such as organic cation transporter. Our data suggest that Cx43 HCs are not a major pathway for b-SPM uptake in the condition of normal extracellular calcium concentration but may be involved in the release of PAs to the extracellular space during viral infection.

• Publisher: MDPI AG,MDPI
• Subject: acetylated polyamines / Acquired immune deficiency syndrome / AIDS / Amino groups / Animal cognition / Animals / Apoptosis / Astrocytes / Astrocytes - metabolism / Astrocytes - virology / astroglial polyamine transporter / Binding sites / Biological Transport - drug effects / Brain / Calcium (extracellular) / Cerebrospinal fluid / Cognition / Connexin 43 / Connexin 43 - metabolism / Experiments / Genomes / HIV / HIV Infections - metabolism / HIV-1 / HIV-Tat / Homogenization / Human immunodeficiency virus / Immune system / Infections / Mice / Mice, Inbred C57BL / Organic cation transporter / Pathology / Polyamines / Primary Cell Culture / Protein transport / Proteins / siRNA / Spermine / Spermine - metabolism / spermine catabolism / Tat protein / Trimers / Viral infections / Viruses