HIV-1 stimulates nuclear entry of amyloid beta via dynamin dependent EEA1 and TGF-β/Smad signaling

Abstract

Clinical evidence indicates increased amyloid deposition in HIV-1-infected brains, which contributes to neurocognitive dysfunction in infected patients. Here we show that HIV-1 exposure stimulates amyloid beta (Aβ) nuclear entry in human brain endothelial cells (HBMEC), the main component of the blood-brain barrier (BBB). Treatment with HIV-1 and/or Aβ resulted in concurrent increase in early endosomal antigen-1 (EEA1), Smad, and phosphorylated Smad (pSmad) in nuclear fraction of HBMEC. A series of inhibition and silencing studies indicated that Smad and EEA1 closely interact by influencing their own nuclear entry; the effect that was attenuated by dynasore, a blocker of GTP-ase activity of dynamin. Importantly, inhibition of dynamin, EEA1, or TGF-β/Smad effectively attenuated HIV-1-induced Aβ accumulation in the nuclei of HBMEC. The present study indicates that nuclear uptake of Aβ involves the dynamin-dependent EEA1 and TGF-β/Smad signaling pathways. These results identify potential novel targets to protect against HIV-1-associated dysregulation of amyloid processes at the BBB level.

Compounds Blocking Methylglyoxal-induced Protein Modification and Brain Endothelial Injury

“…Similar to retinoic acid, U0126 could successfully prevent the damaging effect of MG on the viability and barrier integrity of human brain endothelial cells. Activation of the MAPK signaling pathway is accompanied by increased permeability in brain endothelial cells, which could be restored by U0126, inhibitor of this signaling pathway (72,73), in concordance with the present finding There was similarity in the expression profile of the selected BBB-related genes in the retinoic acid and U0126 cotreatment groups. Therefore, it is tempting to speculate that the protective effect of retinoic acid is mediated, at least partially, through the inhibition of the MAPK/ERK signaling pathway.…”

Transcriptional Profile of HIV-induced Nuclear Translocation of Amyloid β in Brain Endothelial Cells

“…Moreover, inhibition of dynamin by Dy (50 μM Dy pretreatment for 30 min prior to Aβ exposure) effectively attenuated HIV-induced Aβ nuclear uptake (10). To explore the possible mechanisms involved, we investigated gene signature changes associated with this event.…”

“…Human brain microvascular endothelial cells (HBMEC) representing a stable, well-characterized, and differentiated human brain endothelial cell line (11) were cultured as previously reported (10). Briefly, normal human brain endothelial cells were transduced by lentiviral vectors incorporating human telomerase or SV40 T antigen.…”

“…Throughout the study, HBMEC were exposed to HIV particles for 24 h at the p24 level of 30 ng/mL as previously reported (10). Freshly solubilized Aβ (1–40) HCl (Anaspec, San Jose, CA) solutions without pre-aggregation were used to treat cells at a concentration of 1 μM for 10 min as published earlier (10). The inhibitor dynasore hydrate (Dy) (Sigma Aldrich, St. Louis, MO) was dissolved in DMSO and further diluted in cell culture media.…”

“…Recently, we demonstrated that Aβ not only accumulates in the cytoplasm of HIV-exposed cells but also enters the nuclei (10). Inhibition of dynamin by dynasore (Dy), a blocker of GTP-ase activity of dynamin, effectively attenuated HIV-induced Aβ nuclear uptake.…”