HIV-1 Tat triggers nuclear localization of ZO-1 via Rho signaling and cAMP response element-binding protein activation.
The human immunodeficiency virus (HIV)-specific protein trans-activator of transcription (Tat) can contribute to the dysfunction of brain endothelial cells and HIV trafficking into the brain by disrupting tight junction (TJ) integrity at the blood-brain barrier (BBB) level. Specific TJ proteins, such as zonula occludens (ZO) proteins, localize not only at the cell-cell borders but are also present in the nuclei. The objective of the present study was to evaluate the mechanisms and significance of Tat-induced nuclear localization of ZO-1. Treatment of a brain endothelial cell line (hCMEC/D3 cells) with Tat resulted in a decrease in total levels of ZO-1 but significantly upregulated ZO-1 protein expression in the nuclei. In addition, exposure to Tat stimulated Rho signaling and induced phosphorylation and activity of transcription factor cAMP response element-binding protein (CREB), binding sites that have been identified in the proximal region of the ZO-1 promoter. Interestingly, inhibition of the Rho cascade protected against Tat-induced upregulation of ZO-1 in the nuclei and activation of CREB. Depletion of CREB by infection of cells with specific shRNA lentiviral particles attenuated both Tat-induced Rho signaling and nuclear targeting of ZO-1. A decrease in CREB levels also attenuated Tat-induced endothelial and BBB hyperpermeability as well as transendothelial migration of monocytic cells. The role of CREB in Tat-mediated alterations of ZO-1 was confirmed in brain microvessels in mice with CREB shRNA lentiviral particles injected into the cerebral circulation. The present results indicate the crucial role of Rho signaling and CREB in modulation of nuclear localization of ZO-1 and maintaining the integrity of endothelial monolayers.
Molecular Neuroscience and Vascular Biology Laboratory, Department of Neurosurgery, University of Kentucky Medical Center, Lexington, Kentucky 40536, USA.
Yu
Y
Zhong
Bei
B
Zhang
Sung Yong
SY
Eum
Michal
M
Toborek
D000818:Animals; D001812:Blood-Brain Barrier / Q000378:metabolism* / Q000821:virology; D002467:Cell Nucleus / Q000378:metabolism* / Q000821:virology; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism* / Q000821:virology; D057809:HEK293 Cells; D015497:HIV-1 / Q000502:physiology; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D010750:Phosphoproteins / Q000378:metabolism*; D061251:Primary Cell Culture; D015398:Signal Transduction / Q000502:physiology*; D062826:Zonula Occludens-1 Protein; D020741:rho GTP-Binding Proteins / Q000502:physiology*; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000502:physiology*
C115163:CREB1 protein, human; D017362:Cyclic AMP Response Element-Binding Protein; D008565:Membrane Proteins; D010750:Phosphoproteins; C569042:TJP1 protein, human; C569043:Tjp1 protein, mouse; D062826:Zonula Occludens-1 Protein; D054322:tat Gene Products, Human Immunodeficiency Virus; D020741:rho GTP-Binding Proteins