Herpes simplex virus type 1 infection in neurons leads to production and nuclear localization of APP intracellular domain (AICD): implications for Alzheimer's disease pathogenesis.
Several data indicate that neuronal infection with herpes simplex virus type 1 (HSV-1) causes biochemical alterations reminiscent of Alzheimer's disease (AD) phenotype. They include accumulation of amyloid-β (Aβ), which originates from the cleavage of amyloid precursor protein (APP), and hyperphosphorylation of tau protein, which leads to neurofibrillary tangle deposition. HSV-1 infection triggers APP processing and drives the production of several fragments including APP intracellular domain (AICD) that exerts transactivating properties. Herein, we analyzed the production and intracellular localization of AICD following HSV-1 infection in neurons. We also checked whether AICD induced the transcription of two target genes, neprilysin (nep) and glycogen synthase kinase 3β (gsk3β), whose products play a role in Aβ clearance and tau phosphorylation, respectively. Our data indicate that HSV-1 led to the accumulation and nuclear translocation of AICD in neurons. Moreover, results from chromatin immunoprecipitation assay showed that AICD binds the promoter region of both nep and gsk3β. Time course analysis of NEP and GSK3β expression at both mRNA and protein levels demonstrated that they are differently modulated during infection. NEP expression and enzymatic activity were initially stimulated but, with the progression of infection, they were down-regulated. In contrast, GSK3β expression remained nearly unchanged, but the analysis of its phosphorylation suggests that it was inactivated only at later stages of HSV-1 infection. Thus, our data demonstrate that HSV-1 infection induces early upstream events in the cell that may eventually lead to Aβ deposition and tau hyperphosphorylation and further suggest HSV-1 as a possible risk factor for AD.
Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome, Italy. livia.civitelli@liu.se.|Experimental Pathology, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden. livia.civitelli@liu.se.
Livia
L
Civitelli
Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome, Italy.
Maria Elena
ME
Marcocci
Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome, Italy.
Ignacio
I
Celestino
Institute of Human Physiology, Università Cattolica del Sacro Cuore, Rome, Italy.
Roberto
R
Piacentini
IRCCS San Raffaele Pisana, Telematic University, Rome, Italy.
Enrico
E
Garaci
Institute of Human Physiology, Università Cattolica del Sacro Cuore, Rome, Italy.
Claudio
C
Grassi
Institute of Translational Pharmacology, CNR, Rome, Italy.
Giovanna
G
De Chiara
Department of Public Health and Infectious Diseases, Institute Pasteur Cenci Bolognetti Foundation, Sapienza University of Rome, Rome, Italy.
Anna Teresa
AT
Palamara
D000544:Alzheimer Disease / Q000378:metabolism / Q000821:virology*; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D002540:Cerebral Cortex; D047369:Chromatin Immunoprecipitation; D038362:Glycogen Synthase Kinase 3 / Q000096:biosynthesis; D000071679:Glycogen Synthase Kinase 3 beta; D006561:Herpes Simplex / Q000378:metabolism*; D018259:Herpesvirus 1, Human; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D015260:Neprilysin / Q000096:biosynthesis; D009474:Neurons / Q000378:metabolism* / Q000821:virology*; D051381:Rats; D017208:Rats, Wistar; D060888:Real-Time Polymerase Chain Reaction
D016564:Amyloid beta-Protein Precursor; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605508:Gsk3b protein, rat; D038362:Glycogen Synthase Kinase 3; D015260:Neprilysin
AICD; APP; Alzheimer’s disease; GSK3β; Herpes simplex virus (HSV-1); Neprilysin; Neurodegeneration