Several findings suggest that recurrent HSV-1 infections play a co-factorial role in Alzheimer's disease (AD). In particular, we have recently demonstrated that HSV-1 promotes intra-and extra-neuronal accumulation of beta amyloid pepdides. In addition, HSV-1 was reported to inhibit in epithelial cells the not homologous end joining (NHEJ) DNA repair pathway, targeting DNA-dependent protein kinase (DNA-PK) for proteasomal degradation. NHEJ pathway repairs double strand breaks (DBSs), the most dangerous form of DNA damage and relies on the DNA-PK complex. Emerging evidence indicate that unrepaired DSBs and deficiency in NHEJ are implicated in the progressive neuronal loss observed in AD. Aim of this study was to determine whether HSV-1 infections in neurons affect DNA repair system, particularly the NHEJ thus causing DNA damage accumulation and contributing to neurodegeneration. Methods HSV-1-infected rat cortical neurons were analyzed for: gammaH2AX (phosphorylated histone H2AX) accumulation by immunoflorescence and western blot analysis (wb); DNA damage characterization by Comet assays; DNA-PK complex expression levels by wb of cell lysates; NHEJ efficacy by an in vitro NHEJ assay. Results HSV-1 infection in cortical neurons causes accumulation of gammaH2AX, a sensitive marker of DNA damage within chromatin, in the neuronal genome in a time- and multiplicity of infection-dependent manner. Furthermore, comet assay results demonstrate the occurrence of DSBs following HSV-1 infection in neurons. Consistently, HSV-1 infection modulates DNA-PK complex protein levels and affects the efficacy of NHEJ pathway. Conclusions HSV may contribute to neurodegeneration though the impairment of NHEJ and the consequent accumulation of DNA damage.
Herpes simplex virus-type1 (HSV-1) impairs DNA repair in cortical neurons, causing accumulation of DNA damage and contributing to neurodegeneration
De Chiara G;Mollinari C;
2013
Abstract
Several findings suggest that recurrent HSV-1 infections play a co-factorial role in Alzheimer's disease (AD). In particular, we have recently demonstrated that HSV-1 promotes intra-and extra-neuronal accumulation of beta amyloid pepdides. In addition, HSV-1 was reported to inhibit in epithelial cells the not homologous end joining (NHEJ) DNA repair pathway, targeting DNA-dependent protein kinase (DNA-PK) for proteasomal degradation. NHEJ pathway repairs double strand breaks (DBSs), the most dangerous form of DNA damage and relies on the DNA-PK complex. Emerging evidence indicate that unrepaired DSBs and deficiency in NHEJ are implicated in the progressive neuronal loss observed in AD. Aim of this study was to determine whether HSV-1 infections in neurons affect DNA repair system, particularly the NHEJ thus causing DNA damage accumulation and contributing to neurodegeneration. Methods HSV-1-infected rat cortical neurons were analyzed for: gammaH2AX (phosphorylated histone H2AX) accumulation by immunoflorescence and western blot analysis (wb); DNA damage characterization by Comet assays; DNA-PK complex expression levels by wb of cell lysates; NHEJ efficacy by an in vitro NHEJ assay. Results HSV-1 infection in cortical neurons causes accumulation of gammaH2AX, a sensitive marker of DNA damage within chromatin, in the neuronal genome in a time- and multiplicity of infection-dependent manner. Furthermore, comet assay results demonstrate the occurrence of DSBs following HSV-1 infection in neurons. Consistently, HSV-1 infection modulates DNA-PK complex protein levels and affects the efficacy of NHEJ pathway. Conclusions HSV may contribute to neurodegeneration though the impairment of NHEJ and the consequent accumulation of DNA damage.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
