In order to investigate the neuroprotective effects of cyclin-dependent kinase-5 (cdk-5) inhibition in mice with Niemann-Pick disease type C (NPC) (npc-/-), recombinant adeno-associated virus (rAAV) carrying the small interfering RNA (siRNA) specific for cdk-5 gene was injected into 3-day-old npc-/-mice intracerebroventricularly. The rAAV-GFP-injected age-matched npc-/-mice and non-surgery age-matched npc-/-mice were employed as controls (n=6―10/group). From the 4th to 8th week after the treatment, mice were weighed, and evaluated for limb motor activity by using the coat hanger test once a week. Eight-week-old npc-/-mice were sacrificed by decapitation, and brains were quickly dissected and halved sagittally. Immunohistochemistry, Western blotting, and HE staining were used to evaluate the neuropathology in npc-/-mice. The results showed that rAAV-cdk-5-siRNA-GFP significantly reduced the number of axonal spheroids, delayed the death of Purkinje neurons, ameliorated motor defects in npc-/-mice, and significantly attenuated the hyper-phosphorylation of tau proteins. These data suggested that inhibition of cdk-5 activity has neuropro-tective effect on neurons in NPC mice.
Cyclin dependent kinases (cdks) play an important role in the pathogenesis of multiple neurodegenerative diseases. To explore the possibility of cdks-related gene therapy for neurodegen-erative diseases, we packed recombinant adeno-associated virus (rAAV) encoding cdc2-siRNA. The expressing plasmid pAAV-MCS-EGFP-U6-cdc2-siRNA was constructed by using molecular biological techniques. The rAAV encoding cdc2-siRNA (rAAV-EGFP-U6-cdc2-siRNA) was packed by calcium phosphate mediated co-transfection of the plasmid pAAV-MCS-EGFP-U6-cdc2-siRNA, p-RC and p-Helper into AAV-293 cells. DNA sequencing proved the successful construction of U6-cdc2-siRNA in pAAV-MCS-EGFP. Seventy-two h after packaging, the expression of EGFP could be detected in AAV-293 cells. Western blotting revealed that cdc2 gene expression in AAV-293 cells was down-regulated markedly after transfection with rAAV-EGFP-U6-cdc2-siRNA, which evidenced the satisfactory silencing effect of this virus. It was concluded that the packaging of rAAV encoding cdc2-siRNA was successful. rAAV encoding cdc2-siRNA could silence cdc2 gene effectively, which might offer a novel means for the treatment of neurodegenerative diseases.
In order to explore the role of TNF-α in Niemann-Pick type C (NPC) disease, lentivi-ral-delivered RNA interference (RNAi) was used to silence the expression of murine TNF-α gene in vitro and in npc mice. Interference efficiency of the lentivirus expressing TNF-α-siRNA, previously constructed with the concentration of 2×108 ifu/mL, was determined by RT-PCR and ELISA in BV-2 cells and astrocytes. At the same time, the constructed Lenti-TNF-α-siRNA was intracerebroven-tricularly infused into 4-week old npc mice for a 4-week period, and the mice were divided into 3 groups: Lenti-TNF-α-siRNA (n=6), control lentivirus (n=6), and NPC mice without any intervention (n=4). By using immunohistochemistry and real-time PCR, the down-regulation of the target genes was detected. The Lenti-TNF-α-siRNA downregulated the expression of murine TNF-α gene effi-ciently in vitro and the interference efficiency was 66.7%. Lentivirus could be expressed stably for long-term in the npc mice brain. Immunohistochemistry and real-time PCR revealed that, as com-pared with non-intervention group and Lenti-control group, Lenti-TNF-α-siRNA efficiently down-regulated the expression of murine TNF-α gene with the interference efficiency being 66.9%. TNF-α-siRNA downregulated the expression of TNF-α gene in vitro and in vivo, which provided a potential tool for studying and treating neurodegenerative diseases and TNF-α-related diseases.
