No abstract

No abstract

No abstract

Neuron-restrictive silencer elements (NRSEs) were used to target the gene expression of adenoviral vectors specifically to neuron cells in the central nervous system. By generating adenoviral constructs in which NRSE sequences were placed upstream from the ubiquitous phosphoglycerate kinase promoter, the specificity of expression of a luciferase reporter gene was tested in both cell lines and primary cultures. Whereas transgene expression was negligible in nonneuronal cells following infection with an adenovirus containing 12 NRSEs, neuronal cells strongly expressed luciferase when infected with the same adenovirus. The NRSEs restricted expression of the luciferase gene to neuronal cells in vivo when adenoviruses were injected both intramuscularly into mice and intracerebrally into rats. This NRSE strategy may avoid side effects resulting from the ectopic expression of therapeutic genes in the treatment of neurological diseases. In particular, it may allow the direct transfection of motor neurons without promoting transgene expression within inoculated muscles or the secretion of transgene products into the bloodstream.

Neurotrophic factors (NFs) are promising agents for the treatment of peripheral neuropathies such as diabetic neuropathy. However, the value of treatment with recombinant NF is limited by the short half-lives of these molecules, which reduces efficiency, and by their potential toxicity. We explored the use of intramuscular injection of a recombinant adenovirus encoding NT-3 (AdNT-3) to deliver sustained low doses of NT-3. We assessed its effect in two rat models: streptozotocin (STZ)-induced diabetes, a model of early diabetic neuropathy characterized by demyelination, and acrylamide experimental neuropathy, a model of diffuse axonal neuropathy which, like late-onset human diabetic neuropathy, results in a diffuse sensorimotor neuropathy with dysautonomy. Treatment of STZ-diabetic rats with AdNT-3 partially prevented the slowing of motor and sensory nerve conduction velocities (p < 0.01 and p < 0.0001, respectively). Treatment with AdNT-3 of acrylamide-intoxicated rats prevented the slowing of motor and nerve conduction velocities (p < 0.001 and p < 0.0001, respectively) and the decrease in amplitude of compound muscle potentials (p < 0.0001), an index of denervation. Acrylamide-intoxicated rats treated with NT-3 had higher than control levels of muscle choline acetyltransferase activity (p < 0.05), suggesting greater muscle innervation. In addition, treatment of acrylamide-intoxicated rats with AdNT-3 significantly improved behavioral test results. Treatment with AdNT-3 was well tolerated with minimal muscle inflammation and no detectable general side effects. Therefore, our results suggest that NT-3 delivery by adenovirus-based gene therapy is a promising strategy for the prevention of both early diabetic neuropathy and axonal neuropathies, especially late axonal diabetic neuropathy.

Cisplatin-induced sensory peripheral neuropathy is the dose-limiting factor for cisplatin chemotherapy. We describe the preventive effect of NT-3 delivery, using direct gene transfer into muscle by in vivo electroporation in a mouse model of cisplatin-induced neuropathy. Cisplatin-induced neuropathy was produced by weekly injections of cisplatin (five injections). Two doses of plasmid DNA encoding murine NT-3 (pCMVNT-3) were tested (5 and 50 microg/animal/injection). Cisplatin-treated mice were given two intramuscular injections. The first injection of pCMVNT-3 was given 2 days before the first injection of cisplatin and the second injection 2 weeks later. Six weeks after the start of the experiment, measurement of NT-3 levels (ELISA) demonstrated significant levels both in muscle and plasma. We observed a smaller cisplatin-related increase in the latency of the sensory nerve action potential of the caudal nerve in pCMVNT-3-treated mice than in controls (p < 0.0001). Mean sensory distal latencies were not different between the 5- and 50- microg/animal/injection groups. Treatment with gene therapy induced only a slight muscle toxicity and no general side effects. Therefore, neurotrophic factor delivery by direct gene transfer into muscle by electroporation is of potential benefit in the prevention of cisplatin-induced neuropathy and of peripheral neuropathies in general.

No abstract

We show that excitotoxic cell death, which is associated with pathological neurodegenerative processes, can display morphological and biochemical features characteristic of apoptosis, a mode of cell death typical of physiological neuronal elimination during development . Cortical neurons cultured in the absence of serum, stimulated with NMDA, glutamate, or quisqualate after 3-5 days in vitro, showed significant degeneration . This death was blocked by 1 It,M MK-801, indicating that it was mediated by the activation of NMDA receptors. Dying cells displayed an apoptotic morphology, characterized by cytoplasm and chromatin condensation . No internucleosomal DNA degradation was observed, confirming that morphological changes of apoptosis can be dissociated from DNA laddering. Inhibitors of protein or RNA synthesis abolished cell death, and the protective effect of cycloheximide was similar when the drug was applied 2 h before or 8 h after glutamate. These experiments suggest the participation of active gene transcription in the mechanism of death . We thus analyzed the modulation of transcription factors in dying cells using electrophoretic mobility shift assays . The level of factors binding to the 12-O-tetradecanoylphorbol 13-acetate-responsive element (TRE) displayed a late and sustained increase preceding neuronal death, which was not found for factors complexing the Spl P, Oct, and USF binding sites. These results raise the possibility that apoptosis is one of the mechanisms of death in the pathologies linked to excitotoxicity and that activation of TRE-binding factors could play a role in these processes. Key Words: Apoptosis-Excitotoxicity-Neurodegeneration-Transcription factors-12-O-Tetradecanoylphorbol 13-acetate-responsive element.