1. ¹Gene Therapeutics Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048 USA
2. ²Department of Medicine, Johnson Comprehensive Cancer Center, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095, USA

Correspondence: P. R. Lowenstein, Gene Therapeutics Research Institute, Cedars-Sinai Medical Center, Davis Building, Room 5090, 8700 Beverly Boulevard, Los Angeles, CA 90048, USA. Fax: (310) 423-7308. E-mail: lowensteinp@cshs.org

^*Present address: Massachusetts General Hospital, Harvard Medical School, Bldg. 149, 13th Street, 8th floor, PMB, Charlestown MA, 02129, USA.

^†Present address: Department of Surgery, CIMR, Rm. 6.15, Wellcome Trust/MRC Bldg., Addenbrooke's Hospital, Hills Rd., Cambridge CB2 2XY UK.

^‡Present address: Department of Physiology and Neuroscience, Medical University of South Carolina, Cahrleston, SC USA.

^§Present address: Klinik für Neurologie, Alfried Krupp Krankenhaus, Alfried-Krupp-Strae 21, D-45131 Essen, Germany.

^¶These authors should be considered joint first author for this article.

Received 2 April 2004; Accepted 13 May 2004.

Abstract

We tested the activity of the dopaminergic neuron differentiation factor sonic hedgehog, its downstream transcription factor target Gli-1, and an orphan nuclear receptor, Nurr-1, necessary for the induction of the dopaminergic phenotype of nigrostriatal neurons, in an in vivo model of nigrostriatal neurodegeneration. Our preliminary experiments demonstrated that all three constructs expressed the proper molecules and that these had the predicted biological activities in vitro. We expressed the N-terminal of sonic hedgehog (ShhN) and the Gli-1 and Nurr-1 entire coding regions from highly purified, and quality controlled, replication-defective adenoviral vectors injected into the brains of rats and used the dopaminergic growth factor GDNF as a positive control. The neurotoxin 6-hydroxydopamine was used to lesion the nigrostriatal dopaminergic innervation; RAd-ShhN and RAd-Gli-1 protected dopaminergic neuronal cell bodies in the substantia nigra, but not axonal terminals in the striatum, from 6-OHDA-induced cell death, while RAd-Nurr-1 was ineffective in protecting either cell bodies or axons. RAd-GDNF was able to protect both the dopaminergic cell bodies and the striatal axon terminals. Our results establish for the first time, to the best of our knowledge, that gene transfer of ShhN and one of its target transcription factors can selectively protect dopaminergic nigrostriatal neuronal cell bodies from a specific neurotoxic insult. Selective protection of nigrostriatal dopaminergic cell bodies by the differentiation factor ShhN and the transcription factor Gli-1 was achieved in a neurotoxic model that eliminates more than 70% of the nigral neurons under consideration. Differentiation and transcription factors can thus be used for the treatment of neurodegeneration by gene therapy.