The neuronal apoptosis inhibitory protein (NAIP) is known to have anti-apoptotic functions, and its gene is often mutated in severe cases of spinal muscular atrophy (SMA), a disease characterized by motor neuron degeneration. In this study, we examined the distribution of the endogenous NAIP protein in normal human spinal cord and brain tissue by using a polyclonal antibody against NAIP. Immunohistochemical staining demonstrated that NAIP is strongly expressed in anterior horn and motor cortex neurons of normal brains, and it is not altered in the remaining motor neurons of patients with amyotrophic lateral sclerosis (ALS). NAIP is also located in human fetal neurons and in adult choroid plexus cells. These results suggest that the antiapoptotic molecule NAIP may be important in motor neurons, but it specifically does not appear to be altered in ALS.
1Montreal Neurological Institute and Department of Neurology and Neurosurgery, McGill University, 3801 University Street, Montreal, Quebec H3A 2B4, Canada
2School of Science and Engineering, Al-Akhawayn University, Ifrane, Morocco
3Corresponding Author: Josephine Nalbantoglu
Acknowledgements: We thank A. MacKenzie for providing the NAIP cDNA, the rabbit polyclonal anti-NAIP serum and the NAIP fusion protein; J.P. Antel for providing the human fetal neuron cultures. G.P. is supported by a Medical Research Council fellowship; J.N. is a Senior Research Scholar of the Fonds de la recherche en santé du Québec.
Received 20 August 1999; accepted 16 October 1999