JIMD Reports, Volume 44

Masashi Morita, Shun Matsumoto, Airi Sato, Kengo Inoue, Dzmitry G. Kostsin, Kozue Yamazaki, Kosuke Kawaguchi, Nobuyuki Shimozawa, Stephan Kemp, Ronald J. Wanders, Hirotatsu Kojima, Takayoshi Okabe, Tsuneo Imanaka, Morita, Masashi, Matsumoto, Shun, Sato, Airi, Inoue, Kengo, Kostsin, Dzmitry G., Yamazaki, Kozue, Kawaguchi, Kosuke, Shimozawa, Nobuyuki, Kemp, Stephan, Wanders, Ronald J., Kojima, Hirotatsu, Okabe, Takayoshi, Imanaka, Tsuneo

Mutations in the ABCD1 gene that encodes peroxisomal ABCD1 protein cause X-linked adrenoleukodystrophy (X-ALD), a rare neurodegenerative disorder. More than 70% of the patient fibroblasts with this missense mutation display either a lack or reduction of the ABCD1 protein because of posttranslational degradation. In this study, we analyzed the stability of the missense mutant ABCD1 proteins (p.A616T, p.R617H, and p.R660W) in X-ALD fibroblasts and found that the mutant ABCD1 protein p.A616T has the capacity to recover its function by incubating at low temperature. In the case of such a mutation, chemical compounds that stabilize mutant ABCD1 proteins could be therapeutic candidates. Here, we prepared CHO cell lines stably expressing ABCD1 proteins with a missense mutation in fusion with green fluorescent protein (GFP) at the C-terminal. The stability of each mutant ABCD1-GFP in CHO cells was similar to the corresponding mutant ABCD1 protein in X-ALD fibroblasts. Furthermore, it is of interest that the GFP at the C-terminal was degraded together with the mutant ABCD1 protein. These findings prompted us to use CHO cells expressing mutant ABCD1-GFP for a screening of chemical compounds that can stabilize the mutant ABCD1 protein. We established a fluorescence-based assay method for the screening of chemical libraries in an effort to find compounds that stabilize mutant ABCD1 proteins. The work presented here provides a novel approach to finding therapeutic compounds for X-ALD patients with missense mutations.