Non-invasive diagnosis of Alzheimer's disease

2003 Fiscal Year Final Research Report Summary

• Project/Area Number: 14570948
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Psychiatric science
• Research Institution: KANAZAWA MEDICAL UNIVERSITY
• Principal Investigator: NAKAHASHI Takeshi KANAZAWA MEDICAL UNIVERSITY, Department of Geriatric Medicine, Assistant professor, 医学部, 講師 (40350764)
• Co-Investigator(Kenkyū-buntansha): MATSUMOTO Masayuki KANAZAWA MEDICAL UNIVERSITY, Department of Geriatric Medicine, Professor, 医学部, 教授 (50028677)
• Project Period (FY): 2002 – 2003
• Keywords: Alzheimer's disease / Tau protein / Oral cavity epithelium / SNPs

Research Abstract

Alzheimer's disease has been becoming major problem for the Japanese elderly. The aim of this study is to establish non-invasive simple diagnostic method for Alzheimer's disease by using biological marker from oral epithelium. Tau protein profile has been reported to have a good correlation to Alzheimer' disease, and concentration of total tau protein or phosphorylated tau protein in cerebrospinal fluid may predict this disease. Based on our previous examination, tau protein expression in oral epithelium cell significantly increased in patients with Alzheimer's disease, and the immunohistological analysis revealed the similarity between epithelial tau protein and neuronal tau protein. In this term, the gene expression profile of epithelial tau was investigated. Total RNA was isolated from epithelial cell (cultured human keratinocyte cell), and converted to cDNA for RT-PCR analysis. Among 8 different segments of tau RT-PCR products, the segment from exon 4 to exon 7 was focused on, sinc e it contained exon 6 which had been reported to be specific for non neuronal tau protein. The primer set for this amplification (Forward :5' - AAG AAG CAG GCA TTG GAG A, Reverse : 5' - AGA GCT GGG TGG TGT CTT TG) produced short and long product (245 bp and 443 bp, respectively). Sequence analysis by dye-terminator cycle sequence method revealed that short product had 100% homology to exon 4-5-7 of tan protein and long product had 97.3% homology to exon 4-5-6-7 of tau protein. Short product was thought to be compatible to neuronal tau, however long product lacking exon 4a had not been reported. Furthermore, 3 SNP's (single nucleotide polymorphism) may exist on exon 6. These observations may suggest that the expression profile of tau protein of oral epithelium cell is highly similar to that of neuronal tau and tau protein of oral epithelium may be useful for non-invasive diagnosis for Alzheimer's disease, and may contribute to prevention and treatment of this disease.
This investigation was presented at 45^<th> annual meeting of Japanese Geriatrics Society (June 2003, Nagoya)