CHARACTERIZATION OF THE AD7C-NTP CDNA EXPRESSION IN ALZHEIMERS-DISEASE AND MEASUREMENT OF A 41-KD PROTEIN IN CEREBROSPINAL-FLUID

We have isolated a novel Alu sequence-containing cDNA, designated AD7c -NTP, that is expressed in neurons, and overexpressed in brains with A lzheimer's disease (AD). The 1,442-nucleotide AD7c-NTP cDNA encodes an similar to 41-kD protein, Expression of AD7c-NTP was confirmed by nuc leic acid sequencing of reverse transcriptase PCR products isolated fr om brain, AD7c-NTP cDNA probes hybridized with 1.4 kB mRNA transcripts by Northern blot analysis, and monoclonal antibodies generated with t he recombinant protein were immunoreactive with similar to 41-45-kD an d similar to 18-21-kD molecules by Western blot analysis. In situ hybr idization and immunostaining studies localized AD7c-NTP gene expressio n in neurons, Using a quantitative enzyme-linked sandwich immunoassay (Ghanbari, K., I. Beheshti, and H. Ghanbari, manuscript submitted for publication) constructed with antibodies to the recombinant protein, A D7c-NTP levels were measured under code in 323 clinical and postmortem cerebrospinal fluid (CSF) samples from AD, age-matched control, Parki nson's disease, and neurological disease control patients. The molecul ar mass of the AD7c-NTP detected in CSF was similar to 41 kD, In postm ortem CSF, the mean concentration of AD7c-NTP in cases of definite AD (9.2+/-8.2 ng/ml) was higher than in the aged control group (1.6+/-0.9 ; P < 0.0001), In CSF samples from individuals with early possible or probable AD, the mean concentration of AD7c-NTP (4.6+/-3.4) was also e levated relative to the levels in CSF from age-matched (1.2+/-0.7) and neurological disease (1.0+/-0.9) controls, and ambulatory patients wi th Parkinson's disease (1.8+/-1.1) (all P < 0.001), CSF levels of AD7c -NTP were correlated with Blessed dementia scale scores (r = 0.66; P = 0.0001) rather than age (r = -0.06; P > 0.1), In vitro studies demons trated that overexpression of AD7c-NTP in transfected neuronal cells p romotes neuritic sprouting and cell death, the two principal neuroanat omical lesions correlated with dementia in AD. The results suggest tha t abnormal AD7c-NTP expression is associated with AD neurodegeneration , and during the early stages of disease, CSF levels correlate with th e severity of dementia.