EXPRESSION PROFILES OF MULTIPLE GENES IN SINGLE NEURONS OF ALZHEIMERS-DISEASE

Many changes have been described in the brains of Alzheimer's disease (AD) patients, including loss of neurons and formation of senile plaqu es and neurofibrillary tangles. The molecular mechanisms underlying th ese pathologies are unclear. Northern blot, doe-blot, and reverse tran scription-coupled PCR analyses have demonstrated altered expression le vels of multiple messages in AD brain. Because not all cells are equal ly affected by the disease, these methods obviously cannot study the c hanges in relation to disease states of individual cells. We address t his problem by using antisense RNA profiling of single cells. We prese nt expression profiles of single neurons at early and late stages of A D and describe statistical tools for data analysis, With multivariate canonical analysis, we mere able to distinguish the disease state on t he basis of altered expression of multiple messages,To validate this a pproach, we compared results obtained by this approach with results ob tained by in situ hybridization analysis.When the neurofilament medium subunit was used as a marker, our results from an antisense RNA profi ling revealed no change in neurofilament medium subunit expression bet ween early- and late-stage AD, consistent with findings obtained with in situ hybridization. However, our results obtained by either analysi s art the single-cell level differed from the reported decrease in AD neocortex obtained by Northern blot analysis [Kittur, S., Hoh, J., End o, H., Tourtellotte, W., Weeks, B. S., Markesbery, W & Adler, W. (1994 ) J. Geriatr. Psychiatry Neurol. 7, 153-158]. Thus, the strategy of us ing the single-cell antisense RNA approach to identify altered gene ex pression in postmortem AD brain, followed by detailed in situ hybridiz ation studies for genes of interest, is valuable in the study of the m olecular mechanisms underlying AD neuropathology.