Gene Expression Profiling in Cells with Enhanced ?-Secretase Activity

Magold, Alexandra I.; Cacquevel, Matthias; Fraering, Patrick C.

nse to the DAPT treatment. The gene transcription levels of the two cell lines were analyzed using a mouse cDNA microarray ( Fig. 1 and Material and Methods) [20] because of the absence of a readily available DNA microarray based upon hamster gene sequences or cDNA clones. This lack has been noticed, and cross-species reactivity of a mouse microarray hybridized with CHO-derived samples has been investigated recently by De Leon Gatti et al. [21] . This group generated an EST-based CHO microarray and compared it with results from a mouse microarray and vice versa. They state that cross-species hybridization yielded 89.6% overlap in their arrays, noncontradicting results and led only to a decrease in sensitivity resulting in detection of fewer differentially expressed genes. Accordingly, we probably have not detected all differentially expressed genes, but we have detected a significant amount, including clusters of functional relevance. For example, Neprilysin, an Ab-degrading enzyme of functional relevance to AD that has been previously shown to be transcriptionally downregulated in PSEN1/PSEN2 double knock out fibroblasts and to exhibit reduced activity under chemical (DAPT) inhibition of c-secretase in mouse neurons [22] , was not detected in the current study. Collectively, this supports the use of CHO cells with a mouse microarray. The microarray data set discussed in this publication has been deposited in the NCBI Gene Expression Omnibus (GEO, http://www.ncbi.nlm.nih.gov/geo/) and is accessible through GEO Series accession number GSE16379.