Alzheimer's disease-associated presenilin 2 interacts with DRAL, an LIM-domain protein

Using the yeast two-hybrid system, we screened for proteins interacting wit h presenilin 2 (PS2) and cloned DRAL. DRAL is an LIM-only protein containin g four LIM domains and an N-terminal half LIM domain. Previously DRAL has b een cloned as a co-activator of the androgen receptor and as a protein inte racting with a DNA replication regulatory protein, hCDC47. Our yeast two-hy brid assay showed that DRAL interacted with a hydrophilic loop region (amin o acids 269-298) in the endoproteolytic N-terminal fragment of PS2, but not that of PS1, although the region 269-298 of PS2 and the corresponding PS1 sequence differ by only three amino acids. Each point mutation within this region, R275A, T280A, Q282A, R284A, N285A, P287T, I288L, F289A and S296A, i n PS2 abolished the binding. This suggests that DRAL recognizes the PS2 str ucture specifically. The in vitro interaction was confirmed by affinity col umn assay and the physiological interactions between endogenous PS2 and DRA L by co-immunoprecipitation from human lung fibroblast MRC5 cells. Furtherm ore, in PS2-overexpressing HEK293 cells, we found an increase in the amount of DRAL in the membrane fraction and an increase in the amount of DRAL tha t was co-immunoprecipitated with PS2. The potential role of DRAL in the cel lular signaling suggests that DRAL functions as an adaptor protein that lin ks PS2 to an intracellular signaling.