Presenilin-interacting proteins

Familial Alzheimer's disease (FAD) accounts for 5-10% of deaths from Alzheimer's disease (AD), and approximately 50% of these cases have been definitely linked to missense mutations in three genes, encoding the amyloid precursor protein (APP), presenilin 1 (PS1) and presenilin 2 (PS2). Of these, the vast majority of FAD-linked mutations are within PS1. There has been an extensive effort to identify proteins that functionally interact with PS1 and PS2 because of their clear roles in FAD. The goal of this review is to describe these proteins and to discuss in more detail the probable biological functions of a subset of the better-studied interacting proteins. In particular, the review examines APP, Notch, nicastrin, modifier of cellular adhesion (MOCA), beta-catenin, and the group of proteins involved in cell death, calcium metabolism and cell adhesion. We argue that, although a few of the interacting proteins are unambiguously involved in well-studied cellular pathways, their exact roles within these pathways have not been clearly defined, and indeed might vary between cell types. We also question the physiological relevance of some of the work linking PS to cell death pathways. Finally, we point out the value of using flies and worms to sort out the often contradictory work in the PS field, and we mention how knowledge of PS-interacting pathways will contribute to the development of new therapeutic strategies in AD.