The present invention relates to novel compounds and their pharmaceutical or diagnostic use, or use as a pharmacological target. More particularly, the present invention describes the identification of partners of the FE65 protein and the use of these partners, or of any compound which is capable of modulating, at least partially, their interaction with FE65, for regulating the activity of FE65, and in particular the phenomenon of intracellular transport or of endocytosis of the APP.