Received for publication October 27, 2005.
Revised December 20, 2005.
Accepted for publication January 5, 2006.

Identification and Characterization of Compounds that Potentiate NT-3 mediated Trk Receptor Activity

Abstract

Neurotrophins are a family of secreted proteins that play an important role in the development, differentiation and survival of neurons. Studies also suggest aberrant neurotrophin signaling may play a role in processes underlying disease states such as schizophrenia, Alzheimer's disease and depression. While the development of agents that selectively stimulate neurotrophin signaling has proven to be difficult, compounds have been identified that potentiate NT-3 mediated activation of trk A. In the present studies, we extend those initial observations to identify compounds that also potentiate NT-3 mediated activation of trk B. Compound potentiation of NT-3 was observed using several readouts of transfected and endogenous trk receptor activity including trk receptor phosphorylation, MAP kinase phosphorylation, reporter assay activity (-lactamase and luciferase) as well as cell survival and neurite extension assays. Studies using chimeric trk receptors demonstrated the extracellular domain is essential for compound potentiation and rule out interaction with intracellular signaling molecules as a mechanism of compound activity. Thus, the present studies demonstrate trk B receptor activity can be potentiated by small molecule compounds via the extracellular domain of the receptor and provide reagents for further evaluating the role of NT-3 mediated trk A and trk B activity in vivo.

Key words: Neuropeptides, NGF/EGF, MAP Kinase, Mutagenesis/Chimeric approaches