Characterisiation of AMPA receptor auxiliary proteins

• Applicant: Professor Dr. Jakob von Engelhardt
• Subject Area: Molecular Biology and Physiology of Neurons and Glial Cells
• Term: from 2015 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 271649277

Glutamate, the major excitatory transmitter in the central nervous system, exerts its function via activation of different receptor subclasses: AMPA, NMDA, kainate and metabotropic receptors. AMPA receptors, which mediate most of the fast excitatory transmission in the brain, are modulated in their physiological properties by their interaction with auxiliary proteins. For example, proteins of the TARP family promote the surface trafficking and change gating of AMPA receptors in neurons of many brain regions. Several recent studies have shown that the protein network of AMPARs is much larger than had been previously assumed, with many novel AMPA receptor-interacting proteins having recently been identified. Of these, only relatively few (i.e. CKAMP44, cornichons) have been investigated in more detail, and it could be shown that they indeed play an important role in the control of AMPA receptor function in the brain. In this proposal we aim to investigate the function of several novel proteins that might be AMPA receptor auxiliary proteins. Indeed, in preliminary experiments we could show that all of these proteins bind to AMPA receptors, are expressed in the brain and modulate receptor function of in heterologous cells expressed AMPA receptors. However, a detailed analysis of their function and importantly evidence that they play a role in the brain is still missing. We aim to analyze if the new AMPA receptor-interacting proteins influence function or expression of receptors in neurons of the mouse brain and can thus be classified as bona fide AMPA receptor auxiliary proteins. To this end, we will employ electrophysiological and anatomical methods and investigate the role of the AMPA receptor-interacting proteins by using virus-mediated protein knockdown and overexpressing approaches and knockout mice. We will focus the functional and anatomical analysis on brain areas in which the given interacting protein exhibits high expression levels based on our in situ hybridization experiments. Throughout this research, we will specifically address if a given protein influences gating and subcellular localization of AMPARs in neurons in selected brain areas. This study will be the first characterization of the function of the novel proteins. Moreover, the results that will be obtained from this approach might provide invaluable insight into how auxiliary proteins - through their modulation of AMPAR function - fine-tune neuronal communication, thereby ultimately determining how an animal behaves.

• DFG Programme: Research Grants