Ruth A. Sinnamon

Research Summary

Biochemical and structural investigation of the 13 PDZ domains of MPDZ. Alcoholism is a clinically heterogeneous disorder, with interactions between multiple genetic components. Genetic studies have tracked addictive behavior back to the genome and have revealed two glutamate receptors, NMDA and AMPA, and one of their associated scaffolding proteins, MPDZ, as elements of a molecular reward circuit that can be studied to gain a better understanding of how addiction works. MPDZ is a scaffolding protein containing 13 homologous PDZ domains. PDZ domains are protein-protein interaction modules that recognize a broad range of protein sequences 5-7 residues in length and bind to the C-terminus of other proteins and peptides. MPDZ plays an important role in the NMDA-dependent AMPA trafficking cascade by binding to SynGAP and CaMKII and bringing them together. Upon stimulation of NMDA receptors, Ca2+ enters the post-synaptic density causing SynGAP to dissociate from the MPDZ-CaMKII complex. This increases the number of AMPA receptors in the post-synaptic membrane and the potentiation of AMPA signaling. Previous studies have linked phenotypes of alcohol dependence to variation in the MPDZ gene and strengthened AMPA potentiation, but little is known about how MPDZ interacts with proteins in this cascade and the combinatorial code that causes these PDZ domains to interact with specific proteins. I am interested in identifying and characterizing PDZ interactions of MPDZ that are essential for the behavior involved with alcohol addiction. To address this biochemically, I aim to express each of the MPDZ PDZ domains and identify proteins and their peptide sequences that bind to each domain using peptide arrays and fluorescence polarization. Additionally, x-ray crystallography can be used to visualize the physical interaction of these peptides with each domain. Feel free to email me if you're interested and would like to learn more!

Publications

A. Nandal, J.C. Ruiz, P. Subramanian, S. Ghimire-Rijal, R.A. Sinnamon, T.L. Stemmler, R.K. Bruick, and C.C. Philpott (2011) Activation of the HIF prolyl hydroxylase by the iron chaperones PCBP1 and PCBP2. Cell Metab. 14, 647-57.