G-protein coupled receptors (GPCRs) are the largest family of transmembrane proteins, constituting 2% of the human genome. They mediate signaling from a diverse set of ligands, ranging from photons to large peptides. Their intracellular signaling cascades are complex and highly malleable depending on cellular context. Yet, GPCR signaling in vivo is highly specific. Cells maintain this tight control over GPCR signaling through the expression of adaptor proteins. These adaptors regulate GPCR function and activation on many levels - they localize receptors to specific subcellular domains, assemble functional signaling complexes, alter the specificity of G-proteins coupling to the receptor, or regulate receptor traffic to and from the plasma membrane. By balancing the expression of these adaptor proteins, cells control where, when and how long GPCRs signal.
Na+/H+ Exchanger Regulatory Factor 1 (NHERF1), also known as Ezrin binding phosphoprotein 50kDa (EBP50), is the prototypical PDZ adaptor protein. Expression of NHERF1 clusters parathyroid hormone type 1 receptor (PTH1R) and frizzled (Fzd) along actin stress fibers in non-polarized cells at the apical actin cap in polarized cells. In addition to proper localization, interaction with NHERF1 has several signaling manifestations. For PTH1R, interaction with NHERF1 can cause either a G-protein switch or can scaffold a PTH1R-PKA-calcium channel signaling complex. For Fzd, interaction with NHERF1 blocks Wnt-induced -catenin activation. NHERF1 knockout mice exhibit PTH-resistant phosphate excretion and enhanced PTH-induced vitamin D synthesis, as well as increased mammary duct density secondary to heightened Wnt-Fzd signaling. NHERF1 is a prime example of how PDZ adaptor proteins regulate GPCR localization and diversify GPCR signaling in physiologically significant ways.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-12022010-001029 |
| Date | 06 December 2010 |
| Creators | Wheeler, David S. |
| Contributors | Linton M. Traub, Guillermo Romero, Jean-Pierre Vilardaga, Donald DeFranco, Peter A. Friedman |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-12022010-001029/ |
| Rights | restricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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