This project is designed to develop and characterize two prototypic genetically modified mouse models for human diseases of protein folding. These models are required to bring a novel class of target-specific drugs, pharmacoperones, to human (and animal) use. Misfolded mutant proteins are detected by the cellular quality control system (QCS) and are typically retained in the endoplasmic reticulum (ER) for either reprocessing or degradation;frequently, these mutants result in disease. Studies in cell cultures indicate that these mutants can be rescued by target-specific small molecules (pharmacoperones) which enter cells, serve as templates that refold the mutants, and permit their passage to the plasma membrane. Many mutants retain or regain their fundamental properties as ion channels, enzymes or receptors when re-routed correctly. Diseases caused by misfolding (which may benefit from this approach) include cystic fibrosis, hypogonadotropic hypogonadism, nephrogenic diabetes insipidus, retinitis pigmentosa, hypercholesterolemia, cataracts, neurodegenerative diseases (Huntington's, Alzheimer's and Parkinson's), cancers and digestive disorders. It is fair to say that virtually every person will be affected by protein folding diseases during his or her lifetime, either directly or due to the illness of a loved one. In spite of this, there are few model systems, and none in small laboratory animals, that allow the translation of available in vitro data or the testing of """"""""hits"""""""" from high throughput screening on protein rescue into in vivo systems. To date, therapeutic approaches in humans have relied on a small number of studies in end-of-life patients, using drugs that have never been fully characterized in animal models. Such models are needed to address drug safety, the pattern of drug administration required to optimize therapeutic effectiveness, and serve as a test model for new drugs in preclinical studies. The pattern (route, dose and frequency) is particularly important as the persistence of these drugs frequently inhibits the desired activity, once rescue has occurred, so they must be removed. Moreover a convenient laboratory model for these diseases is needed if the use of pharmacoperones is to translate to human well-being, since US law requires animal testing prior to normal human volunteers. The present study will characterize prototypic mouse models of misfolding, relying on an unusually well-characterized mutant of a physiologically important GPCR (i.e. the gonadotropin releasing hormone receptor). There is much information available on the mechanism of activation of the gonadotropin releasing hormone receptor (GnRHR) and on the biochemical mechanism by which the mutant E90K is believed to cause the disease state. This information has been helpful in guiding our choices of mutant E90K and will contribute to the success of this project. The two models to be used are available and have the predicted genotype and necessary phenotype.
This project is designed to develop, characterize, compare and contrast two models for human diseases of protein folding. Diseases caused by misfolding include cystic fibrosis, hypogonadotropic hypogonadism, nephrogenic diabetes insipidus, retinitis pigmentosa, hypercholesterolemia, cataracts, neurodegenerative diseases (Huntington's, Alzheimer's and Parkinson's), particular cancers and a number of digestive disorders resulting from enzyme mutation. A convenient laboratory model for these diseases is needed if the use of pharmacoperones is to translate to human well-being, since US law requires animal testing prior to normal human volunteers.
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|Conn, P Michael; Smith, Emery; Spicer, Timothy et al. (2014) A phenotypic high throughput screening assay for the identification of pharmacoperones for the gonadotropin releasing hormone receptor. Assay Drug Dev Technol 12:238-46|
|Ulloa-Aguirre, Alfredo; Zariñán, Teresa; Dias, James A et al. (2014) Mutations in G protein-coupled receptors that impact receptor trafficking and reproductive function. Mol Cell Endocrinol 382:411-423|
|Tao, Ya-Xiong; Conn, P Michael (2014) Chaperoning G protein-coupled receptors: from cell biology to therapeutics. Endocr Rev 35:602-47|
|Janovick, Jo Ann; Stewart, M David; Jacob, Darla et al. (2013) Restoration of testis function in hypogonadotropic hypogonadal mice harboring a misfolded GnRHR mutant by pharmacoperone drug therapy. Proc Natl Acad Sci U S A 110:21030-5|
|Smithson, David C; Janovick, Jo Ann; Conn, P Michael (2013) Therapeutic rescue of misfolded/mistrafficked mutants: automation-friendly high-throughput assays for identification of pharmacoperone drugs of GPCRs. Methods Enzymol 521:3-16|
|Conn, P Michael; Smith, Emery; Hodder, Peter et al. (2013) High-throughput screen for pharmacoperones of the vasopressin type 2 receptor. J Biomol Screen 18:930-7|
|Aguilar-Rojas, Arturo; Huerta-Reyes, Maira; Maya-Núñez, Guadalupe et al. (2012) Gonadotropin-releasing hormone receptor activates GTPase RhoA and inhibits cell invasion in the breast cancer cell line MDA-MB-231. BMC Cancer 12:550|
|Maya-Núñez, Guadalupe; Ulloa-Aguirre, Alfredo; Janovick, Jo Ann et al. (2012) Pharmacological chaperones correct misfolded GPCRs and rescue function: protein trafficking as a therapeutic target. Subcell Biochem 63:263-89|
|Conn, P Michael; Ulloa-Aguirre, Alfredo (2011) Pharmacological chaperones for misfolded gonadotropin-releasing hormone receptors. Adv Pharmacol 62:109-41|