This project is designed to develop and characterize two prototypic genetically modified mouse models forhuman 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 qualitycontrol system (QCS) and are typically retained in the endoplasmic reticulum (ER) for either reprocessing ordegradation; frequently, these mutants result in disease. Studies in cell cultures indicate that these mutantscan be rescued by target-specific small molecules (pharmacoperones) which enter cells, serve as templatesthat refold the mutants, and permit their passage to the plasma membrane. Many mutants retain or regain theirfundamental properties as ion channels, enzymes or receptors when re-routed correctly. Diseases caused bymisfolding (which may benefit from this approach) include cystic fibrosis, hypogonadotropic hypogonadism,nephrogenic diabetes insipidus, retinitis pigmentosa, hypercholesterolemia, cataracts, neurodegenerativediseases (Huntington's, Alzheimer's and Parkinson's), cancers and digestive disorders. It is fair to say thatvirtually every person will be affected by protein folding diseases during his or her lifetime, either directly or dueto the illness of a loved one. In spite of this, there are few model systems, and none in small laboratoryanimals, that allow the translation of available in vitro data or the testing of 'hits' from high throughputscreening on protein rescue into in vivo systems. To date, therapeutic approaches in humans have relied on asmall number of studies in end-of-life patients, using drugs that have never been fully characterized in animalmodels. Such models are needed to address drug safety, the pattern of drug administration required to optimizetherapeutic 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 desiredactivity, once rescue has occurred, so they must be removed. Moreover a convenient laboratory model forthese diseases is needed if the use of pharmacoperones is to translate to human well-being, since US lawrequires animal testing prior to normal human volunteers. The present study will characterize prototypicmouse models of misfolding, relying on an unusually well-characterized mutant of a physiologically importantGPCR (i.e. the gonadotropin releasing hormone receptor). There is much information available on themechanism of activation of the gonadotropin releasing hormone receptor (GnRHR) and on the biochemicalmechanism by which the mutant E90K is believed to cause the disease state. This information has been helpfulin guiding our choices of mutant E90K and will contribute to the success of this project. The two models to beused 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 ofprotein folding. Diseases caused by misfolding include cystic fibrosis; hypogonadotropic hypogonadism;nephrogenic diabetes insipidus; retinitis pigmentosa; hypercholesterolemia; cataracts; neurodegenerativediseases (Huntington's; Alzheimer's and Parkinson's); particular cancers and a number of digestive disordersresulting from enzyme mutation. A convenient laboratory model for these diseases is needed if the use ofpharmacoperones is to translate to human well-being; since US law requires animal testing prior to normalhuman volunteers.
