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Title: Investigation into the potential of tissue-specific promoters for gene supplementation therapy
Author: Trainer, Alison H.
ISNI:       0000 0001 3535 9417
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1999
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Ornithine transcarbamylase (OTC) is the second enzyme in the hepatic urea cycle. As such, it is important in the metabolism of neurotoxic waste products into a non-toxic, water-soluble compound, urea. In humans deficiency of ornithine transcarbamylase is an X-linked single gene disorder associated with a high mortality and morbidity due to a severe metabolic disturbance. There are two naturally occuring allelic mouse models for OTC deficiency, the sparse fur (Spf) and sparse furASH (SpfASH) mice. In this study, the focus was on the use of tissue specific promoters in driving recombinant gene expression. The main question addressed was whether expression of the OTC gene in a tissue which did not normally express this gene, namely skeletal muscle, would correct the phenotype of the deficient mouse models. The approach taken was generation of conventional transgenic mice using a creatine kinase driven OTC gene construct. In addition as a positive control, supplementation of the endogenous hepatic gene expression was also undertaken by means of hepatic-specific albumin promoter. Three indices were used as a measure of correction of OTC deficiency by transgenesis in the mouse models; a) phenotype of the mice, b) plasma ammonia levels and c) direct OTC activity. Although transgenic mice expressing the OTC cDNA driven by the creatine kinase promoter showed high OTC activity in skeletal muscle, no metabolic or phenotypic correction of the mice was noted. Interestingly, the albumin driven OTC construct did not correct the phenotype of the sparse fur and sparse furASH models either, although in some transgenic lines a significant amelioration of plasma ammonia levels was noted. However, this partial metabolic correction did not correlate with a significant increase in hepatic OTC activity. In addition to these tissue-specific promoters, the potential of a novel keratin 5 minigene construct in targeting recombinant gene expression to the epidermis in a tissue and cell specific manner was assessed. The gene expression pattern of a Lac Z reporter transgenic construct driven by the regulatory sequences of the keratin 5 gene was investigated both in adult mice and during embryogenesis.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Hepatic urea cycle; Ornithine transcarbamylase