The aim of this proposal is to clarify the molecular mechanisms of a gene targeting approach called Small Fragment Homologous Replacement (SFHR). This approach can stably modify a genomic sequence by homologous replacement of a small DNA fragment and could correct mutations within disease genes. However, SFHR mechanisms are poorly understood and its practical application is limited by a low and variable frequency of correction.
We already published experimental evidences about the interconnection between SFHR, DNA methylation, chromatin remodelling, DNA repair and cell cycle pathways. We also published a selection of 18 specific genes within DNA repair and cell cycle pathways involved in the SFHR. Both the general pathways and the related specific genes are excellent targets for SFHR molecular mechanism study and manipulation.
This project will focus on the relationship between the 4 pathways listed above and SFHR, with particular regard to the enhancing of correction efficiency. This relationship will be studied in a reporter cellular system of mouse embryonic fibroblasts and in human Cystic Fibrosis (CF) cells of airway epithelium. Both primary differentiated and long-term stem-induced (by the culture reprogramming condition - CRC - approach) CF airway epithelial cells will be used. Drugs acting on each of the 4 pathways and single-gene targeting will be used to dissect the pathways and to manipulate SFHR efficiency. A possible enhancement of SFHR by the use of CRISPR/Cas 9 method will be evaluated.
These studies will contribute to a better comprehension of the molecular mechanisms of homologous genomic replacement after the uptake and intracellular processing of exogenous DNA. The selection of molecular targets to manipulate will provide suggestions for increasing gene repair efficiency. The application to both differentiated and stem-induced cells may highlight new perspective for SFHR therapeutic applications, in particular to CF.
