The presence of a nonsense mutation leads to the rapid degradation of the carrier mRNA mutation by a mechanism called NMD (nonsense-mediated mRNA decay) \[6, 13\]. There are currently 3 main strategies at least for correcting nonsense mutations: exon skipping, inhibition of NMD and nonsense mutation readthrough. In the laboratory, we developed a strategy for correcting nonsense mutations combining inhibition of NMD and activation of translecture. For this purpose, we have constructed screening systems to identify NMD-inhibiting and/or readthrough enhancers. The molecules thus identified are then tested on cell lines and in murine models carrying a nonsense mutation. One of our goals is to select a set of molecules that can correct effectively nonsense mutations. For this we have to test these molecules on a great diversity of nonsense mutations. This work will: * determine if we can correct all the nonsense mutations tested with at least one of our molecules * determine what is common within a group of mutations corrected by a given molecule * be able to assign the parameters that make one mutation is corrected by one molecule and not or little by another. This study will therefore improve our theoretical knowledge on the recognition of premature stop codons but also to propose therapeutic approaches for the correction of nonsense mutations of the CFTR gene in cystic fibrosis in a targeted way for a patient.
Study Type
OBSERVATIONAL
Enrollment
85
1 smear of nasal fossae during a usual or scheduled visit
Camsp Chu Amiens
Amiens, France
RECRUITINGHopital Femme Mere Enfant - Hcl - Bron
Bron, France
RECRUITINGHôpital Calmette,CHU
Lille, France
RECRUITINGAphm Hopital La Timone - Marseille
Marseille, France
RECRUITINGChu Montpellier
Montpellier, France
RECRUITINGCmp Enfants Aphp Robert Debre - Paris
Paris, France
RECRUITINGHu Paris Centre Site Cochin Aphp - Paris 14
Paris, France
RECRUITINGHopitaux Universitaires de Strasbour
Strasbourg, France
RECRUITINGTransport of iodide ions through the CEVAS membrane
Patient cells with be cultured in BEGM (Lonza) medium and incubated with corrector of nonsense mutations for 20 hours and with a fluorescent molecule called SPQ (for 6-methoxy-N-3'-sulfopropylquinolinium). Iodine can bind SPQ and will quench the SPQ fluorescence. Nitrates bind SPQ without quenching SPQ fluorescence. By placing patient cells first into an iodine-rich medium to quench the SPQ fluorescence and second into a nitrate-rich medium, we will be able to measure the level of functional CFTR protein present in these cells by measuring the re-apparition of fluorescence using fluorimeter. Indeed, nitrate will be able to replace iodine on SPQ without quenching SPQ fluorescence only if iodine exits cells through CFTR channels. This assay allows determining whether a corrector of nonsense mutation is able to lead to the synthesis of functional CFTR protein
Time frame: less than 48hrs after the collect.
Immortalization of patient cells
Immortalization of patient cells will be attempted by transfection of construct expressing the origin-of-replication defective SV40 as described in Gruenert et al.,2004
Time frame: an average 12 months
Expression of the CFTR gene at the mRNA and protein level
Time frame: less than 1 week.
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