A BAC Transgene Expressing Human CFTR under Control of Its Regulatory Elements Rescues Cftr Knockout Mice

Area of Science:

• Genetics
• Physiology
• Pharmacology

Background:

• Cystic fibrosis (CF) is a genetic disorder caused by mutations in the CFTR gene.
• Small-molecule modulators targeting CFTR show therapeutic potential for CF.
• In vivo models are crucial for testing novel CFTR-targeting therapies.

Purpose of the Study:

• To develop a transgenic mouse model expressing functional human CFTR (hCFTR) for in vivo testing of CFTR modulators.
• To characterize the expression and function of hCFTR in the developed mouse model.

Main Methods:

• Generation of a bacterial artificial chromosome (BAC) transgenic mouse carrying the complete hCFTR gene with regulatory elements.
• Breeding hCFTR+ mice with Cftr knockout (KO) mice to create hCFTR+/mCftr- (H+/m-) mice.
• Assessment of hCFTR expression and function using whole genome sequencing, expression studies, nasal potential difference, and short-circuit current (Isc) measurements.

Main Results:

• A BAC transgenic mouse with a single integration site of hCFTR was successfully generated.
• hCFTR+/mCftr- mice exhibited normal survival, growth, and goblet cell function compared to wild-type mice.
• Functional hCFTR expression was confirmed in relevant tissues, with nasal and large intestinal responses to cAMP stimulation comparable to wild-type, though small intestinal responses were reduced.

Conclusions:

• A BAC transgenic mouse model expressing functional hCFTR has been established.
• This model provides a platform for generating hCFTR mutation models via gene editing for in vivo evaluation of new cystic fibrosis therapies.
• The developed mouse model is a valuable tool for advancing the development of CFTR-based treatments.