AUTHOR=Hanstein Regina , Negoro Hiromitsu , Patel Naman K., Charollais Anne , Meda Paolo , Spray David C., Suadicani Sylvia O., Scemes Eliana 

TITLE=Promises and pitfalls of a Pannexin1 transgenic mouse line

JOURNAL=Frontiers in Pharmacology

VOLUME=4

YEAR=2013

URL=https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2013.00061

DOI=10.3389/fphar.2013.00061

ISSN=1663-9812

ABSTRACT=<p>Gene targeting strategies have become a powerful technology for elucidating mammalian gene function. The recently generated knockout (KO)-first strategy produces a KO at the RNA processing level and also allows for the generation of conditional KO alleles by combining FLP/FRT and Cre/loxP systems, thereby providing high flexibility in gene manipulation. However, this multipurpose KO-first cassette might produce hypomorphic rather than complete KOs if the RNA processing module is bypassed. Moreover, the generation of a conditional phenotype is also dependent on specific activity of Cre recombinase. Here, we report the use of an efficient molecular biological approach to test pannexin1 (<italic>Panx1</italic>) mRNA expression in global and conditional Panx1 KO mice derived from the KO-first mouse line, Panx1<sup>tm1a(KOMP)Wtsi</sup>. Using qRT-PCR, we demonstrate that tissues from wild-type (WT) mice show a range of <italic>Panx1</italic> mRNA expression levels, with highest expression in trigeminal ganglia, bladder and spleen. Unexpectedly, we found that in mice homozygous for the KO-first allele, <italic>Panx1</italic> mRNA expression is not abolished but reduced by 70% compared to that of WT tissues. Thus, Panx1 KO-first mice present a hypomorphic phenotype. Crosses of Panx1 KO-first with FLP deleter mice generated Panx1<sup>f/f</sup> mice. Further crosses of the latter mice with mGFAP-Cre or NFH-Cre mice were used to generate astrocyte- and neuron-specific Panx1 deletions, respectively. A high incidence of ectopic Cre expression was found in offspring of both types of conditional Panx1 KO mice. Our study demonstrates that <italic>Panx1</italic> expression levels in the global and conditional Panx1 KO mice derived from KO-first mouse lines must be carefully characterized to ensure modulation of <italic>Panx1</italic> gene expression. The precise quantitation of <italic>Panx1</italic> expression and its relation to function is expected to provide a foundation for future efforts aimed at deciphering the role of Panx1 under physiological and pathological conditions.</p>