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 (Panx1) mRNA expression in global and conditional Panx1 KO mice derived from the KO-first mouse line, Panx1(tm1a(KOMP)Wtsi). Using qRT-PCR, we demonstrate that tissues from wild-type (WT) mice show a range of Panx1 mRNA expression levels, with highest expression in trigeminal ganglia, bladder and spleen. Unexpectedly, we found that in mice homozygous for the KO-first allele, Panx1 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(f/f) 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 Panx1 expression levels in the global and conditional Panx1 KO mice derived from KO-first mouse lines must be carefully characterized to ensure modulation of Panx1 gene expression. The precise quantitation of Panx1 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.
Pubmed ID: 23675350 RIS Download
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Repository of mouse vectors, ES cells, mice, embryos, and sperm generated by NIH KOMP Mutagenesis Project. In addition, KOMP Repository offers services in support of KOMP products, including ES cell microinjection, vector cloning, post-insertional modification of cloned ES cells, cryopreservation, assisted reproduction techniques (IVF, ICSI) and mouse breeding, pathology services, phenotyping services, etc. KOMP Repository is final component of more than $50 million trans-NIH initiative to increase availability of genetically altered mice and related materials. The University of California, Davis (UC Davis) and Children''s Hospital Oakland Research Institute (CHORI) in Oakland, Calif., are collaborating to preserve, protect, and make available about 8,500 types of knockout mice and related products available to research community. Products are generated by two KOMP mutagenesis teams (CSD consortium and Regeneron Inc). All KOMP products generated by CSD consortium and Regeneron are available through KOMP Repository. Notice as of December 19, 2019: Materials from KOMP Repository have been deposited into MMRRC, including all mouse models and mouse embryonic stem cell lines. Eventually www.komp.org will be sunsetting, and IMSR will remove KOMP Repository listings, since they were double listed in MMRRC. MMRRC will contain the most accurate and up to date resource models.
View all literature mentionsCenter that produces knockout mice and carries out high-throughput phenotyping of each line in order to determine function of every gene in mouse genome. These mice will be preserved in repositories and made available to scientific community representing valuable resource for basic scientific research as well as generating new models for human diseases.
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