VCOM Research Day Program Book 2023

Undergraduate Student Research Biomedical

02 Generation of Cardiac-Specific Meis1-Knockout Mice Blast-Induced Spinal Cord Injury

Sondos Elnady; Ranya Ridha; Shreya Raj; Ahmed Elywa; Suzanne Tunder; Jia-Qiang He Corresponding author: Sondos@vt.edu

Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg

Animal model is one of the most important means to study the pathogenesis of human diseases, develop new diagnostic methods, and test new chemical compounds and drugs. In the case of a gain- and loss-of function of a gene of interest, the transgenic mouse probably is the most commonly used species in biomedical research. A previous study demonstrated the myeloid ecotropic viral integration site 1 (Meis1) gene played critical roles in both disease (e.g., acute leukemia) and organ development (e.g., neonatal cardiac regeneration). To establish a new model for cardiac research, the present study aims to create novel transgenic mice with cardiomyocyte-specific knockout (KO) of Meis1 using the Cre-loxP approach,

with a long-term goal to study how this gene is involved in cardiac regeneration and repair under disease conditions. To this end, myosin heavy chain 6 (Myh6) promoter-driven Cre mice [heterozygous (HET) male or female] were bred with loxP (i.e., floxed) mice [HET or homozygous (HOM) female or male]. The offspring carried various genotypes, such as Meis1 f/f ; Myh6 +/- (KO), Meis1 f/- ; Myh6 +/- (HET), Meis1 f/- ; Myh6 -/- [wild-type 1(WT1)], and Meis1 f/- ; Myh6 -/- (WT2), depending on their parental genotypes and number of generations. Each offspring was genotyped using genomic PCR. Briefly, 2-4mm tail tissue was aseptically collected under anesthesia, and followed by DNA extraction, PCR with 5 primers (3

primers for identifying floxed-Meis1 and 2 primers for Myh6-cre), 1.2% gel electrophoresis, and imaging. In the case of the HET/HET breeders we used, 15% of offspring was Meis1-KO; while it was 50% or 90% KO when the breeders were KO/HET or KO/ KO, respectively. We conclude that breeders with one or two KO alleles have a better chance to generate a high percentage of KO offspring and these mice can be used as a new platform to study cardiovascular diseases and development.

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