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Generation and comparative analysis of an Itga8-CreERT2 mouse with preferential activity in vascular smooth muscle cells

ABSTRACT: All current smooth muscle cell (SMC) restricted Cre mice recombine floxed alleles in vascular and visceral SMCs. We generated a tamoxifen-inducible CreERT2 mouse, Itga8-CreERT2, and compared its activity to the widely used Myh11-CreERT2 mouse. Both CreERT2 mice showed similar activity in vascular SMCs; however, Itga8-CreERT2 displayed low activity in visceral SMC-containing tissues (e.g., intestine). Myh11-CreERT2 (but not Itga8-CreERT2) mice exhibited high levels of CreERT2 protein, tamoxifen-independent activity, and an altered transcriptome. Whereas Myh11-CreERT2-mediated knockout of Srf resulted in a lethal intestinal phenotype, loss of Srf with Itga8-CreERT2 (SrfItga8) revealed viable mice with attenuated vascular SMC contractile gene expression, but no evidence of intestinal pathology. Male and female SrfItga8 mice presented with vascular contractile incompetence; however, only male SrfItga8 mice showed systemic changes in blood pressure. These results establish the Itga8-CreERT2 mouse as an alternative to existing SMC Cre strains where gene loss may result in visceral myopathies that obfuscate accurate phenotyping in vascular SMCs.

ORGANISM(S): Mus musculus

PROVIDER: GSE199244 | GEO | 2022/09/13

REPOSITORIES: GEO

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Project description:Smooth muscle cells (SMCs) display dynamic plasticity by changing phenotype under various pathophysiological conditions. Uncovering how SMCs regulate their phenotype is a key to understanding the molecular mechanisms of a number of gastrointestinal diseases. MicroRNAs (miRNAs), generated in cells by Dicer, have been identified as regulators of the differentiation state of SMCs. The goal of this study was to investigate the role of miRNAs during the development of gastrointestinal SMCs in a transgenic animal model. We generated SMC-specific Dicer (smDicer) null animals that express the reporter, green fluorescence protein (eGFP), in a SMC-specific manner. eGFP labeled SMCs were used for morphological, cytometric and genetic studies of smDicer null mutant and wild type control mice. The structure of the bowel wall was examined by confocal microscopy, and function was evaluated by recording spontaneous and evoked contractions. SMCs were purified with fluorescence-activated cell sorting and SM specific gene expression studies were performed with genechip arrays, PCR and quantitative PCR. Bioinformatic analyses were used to characterize the interaction between miRNAs and target genes. SMC-specific knockout of Dicer prevented SMC miRNA biogenesis, causing dramatic changes in phenotype, function, and global gene expression in SMCs. Profiling and bioinformatic analyses showed SMC phenotype is regulated by a complex network of positive and negative feedback by SM miRNAs, serum response factor (SRF), and other transcriptional factors. SM miRNAs play an important role in growth, development and survival of SMCs. Phenotypic changes of SMCs may be regulated through multiple pathways in an interaction network of SM miRNAs, SRF, and additional transcriptional factors. We used microarrays to identify genetic changes during the development of gastric smooth muscle cells in the smDicer null mice. Mouse mRNA microarrays were performed on GeneChipÂ® Mouse Genome 430 2.0 Arrays (Affymetrix). Total RNAs isolated from the jejunal muscularis of the smDicer knockout (KO) and the wild type (WT) control mice at the ages of ~3 weeks were used for the arrays. The cDNA synthesis, hybridization, cDNA labeling, and scanning were performed. Gene expression between the smDicer KO and the WT controls were compared.

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Generation and comparative analysis of an Itga8-CreERT2 mouse with preferential activity in vascular smooth muscle cells

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