MicroRNA‐21 expression analysis in mice (711.6)

Abstract

MicroRNAs (miRNAs) are endogenous, non‐coding RNAs that downregulate the expression levels of specific proteins by translational repression or mRNA degradation. miR‐21 has been implicated in cancer, development, immunity and cardiovascular diseases. However, miR‐21 expression at the cellular level in normal tissues remains controversial.The aim of the study was to analyze miR‐21 expression at the cellular level in normal mouse tissues using a novel transgenic reporter mouse that expresses β‐galactosidase (LacZ) under the endogenous miR‐21 promoter. Mir21tm1Mtm/Mmjax mice were crossed with CAG‐Cre mice to delete the neomycin/miR‐21 cassette and generate lacZ‐KO‐Mir21tm1Mtm/Mmjax mice. Tissues from 10‐week old male lacZ‐KO‐Mir21tm1Mtm/Mmjax mice were embedded in OCT, cryosectioned and LacZ detected by histochemistry.MiR‐21 was highly expressed in the cardiac fibroblasts and tunica media of coronary arteries, periportal hepatocytes, kidney collecting ducts, respiratory epithelium of the bronchus in the lung, and testis seminiferous tubules. In the CNS, miR‐21 was highly expressed in the brain white matter, corpus callosum, anterior commissure, striatum, posterior thalamus and medulla oblongata.Although miR‐21 is expressed in multiple tissues in the adult mice, its expression at the cellular level is highly restricted, suggesting still unexplored roles for miR‐21 in health and disease.Grant Funding Source: Supported by American Heart Association Grant 12SDG8980032.