Regulation and function of miRNA-21 in health and disease

Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Hannover, Germany.
RNA biology (Impact Factor: 4.97). 09/2011; 8(5):706-13. DOI: 10.4161/rna.8.5.16154
Source: PubMed


The small regulatory RNA microRNA-21 (miR-21) plays a crucial role in a plethora of biological functions and diseases including development, cancer, cardiovascular diseases and inflammation. The gene coding for pri-miR-21 (primary transcript containing miR-21) is located within the intronic region of the TMEM49 gene. Despite pri-miR-21 and TMEM49 are overlapping genes in the same direction of transcription, pri-miR-21 is independently transcribed by its own promoter regions and terminated with its own poly(A) tail. After transcription, primiR- 21 is finally processed into mature miR-21. Expression of miR-21 has been found to be deregulated in almost all types of cancers and therefore was classified as an oncomiR. During recent years, additional roles of miR-21 in cardiovascular and pulmonary diseases, including cardiac and pulmonary fibrosis as well as myocardial infarction have been described. MiR-21 additionally regulates various immunological and developmental processes. Due to the critical functions of its target proteins in various signaling pathways, miR-21 has become an attractive target for genetic and pharmacological modulation in various disease conditions.

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    • "Moreover, a positive correlation was observed between these miRNAs and IL-1b in both tumor and peritumoral cortex in GG (Prabowo et al., 2015) and in TSC specimens (miR21 and miR155, present data). Previous studies have shown that miR21 can be induced by NF-jB and may act as negative-feedback regulator of Tolllike receptor signaling via targeting of the pro-inflammatory tumor suppressor PDCD4 (He et al., 2014; Kumarswamy et al., 2011; O'Connell et al., 2012; O'Neill et al., 2011; Sheedy et al., 2010). In the present study, we confirmed the intracellular induction of this microRNA by IL-1b in both astrocytes and SEGA cells. "
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    • "It can exist in several oxidation states through which it can combine with oxygen (O), chlorine (Cl), or sulfur (S) to form inorganic arsenic compounds, with arsenite (As III ) compounds considered to be the most toxic [45, 46]. Arsenite has been shown to upregulate miR-21 [47], an oncogenic miRNA that is commonly upregulated in a host of different cancer types [48]. Although indirect, Xu and colleagues showed that arsenite-transformed malignant human bronchial epithelial (HBE) cells transferred exosomes containing miR-21 to nonneoplastic HBE cells in non-contact co-culture, resulting in the stimulation of proliferation [49], leading them to conclude that exosomal miR-21 may be involved in arsenite-induced malignant transformation. "
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