Dgcr8 knockout approaches to understand microRNA functions in vitro and in vivo

Abstract

Biologic function of the majority of microRNAs (miRNAs) is still unknown. Uncovering the function of miRNAs is hurdled by redundancy among different miRNAs. The deletion of Dgcr8 leads to the deficiency in producing all canonical miRNAs, therefore, overcoming the redundancy issue. Dgcr8 knockout strategy has been instrumental in understanding the function of miRNAs in a variety of cells in vitro and in vivo. In this review, we will first give a brief introduction about miRNAs, miRNA biogenesis pathway and the role of Dgcr8 in miRNA biogenesis. We will then summarize studies performed with Dgcr8 knockout cell models with a focus on embryonic stem cells. After that, we will summarize results from various in vivo Dgcr8 knockout models. Given significant phenotypic differences in various tissues between Dgcr8 and Dicer knockout, we will also briefly review current progresses on understanding miRNA-independent functions of miRNA biogenesis factors. Finally, we will discuss the potential use of a new strategy to stably express miRNAs in Dgcr8 knockout cells. In future, Dgcr8 knockout approaches coupled with innovations in miRNA rescue strategy may provide further insights into miRNA functions in vitro and in vivo.

Keywords: Alternative splicing; Cell cycle; Drosha; Glial progenitor cells; Glycolysis; Immune system; Neural system; Reproductive system.

Fig. 1

Biogenesis pathway of canonical miRNAs. Canonical miRNA-independent functions of key factors are indicated on the right

Fig. 2

Dgcr8 knockout strategy to identify miRNA functions. This strategy has been successfully applied in ESCs and GPCs. However, due to the lack of robust approaches to express miRNAs in Dgcr8 knockout cells in vivo, it has not been widely used in identifying functional miRNAs in vivo