Animal Models to Study MicroRNA Function

Abstract

The discovery of the microRNAs, lin-4 and let-7 as critical mediators of normal development in Caenorhabditis elegans and their conservation throughout evolution has spearheaded research towards identifying novel roles of microRNAs in other cellular processes. To accurately elucidate these fundamental functions, especially in the context of an intact organism various microRNA transgenic models have been generated and evaluated. Transgenic C. elegans (worms), Drosophila melanogaster (flies), Danio rerio (zebrafish), and Mus musculus (mouse) have contributed immensely towards uncovering the roles of multiple microRNAs in cellular processes such as proliferation, differentiation, and apoptosis, pathways that are severely altered in human diseases such as cancer. The simple model organisms, C. elegans, D. melanogaster and D. rerio do not develop cancers, but have proved to be convenient systesm in microRNA research, especially in characterizing the microRNA biogenesis machinery which is often dysregulated during human tumorigenesis. The microRNA-dependent events delineated via these simple in vivo systems have been further verified in vitro, and in more complex models of cancers, such as M. musculus. The focus of this review is to provide an overview of the important contributions made in the microRNA field using model organisms. The simple model systems provided the basis for the importance of microRNAs in normal cellular physiology, while the more complex animal systems provided evidence for the role of microRNAs dysregulation in cancers. Highlights include an overview of the various strategies used to generate transgenic organisms and a review of the use of transgenic mice for evaluating pre-clinical efficacy of microRNA-based cancer therapeutics.

Drosophila melanogaster as an alternative model organism in nutrigenomics

“…Their main type of action is via (a) an inhibited translation and/or (b) by inducing the degradation of the mRNAs, known to be centrally involved in the epigenetic regulation of gene expression [70]. Micro-RNAs play a central role in cellular processes such as proliferation, differentiation, and apoptosis, which are known pathways affected in the development of chronic diseases including cancer [71]. Studies have shown that especially plant bioactives are able to affect miRNA expression which may partly explain their health-promoting properties documented in the development of various chronic inflammatory diseases [72][73][74].…”

“…Initial experiments identified lin-4 as the first miRNA being essential for the normal development of Ceanorhabditis elegans [75]. Drosophila melanogaster has also been successfully used to generate essential information on effects of miRNA, by establishing the Flp-FRT and GAL4-UAS systems, allowing to knock-in or knock-out specific miRNAs with particular functions in the fly [71]. The state-of-the-art technology CRISPR/Cas9 has been recently established in the context of miRNA research as miR-219 and miR-315 have been successfully knocked down in Drosophila melanogaster [76].…”

“…The state-of-the-art technology CRISPR/Cas9 has been recently established in the context of miRNA research as miR-219 and miR-315 have been successfully knocked down in Drosophila melanogaster [76]. This fact points towards an important input in elucidating miRNA-based processes [71]. In addition, it offers the possibility to use the fruit fly as a model organism to elucidate health-promoting or health-declining effects of different macronutrients and/or specific food components potentially related to miRNA modulation.…”

MYC-regulated lncRNA NEAT1 promotes B cell proliferation and lymphomagenesis via the miR-34b-5p-GLI1 pathway in diffuse large B-cell lymphoma

“…MicroRNAs (miRNAs) are endogenous ∼ 22 nt RNAs that can play important regulatory roles in animals and plants by targeting mRNAs for translational repression [10]. The targeting of miRNAs could be a novel therapeutic approach, as evidenced by tumour regression in mouse models and initial promising data from clinical trials [11][12][13][14]. One recent study showed that miR-101, upregulated in DLBCL, suppressed DLBCL cell proliferation and facilitated apoptosis by inhibiting the expression of MEK1 [15], while miR-155, which is downregulated in DLBCL, suppressed DLBCL cell proliferation and facilitated apoptosis by upregulating SOCS3 expression to suppress the JAK-STAT3 signaling pathway [16].…”

Identification and characterization of miRNAs involved in cold acclimation of zebrafish ZF4 cells

“…Usually a single miRNA may target up to hundreds of protein-coding genes, and it is estimated that 74% to 92% of all protein-coding genes are conserved miRNA targets [3][4][5]. Many miRNAs are evolutionarily conserved and involved in growth, development, apoptosis, proliferation, and tumorigenesis of organisms [1,6].…”