miR-322/-503 rescues myoblast defects in myotonic dystrophy type 1 cell model by targeting CUG repeats

Abstract

Myotonic dystrophy type 1 (DM1) is the most common type of adult muscular dystrophy caused by the expanded triple-nucleotides (CUG) repeats. Myoblast in DM1 displayed many defects, including defective myoblast differentiation, ribonuclear foci, and aberrant alternative splicing. Despite many were revealed to function in DM1, microRNAs that regulated DM1 via directly targeting the expanded CUG repeats were rarely reported. Here we discovered that miR-322/-503 rescued myoblast defects in DM1 cell model by targeting the expanded CUG repeats. First, we studied the function of miR-322/-503 in normal C2C12 myoblast cells. Downregulation of miR-322/-503 significantly hindered the myoblast differentiation, while miR-322/-503 overexpression promoted the process. Next, we examined the role of miR-322/-503 in the DM1 C2C12 cell model. miR-322/-503 was downregulated in the differentiation of DM1 C2C12 cells. When we introduced ectopic miR-322/-503 expression into DM1 C2C12 cells, myoblast defects were almost fully rescued, marked by significant improvements of myoblast differentiation and repressions of ribonuclear foci formation and aberrant alternative splicing. Then we investigated the downstream mechanism of miR-322/-503 in DM1. Agreeing with our previous work, Celf1 was proven to be miR-322/-503′s target. Celf1 knockdown partially reproduced miR-322/-503′s function in rescuing DM1 C2C12 differentiation but was unable to repress ribonuclear foci, suggesting other targets of miR-322/-503 existed in the DM1 C2C12 cells. As the seed regions of miR-322 and miR-503 were complementary to the CUG repeats, we hypothesized that the CUG repeats were the target of miR-322/-503. Through expression tests, reporter assays, and colocalization staining, miR-322/-503 was proved to directly and specifically target the expanded CUG repeats in the DM1 cell model rather than the shorter ones in normal cells. Those results implied a potential therapeutic function of miR-322/-503 on DM1, which needed further investigations in the future.

Transcriptome Analysis Reveals Altered Inflammatory Pathway in an Inducible Glial Cell Model of Myotonic Dystrophy Type 1

“…Several miRNAs have been found to be deregulated in tissues and cell models of DM1 [ 52 , 83 , 84 , 85 ]; however, studies in the CNS and particularly in glia cells are lacking. In this work, we detected dysregulated levels of six miRNAs in both in contrasts A and B ( Table 4 ).…”

Long Non-coding RNAs LOC100126784 and POM121L9P Derived From Bone Marrow Mesenchymal Stem Cells Enhance Osteogenic Differentiation via the miR-503-5p/SORBS1 Axis

“…miR-503-5p functions as a tumor suppressor in multiple cancers (Fu et al, 2019;Li et al, 2019;Wei et al, 2020). Moreover, as a mammal-specific member of the miR-15/107 miRNA family, miR-503-5p participates in stress response, tissue differentiation, and tissue remodeling (Jee et al, 2018;Wang et al, 2019;Shen et al, 2020). However, the direction of stem cell differentiation influenced by miR-503-5p remains unclear.…”

Transcriptome Analysis in a Primary Human Muscle Cell Differentiation Model for Myotonic Dystrophy Type 1

“…Regarding the mechanism by which these repeat expansions result in the DM1 phenotype, there are several proposed theories [20]. These include (i) alternative splicing of several mRNAs [21][22][23][24], (ii) altered transcriptional regulation [25][26][27], (iii) inhibited translation [28,29], (iv) repeat associated non-ATG (RAN) translation resulting in the presence of toxic peptides [30][31][32], (v) alternative polyadenylation of several mRNAs [33] and (vi) miRNA misregulation [27,[34][35][36][37][38][39]. These mechanisms are not exclusive; however, they do contribute to the complex clinical phenotype.…”