RNA-Binding Protein MSI2 Binds to miR-301a-3p and Facilitates Its Distribution in Mitochondria of Endothelial Cells

Abstract

Numerous miRNAs have been detected in mitochondria, which play important roles in many physiological and pathophysiological processes. However, the dynamic changes of miRNA distribution in mitochondria and their mechanisms in reactive oxygen species (ROS)-induced endothelial injury remain unclear. Therefore, miRNA levels in whole cells and mitochondria of H2O2-treated endothelial cells were analyzed by small RNA sequencing in the present study. The results showed that H2O2 significantly reduced the relative mitochondrial distribution of dozens of miRNAs in human umbilical vein endothelial cells (HUVECs). Among the high-abundance miRNAs, miR-301a-3p has the most significant changes in the redistribution between cytosol and mitochondria confirmed by absolute quantitative polymerase chain reaction (qPCR). To unravel the mechanism of miR-301a-3p distribution in mitochondria, RNA pull-down followed by label-free quantitative proteomic analysis was performed, and RNA-binding protein Musashi RNA binding protein 2 (MSI2) was found to specifically bind to miR-301a-3p. Western blotting and immunofluorescence colocalization assay showed that MSI2 was located in mitochondria of various cell types. H2O2 significantly downregulated MSI2 expression in whole endothelial cells, promoted the distribution of MSI2 in cytosol and decreased its distribution in the mitochondria. Moreover, overexpression of MSI2 increased the mitochondrial distribution of miR-301a-3p, whereas inhibition of MSI2 decreased its distribution in mitochondria. Thus, MSI2 might be responsible for the distribution of miR-301a-3p between cytosol and mitochondria in endothelial cells. Our findings revealed for the first time that MSI2 was involved in the regulation of miRNA distribution in mitochondria and provided valuable insight into the mechanism of mitochondrial distribution of miRNAs.

Small RNAs derived from tRNA fragmentation regulate the functional maturation of neonatal β cells

“…Interestingly, we found that Msi1 is essential for the mitochondrial enrichment of tiRNA-5 HisGTG . This finding is in line with a recent report on MSI2 transporting miR-301a-3p to mitochondria in human umbilical vein endothelial cells (HUVECs) (Guo et al, 2020).…”

“…Msi1 is essential for the mitochondrial enrichment of tiRNA-5 HisGTG Among tiRNA-5 HisGTG -binding proteins, Msi1 and Msi2 are translational regulators of proliferation in various models, including in pancreatic b cells (Kudinov et al, 2017;Szabat et al, 2011). Furthermore, Msi proteins can modulate mitochondrial respiration and microRNA (miRNA) trafficking to mitochondria in different models (Guo et al, 2020;Lang et al, 2017). In line with the literature, silencing Msi1 in dispersed P10 rat islet cells significantly reduced b cell proliferation (Figures 7E and 7G).…”

Small RNA-big impact: exosomal miRNAs in mitochondrial dysfunction in various diseases

“…Several mitomiRs, including mitomiR-2392, mitomiR-5787, mitomiR-34a, mitomiR-181a and mitomiR-146a, play a role in modulating drug resistance, mitochondrial functions, autophagy and oxidative phosphorylation (OXPHOS) [ 103 , 104 ]. Interestingly, The RNA-binding protein MSI2 has been observed to interact with miR-301a-3p and enhance its distribution in the mitochondria of endothelial cells [ 105 ]. Various isoforms of miRNAs derived from mtDNA have been identified in gametes, zygotes and germ cells (PGCs and spermatogonia), which play a potential role in gamete differentiation and fertilization [ 106 ].…”

RNA binding protein: coordinated expression between the nuclear and mitochondrial genomes in tumors

“…The RNA-binding protein RALY promotes post-transcriptional processing of specific subgroups of miRNAs (miR-483, miR-676, and miR-877), down-regulates the respiratory chain subunits ATP5I, ATP5G1, ATP5G3, and CYC1 in mitochondria, thereby reprogramming mitochondrial metabolism in cancer cells to promote colorectal cancer (CRC) progression [ 107 ]. RNA-binding protein Musashi RNA binding protein 2 (MSI2) might be responsible for the distribution of miR-301a-3p between cytosol and mitochondria in endothelial cells [ 108 ]. These compartmental changes may be the way in which RBP regulates the interaction between nucleus and mitochondria, thereby regulating mitochondrial gene expression and affecting mitochondrial function.…”