Overexpression of NF90-NF45 Represses Myogenic MicroRNA Biogenesis, Resulting in Development of Skeletal Muscle Atrophy and Centronuclear Muscle Fibers

Abstract

d MicroRNAs (miRNAs) are involved in the progression and suppression of various diseases through translational inhibition of target mRNAs. Therefore, the alteration of miRNA biogenesis induces several diseases. The nuclear factor 90 (NF90)-NF45 complex is known as a negative regulator in miRNA biogenesis. Here, we showed that NF90-NF45 double-transgenic (dbTg) mice develop skeletal muscle atrophy and centronuclear muscle fibers in adulthood. Subsequently, we found that the levels of myogenic miRNAs, including miRNA 133a (miR-133a), which promote muscle maturation, were significantly decreased in the skeletal muscle of NF90-NF45 dbTg mice compared with those in wild-type mice. However, levels of primary transcripts of the miRNAs (pri-miRNAs) were clearly elevated in NF90-NF45 dbTg mice. This result indicated that the NF90-NF45 complex suppressed miRNA production through inhibition of pri-miRNA processing. This finding was supported by the fact that processing of pri-miRNA 133a-1 (primiR-133a-1) was inhibited via binding of NF90-NF45 to the pri-miRNA. Finally, the level of dynamin 2, a causative gene of centronuclear myopathy and concomitantly a target of miR-133a, was elevated in the skeletal muscle of NF90-NF45 dbTg mice. Taken together, we conclude that the NF90-NF45 complex induces centronuclear myopathy through increased dynamin 2 expression by an NF90-NF45-induced reduction of miR-133a expression in vivo.M icroRNAs (miRNAs) are functional small noncoding RNAs 21 to 23 nucleotides in length. miRNAs bind to 3= untranslated regions (UTRs) of target mRNAs, leading to either mRNA degradation or translational inhibition. The functions of miRNAs influence biological phenomena and diseases such as development (1, 2), cell proliferation (3), differentiation (4), apoptosis (5), as well as tumorigenesis (6, 7).The biogenesis of miRNAs involves several steps (8). First, miRNA genes are transcribed as primary miRNAs (pri-miRNAs) by RNA polymerase II (9). Subsequently, these pri-miRNAs are processed into precursor miRNAs (pre-miRNAs) by a microprocessor complex composed of Drosha and DGCR8 (10-14). Thereafter, the pre-miRNAs are transported from the nucleus to the cytoplasm (15-17) and processed into mature miRNA duplexes by the Dicer complex (18)(19)(20). The functional strand of the duplex (mature miRNA) is loaded into the RNA-induced silencing complex (RISC) (21-23). As part of the RISC, miRNA binds to target mRNAs and induces their translational inhibition or degradation (20,(22)(23)(24). Recently, it was reported that some RNA-binding proteins negatively regulate miRNA biogenesis. For example, Lin28A/B (25), the Musashi homolog 2/Hu antigen R complex (26), and the nuclear factor 90 (NF90; also referred to as interleukin enhancer binding factor 3 [ILF3], NFAR1, or DRBP76)-nuclear factor 45 (NF45) complex (27) suppress miRNA processing through binding to pri-or pre-miRNAs.NF90 contains a functional nuclear localization signal, two double-stranded RNA (dsRNA)-binding motifs, a zinc finger nucleic acid-binding domain, an...

Suppression of MicroRNA-7 (miR-7) Biogenesis by Nuclear Factor 90-Nuclear Factor 45 Complex (NF90-NF45) Controls Cell Proliferation in Hepatocellular Carcinoma

“…2, H and I, knockdown of NF90 did not significantly influence the levels of both mature miR-21 and pri-miR-21. These results together with our previous findings (12,19) suggest that the regulation of pri-miRNA processing by NF90-NF45 would be coupled with the production of mature miRNA. To verify the inhibitory effect on pri-miR-7 processing by NF90-NF45, we measured the level of pre-miR-7 in the NF90knockdown cells using Northern blotting analysis.…”

“…NF90-NF45 Complex Functions as a Negative Regulator in miR-7 Biogenesis-Our previous study demonstrated that the NF90-NF45 complex inhibits miRNA biogenesis through negative regulation of the pri-miRNA processing step (12,19). To examine miRNA biogenesis suppression by NF90-NF45 in HCC, we performed an miRNA microarray analysis using Huh7 HCC cells that had been depleted of NF90.…”

“…NF90 is known to participate in transcription, mRNA stability, translational inhibition, and RNA export (14 -18). In addition, we previously demonstrated that the NF90-NF45 complex negatively regulates the pri-miRNA processing step, resulting in a reduction of mature miRNA production (12,19).…”

SMARCE1 is required for the invasive progression of in situ cancers

“…Consistent with this, mouse embryonic fibroblasts overexpressing ILF3 up-regulated nearly all of the genes in the SMARCE1-regulated ECM invasion module (63 of 81; P < 7.1 × 10 −8 ; Fig. 6C) (19). Moreover, inhibition of ILF3 caused a twofold reduction in the formation of invasive spheroids in the 3D basement membranes (Fig.…”

Enterovirus 71 Represses Interleukin Enhancer-Binding Factor 2 Production and Nucleus Translocation to Antagonize ILF2 Antiviral Effects

“…Interleukin enhancer-binding factor 2 (ILF2) is a transcriptional activator which regulates interleukin 2 (IL-2) expression [11]. ILF2 together with its binding partner ILF3 regulates DNA replication [12,13], transcription [14], translation [15,16], mRNA splicing [17], and microRNA biogenesis [18][19][20]. ILF2 also plays a role in the progression of pancreatic carcinoma [21,22], hepatocellular carcinoma [20,23], lung cancer [24], esophageal squamous cell carcinoma [25], gastric cancer [26], and breast cancer [27].…”