lncRNAs Regulate Innate Immune Responses and Their Roles in Macrophage Polarization

Figure 1

The diverse function mechanisms of lncRNAs. (a) lncRNAs recruit chromatin-modifying complexes onto specific chromosomal loci, subsequently regulating gene expression in cis (A) and in trans (B). (b) lncRNAs interact with transcription factors and influence the localization and activity of the transcription factors, subsequently regulating gene expression. (A) Transcriptional activation. lncRNAs recruit specific transcriptional factors onto specific chromosomal loci, thus facilitating gene transcription. (B) Transcriptional repression. lncRNAs bind with transcription factors and prevent the binding of the transcription factors with the promoter, subsequently mediating gene silencing. (c) lncRNAs in posttranscriptional regulation. (A) Stabilization of mRNA. By base pairing with mRNA, lncRNAs can increase stabilization of the target mRNA. (B) Regulation of alternative splicing. By base pairing with mRNA, lncRNAs may participate in the formation and maintenance of nuclear paraspeckles, which can facilitate alternative splicing events of nascent transcripts. (C) Degradation of mRNA. Through base pairing between mRNA and lncRNAs, staufen double-stranded RNA-binding protein 1- (STAU1-) mediated mRNA decay is induced. (D) Regulation of translation. By base pairing with mRNA and interacting with ribosomal proteins, lncRNAs can target mRNA to the ribosomes and affect the translation. (E) miRNA sponge. lncRNAs function as molecular “sponges” for miRNAs and regulate the expression of the miRNA target genes. (F) miRNA precursor. lncRNAs can serve as a source of miRNAs after processing. lncRNAs are shown in red, whereas miRNAs are in blue.

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