Table 1.
Classification and functional roles of non-coding RNA (ncRNA) in humans.
| ncRNA | Function |
|---|---|
| House-keeping ncRNAs | |
| transfer RNA (tRNA) | mRNA translation [24] |
| ribosomal RNA (rRNA) | mRNA translation [24] |
| small nucleolar RNA (snoRNA) | rRNA modification [24] |
| small nuclear RNA (including spliceosomal RNA) | RNA splicing, polyadenylation [24] |
| Regulatory ncRNAs: Short ncRNA (<200 nt) | |
| microRNA (miRNA) | degradation of mRNA or repression of translation [25,26] |
| piwi-interacting RNA (piRNA) | regulation of transposon activity and chromatin state [27] |
| repeat-associated short interfering RNA (rasiRNA) | regulate germline transposition activity [28] |
| tRNA-derived RNAs | Translational repression [29] |
| Telomere small RNAs (tel-sRNAs) | Telomere maintenance [30] |
| Centrosome-associated RNAs (crasiRNAs) | Guide local chromatin modifications [31] |
| Regulatory ncRNAs: Long ncRNA (>200 nt) | |
| Intergenic ncRNA | Epigenetic regulators of transcription in cis/in trans [32] |
| Intronic ncRNA | Transcriptional, posttranscriptional regulation, precursors for small ncRNAs [33] |
| Antisense transcript | mRNA stability of its homologous coding gene [34] |
| Pseudogene transcript | Generation of natural antisense transcripts or competing endogenous RNAs, stabilization of its coding transcript by competitively binding miRNA [35,36] |
| Mitochondrial ncRNA (ncmtRNAs) | Cell cycle and proliferation by unknown mechanisms [37] |
| Repeat-associated ncRNA | Regulation of repeat silencing [38] |
| Satellite ncRNA | Involvement of formation and function of centromere-associate complexes [39] |
| Repetitive RNAs | Epigenetic regulation? Other mechanisms? [39] |
| Tiny transcription initiation RNAs (tiRNAs) | Chromatin modifications and protein recruitment for transcriptional initiation [40] |
| Promoter upstream transcripts (PROMPTS) | Chromatin changes [41] |
| Transcripts of unknown function (TUFs) | Stem cell differentiation [42] |
| Regulatory ncRNAs: Diverse sizes | |
| Promoter-associated RNAs (PARs) | Gene repression in cis via interacting with PRC2 [43] |
| Enhancer-like ncRNA (eRNA) | Activation of promoter activity by unknown mechanism [44] |