Genetics Research International / 2012 / Article / Tab 1

Review Article

Mechanistic Roles of Noncoding RNAs in Lung Cancer Biology and Their Clinical Implications

Table 1

Classes of human non-coding RNAs.

TypeClassCharacteristics and functionReferences

Small ncRNA (<200 nt)Small Interfering RNAs (siRNAs)21-22 nt double-stranded RNAs produced by Dicer and involved in gene silencing and viral defence[163]
microRNAs (miRNAs)18–25 nt RNAs that modulate gene expression posttranscriptionally[163, 164]
Transfer RNAs (tRNA)An adaptor molecule with an inverted L structure involved in translation of mRNA into protein[165]
PIWI-interacting RNAs (piRNAs)Dicer independent 26–31 nt RNAs located in the germline and adjacent somatic cells, involved in germline development and stability through the regulation of transposons[163]
Small nucleolar RNAs (snoRNAs)Guide molecules for modification and processing of rRNA, specifically site-specific methylation and pseudouridylation[164]
microRNA-offset RNAs (moRNAs)RNAs derived from the ends of pre-miRNAs, predominantly from the 5′ end, independent of the mature miRNA. The function of moRNAs are currently unknown[16]
Ribosomal 5.8STranscribed by pol I as a part of the 45S precursor, 5.8S is a component of the large ribosomal subunit in eukaryotes, and thus involved in protein translation[166]
Promoter-associated short RNAs (PASRs)Transcripts within a few hundred bases of protein coding or noncoding transcription start site that may regulate gene expression[167]

Long ncRNA (>200 nt)Long ncRNAA broad class of RNAs > 200 nt with functions in epigenetic regulation, splicing, and cellular localization[40]
Transcribed ultraconserved regions (T-UCR)Non-coding sequences 100% conserved among humans, mice, and rats, with roles in the regulation of alternative splicing and gene expression, and altered in a number of human cancers[168]
PseudogenesNonfunctional sequences of genomic DNA originally derived from functional genes but with mutations or premature stop codons that prevent their expression. Known to regulate gene expression and recombination[161, 169]
Promoter associated long RNAs (PARs)Transcripts 250–500 nt long within a few hundred bases of protein coding or non coding transcription start sites that may regulate gene expression[167]
Antisense RNAsSingle stranded RNA complementary to a transcribed mRNA, capable of binding and blocking translation of its complementary mRNA, and promoting target decay.[170]

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