WritinGenomics

Exploring the Language of Life

A blog by Matteo Cortese, PhD

How many types of non-coding RNA do you know?

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Matteo Cortese, PhD
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Only 2% of the human genome codes for a protein [1], and yet 75% is transcribed [2]. These non-coding RNAs (ncRNAs) show a mind-boggling heterogeneity of sizes, shapes, origins and functions. Many ncRNAs are essential, either directing or fine-tuning cellular, and a few types are so poorly understood that they may even be junk.

I have counted at least 22 types of ncRNAs. I have compiled them in a list, with the celebrities of the RNA world (ribosomal RNAs, transfer RNAs, microRNAs..) and the obscure, more exotic underdogs (microRNA-offset RNAs, transcribed-ultraconserved regions, promoter-associated RNAs…)


We are going to discuss them all, 3 types of ncRNA on my blog.and on my LinkedIn profile

The travel start this Sunday, fellow travellers!

The journey so far:

  • Episode 1/7: ribosomal RNA (rRNA), transfer RNA (tRNA) and transfer-derived small RNA (tsRNA),
  • Episode 2/7: small nucleolar RNA (snoRNA), sno-derived RNAs ( sdRNA ), small Cajal-specific RNA (scaRNA).
  • Episode 3/7: microRNA (miRNA), endogenous-small interfering RNA (endo-siRNA), PIWI-interacting RNA (piRNA),
  • Episode 4/7: microRNA-offset RNA (moRNA), circular RNA (circRNA), small nuclear RNA (snRA).


Subscribe to this blog, and connect on LinkedIn for skinny-dipping in the RNA world!

REFERENCES

  1. Djebali et al. Landscape of transcription in human cells (2012) Nature
  2. Piovesan et al, Human protein-coding genes and gene feature statistics in 2019 (2019) BMC Res Notes.

Comments

3 responses to “How many types of non-coding RNA do you know?”

  1. Not All Exons Code for a Protein [Common Misconceptions in Genomics, EP. 2] – WritinGenomics avatar
    Not All Exons Code for a Protein [Common Misconceptions in Genomics, EP. 2] – WritinGenomics

    […] Not every gene is transcribed into a mRNA, and eventually translated into a protein. In fact, cells express a huge number and variety of RNAs that do not code for a protein, the non-coding RNAs (ncRNAs). These transcripts often have a modular structure much like mRNAs, with exons and introns. Some ncRNAs, such the long non-coding RNAs (lncRNA), are spliced by the spliceosome (just like protein-coding mRNA!); while others use unique biochemical pathways. This is the case of some transfer RNAs (tRNAs)–we discussed these molecules just last month, to commemorate the 60th anniversary of the sequencing of the first nucleic acid!How abundant are ncRNAs? Our protein-coding genes are an island in an ocean of non-coding DNA: for every nucleotide transcribed in an mRNA, 15 to 45 are transcribed but not translated [4]. The level of transcription for many ncRNAs is weak, but two types of small non-coding RNA, tRNA and rRNA, account for more than 90% of all RNAs in a cell [5]. The primacy of ncRNA is further underscored by the Encyclopedia of DNA elements (ENCODE): twice as many genes code for ncRNAs (over 43,000) than for proteins (nearly 20,000) [6].EDIT: interested in the mysterious universe of ncRNAs? Read my series “How many ncRNAs do you know?“ […]

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  2. 1965 — Deciphering the Code of Life [A Chronicle of DNA Sequencing, EP2] – WritinGenomics avatar
    1965 — Deciphering the Code of Life [A Chronicle of DNA Sequencing, EP2] – WritinGenomics

    […] (at the time incomplete) by Marshall W. Nirenberg in 1965. This document was key to interpreting the protein-coding portion of the genomes we would start sequencing in a decade.[This is Episode 2 of A Chronicle of DNA […]

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    Adieu Copy-Paste: A Brief Guide to Making the Em Dash – WritinGenomics

    […] post is a little different from the others. I am taking a brief detour from genomics here – no non-coding RNAs, no misconceptions in genomics, no history of DNA sequencing. This post explores the other side of […]

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