Non-Coding RNAs

BIOL 209: Non-Coding RNAs

Two Broad Classes of Genes

Protein-coding RNA:

  • (mRNA) is a type of RNA that carries genetic info from DNA to RNA to the ribosomes where proteins are synthesized

Non-coding RNA/functional RNA:

  • involves tRNA, rRNA, miRNA, and IncRNAs, these are all ncRNAs which is noncoding RNAs)

mRNA only coding, only functional

18.1: Overview of Non-Coding RNAs

  • ncRNAs can Bind to Different Types of Molecules

  • ncRNAs can Perform a Diverse Set of Functions

    • Scaffolding

      • formation of a complex

  • Guide

    • Movement of molecule to a specific site

      • Alteration of Protein Function of Stability

        • Go in and alter struct. which alt. the func. can affect the ability of a protien to act as a catalyst, affect how a protein can bind to another DNA or it can affect stablility

      • Ribozyme

        • RNAs with catalysic function, some of them func as ribozyme

      • Blocker

        • physically block a process from occuring

      • Decoy

        • Recongnize other ncRNAs and stop them from working

ncRNAs categorized based on size

  • long non-coding RNAs (lncRNAs): —> 200 nts (red marker)

  • small regulatory RNAs (short ncRNAs): —> 200 nts (blue marker)

  • Both/Niether (purple marker)

Type of RNA

Found in

Plays a role in

Description

Telomerase RNA component (TERC)

Eukaryotes

DNA Replication

Facilitates the binding of telomerase to the telomere and acts as a template for DNA replication

X inactive-specific transcript (XIST)

Eukaryotes

Chromatin structure, transcription

Coats one if the X chromosomes in females mammals and plays a role in its compaction and resulting inactivation X inactivation

Hox transcript antisense intergenic RNA (HOTAIR)

Eukaryotes

Chromatin structure, transcription

Alters chromatin structure and thereby represses transcription by guiding histone-modifying enzymes to target genes

RNaseP RNA

Eukaryotes

Processing of tRNA molecules

Processing of tRNA molecules.

Small nuclear RNA (snRNA)

Eukaryotes

Splicing

Form the subunits of the spliceosome with proteins, processing mRNA

Small nucleolar RNA (snoRNA)

Eukaryotes

Processing of rRNA molecules

Processing and assembly of rRNA, process rRNA through cleve

Transfer RNA (tRNA)

Eukaryotes and Prokaryotes

Translation

Recognize mRNA codons during translation and carry the appropriate amino acid. Help in translation

Ribosomal RNA (rRNA)

Eukaryotes and Prokaryotes

Translation

Structural and functional components of ribosomes. Makes the ribosome, serves as a site. Comes in sizes like 18S, 5S, 45S, come in diffrent legnths.

Antisense RNA

Eukaryotes

Translation

Complementary to an mRNA; blocks translation

MicroRNA (miRNA)

Eukaryotes

Translation and

RNA degradation

Regulate expression and degradation of mRNAs. RNA interferance (RNAi)

reg gene expression

Small interfering RNA (siRNA)

Eukaryotes

Translation and

RNA degradation

Regulate expression and degradation of mRNAs. stops translation

fight viral infections

RNA component of signal recognition particle (SRP)

Eukaryotes and Prokaryotes

Protein targeting

and secretion

Directs polypeptides to proper location. involved in the process that moves proteins around the cell to what ever place it needs to go

Viral RNA

Viruses

Genome

Make up some viral genomes

CRISPR RNA (crRNA)

Prokaryotes

Genome Defense

Guides endonucleases to foreign DNA in prokaryotes

PIWI-interacting RNA (piRNA)

Eukaryotes

Genome Defense

Prevents the movement of transposable elements. stop transposons from moving around in germ cells

Guide RNAs

Eukaryotes

mRNA modification

Serves as a template to alter mRNA molecukes. RNA editing

18.2 Non-coding RNAs: Effects on Chromatin Structure and Transcription

HOTAIR (Hox transcript antisense intergenic RNA)

Alters chromatin structure and thus, represses gene transcription as shown below:

Hotair

18.3 Non-coding RNAs: Effects on Translation and mRNA Degradation

RNA Interference (RNAi) can be carried out by microRNAs (miRNAs) and small interfering RNAs (siRNAs).

Compare and Contrast miRNAs and siRNAs DNA interference- How it works

*Dysfunctional HOTAIR can lead to breast cancer *RNAi benefits

-gene regulation

-defense against viruses

18.4 Non-coding RNAs and Protein Targeting

Signal Recognition Particle (SRP) is involved in the process that moves proteins around the cell to the proper location for its function.

Hotair

18.5 Non-coding RNAs and Genome Defense

CRISPR-Cas System is the equivalent of an immune system in bacteria. (below)

PIWI-Interacting RNAs (piRNAs) silence transposable elements in the germ cells of animals

Hotair

18.6 Role of Non-Coding RNAs in Human Disease

Abnormalities in the expression of ncRNAs is associated with human diseases.

First ncRNA associated with disease was RNaseMRP, RNA-protein complex that processes some rRNAs, mRNAs, mitoRNAs. Characteristics of Cartilage-hair hypoplasia (CHH): short stature, underdeveloped hair, short limbs, defects in T-cell immunity, predisposition to lymphoma and other cancers

ncRNAs may be used to treat certain diseases

  • anti-miRNA oligonucleotides (AMOs): used to treat some cancers by inhibiting miRNAs

  • restore the miRNA using viral vectors, drugs, reversing epigenetic changes