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RNA granules

  • Posted By
    10Pointer
  • Categories
    Science & Technology
  • Published
    17th May, 2022

Context

Researchers at IISC Bangalore have identified a protein in yeast cells that dissolves RNA-protein complexes, also known as RNA granules.

Key-findings

  • In recent years, a strong link has emerged between RNA granules and neurodegenerative disorders such as Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD). 
  • A recent study has identified a protein (Sbp1) as a factor that dissolves the RNA granules (P-bodies).
  • The work also concluded that low complexity sequences (containing repeats of arginine (R) and glycine (G) amino acids — RGG) which normally promote granule formation, in this case promote the disintegration of RNA granules in yeast cells.
  • The identified protein Sbp1 is specific for dissolving P-bodies and not stress granules which are related RNA granule types also present in the cytoplasm.
  • This finding can be used to treat neurodegenerative disorders such as Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD).

What is mRNA?

  • Messenger RNA (mRNA) is a single-stranded RNA (RiboNucleic Acid) molecule that is complementary to one of the DNA strands of a gene.
  • The mRNA is an RNA version of the gene that leaves the cell nucleus and moves to the cytoplasm where proteins are made.
  • During protein synthesis, an organelle called a ribosome moves along the mRNA, reads its base sequence, and uses the genetic code to translate each three-base triplet, or codon, into its corresponding amino acid.

What is an RNA granule?

  • In the cytoplasm of any cell one comes across structures made of messenger RNA (mRNA) and proteins known as RNA granules.
  • Unlike other structures in the cell (such as mitochondria), the RNA granules are not covered and confined by a membrane.
  • This makes them highly dynamic in nature, thereby allowing them to constantly exchange components with the surrounding.
  • RNA granules are present in the cytoplasm at low numbers under normal conditions but increase in number and size under stressful conditions including diseases.
  • A defining feature which does not change from one organism to another (conserved) of the RNA granule protein components is the presence of stretches containing repeats of certain amino acids.
  • Such stretches are referred to as low complexity regions. 
    • Repeats of arginine (R), glycine (G) and glycine (G) — known as RGG — are an example of low complexity sequence.

Treatment of disease

  • In recent years, a strong link has emerged between RNA granules and neurodegenerative disorders such as Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD).
  • The proteins implicated in these diseases are RNA binding proteins that can reside in RNA granules.
  • These proteins also contain low complexity sequences (repeats of amino acids) that are important for their movement into RNA granules.
  • In fact, these proteins are deposited as insoluble granules/aggregates in the neurons of ALS and FTD patients which are believed to contribute to the pathophysiology of these diseases.
  • Finding ways of solubilizing these aggregates could provide a breakthrough in treating these diseases.

Significance of the study

  • This study has highlighted the potential of amino acid repeats (RGG) as a therapeutic intervention.
  • The study may help analyze the effect of repeat sequences in genetically engineered mice that accumulate insoluble pathological aggregates in brain cells.
  • This could possibly help in treating neurodegenerative disorders such as Alzheimer’s disease.

Verifying, please be patient.

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