RNA Granules

  • IASbaba
  • May 16, 2022
  • 0
Science and Technology
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Why in News: In yeast cells, a protein (sbp1) promotes disintegration of RNA granules, the study found that the Sbp1 protein helps in reducing the aggregates of human proteins involved in neurodegenerative disorders.

What is an RNA granule?

  • In the cytoplasm of any cell and 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.

Protein Synthesis

  • Messenger RNAs are converted to proteins (building blocks of the cell) by the process of translation.
  • RNA granules determine messenger RNA (mRNA) fate by deciding when and how much protein would be produced from mRNA.
  • Protein synthesis is a multi-step and energy expensive process.
  • Therefore, a common strategy used by cells when it encounters unfavorable conditions is to shut down protein production and conserve energy to deal with the stressful situation.
  • RNA granules help in the process of shutting down protein production.
  • Some RNA granule types (such as Processing bodies or P-bodies) not only regulate protein production but also accomplish degradation and elimination of the mRNAs, which in turn helps in reducing protein production.

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.

Findings of the study

  • 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).

Previous Year Questions (PYQs)

Q.1) RNA interference (RNAi)’ technology has gained popularity in the last few years. why? (2019)

  1. It is used in developing gene silencing therapies.
  2. It can be used in developing therapies for the treatment of cancer.
  3. It can be used to develop hormone replacement therapies.
  4. It can be used to produce crop plants that are resistant to virtual pathogens.

Select the correct answer using the code given below.

  1. 1, 2 and 4
  2. 2 and 3
  3. 1 and 3
  4. 1 and 4 only

Source: The Hindu


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