Intron retention

Definition

Intron retention is a post-transcriptional regulatory mechanism where an intron, which is normally spliced out during mRNA processing, remains within the mature mRNA transcript. This phenomenon can lead to the production of alternative protein isoforms and plays a significant role in gene expression regulation. The retention of introns can affect mRNA stability, localization, and translation efficiency, highlighting its importance in the complexity of cellular responses.

5 Must Know Facts For Your Next Test

1. Intron retention can be a mechanism for generating protein diversity without altering the underlying DNA sequence.
2. This process has been linked to various biological functions, including stress responses and development.
3. Intron retention may contribute to the regulation of gene expression by influencing the stability and localization of mRNA transcripts.
4. Some retained introns can contain regulatory elements that affect the translation of the resulting protein products.
5. Dysregulation of intron retention has been associated with several diseases, including cancer and neurodegenerative disorders.

Review Questions

• How does intron retention influence gene expression and protein diversity?
  • Intron retention affects gene expression by allowing certain mRNA transcripts to retain non-coding sequences that can influence translation efficiency and mRNA stability. This can lead to the production of different protein isoforms from the same gene, contributing to protein diversity. In some cases, retained introns can encode functional domains or regulatory elements that further modify the resulting proteins' function.
• Discuss the potential implications of intron retention in cellular stress responses.
  • Intron retention can play a critical role in cellular stress responses by modulating the levels of specific proteins involved in stress pathways. When cells are under stress, certain genes may utilize intron retention as a strategy to produce alternative isoforms that can better cope with the stressful environment. This allows cells to rapidly adapt by fine-tuning their protein synthesis based on immediate needs.
• Evaluate how abnormalities in intron retention could contribute to disease mechanisms in cancer or neurodegenerative disorders.
  • Abnormalities in intron retention can lead to dysregulated gene expression patterns, which may contribute to disease mechanisms in conditions such as cancer and neurodegenerative disorders. For instance, retained introns can produce non-functional or dominant-negative protein isoforms that interfere with normal cellular functions. In cancer, altered splicing patterns including excessive intron retention may promote tumorigenesis by enabling uncontrolled cell growth or evasion from apoptosis, while in neurodegenerative diseases, these changes might disrupt neural function and survival.

Related terms

Alternative splicing: A process during RNA processing where different combinations of exons are joined together, resulting in multiple mRNA variants from a single gene.

Pre-mRNA: The primary transcript that is synthesized from DNA during transcription before any processing, including splicing, takes place.

Spliceosome: A complex molecular machine that facilitates the removal of introns from pre-mRNA during the splicing process.