Translation Regulation in Eukaryotes: MicroRNA-mediated Regulation

Translation Regulation in Eukaryotes

MicroRNA-mediated Regulation

• MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression at the post-transcriptional level
• miRNAs bind to messenger RNA (mRNA) and prevent its translation or induce its degradation
• miRNAs recognize specific mRNA targets through complementary base pairing
• Regulation of miRNA-mediated translation:
  • miRNA-mRNA binding leads to inhibition of translation initiation
  • miRNA-mRNA binding can also induce deadenylation and decapping of mRNA, leading to its degradation

MRNA Capping

• mRNA capping is the process of adding a 7-methylguanosine (m7G) cap to the 5' end of mRNA
• The cap is recognized by the eukaryotic translation initiation factor 4E (eIF4E)
• Capping is essential for:
  • Translation initiation: the cap recruits eIF4E, which interacts with the ribosome to initiate translation
  • mRNA stability: the cap protects the mRNA from degradation by exonucleases

Polyadenylation

• Polyadenylation is the process of adding a poly(A) tail to the 3' end of mRNA
• The poly(A) tail is recognized by the poly(A)-binding protein (PABP)
• Polyadenylation is essential for:
  • Translation initiation: PABP interacts with eIF4G, which recruits the ribosome to initiate translation
  • mRNA stability: the poly(A) tail protects the mRNA from degradation by exonucleases

RNA-binding Proteins

• RNA-binding proteins (RBPs) are proteins that bind to specific mRNA sequences or structures
• RBPs can regulate translation by:
  • Blocking or masking the mRNA 5' cap or 3' poly(A) tail
  • Recruiting or inhibiting translation initiation factors
  • Modulating mRNA localization and stability
• Examples of RBPs:
  • HuR: stabilizes mRNA by binding to the 3' UTR
  • AU-binding proteins: bind to AU-rich elements in the 3' UTR and regulate mRNA stability and translation

MicroRNA-mediated Regulation

• MicroRNAs (miRNAs) regulate gene expression at the post-transcriptional level by binding to messenger RNA (mRNA) and preventing its translation or inducing its degradation
• miRNAs recognize specific mRNA targets through complementary base pairing
• miRNA-mRNA binding leads to inhibition of translation initiation
• miRNA-mRNA binding can also induce deadenylation and decapping of mRNA, leading to its degradation

mRNA Capping

• mRNA capping is the process of adding a 7-methylguanosine (m7G) cap to the 5' end of mRNA
• The cap is recognized by the eukaryotic translation initiation factor 4E (eIF4E)
• Capping is essential for translation initiation, as the cap recruits eIF4E, which interacts with the ribosome to initiate translation
• Capping is essential for mRNA stability, as the cap protects the mRNA from degradation by exonucleases

Polyadenylation

• Polyadenylation is the process of adding a poly(A) tail to the 3' end of mRNA
• The poly(A) tail is recognized by the poly(A)-binding protein (PABP)
• Polyadenylation is essential for translation initiation, as PABP interacts with eIF4G, which recruits the ribosome to initiate translation
• Polyadenylation is essential for mRNA stability, as the poly(A) tail protects the mRNA from degradation by exonucleases

RNA-binding Proteins

• RNA-binding proteins (RBPs) are proteins that bind to specific mRNA sequences or structures
• RBPs can regulate translation by blocking or masking the mRNA 5' cap or 3' poly(A) tail
• RBPs can regulate translation by recruiting or inhibiting translation initiation factors
• RBPs can regulate translation by modulating mRNA localization and stability
• Examples of RBPs:
  • HuR: stabilizes mRNA by binding to the 3' UTR
  • AU-binding proteins: bind to AU-rich elements in the 3' UTR and regulate mRNA stability and translation

This quiz covers the role of microRNAs in regulating gene expression at the post-transcriptional level, including their binding to mRNA and prevention of translation or degradation.