Translation Regulation in Eukaryotes: MicroRNA-mediated Regulation

Study Notes

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 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 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 (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

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 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 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 (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