fate of mrna after rna processing events in nucleus hafidh adv exp med biol. 722:118, 2011
TRANSCRIPT
Fate of mRNA after RNA processing events in nucleus
Hafidh Adv Exp Med Biol. 722:118, 2011
“Proofreading and spellchecking: A two-tier strategy for pre-mRNA splicing quality control”
Egecioglu & Chanfreau RNA 17: 383, 2011
DEAD-box helicases (ATPase Prp proteins) unwind incorrect base-pairing
What happens if splicing pathway is defective?
Egecioglu & Chanfreau RNA 17: 383, 2011
RNA degradation pathways for RNAs that escaped splicing or have splicing mistakes
“Quality control” removal of defective transcripts
Nonsense-mediated mRNA decay (NMD)
- surveillance system to remove defective RNAs
- mRNAs with premature stop codons are rapidly degraded
Gonzalez Gene 274: 15, 2001
Observations:
- in “pioneer round” of translation, if EJC (exon joining complex) not removed by ribosomal machinery, it acts as tag for RNA degradation pathway
Wilusz Genes & Dev 15:2781, 2001
Steady state levels of RNase-L mRNA quantified by qPCR and normalized relative to constitutively expressed rpl13a mRNA
3’UTR deletion constructs
Example of AREs (AU-rich cis-elements) in 3’ UTR of RNase-L mRNA
Deletion constructs were transfected into 293T cells and RNase-L expression was monitored by Western blots
Li et al. J Biol Chem 282:7950, 2007
Interpretation of data? What experiments might be interesting to do next?
Cis-determinants of mRNA stability
ZC5+
Kloc Cell 108: 533, 2002
Drosophila egg: nanos mRNA
Xenopus oocyte: fatVg mRNA
Chicken fibroblast: -actinmRNA (red) in leading lamellae
Mechanisms that target certain mRNAs to appropriate subcellular site?
Heredia Curr Opin Cell Biol 16:80, 2004
Localization of mRNAs within eukaryotic cells
Becalska & Gavis Develop 136:2493, 2009
“Lighting up mRNA localization in Drosophila oogenesis”
Advantages of mRNA subcellular localization (and localized translation)?
Martin & Ephrussi Cell 136:719, 2009
- mRNAs (eg nanos, bicoid, oscar, K10…) important for developmental processes are synthesized in nurse cells and move to oocyte along microtubules
mRNA localization in Drosophila oocyte / embryo
Saxton Cell 107:707, 2001
Kloc & Etkin J.Cell Sci. 118:269, 2005 (Fig.4)
Serano Develop. 121: 3809, 1995
44 nt TLS (transport/localization sequence) with stem-loop structure in 3’UTR
Model for Drosophila K10 mRNA movement?
KSD
Serano Develop. 121: 3809, 1995
Mutational analysis of stem-loopin 3’ UTR of K10 mRNA
Huang Curr Opin Cell Biol 16:308, 2004
Mechanisms for localized translation of mRNAs