A novel mRNA-decapping activity in HeLa cytoplasmic extracts is regulated by AU-rich elements.
While decapping plays a major role in mRNA turnover in yeast, biochemical evidence for a similar activity in mammalian cells has been elusive. We have now identified a decapping activity in HeLa cytoplasmic extracts that releases (7me)GDP from capped transcripts. Decapping is activated in extracts by the addition of (7me)GpppG, which specifically sequesters cap-binding proteins such as eIF4E and the deadenylase DAN/PARN. Similar to in vivo observations, the presence of a poly(A) tail represses decapping of RNAs in vitro in a poly(A)-binding protein-dependent fashion. AU-rich elements (AREs), which act as regulators of mRNA stability in vivo, are potent stimulators of decapping in vitro. The stimulation of decapping by AREs requires sequence-specific ARE-binding proteins. These data suggest that cap recognition and decapping play key roles in mediating mRNA turnover in mammalian cells.
Gao
M
M
Department of Microbiology and Molecular Genetics, UMDNJ-New Jersey Medical School, Newark, NJ 07103, USA.
Wilusz
C J
CJ
Peltz
S W
SW
Wilusz
J
J
D020856:AT Rich Sequence / Q000235:genetics; D001667:Binding, Competitive; D002457:Cell Extracts; D003593:Cytoplasm / Q000378:metabolism*; D015226:Dinucleoside Phosphates / Q000378:metabolism; D039561:Eukaryotic Initiation Factor-4E; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008957:Models, Genetic; D010448:Peptide Initiation Factors / Q000378:metabolism; D011061:Poly A / Q000235:genetics / Q000378:metabolism; D039102:Poly(A)-Binding Proteins; D012315:RNA Caps / Q000235:genetics*; D020871:RNA Stability / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D012441:Saccharomyces cerevisiae
D002457:Cell Extracts; D015226:Dinucleoside Phosphates; D039561:Eukaryotic Initiation Factor-4E; D010448:Peptide Initiation Factors; D039102:Poly(A)-Binding Proteins; D012315:RNA Caps; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C111106:7-methylguanosine 5'-diphosphate; D006153:Guanosine Diphosphate; D011061:Poly A; C062229:7-methyl-diguanosine triphosphate