Poly(A) binding protein C1 is essential for efficient L1 retrotransposition and affects L1 RNP formation.
Poly(A) binding proteins (PABPs) specifically bind the polyadenosine tail of mRNA and have been shown to be important for RNA polyadenylation, translation initiation, and mRNA stability. Using a modified L1 retrotransposition vector, we examined the effects of two PABPs (encoded by PABPN1 and PABPC1) on the retrotransposition activity of the L1 non-long-terminal-repeat (non-LTR) retrotransposon in both HeLa and HEK293T cells. We demonstrated that knockdown of these two genes by RNA interference (RNAi) effectively reduced L1 retrotransposition by 70 to 80% without significantly changing L1 transcription or translation or the status of the poly(A) tail. We identified that both poly(A) binding proteins were associated with the L1 ribonucleoprotein complex, presumably through L1 mRNA. Depletion of PABPC1 caused a defect in L1 RNP formation. Knockdown of the PABPC1 inhibitor PAIP2 increased L1 retrotransposition up to 2-fold. Low levels of exogenous overexpression of PABPN1 and PABPC1 increased L1 retrotransposition, whereas unregulated overexpression of these two proteins caused pleiotropic effects, such as hypersensitivity to puromycin and decreased L1 activity. Our data suggest that PABPC1 is essential for the formation of L1 RNA-protein complexes and may play a role in L1 RNP translocation in the host cell.
High Throughput Biology Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Lixin
L
Dai
Martin S
MS
Taylor
Kathryn A
KA
O'Donnell
Jef D
JD
Boeke
D000241:Adenosine / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D020084:Long Interspersed Nucleotide Elements / Q000235:genetics*; D010442:Peptide Chain Initiation, Translational; D039122:Poly(A)-Binding Protein I / Q000235:genetics / Q000378:metabolism*; D026723:Polyadenylation; D011108:Polymers / Q000378:metabolism; D014176:Protein Biosynthesis; D021381:Protein Transport; D011691:Puromycin / Q000494:pharmacology; D034622:RNA Interference; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics; D012261:Ribonucleoproteins / Q000235:genetics / Q000378:metabolism*
D002352:Carrier Proteins; C576588:PABPN1 protein, human; C488448:PAIP2 protein, human; D039122:Poly(A)-Binding Protein I; D011108:Polymers; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D012261:Ribonucleoproteins; C069424:polyadenosine; D011691:Puromycin; D000241:Adenosine