Proteins associated with the exon junction complex also control the alternative splicing of apoptotic regulators.
Several apoptotic regulators, including Bcl-x, are alternatively spliced to produce isoforms with opposite functions. We have used an RNA interference strategy to map the regulatory landscape controlling the expression of the Bcl-x splice variants in human cells. Depleting proteins known as core (Y14 and eIF4A3) or auxiliary (RNPS1, Acinus, and SAP18) components of the exon junction complex (EJC) improved the production of the proapoptotic Bcl-x(S) splice variant. This effect was not seen when we depleted EJC proteins that typically participate in mRNA export (UAP56, Aly/Ref, and TAP) or that associate with the EJC to enforce nonsense-mediated RNA decay (MNL51, Upf1, Upf2, and Upf3b). Core and auxiliary EJC components modulated Bcl-x splicing through different cis-acting elements, further suggesting that this activity is distinct from the established EJC function. In support of a direct role in splicing control, recombinant eIF4A3, Y14, and Magoh proteins associated preferentially with the endogenous Bcl-x pre-mRNA, interacted with a model Bcl-x pre-mRNA in early splicing complexes, and specifically shifted Bcl-x alternative splicing in nuclear extracts. Finally, the depletion of Y14, eIF4A3, RNPS1, SAP18, and Acinus also encouraged the production of other proapoptotic splice variants, suggesting that EJC-associated components are important regulators of apoptosis acting at the alternative splicing level.
Département de Microbiologie et d’Infectiologie, Université de Sherbrooke, Sherbrooke, Québec, Canada.
Laetitia
L
Michelle
Alexandre
A
Cloutier
Johanne
J
Toutant
Lulzim
L
Shkreta
Philippe
P
Thibault
Mathieu
M
Durand
Daniel
D
Garneau
Daniel
D
Gendron
Elvy
E
Lapointe
Sonia
S
Couture
Hervé
H
Le Hir
Roscoe
R
Klinck
Sherif Abou
SA
Elela
Panagiotis
P
Prinos
Benoit
B
Chabot
D017398:Alternative Splicing; D017209:Apoptosis / Q000235:genetics*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics; D056970:Co-Repressor Proteins; D053487:DEAD-box RNA Helicases / Q000235:genetics; D039601:Eukaryotic Initiation Factor-4A; D005091:Exons; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics; D012261:Ribonucleoproteins / Q000235:genetics; D017381:Spliceosomes; D051020:bcl-X Protein / Q000235:genetics*
C121310:ACIN1 protein, human; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; D056970:Co-Repressor Proteins; D009687:Nuclear Proteins; C406243:RBM8A protein, human; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C084538:RNPS1 protein, human; D012261:Ribonucleoproteins; C498650:SAP18 protein, human; D051020:bcl-X Protein; D039601:Eukaryotic Initiation Factor-4A; C403493:EIF4A3 protein, human; D053487:DEAD-box RNA Helicases