The RNA binding motif protein 15B (RBM15B/OTT3) is a functional competitor of serine-arginine (SR) proteins and antagonizes the positive effect of the CDK11p110-cyclin L2α complex on splicing.
Here, we report the identification of the RNA binding motif protein RBM15B/OTT3 as a new CDK11(p110) binding partner that alters the effects of CDK11 on splicing. RBM15B was initially identified as a binding partner of the Epstein-Barr virus mRNA export factor and, more recently, as a cofactor of the nuclear export receptor NXF1. In this study, we found that RBM15B co-elutes with CDK11(p110), cyclin L2α, and serine-arginine (SR) proteins, including SF2/ASF, in a large nuclear complex of ∼1-MDa molecular mass following size exclusion chromatography. Using co-immunoprecipitation experiments and in vitro pulldown assays, we mapped two distinct domains of RBM15B that are essential for its direct interaction with the N-terminal extension of CDK11(p110), cyclin L2α, and SR proteins such as 9G8 and SF2/ASF. Finally, we established that RBM15B is a functional competitor of the SR proteins SF2/ASF and 9G8, inhibits formation of the functional spliceosomal E complex, and antagonizes the positive effect of the CDK11(p110)-cyclin L2α complex on splicing both in vitro and in vivo.
INSERM UMR 991 Foie, Métabolismes et Cancer, IFR140, Université de Rennes 1, Hôpital Pontchaillou, 35033 Rennes, France.
Pascal
P
Loyer
Adeline
A
Busson
Janeen H
JH
Trembley
Judith
J
Hyle
Jose
J
Grenet
Wei
W
Zhao
Catherine
C
Ribault
Tristan
T
Montier
Vincent J
VJ
Kidd
Jill M
JM
Lahti
D000818:Animals; D001667:Binding, Competitive; D002467:Cell Nucleus / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D016213:Cyclins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D029543:Nucleocytoplasmic Transport Proteins / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000068103:Serine-Arginine Splicing Factors; D017381:Spliceosomes / Q000378:metabolism
D016213:Cyclins; D009687:Nuclear Proteins; D029543:Nucleocytoplasmic Transport Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D000068103:Serine-Arginine Splicing Factors; D018844:Cyclin-Dependent Kinases