Poster abstracts
Poster number 27 submitted by Rohan Krishna
eIF4B and eIF4H Define Complementary Translational Programs via Context-Dependent mRNA Selection
Rohan Krishna (Department of Biochemistry, Case Western Reserve University), Joseph Luna (Department of Biochemistry, Case Western Reserve University)
Abstract:
Efficient translation of structured mRNAs require eIF4A, a DEAD-box RNA helicase that unwinds complex secondary structures in 5’ untranslated regions (5’ UTRs). Eukaryotic translation initiation factors eIF4B and eIF4H are the primary RNA-binding proteins that act as cofactors to eIF4A to stimulate its activity. eIF4B and eIF4H have long been considered functionally redundant, yet they bind to mutually exclusive sites on eIF4A, raising the question of whether they direct distinct translational programs. Using CLIP-seq, we find that eIF4A exhibits different mRNA binding patterns depending on its association with eIF4B versus eIF4H under mock conditions and during the interferon (IFN) response, demonstrating that cofactor identity shapes mRNA target selection. To define how each cofactor contributes to the translational landscape, we performed ribosome profiling in eIF4B and eIF4H knockout cell lines. While loss of eIF4B produces modest changes in translational efficiency, loss of eIF4H dramatically broadens the distribution of translational change, revealing a specialized eIF4B-dependent translational program that is otherwise concealed by eIF4H. Furthermore, integrating ribosome profiling with CLIP-seq data shows that mRNAs bound by eIF4B or eIF4H undergo corresponding translational changes in the matching knockout, linking binding specificity to selective translation. Together, these results challenge the redundancy model and establish eIF4B and eIF4H as functionally asymmetric regulators of eIF4A-dependent translation. Current work aims to determine how RNA sequence and structural features of target mRNAs drive the selectivity of eIF4B and eIF4H binding. These results will reveal fundamental principles governing cofactor-dependent translational control and establish a new framework for understanding how eIF4A activity is selectively regulated through its cofactors.
Keywords: Translation, Cofactor, eIF4A