Related Experiment Video
Updated: Jun 10, 2026

Studying RNA Interactors of Protein Kinase RNA-Activated during the Mammalian Cell Cycle
Published on: March 5, 2019
RAF associates with phosphorylated nuclear BubR1 during endoreduplication induced by JAK inhibition
Gudrun Reiterer1, Lihua Chen, Ryan Tassef
1Department of Biomedical Sciences, Cornell University, Ithaca, NY, USA.
Abstract:
The role of JAK signaling in cell cycle transit and maintenance of genomic stability was determined in HL-60 human myeloblastic leukemia cells. We have previously reported that a pan-JAK inhibitor caused ERK-dependent endoreduplication. In the current study we find that JAK inhibition caused nuclear re-localization of RAF-1 which could be inhibited by RAF inhibitor GW5074. GW5074 also inhibited JAK inhibitor-induced appearance of nuclear phosphorylated RAF-1(pS621RAF) and MEK; and it inhibited the JAK inhibitor-induced co-immunoprecipitation of nuclear RAF-1 and MEK. JAK inhibition also increased nuclear BubR1 phosphorylation, which was diminished by RAF inhibitor GW5074. RAF-1 and BubR1 in the nucleus co-immunoprecipitated; and GW5074 eliminated this. Furthermore, inhibiting RAF with GW5074 blocked the pan-JAK inhibitor-induced endoreduplication. These data thus show that JAK inhibition causes nuclear relocalization and phosphorylation of RAF and MEK where RAF binds BubR1 with ensuing nuclear RAF-dependent BubR1 phosphorylation. Inhibiting RAF inhibited this and endoreduplication. The results suggest that there is a JAK/RAF/MEK/BubR1 axis that can regulate genomic stability. In this hypothetical model JAK suppresses RAF/MEK phosphorylation and nuclear re-localization, but JAK inhibition induces the phosphorylations and relocalization with association of RAF and phosphorylated BubR1 in the nucleus leading to endoreduplication.
More Related Videos
06:44Bioluminescence Resonance Energy Transfer (BRET)-Based Assay for Measuring Interactions of CRAF with 14-3-3 Proteins in Live Cells
Published on: March 1, 2024
10:27Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells
Published on: March 9, 2012
Related Concept Videos
Restarting Stalled Replication Forks
Regulation of the Unfolded Protein Response
The JAK-STAT Signaling Pathway
Anaphase Promoting Complex
MAPK Signaling Cascades
The Unfolded Protein Response