Project description:The small GTPase RAN plays a role in the biogenesis of mature miR-126, which is supplied by the bone marrow arterioles to leukemic stem cells (LSCs). MiR-126 supports the homeostasis of LSCs that initiate and maintain acute myeloid leukemia (AML). While therapeutic targeting of RAN has been difficult due to its structural features, through molecular dynamics simulations and docking studies, we have identified MAR-3.6.2 as a novel allosteric inhibitor that binds in a cryptic pocket in the C-terminal domain of RAN. We showed that MAR-3.6.2 disrupted RAN interaction with its guanine nucleotide exchange factor RCC1 and prevented the nuclear switch of RAN-GDP to RAN-GTP. This in turn led to RAN nuclear retention and reduced the RAN/XPO5-mediated export of pre-miR-126, thereby limiting mature miR-126 biogenesis in endothelial cells and their exogenous supply of mature miR-126 to LSCs. In a MllPTD/WT/Flt3ITD/ITD AML murine model, MAR-3.6.2 reduced leukemia burden, prolonged survival, and decreased LSC frequency in secondary transplants. These findings highlight MAR-3.6.2 and future, potential derivates as a promising small molecule-based approach to eradicate AML LSCs via inhibition of RAN/XPO5 trafficking and block of miR-126 biogenesis.
Project description:Comparing transcriptome of the leaves of Ran-GDP and Ran-GTP overexpression transgenic plants before and after dark incubation, we discovered 851 differentially expressed genes that designated as Ran-regulated genes. The RNA-seq result confirmed the early senescence phenotype of Ran-GTP overexpression plants and the up-regulation of several signaling pathways, implied their positive roles in Ran-regulated senescence and suggest potential downstream targets of Ran. This study provided a mechanism that senescence process could be regulated by nuclear transportation machinery in Arabidopsis.