Understanding the role of RUNX1-TLE1 interaction in the pathogenesis of familial platelet disorder with associated myeloid malignancy

Authors

• HI Alkadi
• Y Gao
• TS Karpova
• L Garret
• S Wincovitch
• A Sorrell
• DA Ball
• JJ Greene
• L Cheng
• PP Liu

Abstract

Familial platelet disorder with associated myeloid malignancy (FPDMM), also known as familial platelet disorder/acute myeloid leukemia (FPD/AML), is characterized with defective megakaryopoiesis and propensity for leukemia (~60% of patients). FPDMM is caused by inherited heterozygous mutations in RUNX1, which encodes a transcription factor. An FPDMM family was identified carrying a novel GC insertion in RUNX1, leading to a frameshift mutation (L472fsX). This caused a disruption of the VWRPY domain; a conserved binding site for the repressor protein TLE1. My research is aimed to unravel how the actions of these proteins contribute to the development of FPDMM, which represents a novel mechanism in FPDMM pathogenesis. To evaluate the physical and functional interaction between RUNX1 (L742fsX) and TLE1, I performed forster resonance energy transfer (FRET), and transactivation assay of RUNX1’s target promoter. When YFP-TLE1 was co-transfected with CFP-RUNX1-wt, it gave a FRET efficiency of 10% ± 3.3%. When YFP-TLE1 was co-transfected with CFP-RUNX1 (L472fsX), the FRET efficiency was only 0.65% ± 1.8%, indicating no binding between RUNX1 (L742fsX) and TLE1. Moreover, TLE1 repressed RUNX1-wt activity when co-transfected with its co-factor CBFβ. On the other hand, TLE1 did not repress RUNX1 (L472fsX) activity. These findings demonstrate that the L472fsX mutation disrupts RUNX1-TLE1 interaction and RUNX1-repression by TLE1. To further understand the role of RUNX1-TLE1 interaction in FPDMM pathogenesis, I will characterize megakaryopoiesis and use RNA-seq to profile gene expression in two models: induced pluripotent stem cells (iPS) derived from the patients’ cells, and Runx1 mutant mice generated with CRISPR-Cas9.

Scientific Focus Area: Genetics and Genomics

This page was last updated on Friday, March 26, 2021