HIGHLY EFFICIENT RUNX1 ENHANCER (ER1)- MEDIATED GENETIC ENGINEERING FOR HEMATOPOIETIC STEM CELLS

Abstract

THERE HAS BEEN CONSIDERABLE INTEREST IN IDENTIFYING CIS-REGULATORY ELEMENTS THAT TARGET GENE EXPRESSION TO STEM CELLS. THESE ELEMENTS COULD SERVE AS MOLECULAR HANDLES FOR STEM CELL-SPECIFIC GENETIC ENGINEERING TOOLS, THEREBY BECOMING INVALUABLE TO STEM CELL RESEARCH. HERE, WE SHOW THE SUCCESSFUL GENERATION OF A TAMOXIFEN (TM)-INDUCIBLE TRANSGENIC (TG) MOUSE MODEL EMPLOYING PREVIOUSLY IDENTIFIED HSC-SPECIFIC RUNX1 ENHANCER, ER1 (+24M). THE KINETICS ANALYSIS AFTER TM INJECTION AND BONE MARROW TRANSPLANTATION ASSAYS CLEARLY REVEALED THAT ER1-DRIVEN CREERT2 ACTIVITY WAS LIMITED TO A SUBSET OF LONG TERM-HSCS (LT-HSCS) IN THE CD34-FLT3-C-KIT+SCA1+LINEAGE- FRACTION. THE ACTIVATION OF ONCOGENIC KRAS INITIATED HEMATOPOIETIC MALIGNANCIES IN THE TM-INJECTED ER1-CREERT2 TG; KRAS-LSL-G12D MICE, WHEREAS NEVER IN NON-TM INJECTED MICE. FURTHERMORE, ER1 IS HIGHLY ACTIVE IN LEUKEMIA STEM CELLS (LSCS). TRANSPLANTATION OF ER1-DRIVEN EGFPHIGH, BUT NOT EGFP-/EGFPLOW, CELLS WITH ONCOGENIC KRAS MUTANT WERE CA