PML/RARα fusion protein transactivates the tissue factor promoter through a GAGC-containing element without direct DNA association

Abstract

A severe coagulopathy is a life-threatening complication of acute promyelocytic leukemia (APL) and is ascribable mainly to the excessive levels of tissue factor (TF) in APL cells regulated in response to the promyelocytic leukemia/retinoic acid receptor α (PML/RARα) fusion protein. The underlying molecular mechanisms for this regulation remain ill-defined. With U937-PR9 cell lines stably expressing luciferase reporter gene under the control of different mutants of the TF promoter, both luciferase and ChIP data allowed the localization of the PML/RARα-responsive sequence in a previously undefined region of the TF promoter at position −230 to −242 devoid of known mammalian transcription factor binding sites. Within this sequence a GAGC motif (−235 to −238) was shown to be crucial because deletion or mutation of these nucleotides impaired both PML/RARα interaction and promoter transactivation. However, EMSA results showed that PML/RARα did not bind to DNA probes encompassing the −230 to −242 sequences, precluding a direct DNA association. Mutational experiments further suggest that the activator protein 1 (AP-1) sites of the TF promoter are dispensable for PML/RARα regulation. This study shows that PML/ RARα transactivates the TF promoter through an indirect interaction with an element composed of a GAGC motif and the flanking nucleotides, independent of AP-1 binding.transcription | regulation | GAGC motif | acute promyelocytic leukemia | coagulopathy

Characterization of the thrombin generation potential of leukemic and solid tumor cells by calibrated automated thrombography

“…In this subtype of leukemia, the fusion product of the t(15-17) translocation PML/RARα, can transactivate the TF promoter. 20 Our finding of elevated thrombin generation capacity and TF expression in NB4 cells is in agreement with results of a previous study, showing that blast cells isolated from patients with acute promyelocytic leukemia express the highest amount of procoagulant activity compared to blasts from other types of myeloid leukemia. 21 In addition, acute promyelocytic cell-associated procoagulants have been involved in the pathogenesis of life-threatening coagulopathy associated with this disease.…”

Phosphatidylserine index as a marker of the procoagulant phenotype of acute myelogenous leukemia cells

“…TF expression has been shown to contribute to leukemic cell procoagulant activity (2–5). Several leukemia-specific oncogenic alleles, including the pathognomonic t(15;17) translocation in AML M3, have been shown to induce overexpression of TF (6, 7). Co-localization of fibrin with leukemia blast cells in marrow and peripheral vasculature suggests a causal relationship between the presence of AML cells and aberrant, intravascular blood coagulation (8, 9).…”

The DNA Binding Property of PML/RARA but Not the Integrity of PML Nuclear Bodies Is Indispensable for Leukemic Transformation

“…Three recently published reports demonstrated that PML/RARA regulates a novel class of target genes such as ID1 and TF through interaction with other transcription factors, without directly binding to the DNA, defining a gain-of-function for the oncoprotein [17], [18]. The contribution of this gain of function of PML/RARA in the transformation of primary hematopoietic progenitor cells was never tested.…”

“…PML/RARA was also shown to transactivate the TF promoter through an indirect interaction with an element composed of a GAGC motif and the flanking nucleotides [18]. It is also reported that PML/RARA predominantly targets PU.1-regulated promoters through both protein-protein interaction and DNA binding via retinoic acid response element (RARE) half sites forming complex binding motifs [19].…”