Contribution of the Integrator subunit INTS12 in transcription elongation control during human erythropoiesis and in a rare congenital erythroid disorder.

About This Grant

Project Summary INTS12 is a chromatin interacting subunit of the mammalian Integrator complex that binds to accessible chromatin and controls various aspects of transcription such as elongation and termination. INTS12 interacts with negative elongation factors as well as RNA Polymerase II and regulates its pausing and release into productive elongation. Studies on INTS12 biology in various mammalian systems such as hematopoietic tissues is lacking despite ample evidence of its presence and likely contributions to hematopoietic development and disease. For instance, INTS12 is highly expressed in early stage erythroid progenitor cells during ex vivo erythroid differentiation of human CD34+ hematopoietic stem cells, and it is significantly reduced in the rare hemolytic anemia Congenital Dyserythropoietic Anemia Type IV (CDA IV; CDAN4), which affects young children and renders them transfusion dependent. This proposal will address our core hypothesis that INTS12 function is important for transcription regulation during normal human red cell development and reduced INTS12 levels in CDA IV red cells contributes to ineffective erythropoiesis due to disrupted RNA Polymerase II elongation control. To achieve this, a newly established erythroid progenitor cell line called BEL-A that can be expanded indefinitely, and differentiated to mature erythroid cells will be used. Aim1 will focus on INTS12 chromatin binding in normal wild type (WT) and CDA IV mutant BEL-A cells, and this will be correlated with existing unpublished chromatin accessibility and transcription factor binding data from erythroid stage-matched WT and CDA IV BEL-A cells. Further, the effect of depleting or overexpressing INTS12 on red cell development in WT and CDA IV will also be characterized. In Aim2, we will explore INTS12 functions in transcription by assessing the impact of INTS12 perturbations such as depletion and overexpression on nascent gene expression and RNA Polymerase II occupancy. These data will be correlated with INTS12 occupancy determined from Aim1, and any alterations in nascent transcription leading to changes in RNA Pol II pausing and elongation due to perturbed INTS12 levels will suggest that INTS12 contributes to altered transcription regulation in CDA IV. Transcription elongation by RNA Polymerase II is highly regulated and involves many transcription co- factors and epigenetic mechanisms, some of which are chemotherapy targets for certain hematological malignancies. Further, INTS12 interacts with chromatin using a conserved PHD domain that is being investigated as a potential chemotherapy target using derivatives of a class of compounds known as Amiodarones. The knowledge harnessed from this proposal will thus enable future investigations into INTS12 and Integrator complex biology in erythropoiesis, as well as translational studies on the potential for INTS12 as a therapeutic target in CDA IV patients.