P53 tumor suppressor protein affects hematopoietic stem cell differentiation in the megakaryocyte compartment

BIOT 6

Peter G. Fuhrken, p-fuhrken@northwestern.edu1, Pani Apostolidis, pani-apostolidis@northwestern.edu1, Stephan Lindsey, s-lindsey@northwestern.edu1, William M. Miller, wmmiller@northwestern.edu2, and E. Terry Papoutsakis, e-paps@northwestern.edu2. (1) Department of Chemical and Biological Engineering, Northwestern University, 2145 N. Sheridan Road, Evanston, IL 60208, (2) Department of Chemical & Biological Engineering and The Interdepartmental Biological Sciences Program, Northwestern University, 2145 Sheridan Road, Room E-136, Evanston, IL 60208-3120
The molecular mechanisms underlying differentiation of hematopoietic stem cells (HSCs) into megakaryocytes is poorly understood. During megakaryopoiesis, committed progenitor cells undergo endomitosis resulting in polyploid, multi-lobated nuclei. Subsequently, a constitutive program of apoptosis is linked to proplatelet formation. Transformation-related protein p53 can act as a transcription factor affecting both cell cycle control and apoptosis. The up-regulation of several known p53 target genes during megakaryocyte differentiation led to a hypothesis that p53 activation is involved in regulating megakaryopoiesis. A p53-DNA binding activity assay showed increased p53 activity during megakaryocytic differentiation in a validated human model cell-line system (CHRF cells). We generated stable CHRF clones expressing microRNAs that knock down p53 expression. Phorbol-ester-induced megakaryocytic differentiation of these cells results in higher ploidy and viability than cells expressing scrambled controls. This work broadens our understanding of the p53 regulon's role in HSC differentiation and points to ways of manipulating stem cell fate in vitro.
 

Stem Cells: Quantifying, Modeling and Controlling Stem Cell Fate
8:20 AM-10:40 AM, Sunday, August 19, 2007 BCEC -- 108, Oral

Division of Biochemical Technology

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007