The role of HIF prolyl hydroxylase-2 (PHD2) during physiological and pathological processes in mice

• Applicant: Professor Ben Wielockx, Ph.D.
• Subject Area: Pathology
• Term: from 2007 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 35183441

With the current proposal I would like to apply for an additional 6th Emmy Noether year. The reasoning is that apart from several recent publications, our main research results are currently either under review in a high impact factor journal or almost ready to be submitted. Moreover, based on the research performance of my group, the department of hematology (TU Dresden) has committed itself to apply with me for a Heisenberg professorship in the future. Therefore, I believe that this 6th E.N. year would be an excellent opportunity to publish our results, finalize other promising research lines and get qualified for a professorship. During the last 4.5 years, research in our group has been focused on the role of oxygen-sensors in mice. These proteins are indispensable in all living beings as it enables the cells to instantaneously adapt to inappropriate pO2. This machinery mainly relies on the HIF-prolyl hydroxylases (PHD1-3), enzymes that hydroxylate hypoxia inducible factor (HIF) and lead to their inactivation. Using different genetic approach we found that PHD2 is of utmost importance during the control of red blood cell mass, skin wound healing and maintenance of hematopoietic stem cells (HSCs) (Franke et al., under review). Using a new conditional PHD2 deficient mouse line (CD68:cre-PHD2f/f) we showed that loss of PHD2 in the HSC compartment induces self-renewal of multipotent progenitors (MPP) and HSCs in a HIF1a-dependent manner. During this additional E.N research year we want to expand these findings. Although we found a direct link between PHD2 and HIF1a in HSCs, we propose to perform gene profiling on the most immature hematopoietic cells under severe stress. We are convinced that this will enable us to find the responsible genes involved in PHD2-related inhibition of differentiation in HSCs and maintaining of their multipotency. Our findings have also important implications with regard to hematological malignancies. We therefore plan to study the PHD2-HIF1 angle in a newly developed acute myeloid leukemia mouse model (AML) using our Vav:cre-PHD2f/f mice; deficient for PHD2 only in the hematopoietic system. In an acute colitis model we found that CD68:cre-PHD2f/f mice are much more susceptible than their WT counterparts. Intense research has now demonstrated that PHD2-deficiency in colon epithelial cells is responsible for this sensitivity although independent of their hydroxylation activity. During this extra year we want to perform some very defined ex vivo experiments that will help us to find the responsible pathway (e.g. TGFbeta, NFkB…). In a recent Cancer Research publication from our group we described in detail the role of PHD2 during tumor development. We now also found that loss of PHD2 in myeloid and T-cells can control tumor growth. Using genetically induced tumor models (MMTV-pyMT-cre-PHD2f/f) we will expand these findings in search of the role of PHD2 in inflammatory cells during tumor development in a clinically relevant model.

• DFG Programme: Independent Junior Research Groups