Rolle von dem non-kanonischen Wnt Regulator Wnt5a bei der normalen und malignen Hämatopoese
Zusammenfassung der Projektergebnisse
HSC reside in specialized niches maintaining their activity for the lifetime of an individual. It is still poorly understood how the niche regulates HSC. In this project, we defined niche factors affecting HSC and investigated through which mechanisms these factors regulate normal and malignant hematopoiesis. We found that deletion of Sfrp1, Sfrp2, or Wnt5a expression in the niche strongly affected the response of HSC to different forms of stress (in vitro culture, in vivo treatments with 5FU, irradiation, or in transplantation assays). Deletion mutants of these separate molecules showed varying degrees of HSC attrition in a non-redundant manner. In primary transplants into Sfrp2-/- mice, increased engraftment was noted with upregulation of canonical Wnt signaling. However, in subsequent transplantation, HSC were progressively lost with associated reduction of canonical Wnt signals. In heterozygous deletion mutants of the non-canonical Wnt mediator Wnt5a no changes in engraftment were noted. But, HSC regenerated in the Wnt5a+/- environment showed failure to engraft in subsequent recipients. As in the HSC regenerated in Wnt5a mutants, the mechanisms of HSC reduction or failure was not clear, we performed transcriptome analyses of regenerated HSC. These analyses showed a clearly deregulated transcriptome, particularly in actin-dependent processes. Validation studies in HSC isolated from Wnt5a+/- recipients, 16 weeks post transplantation, showed no changes in canonical Wnt signaling, but confirmed deregulation of non-canonical Wnt mediators in the actin-regulatory pathway. Importantly, these changes lead to reduced adhesion, migration, and homing activity of HSC regenerated in Wnt5a+/- recipients. Equally interestingly, regenerated donor cells from Wnt5a+/- recipients showed activation of CDC42, suggesting that HSC attrition in these recipients shows similarities with loss of HSC in normal aging. Preliminary studies in conditional mutants show that when either Sfrp1 or Wnt5a are deleted in the context of Sp7/Osterix-expressing cells (OS1D/D and O5AD/D, respectively), HSC show defective repopulation behavior, even without prior transplantation. Furthermore, in experiments designed to determine whether whether Sfrp1 or Wnta expression contribute to leukemogenesis, we found that deletion of niche Sfrp1 in OS1D/D mice is a contributing factor in BCR-ABL1+ leukemia. In contrast, leukemogenesis in Wnt5a+/- recipients was reduced. Thus, whereas in normal hematopoiesis Sfrp1, Sfrp2, and Wnt5a all contribute similarly to HSC maintenance, in leukemogenesis, Sfrp1 acts as a tumor suppressor, whereas Wnt5a expression promotes development of BCR-ABL1+ leukemia, at least in part through maintaining correct actin assembly in malignant cells. These results suggest that the balance between canonical and non-canonical Wnt signaling is differentially regulated in normal and malignant hematopoiesis.
Projektbezogene Publikationen (Auswahl)
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How the niche regulates hematopoietic stem cells. Chem Biol Interact. 2010; 184: 7-15
Renström J, Kröger M, Peschel C, Oostendorp RAJ
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Stromal pleiotrophin regulates repopulation behavior of hematopoietic stem cells. Blood. 2011; 118: 2712-22
Istvanffy R, Kröger M, Eckl C, Gitzelmann S, Vilne B, Bock F, Graf S, Schiemann M, Keller UB, Peschel C, Oostendorp RAJ
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Role of secreted factors in the regulation of hematopoietic stem cells by the bone marrow microenvironment. Front Biosci (Landmark Ed). 2012; 17: 876-91
Kaur-Bollinger P, Gotze KS, Oostendorp RAJ
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A canonical to non-canonical Wnt signalling switch in haematopoietic stem-cell ageing. Nature, 2013; 503:3 92-396
Florian MC, Kalpana J. Nattamai KJ, Dörr K, Marka G, Überle B, Vas V, Eckl C, Andrä I, Schiemann M, Oostendorp RAJ, Scharffetter-Kochanek K, Kestler HA, Zheng Y, Geiger H
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Protein Kinase C-b-Dependent Activation of NF-kB in Stromal Cells Is Indispensable for the Survival
of Chronic Lymphocytic Leukemia B Cells In Vivo. Cancer Cell, 2013; 23: 77-92
Lutzny G, Kocher T, Schmidt-Supprian M, Rudelius M, Klein-Hitpass R, Finch AJ, Dürig J, Wagner M, Haferlach C, Kohlmann A, Schnittger S, Seifert M, Wanninger S, Zaborsky N, Oostendorp R, Ruland J, Leitges M, Kuhnt T, Schäfer Y, Lampl B, Peschel C, Egle A, Ringshausen I
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Distinct Stromal Cell Factor Combinations Can Separately Control Hematopoietic Stem Cell Survival, Proliferation, and Self-Renewal. Cell Rep. 2014; 7: 1956-67
Wöhrer S, Knapp DJ, Copley MR, Benz C, Kent DG, Rowe K, Babovic S, Mader H, Oostendorp RAJ, Eaves CJ
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Regulation of hematopoiesis by activators and inhibitors of Wnt signaling from the niche. Ann N Y Acad Sci. 2014; 1310: 32-43
Schreck C, Bock F, Grziwok S, Oostendorp RAJ, Istvánffy R
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Cks1 is a critical regulator of hematopoietic stem cell quiescence and cell cycling, operating upstream of Cdk inhibitors. Oncogene. 2015; 34: 4347-57
Tomiatti V, Istvanffy R, Pietschmann E, Kratzat S, Hoellein A, Quintinilla-Fend L, von Bubnoff N, Peschel C, Oostendorp RAJ, Keller U
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Costa O, Berndt J, Stümpflen V, Götze KS, Schiemann M, Peschel C, Mewes HW, Oostendorp RAJ. Stroma-derived connective tissue growth factor maintains cell cycle progression and repopulation activity of hematopoietic stem cells in vitro. Stem Cell Reports. 2015; 5: 702-715
Istvánffy R, Vilne B, Schreck C, Ruf F, Pagel C, Grziwok S, Henkel L, Prazeras da Costa O, Berndt J, Stümpflen V, Götze KS, Schiemann M, Peschel C, Mewes HW, Oostendorp RAJ
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n vivo hematopoietic Myc activation directs a transcriptional signature in endothelial cells within the bone marrow microenvironment. Oncotarget. 2015; 6: 21827-21839
Franke K, Vilne B, Prazeres da Costa O, Rudelius M, Peschel C, Oostendorp RAJ, Keller U
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Loss of Sfrp2 in the niche amplifies stress-induced cellular responses, and impairs the in vivo regeneration of the hematopoietic stem cell pool. Stem Cells. 2016; 34: 2381-92
Ruf F, Schreck C, Wagner A, Grziwok S, Pagel C, Romero S, Kieslinger M, Shimono A, Peschel C, Götze KS, Istvánffy R, Oostendorp RAJ
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Niche WNT5A regulates the actin cytoskeleton during regeneration of hematopoietic stem cells. J Exp Med. 2017; 214: 165-181
Schreck C, Istvánffy R, Ziegenhain C, Sippenauer T, Ruf F, Henkel L, Gärtner F, Vieth B, Florian MC, Mende N, Taubenberger A, Prendergast Á, Wagner A, Pagel C, Grziwok S, Götze KS, Guck J, Dean DC, Massberg S, Essers M, Waskow C, Geiger H, Schiemann M, Peschel C, Enard W, Oostendorp RAJ
