title: Normal hematopoietic stem cell function in mice with enforced expression of the Hippo signaling effector YAP1.
abstract: The Hippo pathway has recently been implicated in the regulation of organ size and stem cells in multiple tissues. The transcriptional cofactor yes-associated protein 1 (Yap1) is the most downstream effector of Hippo signaling and is functionally repressed by the upstream components of the pathway. Overexpression of YAP1 stimulates proliferation of stem and progenitor cells in many tissues, consistent with inhibition of Hippo signaling. To study the role of Hippo signaling in hematopoietic stem cells (HSCs), we created a transgenic model with inducible YAP1 expression exclusively within the hematopoietic system. Following 3 months induction, examination of blood and bone marrow in the induced mice revealed no changes in the distribution of the hematopoietic lineages compared to control mice. Moreover, the progenitor cell compartment was unaltered as determined by colony forming assays and immunophenotyping. To address whether YAP1 affects the quantity and function of HSCs we performed competitive transplantation experiments. We show that ectopic YAP1 expression does not influence HSC function neither during steady state nor in situations of hematopoietic stress. This is in sharp contrast to effects seen on stem- and progenitor cells in other organs and suggests highly tissue specific functions of the Hippo pathway in regulation of stem cells.
authors.affiliation: Molecular Medicine and Gene Therapy, Lund Stem Cell Center, Lund University, Lund, Sweden.
authors.forename: Lina
authors.initials: L
authors.lastname: Jansson
authors.forename: Jonas
authors.initials: J
authors.lastname: Larsson
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D002452:Cell Count; D018797:Cell Cycle Proteins; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism*; D006413:Hematopoietic System / Q000166:cytology / Q000378:metabolism; D006801:Humans; D051379:Mice; D023421:Models, Animal; D009928:Organ Specificity / Q000235:genetics; D010750:Phosphoproteins / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D015398:Signal Transduction; D000091102:YAP-Signaling Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D010750:Phosphoproteins; D000091102:YAP-Signaling Proteins; C486223:Yap1 protein, mouse; D017346:Protein Serine-Threonine Kinases