title: Phosphoinositide 3-kinase signalling regulates early development and developmental haemopoiesis.
abstract: Phosphoinositide 3-kinase (PI3K)-dependent signalling regulates a wide variety of cellular functions including proliferation and differentiation. Disruption of class I(A) PI3K isoforms has implicated PI3K-mediated signalling in development of the early embryo and lymphohaemopoietic system. We have used embryonic stem (ES) cells as an in vitro model to study the involvement of PI3K-dependent signalling during early development and haemopoiesis. Both pharmacological inhibition and genetic manipulation of PI3K-dependent signalling demonstrate that PI3K-mediated signals, most likely via 3-phosphoinositide-dependent protein kinase 1 (PDK1), are required for proliferation of cells within developing embryoid bodies (EBs). Surprisingly, the haemopoietic potential of EB-derived cells was not blocked upon PI3K inhibition but rather enhanced, correlating with modest increases in expression of haemopoietic marker genes. By contrast, PDK1-deficient EB-derived progeny failed to generate terminally differentiated haemopoietic lineages. This deficiency appeared to be due to a requirement for PI3K signalling during the proliferative phase of blast-colony-forming cell (BL-CFC) expansion, rather than as a result of effects on differentiation per se. We also demonstrate that PI3K-dependent signalling is required for optimal generation of erythroid and myeloid progenitors and their differentiation into mature haemopoietic colony types. These data demonstrate that PI3K-dependent signals play important roles at different stages of haemopoietic development.
authors: Department of Pharmacy and Pharmacology, Centre for Regenerative Medicine, University of Bath, Claverton Down, Bath, BA2 7AY, UK.
authors: Heather K
authors: HK
authors: Bone
authors: Melanie J
authors: MJ
authors: Welham
mesh_terms: D064413:3-Phosphoinositide-Dependent Protein Kinases; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D019070:Cell Lineage / Q000502:physiology; D049109:Cell Proliferation; D004622:Embryo, Mammalian / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D047108:Embryonic Development / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006410:Hematopoiesis / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*
chemical_list: D064413:3-Phosphoinositide-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; C578564:Pdpk1 protein, mouse