title: Nuclear translocation of active AKT is required for erythroid differentiation in erythropoietin treated K562 erythroleukemia cells.
abstract: Erythroid differentiation of human erythroleukemia cell line K562 induced by erythropoietin is a complex process that involves modifications at nuclear level, including nuclear translocation of phosphatidyl-inositol 3-kinase. In this work we show that erythropoietin stimulation of K562 cells can induce nuclear translocation of active Akt, a downstream molecule of the phosphatidyl-inositol 3-kinase signaling pathway. Akt shows a peak of activity in whole cell homogenates at earlier stage when compared to the nucleus, which shows a peak delayed of 10 min. Akt increases its intranuclear amount and activity rapidly and transiently in response to EPO. Almost all Akt kinase that translocates to the nucleus shows a marked phosphorylation on serine 473. Nuclear enzyme translocation is blocked by the phosphatidyl-inositol 3-kinase inhibitor Ly294002 or Wortmannin. The specific Akt pharmacological inhibitor VI, VII and VIII that act as blocking enzyme activation inhibited translocation as well, whereas Akt inhibitor IX, that inhibits Akt activity, did not block Akt nuclear translocation. When cells were treated by means of siRNA sequences or with the Akt inhibitors the differentiation process was arrested, thus showing the requirement of the nuclear translocation of the active enzyme to differentiate. These findings strongly suggest that the intranuclear translocation of active Akt kinase represents an important step in the signaling pathway that mediates erythropoietin-induced erythroid differentiation.
authors.affiliation: Dipartimento di Morfologia ed Embriologia, Sezione di Anatomia Umana, Signal Transduction Unit, Universita' di Ferrara, Ferrara, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Missiroli
authors.forename: Daniela
authors.initials: D
authors.lastname: Etro
authors.forename: Francesca
authors.initials: F
authors.lastname: Buontempo
authors.forename: Keqiang
authors.initials: K
authors.lastname: Ye
authors.forename: Silvano
authors.initials: S
authors.lastname: Capitani
authors.forename: Luca Maria
authors.initials: LM
authors.lastname: Neri
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000730:Androstadienes / Q000494:pharmacology; D002454:Cell Differentiation; D019070:Cell Lineage; D002467:Cell Nucleus / Q000378:metabolism*; D002867:Chromones / Q000494:pharmacology; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism*; D004921:Erythropoietin / Q000378:metabolism*; D006801:Humans; D020014:K562 Cells; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism* / Q000473:pathology; D009025:Morpholines / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D015398:Signal Transduction; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D002867:Chromones; D009025:Morpholines; D000081082:Phosphoinositide-3 Kinase Inhibitors; D004921:Erythropoietin; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D051057:Proto-Oncogene Proteins c-akt; D000077191:Wortmannin