Identification of K-ras as the major regulator for cytokine-dependent Akt activation in erythroid progenitors in vivo
Despite intensive investigation, controversial results have been obtained concerning the precise signaling pathway(s) regulated by K-ras in different cell types. We show that in primary fetal liver erythroid progenitors, erythropoietin activates all three Ras isoforms, but preferentially N- and K-ras. In K-ras(-/-) fetal liver cells (FLC), erythropoietin- or stem cell factor-dependent Akt activation is greatly reduced, whereas other pathways including Stat5 and p44/p42 MAP kinase are activated normally. We further studied the effects of reduced cytokine-dependent Akt activation in erythroid differentiation. We find that freshly isolated K-ras(-/-) FLC show an approximately 7-fold increase of apoptosis and delayed erythroid differentiation, but only at the stage of erythroid progenitors and very early erythroblasts. When K-ras(-/-) erythroid progenitors are cultured in vitro, there is a significant delay in erythroid differentiation but little increase in apoptosis. Furthermore, we show that partial pharmacologic inhibition of the phosphatidylinositol 3-kinase/Akt pathway in wild-type erythroid progenitors leads to a delay in erythroid differentiation similar to that observed in K-ras(-/-) FLC. Taken together, our data identify K-ras as the major regulator for cytokine-dependent Akt activation, which is important for erythroid differentiation in vivo.
| Medienart: |
Artikel |
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| Erscheinungsjahr: |
2005 |
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| Erschienen: |
2005 |
| Enthalten in: |
Zur Gesamtaufnahme - volume:102 |
|---|---|
| Enthalten in: |
Proceedings of the National Academy of Sciences of the United States of America - 102(2005), 41 vom: 11. Okt., Seite 14605-10 |
| Sprache: |
Englisch |
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| Beteiligte Personen: |
Zhang, Jing [VerfasserIn] |
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| Anmerkungen: |
Date Completed 20.04.2006 Date Revised 13.11.2018 published: Print-Electronic Citation Status MEDLINE |
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| Förderinstitution / Projekttitel: |
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| PPN (Katalog-ID): |
NLM158152204 |
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| 245 | 1 | 0 | |a Identification of K-ras as the major regulator for cytokine-dependent Akt activation in erythroid progenitors in vivo |
| 264 | 1 | |c 2005 | |
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| 500 | |a Date Completed 20.04.2006 | ||
| 500 | |a Date Revised 13.11.2018 | ||
| 500 | |a published: Print-Electronic | ||
| 500 | |a Citation Status MEDLINE | ||
| 520 | |a Despite intensive investigation, controversial results have been obtained concerning the precise signaling pathway(s) regulated by K-ras in different cell types. We show that in primary fetal liver erythroid progenitors, erythropoietin activates all three Ras isoforms, but preferentially N- and K-ras. In K-ras(-/-) fetal liver cells (FLC), erythropoietin- or stem cell factor-dependent Akt activation is greatly reduced, whereas other pathways including Stat5 and p44/p42 MAP kinase are activated normally. We further studied the effects of reduced cytokine-dependent Akt activation in erythroid differentiation. We find that freshly isolated K-ras(-/-) FLC show an approximately 7-fold increase of apoptosis and delayed erythroid differentiation, but only at the stage of erythroid progenitors and very early erythroblasts. When K-ras(-/-) erythroid progenitors are cultured in vitro, there is a significant delay in erythroid differentiation but little increase in apoptosis. Furthermore, we show that partial pharmacologic inhibition of the phosphatidylinositol 3-kinase/Akt pathway in wild-type erythroid progenitors leads to a delay in erythroid differentiation similar to that observed in K-ras(-/-) FLC. Taken together, our data identify K-ras as the major regulator for cytokine-dependent Akt activation, which is important for erythroid differentiation in vivo | ||
| 650 | 4 | |a Comparative Study | |
| 650 | 4 | |a Journal Article | |
| 650 | 4 | |a Research Support, N.I.H., Extramural | |
| 650 | 4 | |a Research Support, Non-U.S. Gov't | |
| 650 | 4 | |a Research Support, U.S. Gov't, P.H.S. | |
| 650 | 7 | |a Chromones |2 NLM | |
| 650 | 7 | |a Cytokines |2 NLM | |
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