The CCAAT/enhancer binding protein α (C/EBPα) is a transcription factor required for differentiation of myeloid progenitors. In acute myeloid leukemia (AML) cells expressing the constitutively active FLT3-ITD receptor tyrosine kinase, MAP kinase-dependent phosphorylation of serine 21 (S21) inhibits the ability of C/EBPα to induce granulocytic differentiation. To assess whether this post-translational modification also modulates the activity of C/EBPα in BCR/ABL-expressing cells, we tested the biological effects of wild-type and mutant C/EBPα mimicking phosphorylated or non-phosphorylatable serine 21 (S21D and S21A, respectively) in K562 cells ectopically expressing tamoxifen-regulated C/EBPα-ER chimeric proteins. We show here that S21D C/EBPα-ER induced terminal granulocytic differentiation of K562 cells almost as well as wild-type C/EBPα-ER, while S21A C/EBPα-ER was less efficient. Furthermore, wild-type C/EBPα suppressed the proliferation and colony formation of K562 cells vigorously, while S21D and S21A C/EBPα mutants had more modest anti-proliferative effects. Both mutants were less effective than wild-type C/EBPα in suppressing endogenous E2F-dependent transactivation and bound less E2F-2 and/or E2F-3 proteins in anti-C/EBPα immunoprecipitates. Together, these findings suggest that mutation of S21 more than its phosphorylation inhibits the anti-proliferative effects of C/EBPα due to reduced interaction with or impaired regulation of the activity of E2F proteins. By contrast, phosphorylation of serine 21 appears to have a modest role in modulating the differentiation-inducing effects of C/EBPα in K562 cells.

Phosphorylation of serine 21 modulates the proliferation inhibitory more than the differentiation inducing effects of C/EBPα in K562 cells / Fragliasso, Valentina; Y., Chiodo; Ferrari, Giovanna; Soliera, Angela Rachele; Manzotti, Gloria; Cattelani, Sara; Candini, Olivia; Grisendi, Giulia; J., Vergalli; Sa, Mariani; Guerzoni, Clara; Calabretta, Bruno. - In: JOURNAL OF CELLULAR BIOCHEMISTRY. - ISSN 0730-2312. - ELETTRONICO. - 113:(2012), pp. 1704-1713. [10.1002/jcb.24040]

Phosphorylation of serine 21 modulates the proliferation inhibitory more than the differentiation inducing effects of C/EBPα in K562 cells.

FRAGLIASSO, VALENTINA;FERRARI, Giovanna;SOLIERA, Angela Rachele;MANZOTTI, GLORIA;CATTELANI, Sara;CANDINI, Olivia;GRISENDI, Giulia;GUERZONI, Clara;CALABRETTA, Bruno
2012

Abstract

The CCAAT/enhancer binding protein α (C/EBPα) is a transcription factor required for differentiation of myeloid progenitors. In acute myeloid leukemia (AML) cells expressing the constitutively active FLT3-ITD receptor tyrosine kinase, MAP kinase-dependent phosphorylation of serine 21 (S21) inhibits the ability of C/EBPα to induce granulocytic differentiation. To assess whether this post-translational modification also modulates the activity of C/EBPα in BCR/ABL-expressing cells, we tested the biological effects of wild-type and mutant C/EBPα mimicking phosphorylated or non-phosphorylatable serine 21 (S21D and S21A, respectively) in K562 cells ectopically expressing tamoxifen-regulated C/EBPα-ER chimeric proteins. We show here that S21D C/EBPα-ER induced terminal granulocytic differentiation of K562 cells almost as well as wild-type C/EBPα-ER, while S21A C/EBPα-ER was less efficient. Furthermore, wild-type C/EBPα suppressed the proliferation and colony formation of K562 cells vigorously, while S21D and S21A C/EBPα mutants had more modest anti-proliferative effects. Both mutants were less effective than wild-type C/EBPα in suppressing endogenous E2F-dependent transactivation and bound less E2F-2 and/or E2F-3 proteins in anti-C/EBPα immunoprecipitates. Together, these findings suggest that mutation of S21 more than its phosphorylation inhibits the anti-proliferative effects of C/EBPα due to reduced interaction with or impaired regulation of the activity of E2F proteins. By contrast, phosphorylation of serine 21 appears to have a modest role in modulating the differentiation-inducing effects of C/EBPα in K562 cells.
113
1704
1713
Phosphorylation of serine 21 modulates the proliferation inhibitory more than the differentiation inducing effects of C/EBPα in K562 cells / Fragliasso, Valentina; Y., Chiodo; Ferrari, Giovanna; Soliera, Angela Rachele; Manzotti, Gloria; Cattelani, Sara; Candini, Olivia; Grisendi, Giulia; J., Vergalli; Sa, Mariani; Guerzoni, Clara; Calabretta, Bruno. - In: JOURNAL OF CELLULAR BIOCHEMISTRY. - ISSN 0730-2312. - ELETTRONICO. - 113:(2012), pp. 1704-1713. [10.1002/jcb.24040]
Fragliasso, Valentina; Y., Chiodo; Ferrari, Giovanna; Soliera, Angela Rachele; Manzotti, Gloria; Cattelani, Sara; Candini, Olivia; Grisendi, Giulia; J., Vergalli; Sa, Mariani; Guerzoni, Clara; Calabretta, Bruno
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

Caricamento pubblicazioni consigliate

Licenza Creative Commons
I metadati presenti in IRIS UNIMORE sono rilasciati con licenza Creative Commons CC0 1.0 Universal, mentre i file delle pubblicazioni sono rilasciati con licenza Attribuzione 4.0 Internazionale (CC BY 4.0), salvo diversa indicazione.
In caso di violazione di copyright, contattare Supporto Iris

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/745402
Citazioni
  • ???jsp.display-item.citation.pmc??? 3
  • Scopus 5
  • ???jsp.display-item.citation.isi??? 5
social impact