Cell Signaling Technology

Product Pathways - PI3K / Akt Signaling

Phospho-FoxO3a (Ser294) Antibody #5538

Applications Reactivity Sensitivity MW (kDa) Source
W IP H M R Mk Endogenous 82 to 97 Rabbit

Applications Key:  W=Western Blotting  IP=Immunoprecipitation
Reactivity Key:  H=Human  M=Mouse  R=Rat  Mk=Monkey
Species cross-reactivity is determined by western blot. Species enclosed in parentheses are predicted to react based on 100% sequence homology.

Protocols

Specificity / Sensitivity

Phospho-FoxO3a (Ser294) Antibody detects exogenous and endogenous levels of FoxO3a protein only when phosphorylated at serine 294.

Source / Purification

Polyclonal antibodies are produced by immunizing animals with a synthetic peptide surrounding Ser294 of human FoxO3a. Antibodies are purified by protein A and peptide affinity chromatography.

Western Blotting

Western Blotting

Western blot analysis of extracts from 293T cells, transfected with tagged FoxO3a, using Phospho-FoxO3a (Ser294) Antibody.

Western Blotting

Western Blotting

Western blot analysis of extracts from C2C12 cells, untreated or H2O2 treated, using Phospho-FoxO3a (Ser294) Antibody (upper) or FoxO3a (75D8) Rabbit mAb #2497 (lower).

Background

The Forkhead family of transcription factors is involved in tumorigenesis of rhabdomyosarcoma and acute leukemias (1-3). Within the family, three members (FoxO1, FoxO4, and FoxO3a) have sequence similarity to the nematode orthologue DAF-16, which mediates signaling via a pathway involving IGFR1, PI3K, and Akt (4-6). Active forkhead members act as tumor suppressors by promoting cell cycle arrest and apoptosis. Increased expression of any FoxO member results in the activation of the cell cycle inhibitor p27 Kip1. Forkhead transcription factors also play a part in TGF-β-mediated upregulation of p21 Cip1, a process negatively regulated through PI3K (7). Increased proliferation results when forkhead transcription factors are inactivated through phosphorylation by Akt at Thr24, Ser256, and Ser319, which results in nuclear export and inhibition of transcription factor activity (8). Forkhead transcription factors can also be inhibited by the deacetylase sirtuin (SirT1) (9).

Erk phosphorylates FoxO3a at Ser294, Ser344 and Ser425, resulting in degradation of FoxO3a through the MDM2-mediated ubiquitin-proteasome pathway. Thus, Erk promotes proliferation and tumor progression by inhibiting FoxO3a (10).

  1. Anderson, M.J. et al. (1998) Genomics 47, 187-199.
  2. Galili, N. et al. (1993) Nat. Genet. 5, 230-235.
  3. Borkhardt, A. et al. (1997) Oncogene 14, 195-202.
  4. Nakae, J. et al. (1999) J. Biol. Chem. 274, 15982-15985.
  5. Rena, G. et al. (1999) J. Biol. Chem. 274, 17179-17183.
  6. Guo, S. et al. (1999) J. Biol. Chem. 274, 17184-17192.
  7. Seoane, J. et al. (2004) Cell 117, 211-223.
  8. Arden, K.C. (2004) Mol. Cell 14, 416-418.
  9. Yang, Y. et al. (2005) EMBO J. 24, 1021-1032.
  10. Yang, J.Y. et al. (2008) Nat Cell Biol 10, 138-48.

Application References

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For Research Use Only. Not For Use In Diagnostic Procedures.

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