Cell Signaling Technology

Product Pathways - Akt Signaling

Phospho-FoxO1 (Ser319)/FoxO4 (Ser262) Antibody #2487

Applications Reactivity MW (kDa) Source
W H 65 (FoxO4) and 120 (GFP-FoxO1) Rabbit

Applications Key:  W=Western Blotting
Reactivity Key:  H=Human
Species enclosed in parentheses are predicted to react based on 100% sequence homology. Species cross-reactivity is determined by Western blot.

Specificity / Sensitivity

Phospho-FoxO1 (Ser319)/FoxO4 (Ser262) Antibody detects exogenous levels of FoxO1 only when phosphorylated at serine 319 and exogenous levels of FoxO4 only when phosphorylated at serine 262. The antibody does not cross-react with FoxO1 phosphorylated at other sites, FoxO4 phosphorylated at other sites nor with FoxO3a phosphorylated at any sites.

Source / Purification

Polyclonal antibodies are produced by immunizing rabbits with a synthetic phospho-peptide (KLH-coupled) corresponding to residues surrounding Ser262 of human FoxO4. Antibodies are purified by protein A and peptide affinity chromatography.

Western Blotting

Western Blotting

Western blot analysis of extracts from serum-treated COS-7 cells exogenously expressing FoxO4 or Fox03a, using Phospho-FoxO1 (Ser319)/FoxO4 (Ser262) Antibody. The phospho-specificity of the antibody was verified by treating the membrane with (+) or without (-) calf intestinal phosphatase (CIP) after Western transfer.

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 p27Kip1. Forkhead transcription factors also play a part in TGF-β-mediated upregulation of p21CIP1, 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).

  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.

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