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Insulin-like growth factor-1-induced phosphorylation of the forkhead family transcription factor FKHRL1 is mediated by Akt kinase in PC12 cells.
J Biol Chem. 2000 Dec 15; 275(50):39152-8.JB

Abstract

The Forkhead family transcription factor FKHRL1, a mammalian homolog of DAF16 in the nematode Caenorhabditis elegans, is an inducer of apoptosis in its unphosphorylated form and was recently reported as a substrate of Akt kinases. Insulin-like growth factor (IGF-1) is a potent stimulant of Akt kinase, leading to inhibition of the apoptotic pathway. In this study, we characterized the phosphorylation of FKHRL1 induced by IGF-1 in PC12 cells and various neuronal cell types and examined the potential role of Akt in this regard. IGF-1 rapidly induced the phosphorylation of Akt and FKHRL1 in PC12 cells. The phosphorylation of Akt and FKHRL1 induced by 10 nm IGF-1 was inhibited by the phosphatidylinositide 3-kinase (PI3K) inhibitors wortmannin (0.25-2 microm) and LY294002 (12.5-100 microm), but not by the MEK inhibitor PD98059 (50 microm) or the p70 S6 kinase pathway inhibitor rapamycin (50 nm), suggesting that the phosphorylation of FKHRL1 induced by IGF-1 is mediated by the PI3K pathway. As observed for IGF-1, an in vitro kinase assay with purified active Akt kinase demonstrated that the kinase is capable of directly phosphorylating FKHRL1 at Thr(32) and Ser(253), leading to inhibition of its pro-apoptotic properties. Moreover, transient expression of constitutively active Akt (MS-Akt, where MS is a myristylation signal) increased the phosphorylation of FKHRL1, whereas the expression of kinase-dead Akt (M179A Akt) attenuated the phosphorylation of FKHRL1 induced by 10 nm IGF-1 in PC12 cells. Interestingly, FKHRL1 co-immunoprecipitated with Akt in PC12 cells, indicating that these two proteins can associate in these cells. As IGF-1 also induced the phosphorylation of FKHRL1 in primary cortical and cerebellar neuronal cultures, these data, taken together, demonstrate that IGF-1, acting via the PI3K/Akt kinase pathway, can regulate the phosphorylation of FKHRL1, leading to inhibition of this apoptotic transcription factor in neuronal cells.

Authors+Show Affiliations

Douglas Hospital Research Center, Departments of Psychiatry and of Pharmacology and Therapeutics, McGill University, Montreal, Quebec H4H 1R3, Canada.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

10995739

Citation

Zheng, W H., et al. "Insulin-like Growth Factor-1-induced Phosphorylation of the Forkhead Family Transcription Factor FKHRL1 Is Mediated By Akt Kinase in PC12 Cells." The Journal of Biological Chemistry, vol. 275, no. 50, 2000, pp. 39152-8.
Zheng WH, Kar S, Quirion R. Insulin-like growth factor-1-induced phosphorylation of the forkhead family transcription factor FKHRL1 is mediated by Akt kinase in PC12 cells. J Biol Chem. 2000;275(50):39152-8.
Zheng, W. H., Kar, S., & Quirion, R. (2000). Insulin-like growth factor-1-induced phosphorylation of the forkhead family transcription factor FKHRL1 is mediated by Akt kinase in PC12 cells. The Journal of Biological Chemistry, 275(50), 39152-8.
Zheng WH, Kar S, Quirion R. Insulin-like Growth Factor-1-induced Phosphorylation of the Forkhead Family Transcription Factor FKHRL1 Is Mediated By Akt Kinase in PC12 Cells. J Biol Chem. 2000 Dec 15;275(50):39152-8. PubMed PMID: 10995739.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Insulin-like growth factor-1-induced phosphorylation of the forkhead family transcription factor FKHRL1 is mediated by Akt kinase in PC12 cells. AU - Zheng,W H, AU - Kar,S, AU - Quirion,R, PY - 2000/9/21/pubmed PY - 2001/3/3/medline PY - 2000/9/21/entrez SP - 39152 EP - 8 JF - The Journal of biological chemistry JO - J Biol Chem VL - 275 IS - 50 N2 - The Forkhead family transcription factor FKHRL1, a mammalian homolog of DAF16 in the nematode Caenorhabditis elegans, is an inducer of apoptosis in its unphosphorylated form and was recently reported as a substrate of Akt kinases. Insulin-like growth factor (IGF-1) is a potent stimulant of Akt kinase, leading to inhibition of the apoptotic pathway. In this study, we characterized the phosphorylation of FKHRL1 induced by IGF-1 in PC12 cells and various neuronal cell types and examined the potential role of Akt in this regard. IGF-1 rapidly induced the phosphorylation of Akt and FKHRL1 in PC12 cells. The phosphorylation of Akt and FKHRL1 induced by 10 nm IGF-1 was inhibited by the phosphatidylinositide 3-kinase (PI3K) inhibitors wortmannin (0.25-2 microm) and LY294002 (12.5-100 microm), but not by the MEK inhibitor PD98059 (50 microm) or the p70 S6 kinase pathway inhibitor rapamycin (50 nm), suggesting that the phosphorylation of FKHRL1 induced by IGF-1 is mediated by the PI3K pathway. As observed for IGF-1, an in vitro kinase assay with purified active Akt kinase demonstrated that the kinase is capable of directly phosphorylating FKHRL1 at Thr(32) and Ser(253), leading to inhibition of its pro-apoptotic properties. Moreover, transient expression of constitutively active Akt (MS-Akt, where MS is a myristylation signal) increased the phosphorylation of FKHRL1, whereas the expression of kinase-dead Akt (M179A Akt) attenuated the phosphorylation of FKHRL1 induced by 10 nm IGF-1 in PC12 cells. Interestingly, FKHRL1 co-immunoprecipitated with Akt in PC12 cells, indicating that these two proteins can associate in these cells. As IGF-1 also induced the phosphorylation of FKHRL1 in primary cortical and cerebellar neuronal cultures, these data, taken together, demonstrate that IGF-1, acting via the PI3K/Akt kinase pathway, can regulate the phosphorylation of FKHRL1, leading to inhibition of this apoptotic transcription factor in neuronal cells. SN - 0021-9258 UR - https://www.unboundmedicine.com/medline/citation/10995739/Insulin_like_growth_factor_1_induced_phosphorylation_of_the_forkhead_family_transcription_factor_FKHRL1_is_mediated_by_Akt_kinase_in_PC12_cells_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0021-9258(19)55845-8 DB - PRIME DP - Unbound Medicine ER -