Tags

Type your tag names separated by a space and hit enter

Phosphorylation of PTP1B at Ser(50) by Akt impairs its ability to dephosphorylate the insulin receptor.
Mol Endocrinol 2001; 15(10):1768-80ME

Abstract

PTP1B is a protein tyrosine phosphatase that negatively regulates insulin sensitivity by dephosphorylating the insulin receptor. Akt is a ser/thr kinase effector of insulin signaling that phosphorylates substrates at the consensus motif RXRXXS/T. Interestingly, PTP1B contains this motif (RYRDVS(50)), and wild-type PTP1B (but not mutants with substitutions for Ser(50)) was significantly phosphorylated by Akt in vitro. To determine whether PTP1B is a substrate for Akt in intact cells, NIH-3T3(IR) cells transfected with either wild-type PTP1B or PTP1B-S50A were labeled with [(32)P]-orthophosphate. Insulin stimulation caused a significant increase in phosphorylation of wild-type PTP1B that could be blocked by pretreatment of cells with wortmannin or cotransfection of a dominant inhibitory Akt mutant. Similar results were observed with endogenous PTP1B in untransfected HepG2 cells. Cotransfection of constitutively active Akt caused robust phosphorylation of wild-type PTP1B both in the absence and presence of insulin. By contrast, PTP1B-S50A did not undergo phosphorylation in response to insulin. We tested the functional significance of phosphorylation at Ser(50) by evaluating insulin receptor autophosphorylation in transfected Cos-7 cells. Insulin treatment caused robust receptor autophosphorylation that could be substantially reduced by coexpression of wild-type PTP1B. Similar results were obtained with coexpression of PTP1B-S50A. However, under the same conditions, PTP1B-S50D had an impaired ability to dephosphorylate the insulin receptor. Moreover, cotransfection of constitutively active Akt significantly inhibited the ability of wild-type PTP1B, but not PTP1B-S50A, to dephosphorylate the insulin receptor. We conclude that PTP1B is a novel substrate for Akt and that phosphorylation of PTP1B by Akt at Ser(50) may negatively modulate its phosphatase activity creating a positive feedback mechanism for insulin signaling.

Authors+Show Affiliations

Cardiology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

11579209

Citation

Ravichandran, L V., et al. "Phosphorylation of PTP1B at Ser(50) By Akt Impairs Its Ability to Dephosphorylate the Insulin Receptor." Molecular Endocrinology (Baltimore, Md.), vol. 15, no. 10, 2001, pp. 1768-80.
Ravichandran LV, Chen H, Li Y, et al. Phosphorylation of PTP1B at Ser(50) by Akt impairs its ability to dephosphorylate the insulin receptor. Mol Endocrinol. 2001;15(10):1768-80.
Ravichandran, L. V., Chen, H., Li, Y., & Quon, M. J. (2001). Phosphorylation of PTP1B at Ser(50) by Akt impairs its ability to dephosphorylate the insulin receptor. Molecular Endocrinology (Baltimore, Md.), 15(10), pp. 1768-80.
Ravichandran LV, et al. Phosphorylation of PTP1B at Ser(50) By Akt Impairs Its Ability to Dephosphorylate the Insulin Receptor. Mol Endocrinol. 2001;15(10):1768-80. PubMed PMID: 11579209.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Phosphorylation of PTP1B at Ser(50) by Akt impairs its ability to dephosphorylate the insulin receptor. AU - Ravichandran,L V, AU - Chen,H, AU - Li,Y, AU - Quon,M J, PY - 2001/10/2/pubmed PY - 2002/2/22/medline PY - 2001/10/2/entrez SP - 1768 EP - 80 JF - Molecular endocrinology (Baltimore, Md.) JO - Mol. Endocrinol. VL - 15 IS - 10 N2 - PTP1B is a protein tyrosine phosphatase that negatively regulates insulin sensitivity by dephosphorylating the insulin receptor. Akt is a ser/thr kinase effector of insulin signaling that phosphorylates substrates at the consensus motif RXRXXS/T. Interestingly, PTP1B contains this motif (RYRDVS(50)), and wild-type PTP1B (but not mutants with substitutions for Ser(50)) was significantly phosphorylated by Akt in vitro. To determine whether PTP1B is a substrate for Akt in intact cells, NIH-3T3(IR) cells transfected with either wild-type PTP1B or PTP1B-S50A were labeled with [(32)P]-orthophosphate. Insulin stimulation caused a significant increase in phosphorylation of wild-type PTP1B that could be blocked by pretreatment of cells with wortmannin or cotransfection of a dominant inhibitory Akt mutant. Similar results were observed with endogenous PTP1B in untransfected HepG2 cells. Cotransfection of constitutively active Akt caused robust phosphorylation of wild-type PTP1B both in the absence and presence of insulin. By contrast, PTP1B-S50A did not undergo phosphorylation in response to insulin. We tested the functional significance of phosphorylation at Ser(50) by evaluating insulin receptor autophosphorylation in transfected Cos-7 cells. Insulin treatment caused robust receptor autophosphorylation that could be substantially reduced by coexpression of wild-type PTP1B. Similar results were obtained with coexpression of PTP1B-S50A. However, under the same conditions, PTP1B-S50D had an impaired ability to dephosphorylate the insulin receptor. Moreover, cotransfection of constitutively active Akt significantly inhibited the ability of wild-type PTP1B, but not PTP1B-S50A, to dephosphorylate the insulin receptor. We conclude that PTP1B is a novel substrate for Akt and that phosphorylation of PTP1B by Akt at Ser(50) may negatively modulate its phosphatase activity creating a positive feedback mechanism for insulin signaling. SN - 0888-8809 UR - https://www.unboundmedicine.com/medline/citation/11579209/Phosphorylation_of_PTP1B_at_Ser_50__by_Akt_impairs_its_ability_to_dephosphorylate_the_insulin_receptor_ L2 - https://academic.oup.com/mend/article-lookup/doi/10.1210/mend.15.10.0711 DB - PRIME DP - Unbound Medicine ER -