Protein Tyrosine Phosphatase 1B Regulates Pyruvate Kinase M2 Tyrosine Phosphorylation

Ahmed Bettaieb,Jesse Bakke,Naoto Nagata,Kosuke Matsuo,Yannan Xi,Siming Liu,Daniel Aboubechara,Ramzi Melhem,Kimber Stanhope,Bethany Cummings,James Graham,Andrew Bremer,Sheng Zhang,Costas A Lyssiotis,Zhong-Yin Zhang,Lewis C Cantley,Peter J Havel,Fawaz G Haj

doi:10.1074/jbc.m112.441469

Abstract

Protein-tyrosine phosphatase 1B (PTP1B) is a physiological regulator of glucose homeostasis and adiposity and is a drug target for the treatment of obesity and diabetes. Here we identify pyruvate kinase M2 (PKM2) as a novel PTP1B substrate in adipocytes. PTP1B deficiency leads to increased PKM2 total tyrosine and Tyr(105) phosphorylation in cultured adipocytes and in vivo. Substrate trapping and mutagenesis studies identify PKM2 Tyr-105 and Tyr-148 as key sites that mediate PTP1B-PKM2 interaction. In addition, in vitro analyses illustrate a direct effect of Tyr-105 phosphorylation on PKM2 activity in adipocytes. Importantly, PTP1B pharmacological inhibition increased PKM2 Tyr-105 phosphorylation and decreased PKM2 activity. Moreover, PKM2 Tyr-105 phosphorylation is regulated nutritionally, decreasing in adipose tissue depots after high-fat feeding. Further, decreased PKM2 Tyr-105 phosphorylation correlates with the development of glucose intolerance and insulin resistance in rodents, non-human primates, and humans. Together, these findings identify PKM2 as a novel substrate of PTP1B and provide new insights into the regulation of adipose PKM2 activity.

Highlights

Tyrosine phosphorylation of pyruvate kinase M2 (PKM2) inhibits its activity; the phosphatase(s) that regulates PKM2 phosphorylation remains unidentified
Protein-tyrosine phosphatase 1B (PTP1B) Regulates PKM2 Tyrosine Phosphorylation—Initially, we examined the expression of the M1 splice isoform (PKM1) of the PKM gene and M2 isoform (PKM2) in brown [21] and white (3T3-L1) adipose cell lines
Because mass spectroscopy identified peptides that are common to PKM1 and PKM2, we investigated the coassociation of each isoform with PTP1B

Summary

Background

Tyrosine phosphorylation of PKM2 inhibits its activity; the phosphatase(s) that regulates PKM2 phosphorylation remains unidentified. Protein-tyrosine phosphatase 1B (PTP1B) is a physiological regulator of glucose homeostasis and adiposity and is a drug target for the treatment of obesity and diabetes. Decreased PKM2 Tyr-105 phosphorylation correlates with the development of glucose intolerance and insulin resistance in rodents, non-human primates, and humans. Together, these findings identify PKM2 as a novel substrate of. Genetic and molecular studies identify tyrosine phosphorylation as a regulator of adipose tissue function, systemic glucose homeostasis, and energy balance [5,6,7,8,9]. We identify PKM2 as a novel PTP1B substrate and provide new insights into the regulation of adipose PKM2 activity

EXPERIMENTAL PROCEDURES

RESULTS

DISCUSSION