TY - JOUR
T1 - Importin-α protein binding to a nuclear localization signal of carbohydrate response element-binding protein (ChREBP)
AU - Ge, Qiang
AU - Nakagawa, Tsutomu
AU - Max Wynn, R.
AU - Chook, Yuh Min
AU - Miller, Bonnie C.
AU - Uyeda, Kosaku
N1 - Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.
PY - 2011/8/12
Y1 - 2011/8/12
N2 - Carbohydrate response element-binding protein (ChREBP) is a glucose-responsive transcription factor that plays a critical role in the glucose-mediated induction of genes involved in hepatic glycolysis and lipogenesis. Circulating blood glucose levels affect ChREBP activity in hepatocytes largely by post-translational mechanisms that include phosphorylation-dependent subcellular localization. Previously, we showed that ChREBP is retained in the cytosol by phosphorylation-dependent binding to 14-3-3 protein dimers and identified the α2 helix (residues 125-135) phospho-Ser 140 domain as the primary 14-3-3 binding site (Sakiyama, H., Wynn, R. M., Lee, W. R., Fukasawa, M., Mizuguchi, H., Gardner, K. H., Repa, J. J., and Uyeda, K. (2008) J. Biol. Chem. 283, 24899-24908). To enter the nucleus in response to high glucose, ChREBP must bind importin-α; this heterodimer then forms a complex with importin-β to interact with the nuclear pore complex. In this work, we recharacterized the importin-α binding nuclear localization signal (NLS) of rat ChREBP, identifying it as an extended classical bipartite NLS encompassing minimally residues 158-190. Replacing Lys 159/Lys 190 residues of ChREBP with alanine resulted in loss of importin-α binding, glucose-stimulated transcriptional activity and nuclear localization.Asecondary 14-3-3 protein binding site also was identified, the α3 helix (residues 170-190) phospho-Ser 196 domain. Importin-α and 14-3-3 were found to bind competitively to this secondary site. These results suggest an important mechanism by which importin-α and 14-3-3 control movement of ChREBP in and out of the nucleus in response to changes in glucose levels in liver and thus further suggest that the extended NLS of ChREBP is a critical glucose-sensing, glucose-responsive site.
AB - Carbohydrate response element-binding protein (ChREBP) is a glucose-responsive transcription factor that plays a critical role in the glucose-mediated induction of genes involved in hepatic glycolysis and lipogenesis. Circulating blood glucose levels affect ChREBP activity in hepatocytes largely by post-translational mechanisms that include phosphorylation-dependent subcellular localization. Previously, we showed that ChREBP is retained in the cytosol by phosphorylation-dependent binding to 14-3-3 protein dimers and identified the α2 helix (residues 125-135) phospho-Ser 140 domain as the primary 14-3-3 binding site (Sakiyama, H., Wynn, R. M., Lee, W. R., Fukasawa, M., Mizuguchi, H., Gardner, K. H., Repa, J. J., and Uyeda, K. (2008) J. Biol. Chem. 283, 24899-24908). To enter the nucleus in response to high glucose, ChREBP must bind importin-α; this heterodimer then forms a complex with importin-β to interact with the nuclear pore complex. In this work, we recharacterized the importin-α binding nuclear localization signal (NLS) of rat ChREBP, identifying it as an extended classical bipartite NLS encompassing minimally residues 158-190. Replacing Lys 159/Lys 190 residues of ChREBP with alanine resulted in loss of importin-α binding, glucose-stimulated transcriptional activity and nuclear localization.Asecondary 14-3-3 protein binding site also was identified, the α3 helix (residues 170-190) phospho-Ser 196 domain. Importin-α and 14-3-3 were found to bind competitively to this secondary site. These results suggest an important mechanism by which importin-α and 14-3-3 control movement of ChREBP in and out of the nucleus in response to changes in glucose levels in liver and thus further suggest that the extended NLS of ChREBP is a critical glucose-sensing, glucose-responsive site.
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U2 - 10.1074/jbc.M111.237016
DO - 10.1074/jbc.M111.237016
M3 - Article
C2 - 21665952
AN - SCOPUS:80051505722
SN - 0021-9258
VL - 286
SP - 28119
EP - 28127
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 32
ER -