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|Title:||The CCT/TRiC chaperonin is required for maturation of sphingosine kinase 1|
|Citation:||International Journal of Biochemistry & Cell Biology, 2009; 41(4):822-827|
|Publisher:||Pergamon-Elsevier Science Ltd|
|Julia R. Zebol, Niamh M. Hewitt, Paul A. B. Moretti, Helen E. Lynn, Julie A. Lake, Peng Li, Mathew A. Vadas, Binks W. Wattenberg and Stuart M. Pitson|
|Abstract:||Sphingosine kinase 1 (SK1) catalyses the generation of sphingosine 1-phosphate (S1P), a bioactive phospholipid that influences a diverse range of cellular processes, including proliferation, survival, adhesion, migration, morphogenesis and differentiation. SK1 is controlled by various mechanisms, including transcriptional regulation, and post-translational activation by phosphorylation and protein–protein interactions which can regulate both the activity and localisation of this enzyme. To gain a better understanding of the regulatory mechanisms controlling SK1 activity and function we performed a yeast two-hybrid screen to identify SK1-interacting proteins. Using this approach we identified that SK1 interacts with subunit 7 (η) of cytosolic chaperonin CCT (chaperonin containing t-complex polypeptide, also called TRiC for TCP-1 ring complex), a hexadecameric chaperonin that binds unfolded polypeptides and mediates their folding and release in an ATP-dependent manner. Further analysis of the SK1–CCTη interaction demonstrated that other CCT/TRiC subunits also associated with SK1 in HEK293T cell lysates in an ATP-sensitive manner, suggesting that the intact, functional, multimeric CCT/TRiC complex associated with SK1. Furthermore, pulse-chase studies indicated that CCT/TRiC binds specifically to newly translated SK1. Finally, depletion of functional CCT/TRiC through the use of RNA interference in HeLa cells or temperature sensitive CCT yeast mutants reduced cellular SK1 activity. Thus, combined this data suggests that SK1 is a CCT/TRiC substrate, and that this chaperonin facilitates folding of newly translated SK1 into its mature active form.|
|Keywords:||Leukocytes; Hela Cells; Fibroblasts; Humans; Saccharomyces cerevisiae; Sphingosine; Phosphotransferases (Alcohol Group Acceptor); Lysophospholipids; Chaperonins; Two-Hybrid System Techniques; Transfection; Protein Conformation; Protein Folding; Transcriptional Activation; Chaperonin Containing TCP-1|
|Description:||Copyright © 2008 Elsevier|
|Appears in Collections:||Medicine publications|
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