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- Title
Pyrvinium pamoate does not activate protein kinase CK1, but promotes Akt/PKB down-regulation and GSK3 activation.
- Authors
VENERANDO, Andrea; GIRARDI, Cristina; RUZZENE, Maria; PINNA, Lorenzo A.
- Abstract
It has been reported that pyrvinium pamoate (PyrPam), an FDA (U.S. Food and Drug Administration)-approved anthelminthic drug, is a potent inhibitor of Wnt signalling by a mechanism which implies the direct activation of protein kinase CK1α. In the present paper, we provide data ruling out any direct stimulatory effect of PyrPam on CK1, by showing that the catalytic activity of CK1α and those of its isoforms d and ? 1 are not significantly affected by PyrPam when tested with the aid of specific peptide and protein substrates. Accordingly, cell treatment with PyrPam has no significant effect on the phosphorylation of β-catenin Ser45. By contrast, the phosphorylation of β-catenin Thr41 is increased upon cell treatment with PyrPam, through a mechanism that implies the upstream dephosphorylation of Akt/PKB (protein kinase B) and of GSK3 (glycogen synthase kinase 3). It can be concluded from the present study that PyrPam is not a bona fide activator of CK1, its perturbation of cell signalling pathways being mediated by a complex mechanism initiated by a fall in Akt phosphorylation whose down-regulation promotes reduced phosphorylation and activation of GSK3. Consistent with this, lysates of cells treated with PyrPam display enhanced protein phosphorylation which is unaffected by CK1 inhibition, while disappearing upon inhibition of GSK3. Our data are consistent with the observation that PyrPam ultimately inhibits Wnt signalling despite its lack of efficacy on CK1.
- Subjects
UNITED States. Food &; Drug Administration; ANTHELMINTICS; WNT proteins; GLYCOGEN synthase kinase-3; PHOSPHORYLATION kinetics; CATENINS
- Publication
Biochemical Journal, 2013, Vol 452, Issue 1, p131
- ISSN
0264-6021
- Publication type
Article
- DOI
10.1042/BJ20121140