Abstract
Wnt5a regulates multiple intracellular signalling cascades, but how Wnt5a determines the specificity of these pathways is not well understood. This study examined whether the internalization of Wnt receptors affects the ability of Wnt5a to regulate its signalling pathways. Wnt5a activated Rac in the beta-catenin-independent pathway, and Frizzled2 (Fz2) and Ror1 or Ror2 were required for this action. Fz2 was internalized through a clathrin-mediated route in response to Wnt5a, and inhibition of clathrin-dependent internalization suppressed the ability of Wnt5a to activate Rac. As another action of Wnt5a, it inhibited Wnt3a-dependent lipoprotein receptor-related protein 6 (LRP6) phosphorylation and beta-catenin accumulation. Wnt3a-dependent phosphorylation of LRP6 was enhanced in Wnt5a knockout embryonic fibroblasts. Fz2 was also required for the Wnt3a-dependent accumulation of beta-catenin, and Wnt5a competed with Wnt3a for binding to Fz2 in vitro and in intact cells, thereby inhibiting the beta-catenin pathway. This inhibitory action of Wnt5a was not affected by the impairment of clathrin-dependent internalization. These results suggest that Wnt5a regulates distinct pathways through receptor internalization-dependent and -independent mechanisms.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Animals
-
Binding, Competitive
-
CHO Cells
-
Cell Line
-
Clathrin / metabolism
-
Cricetinae
-
Cricetulus
-
Frizzled Receptors / metabolism*
-
HeLa Cells
-
Humans
-
L Cells
-
LDL-Receptor Related Proteins / metabolism
-
Low Density Lipoprotein Receptor-Related Protein-6
-
Mice
-
Mice, Inbred C57BL
-
Mice, Knockout
-
Phosphorylation
-
Protein Binding
-
Proto-Oncogene Proteins / antagonists & inhibitors
-
Proto-Oncogene Proteins / genetics
-
Proto-Oncogene Proteins / metabolism*
-
Proto-Oncogene Proteins / pharmacology
-
RNA, Small Interfering / genetics
-
Receptors, G-Protein-Coupled / metabolism*
-
Recombinant Proteins / genetics
-
Recombinant Proteins / metabolism
-
Signal Transduction
-
Wnt Proteins / antagonists & inhibitors
-
Wnt Proteins / deficiency
-
Wnt Proteins / genetics
-
Wnt Proteins / metabolism*
-
Wnt Proteins / pharmacology
-
Wnt-5a Protein
-
Wnt3 Protein
-
Wnt3A Protein
-
beta Catenin / metabolism
-
rac GTP-Binding Proteins / metabolism
Substances
-
CTNNB1 protein, human
-
Clathrin
-
FZD2 protein, human
-
Frizzled Receptors
-
LDL-Receptor Related Proteins
-
LRP6 protein, human
-
Low Density Lipoprotein Receptor-Related Protein-6
-
Lrp6 protein, mouse
-
Proto-Oncogene Proteins
-
RNA, Small Interfering
-
Receptors, G-Protein-Coupled
-
Recombinant Proteins
-
WNT3A protein, human
-
WNT5A protein, human
-
Wnt Proteins
-
Wnt-5a Protein
-
Wnt3 Protein
-
Wnt3A Protein
-
Wnt3a protein, mouse
-
Wnt5a protein, mouse
-
beta Catenin
-
rac GTP-Binding Proteins