{Reference Type}: Journal Article
{Title}: DKK1 Activates the PI3K/AKT Pathway via CKAP4 to Balance the Inhibitory Effect on Wnt/β-Catenin Signaling and Regulates Wnt3a-Induced MSC Migration.
{Author}: Chen H;Hu Y;Xu X;Dai Y;Qian H;Yang X;Liu J;He Q;Zhang H;
{Journal}: Stem Cells
{Volume}: 42
{Issue}: 6
{Year}: 2024 Jun 14
{Factor}: 5.845
{DOI}: 10.1093/stmcls/sxae022
{Abstract}: Wnt/β-catenin signaling plays a crucial role in the migration of mesenchymal stem cells (MSCs). However, our study has revealed an intriguing phenomenon where Dickkopf-1 (DKK1), an inhibitor of Wnt/β-catenin signaling, promotes MSC migration at certain concentrations ranging from 25 to 100 ng/mL while inhibiting Wnt3a-induced MSC migration at a higher concentration (400 ng/mL). Interestingly, DKK1 consistently inhibited Wnt3a-induced phosphorylation of LRP6 at all concentrations. We further identified cytoskeleton-associated protein 4 (CKAP4), another DKK1 receptor, to be localized on the cell membrane of MSCs. Overexpressing the CRD2 deletion mutant of DKK1 (ΔCRD2), which selectively binds to CKAP4, promoted the accumulation of active β-catenin (ABC), the phosphorylation of AKT (Ser473) and the migration of MSCs, suggesting that DKK1 may activate Wnt/β-catenin signaling via the CKAP4/PI3K/AKT cascade. We also investigated the effect of the CKAP4 intracellular domain mutant (CKAP4-P/A) that failed to activate the PI3K/AKT pathway and found that CKAP4-P/A suppressed DKK1 (100 ng/mL)-induced AKT activation, ABC accumulation, and MSC migration. Moreover, CKAP4-P/A significantly weakened the inhibitory effects of DKK1 (400 ng/mL) on Wnt3a-induced MSC migration and Wnt/β-catenin signaling. Based on these findings, we propose that DKK1 may activate the PI3K/AKT pathway via CKAP4 to balance the inhibitory effect on Wnt/β-catenin signaling and thus regulate Wnt3a-induced migration of MSCs. Our study reveals a previously unrecognized role of DKK1 in regulating MSC migration, highlighting the importance of CKAP4 and PI3K/AKT pathways in this process.