DKK1 Activates the PI3K/AKT Pathway via CKAP4 to Balance the Inhibitory Effect on Wnt/β-Catenin Signaling and Regulates Wnt3a-Induced MSC Migration

• Published in: Stem cells (Dayton, Ohio) Ohio), 2024-06, Vol.42 (6), p.567
• Main Authors: Chen, Huanhuan, Hu, Ya'nan, Xu, Xiaojing, Dai, Yan, Qian, Hongxiang, Yang, Xinyu, Liu, Jinming, He, Qisheng, Zhang, Huanxiang
• Format: Article
• Language: English
• Subjects: Animals; beta Catenin - metabolism; Cell Movement - drug effects; Humans; Intercellular Signaling Peptides and Proteins - metabolism; Low Density Lipoprotein Receptor-Related Protein-6 - genetics; Low Density Lipoprotein Receptor-Related Protein-6 - metabolism; Mesenchymal Stem Cells - metabolism; Mice; Phosphatidylinositol 3-Kinases - metabolism; Phosphorylation - drug effects; Proto-Oncogene Proteins c-akt - metabolism; Wnt Signaling Pathway - drug effects; Wnt3A Protein - metabolism
• ISSN: 1066-5099; 1549-4918; 1549-4918
• DOI: 10.1093/stmcls/sxae022

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.