EphB4/EphrinB2 signaling regulates pericyte-like function of DPSCs in angiogenesis via transcriptional factor SRF.

BACKGROUND

During angiogenesis, pericytes (PCs) drive vascular stabilization and maturation, a process largely regulated by the transcription factor serum response factor (SRF). Dental pulp stem cells (DPSCs) possess the potential to acquire PC-like properties and regulate angiogenesis. While EphB4/EphrinB2 signaling is reported to be involved in DPSC-mediated angiogenesis, its role in modulating PC-like function remains unexplored. Therefore, this study aims to investigate how EphB4/EphrinB2 signaling regulates the PC-like properties of DPSCs.

METHODS

DPSCs were transfected with lentivirus to knock down or overexpress EphB4. Cell proliferation was assessed by cell counting kit-8 (CCK-8) assay and Ki-67 staining, and cell motility was evaluated using the Boyden chamber assay. To examine the PC-like function of DPSCs, the expression of contractile markers, including alpha-smooth muscle actin (α-SMA), calponin1, and smooth muscle 22-alpha (SM22-α), was analyzed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), Western blot, and immunofluorescence staining, along with collagen contraction assay. Transcriptome profiling was performed to explore the potential downstream factor. The association between EphB4/EphrinB2 signaling and SRF was determined by Western blot and further verified using small interfering RNA (siRNA), followed by collagen contraction assay. Functional PC behavior of DPSCs was evaluated in a three-dimensional (3D) spheroid sprouting model with human umbilical vein endothelial cells (HUVECs).

RESULTS

EphB4 knockdown in DPSCs suppressed the expression of contractile markers and impaired contractility, whereas its overexpression enhanced both. RNA sequencing results revealed an enrichment of differentially expressed genes (DEGs) involved in smooth muscle contraction and Ephrin pathway after EPHB4 silencing. Gene set enrichment analysis (GSEA) showed significant enrichment of smooth muscle contraction, angiogenesis, and neovascularisation-related genes among downregulated genes in EphB4-deficient DPSCs. Moreover, transcription factor binding site (TFBS) of SRF was significantly downregulated. SRF expression closely correlated with EphB4 levels, and SRF silencing abolished EphB4-induced functional enhancement of DPSCs, suggesting SRF as a downstream effector of EphB4/EphrinB2 signaling. 3D spheroid sprouting assay confirmed that EphB4-deficient and SRF-silenced DPSCs failed to restrain HUVEC sprouting due to the impaired PC-like function of DPSCs.

CONCLUSIONS

This study elucidates a novel EphB4/EphrinB2/SRF signaling axis that is pivotal in regulating DPSCs into functional PC-like cells during angiogenesis.