PELP1 promotes the expression of RUNX2 via the ERK pathway during the osteogenic differentiation of human periodontal ligament stem cells.

• PELP1 was upregulated during PDLSCs osteogenic differentiation. • Runx2 expression and ERK phosphorylation were controlled by PELP1 in PDLSCs. • ERK inhibition restrained PELP1 induced Runx2 expression in PDLSCs. The aim of this study was to determine the physiological function and mechanism of proline-, glutamic acid-, and leucine-rich protein 1 (PELP1) in the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) at the molecular level in vitro. During the osteogenic differentiation of hPDLSCs, the change of PELP1 and the osteogenic commitment markers runt-related transcription factor 2(RUNX2), alkaline phosphatase (ALP) and osteocalcin (OCN) were monitored by quantitative real-time PCR (qRT-PCR) and western blots. To elucidate how PELP1 regulates RUNX2 , the expression of RUNX2 , the phosphorylation of extracellular regulated protein kinases (ERK) and subcellular location of PELP1 were detected under conditions that PELP1 was either knockdown by specific siRNA or overexpressed. A pharmacological inhibitor of ERK, U0126 was used while PELP1 was overexpressed, and the expression of RUNX2 was monitored by qRT-PCR. PELP1 was upregulated during the osteogenic differentiation of hPDLSCs. Knockdown of PELP1 suppressed the expression of RUNX2 , whereas overexpression of PELP1 increased RUNX2 expression. Moreover, PELP1 knockdown resulted in reduced ERK phosphorylation and RUNX2 expression, and PELP1 overexpression induced RUNX2 expression was inhibited by U0126 in the hPDLSCs. PELP1 regulates the expression of RUNX2 during the osteogenic differentiation of hPDLSCs and that the ERK pathway is involved in this process. [ABSTRACT FROM AUTHOR]