AimThe present study aimed to investigate the bio-function and mechanism of cellular repressor of E1A-stimulated genes (CREG) protein on the migration of vascular smooth muscle cells (SMCs).MethodsHuman wild-type and glycosylation mutant CREG proteins (named wtCREG or mCREG) were transfected and purified in human 293F cells.Human SMCs with CREG knocked-down expression (named OB2) were used to evaluate the effects of two kinds of recombinant CREG protein.The migration of OB2 cells was evaluated by wound-healing assay.The expression and activity was detected by Western blot and gelatin zymography.The differentiational marker proteins of SMCs were i- dentified to express by Western blot analysis.Furthermore, using soluble mannose-6-phosphate/insulin-like growth factor-2 receptor (M6P/IGF2R) fragments and M6P/IGF2R neutralizing antibody, the blocking analysis was finished by detecting the migration of OB2 cells.ResultsBoth wtCREG and mCREG (400 nmol/L) inhibit the migration of OB2 cells.Meanwhile, the expression and activity of matrix metalloproteinase-2 (MMP2) and matrix metalloproteinase-9 (MMP9) were identified to reduce in OB2 cells when treated with recombinant CREG protein.Reversely, the expressions of myocardin, smooth muscle α-actin (SM α-actin), myosin heavy chain (MHC) and caldesmin were detected to enhance obviously.Further blocking experiments using soluble M6P/IGF2R fragments and M6P/IGF2R neutralizing antibody suggest that two kinds of recombinant protein are adequate for modulating SMC migration by binding to domains 11-13.ConclusionThese data suggest that soluble CREG protein can exert its biological function via binding to cell surface M6P/IGF2R, and thereby provide novel insights into CREG modulation of SMC phenotypic switching from contractile to migration.