AIM: To investigate the cell status of dental pulp cells (DPCs) in a sphingosine-1-phosphate (S1P)-induced microinflammation environment and the possible mechanisms of cell homoeostasis maintenance by S1P. METHODOLOGY: Sphingosine-1-phosphate receptor (S1PR) expression was examined in DPCs within a local S1P-induced microinflammation model established using 1 μmol L(-1) S1P. U0126 [extracellular signal-regulated kinase (ERK) inhibitor], LY294002 (AKT inhibitor) and Y27632 (ROCK inhibitor) were used to inhibit corresponding signalling pathways of DPCs. CCK8 and cell cycle analysis tested cell proliferation. Immunofluorescence staining JC-1 detected changes of mitochondrial membrane potential (ΔΨm). Tests for apoptosis and the apoptosis-related proteins Bax and Bcl-2 were assessed by flow cytometry and western blot analysis, respectively. Expressions of ERK and AKT were evaluated by western blot analysis. The results were analysed using the Student's t-test and the significance level set at P < 0.05. RESULTS: Expressions of S1PR1, S1PR2 and S1PR3 in DPCs differed amongst individuals. DPCs maintained self-homoeostasis in response to S1P-induced microinflammation via S1PRs. During this repair process, ERK, AKT and ROCK had a short-term complementary interaction at 60 min, but then AKT and ERK gradually played decisive roles after 24 h in proliferation enhancement and apoptosis inhibition, respectively (P > 0.05). CONCLUSIONS: The AKT-ERK balance may determine whether DPC homoeostasis in S1P-induced microinflammation is maintained by synergistic regulation of cell growth and apoptosis.
AIM: To investigate the cell status of dental pulp cells (DPCs) in a sphingosine-1-phosphate (S1P)-induced microinflammation environment and the possible mechanisms of cell homoeostasis maintenance by S1P. METHODOLOGY:Sphingosine-1-phosphate receptor (S1PR) expression was examined in DPCs within a local S1P-induced microinflammation model established using 1 μmol L(-1) S1P. U0126 [extracellular signal-regulated kinase (ERK) inhibitor], LY294002 (AKT inhibitor) and Y27632 (ROCK inhibitor) were used to inhibit corresponding signalling pathways of DPCs. CCK8 and cell cycle analysis tested cell proliferation. Immunofluorescence staining JC-1 detected changes of mitochondrial membrane potential (ΔΨm). Tests for apoptosis and the apoptosis-related proteins Bax and Bcl-2 were assessed by flow cytometry and western blot analysis, respectively. Expressions of ERK and AKT were evaluated by western blot analysis. The results were analysed using the Student's t-test and the significance level set at P < 0.05. RESULTS: Expressions of S1PR1, S1PR2 and S1PR3 in DPCs differed amongst individuals. DPCs maintained self-homoeostasis in response to S1P-induced microinflammation via S1PRs. During this repair process, ERK, AKT and ROCK had a short-term complementary interaction at 60 min, but then AKT and ERK gradually played decisive roles after 24 h in proliferation enhancement and apoptosis inhibition, respectively (P > 0.05). CONCLUSIONS: The AKT-ERK balance may determine whether DPC homoeostasis in S1P-induced microinflammation is maintained by synergistic regulation of cell growth and apoptosis.