OBJECTIVETo determine the effect of type I transmembrane protein (IRE1alpha) deletions on the cell cycle of human periodontal ligament fibroblasts (hPDLFs) cells.

METHODSBased on the IRE1alpha deletions, a full-length model was successfully constructed. Moreover, overlapping polymerase chain reaction mutagenesis facilitated the establishment of two deletion mutants of IREla (pD-Kinase, pD-Rnase). The full-length model and two mutant eukaryotic expression vectors were transfected into hPDLFs cells. Western blot analysis was performed to identify the expression in the cells. The changes in the cell cycle of hPDLFS cells were detected by flow cytometry (FCM).

RESULTSThe two deletion mutants of IRE1alpha with eukaryotic expression vectors were successfully constructed and correctly expressed in hPDLFs cells based on Western blot analysis. Under stress conditions, the FCM assay showed that cell percentage of S phases increased, whereas that of G1 phases decreased in the IRE1alpha group (P < 0.05) compared with the control group of tunicamycin (TM) treatment. Moreover, the cell percentage of the S phases decreased, whereas that of the G1 phases increased in the D-Rnase group (P < 0.05) compared with the control. The deletion mutant D-Kinase had no influence on hPDLFS cell proliferation and cycle (P>0.05).

CONCLUSIONUnder stress conditions, IRE1alpha can improve the cell cycle of hPDLFs cells from the G1 to the S phase. The deletion mutant D-Rnase cause hPDLFs cell growth arrest at the G1 phase, whereas deletion mutant D-Kinase has no significant effect.