Aplastic anemia (AA) is a serious blood system disease that threatens human health. At present, the main cause of this disease is believed to be immune hyperfunction. However, the specific metabolic mode involved in the occurrence of lymphocytes in AA is still unknown. In addition, whether rapamycin, a specific blocker of the mTOR signaling pathway, plays a therapeutic role by inhibiting lymphocyte metabolism remains unclear. We induced an AA mouse model through the classical immune-mediated pathway and simultaneously administered rapamycin intervention therapy. First, the AA-associated phenotypic changes and the efficacy of rapamycin in the treatment of AA were discussed. Second, the proliferation and metabolic pathway of bone marrow (BM) lymphocytes in AA and the effect of rapamycin on this process were determined. Finally, the expression levels of mTOR pathway-related proteins were analyzed. By inhibiting the mTOR signaling pathway, rapamycin could ameliorate the phenotype of the immune-mediated AA model and inhibit the proliferation of T cells by preventing cell cycle transition from G0 to G1 phase. Moreover, we found that mitochondrial oxidative phosphorylation is involved in the metabolic reprogramming of T cells in AA and that rapamycin can inhibit this process. We confirmed that mitochondrial oxidative phosphorylation is involved in the metabolic reprogramming of T cells in AA and further extended the mechanism of rapamycin in treating AA by inhibiting the mTOR signaling pathway. This viewpoint may provide a new therapeutic idea for clinical applications.

MicroRNAs (miRNAs), which are genomically encoded small RNAs, negatively regulate target gene expression at the post-transcriptional level. Our recent study indicated that microRNA-155 (miR-155) might be negatively correlated with blood pressure, and it has been suggested that miR-155-mediated target genes could be involved in the cardiovascular diseases. Bioinformatic analyses predict that angiotensin II type 1 receptor (AT(1)R) is a miR-155 target gene. The present study investigated the potential role of miR-155 in regulating AT(1)R expression and phenotypic differentiation in rat aortic adventitial fibroblasts (AFs). Luciferase assay demonstrated that miR-155 suppressed AT(1)R 3'-UTR reporter construct activity. miR-155 overexpression in AFs did not reduce target mRNA levels, but significantly reduced target protein expression. In addition, AFs transfected with pSUPER/miR-155 exhibited reduced Ang II-induced ERK1/2 activation. miR-155 overexpression in cells attenuated Ang II-induced α-smooth muscle actin (α-SMA, produces myofibroblast) expression, but did not transform growth factor beta-1 (TGF-β1). This study demonstrated that miR-155 could have an important role in regulating adventitial fibroblast differentiation and contribute to suppression of AT(1)R expression.

Leucine-rich repeat containing G-protein-coupled receptor 6 (LGR6) is a member of the rhodopsin-like 7-transmembrane domain receptor superfamily and has high homology to LGR4 and LGR5. LGR6 is highly expressed in osteoblastic progenitors, and LGR6-deficient mice show nail and bone regeneration defect. However, the effect of LGR6 on the osteogenic differentiation of osteoblastic progenitors and its underlying mechanisms are largely unknown. In this study, we overexpressed and knockdown LGR6 with lentivirus in the preosteoblastic cell MC3T3-E1 to observe the effect of LGR6 on osteogenic differentiation and explore its possible molecular mechanism. LGR6 overexpression promoted osteogenic differentiation and mineralization by stabilizing β-catenin to potentiate the Wnt/β-catenin signaling pathway in MC3T3-E1 cells. Conversely, LGR6 knockdown inhibited osteogenic differentiation and mineralization by enhancing β-catenin degradation to inactivate the Wnt/β-catenin signaling pathway. These results reveal that LGR6 is highly expressed in osteoblastic progenitors, and promotes osteogenesis by enhancing β-catenin stability to strengthen the Wnt signaling pathway. This study provides an important reference into the exact mechanisms of osteogenic differentiation.