Interferon regulatory factor-1 together with reactive oxygen species promotes the acceleration of cell cycle progression by up-regulating the cyclin E and CDK2 genes during high glucose-induced proliferation of vascular smooth muscle cells.

BACKGROUND: The high glucose-induced proliferation of vascular smooth muscle cells (VSMCs) plays an important role in the development of diabetic vascular diseases. In a previous study, we confirmed that Interferon regulatory factor-1 (Irf-1) is a positive regulator of the high glucose-induced proliferation of VSMCs. However, the mechanisms remain to be determined. METHODS: The levels of cyclin/CDK expression in two cell models involving Irf-1 knockdown and overexpression were quantified to explore the relationship between Irf-1 and its downstream effectors under normal or high glucose conditions. Subsequently, cells were treated with high glucose/NAC, normal glucose/H2O2, high glucose/U0126 or normal glucose/H2O2/U0126 during an incubation period. Then proliferation, cyclin/CDK expression and cell cycle distribution assays were performed to determine whether ROS/Erk1/2 signaling pathway was involved in the Irf-1-induced regulation of VSMC growth under high glucose conditions. RESULTS: We found that Irf-1 overexpression led to down-regulation of cyclin D1/CDK4 and inhibited cell cycle progression in VSMCs under normal glucose conditions. In high glucose conditions, Irf-1 overexpression led to an up-regulation of cyclin E/CDK2 and an acceleration of cell cycle progression, whereas silencing of Irf-1 suppressed the expression of both proteins and inhibited the cell cycle during the high glucose-induced proliferation of VSMCs. Treatment of VSMCs with antioxidants prevented the Irf-1 overexpression-induced proliferation of VSMCs, the up-regulation of cyclin E/CDK2 and the acceleration of cell cycle progression in high glucose conditions. In contrast, under normal glucose conditions, H2O2 stimulation and Irf-1 overexpression induced cell proliferation, up-regulated cyclin E/CDK2 expression and promoted cell cycle acceleration. In addition, overexpression of Irf-1 promoted the activation of Erk1/2 and when VSMCs overexpressing Irf-1 were treated with U0126, the specific Erk1/2 inhibitor abolished the proliferation of VSMCs, the up-regulation of cyclin E/CDK2 and the acceleration of cell cycle progression under high glucose or normal glucose/H2O2 conditions. CONCLUSIONS: These results demonstrate that the downstream effectors of Irf-1 are cyclin E/CDK2 during the high glucose-induced proliferation of VSMCs, whereas they are cyclin D1/CDK4 in normal glucose conditions. The Irf-1 overexpression-induced proliferation of VSMCs, the up-regulation of cyclin E/CDK2 and the acceleration of cell cycle progression are associated with ROS/Erk1/2 signaling pathway under high glucose conditions.

Rat marrow-derived multipotent adult progenitor cells differentiate into skin epidermal cells in vivo.

Wound repair and functional reconstruction are two key aspects for treatment of skin injury. Research on cell source for skin repair has become a focus of study. The immune rejection induced by allograft cells and the limited source of autologous epidermal stem cells have led to more attention on the multipotent adult progenitor cells (MAPC). In this study, we examined the influence of the local environment of skin injury on the migration and differentiation of MAPC in nude mice. The homing of MAPC to the wounds and the epidermal differentiation of MAPC were investigated by detecting the expression of specific antigens of rat major histocompatibility complex I (MHC-I) antigen and the tracing markers. Three weeks after transplantation, hair follicle-like structure appeared and rat MHC-I antigen was positive in the follicles of the healed skin. PKH26-labeled cells expressing cytokeratin were found in the regenerated follicle-like structures, sebaceous glands and sweat glands. Our findings indicate that MAPC can migrate to the skin injury site and the hair follicles, and participate in skin wound healing by differentiating into epidermal cells, which contributes to the theoretical research of MAPC plasticity and provides theoretical evidence for clinical application of transplantation therapy with MAPC.

Simultaneous expression of Oct4 and genes of three germ layers in single cell-derived multipotent adult progenitor cells.

Future application of adult stem cells in clinical therapies largely depends on the successful isolation of homogeneous stem cells with high plasticity. Multipotent adult progenitor cells (MAPCs) are thought to be a more primitive stem cell population capable of extensive in vitro proliferation with no senescence or loss of differentiation capability. The present study was aimed to find a less complicated and more economical protocol for obtaining single cell-derived MAPCs and understand the molecule mechanism of multi-lineage differentiation of MAPCs. We successfully obtained a comparatively homogeneous population of MAPCs and confirmed that single cell-derived MAPCs were able to transcribe Oct4 and genes of three germ layers simultaneously, and differentiate into multiple lineages. Our observations suggest that single cell-derived MAPCs under appropriate circumstances could maintain not only characteristics of stem cells but multi-lineage differentiation potential through quantitative modulation of corresponding regulating gene expression, rather than switching on expression of specific genes.

[Clonal culture of rat bone marrow-derived multipotential adult progenitor cells and study of their biological properties].

OBJECTIVE: To optimize the culture conditions for clonal isolation of rat bone marrow-derived multipotential adult progenitor cells (rMAPC) and identify their surface markers and differentiation potentials. METHODS: By using a low concentration of fetal bovine serum culture medium, rMAPCs were primarily isolated from bone marrow by attachment culture and clonal-like cells were selected by single cell limiting dilution. The surface antigens of the cloned rMAPC were analyzed by flow cytometry and immunocytochemistry. Multi-differentiation capacities were evaluated by lipoblasts and osteoblasts and neuroblasts differentiation induction. The expressions of Oct-4 and three embryonic germ layer markers were detected by RT-PCR. RESULTS: Single cell-derived rMAPC could be expanded to passage 20 in vitro which still maintained active proliferation ability. The expanded rMAPCs expressed CD71, alpha-SMA and vimentin, but not CD34, CD44 and CD45. About 83% of the rMAPCs was in the resting phase(G0 + G1) of cell cycle and 17% in S + G2 + M phase. They could be induced to differentiate into adipogenic cells, osteogenic cells and neural like cells. RT-PCR demonstrated that there were expressions of oct-4 gene and three embryonic germ layer markers on the rMAPCs. CONCLUSIONS: Cloned rMAPC can maintain the phenotypes of stem cell during in vitro culturing. It might be an potential adult stem cell source for therapeutic stem cell transplanting and tissue engineering.