Long non-coding RNAs (lncRNAs) have been established to participate in the complex network of various biological processes and play important roles in the differentiation of mesenchymal stem cells (MSCs). However, the roles of lncRNAs in the mechanisms of the osteogenic differentiation of human bone marrow-derived MSCs (HBMSCs) are poorly understood. Thus, this study aimed to investigate the effects of the lncRNA, differentiation antagonizing non-protein coding RNA (DANCR), on the proliferation and osteogenic differentiation of HBMSCs. We found that lncRNA DANCR was abnormally decreased in HBMSCs during osteogenic differentiation. DANCR knockdown induced by transfection with siRNA targeting DANCR (si-DANCR) significantly enhanced the proliferation and osteogenic differentiation of HBMSCs. By contrast, when DANCR expression was enhanced by transfection with a DANCR overexpression vector (pcDNA-DANCR), the proliferation and osteogenic differentiation of the HBMSCs were markedly inhibited. We further found that mitogen-activated protein kinase (MAPK) pathways were involved in the DANCR-mediated proliferation and osteogenic differentiation of HBMSCs. Moreover, DANCR was found to mediate the proliferation and osteogenic differentiation of HBMSCs via p38 MAPK inactivation, but not via extracellular signal-regulated protein kinase (ERK)1/2 or c-Jun N-terminal kinase (JNK) MAPKs, but. Combination treatment (pcDNA-DANCR and with the p38 specific inhibitor, SB203580) led to synergistic inhibitory effects, and these inhibitory effects were reversed by DANCR knockdown. These findings not only provide a novel interpretation for the mechanisms of the proliferation and osteogenic differentiation of HBMSCs, but also suggest that DANCR may be a novel therapeutic target for bone-destructive diseases in the future.
Abscisic acid (ABA) signaling plays important roles in plant growth, development and adaptation to various stresses. RCAR1/PYL9 has been known as a cytoplasm and nuclear ABA receptor in Arabidopsis. To obtain further insight into the regulatory mechanism of RCAR1/PYL9, a yeast two-hybrid approach was performed to screen for RCAR1/PYL9-interacting proteins and an R2R3-type MYB transcription factor, AtMYB44, was identified. The interaction between RCAR1/PYL9 and AtMYB44 was further confirmed by glutathione S-transferase (GST) pull-down and bimolecular fluorescence complementation (BiFC) assays. Gene expression analysis showed that AtMYB44 negatively regulated the expression of ABA-responsive gene RAB18, in contrast to the opposite role reported for RCAR1/PYL9. Competitive GST pull-down assay and analysis of phosphatase activity demonstrated that AtMYB44 and ABI1 competed for binding to RCAR1/PYL9 and thereby reduced the inhibitory effect of RCAR1/PYL9 on ABI1 phosphatase activity in the presence of ABA in vitro. Furthermore, transient activation assay in protoplasts revealed AtMYB44 probably also decreased RCAR1/PYL9-mediated inhibition of ABI1 activity in vivo. Taken together, our work provides a reasonable molecular mechanism of AtMYB44 in ABA signaling.
Neovascularization and the formation of collateral vessels are often impaired in diabetes mellitus (DM) population compared with non-diabetics. Alterations in vascular endothelial growth factor (VEGF) signaling and endothelial nitric oxide synthase (eNOS) dysfunction have been confirmed to play a crucial role in impaired neovascularization in diabetic mice. Accumulating data have suggested that Rg1, a main component of Panax ginseng, has the ability to promote tubulogenesis of human umbilical vein endothelial cells (HUVECs) in vitro, and that the mechanism involves increased expression level of VEGF as well as increased eNOS activation. Thus, we speculated that Rg1 might also have therapeutic effects on the impairment of neovascularization in diabetic individuals. The aim of the present study was to investigate whether Rg1 could improve angiogenesis in ischemic hindlimb of diabetic mice in vivo. Our data demonstrated that Rg1 treatment resulted in improved angiogenesis in the diabetic ischemic hindlimb, and the potential mechanism might involve increased eNOS activation, upregulated VEGF expression, and inhibited apoptosis. Our results suggest that Rg1 may be used as a novel and useful adjunctive drug for the therapy of peripheral arterial disease in DM.
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