The umbilical cord provides a rich source of primitive mesenchymal stem cells (human umbilical cord mesenchymal stem cells (HUMSCs)), which have the potential for transplantation-based treatments of Parkinson's Disease (PD). Our pervious study indicated that adenovirus-associated virus-mediated intrastriatal delivery of human vascular endothelial growth factor 165 (VEGF 165) conferred molecular protection to the dopaminergic system. As both VEGF and HUMSCs displayed limited neuroprotection, in this study we investigated whether HUMSCs combined with VEGF expression could offer enhanced neuroprotection. HUMSCs were modified by adenovirus-mediated VEGF gene transfer, and subsequently transplanted into rotenone-lesioned striatum of hemiparkinsonian rats. As a result, HUMSCs differentiated into dopaminergic neuron-like cells on the basis of neuron-specific enolase (NSE) (neuronal marker), glial fibrillary acidic protein (GFAP) (astrocyte marker), nestin (neural stem cell marker) and tyrosine hydroxylase (TH) (dopaminergic marker) expression. Further, VEGF expression significantly enhanced the dopaminergic differentiation of HUMSCs in vivo. HUMSC transplantation ameliorated apomorphine-evoked rotations and reduced the loss of dopaminergic neurons in the lesioned substantia nigra (SNc), which was enhanced significantly by VEGF expression in HUMSCs. These findings present the suitability of HUMSC as a vector for gene therapy and suggest that stem cell engineering with VEGF may improve the transplantation strategy for the treatment of PD.

Primary human fibroblasts undergoing oncogene-induced or replicative senescence are known to form senescence-associated heterochromatin foci (SAHF), which can stabilize the state of senescence. The retinoblastoma (RB) protein has an important role in SAHF; cells that lack active RB pathway fail to form SAHF. It has been known that the posttranslational modifications of RB, for example, phosphorylation, regulate its function. To date, whether methylation of RB impacts on the SAHF formation is unknown. Here we report that JMJD3, a histone demethylase catalyzing the tri-methylation of H3K27 (H3K27me3), can demethylate the nonhistone protein RB at the lysine810 residue (K810), which is a target of the methyltransferase Set7/9. We detected a significant upregulation of JMJD3 during cellular senescence and SAHF formation in WI38 cells induced by H-RasV 12 , and we found that ectopic expression of JMJD3 promoted cellular senescence and SAHF formation in WI38 cells. Furthermore, during the process of SAHF assembly, JMJD3 was transported to the cytoplasm and interacted with RB through its demethylase domain JmjC. Significantly, our data demonstrated that the JMJD3-mediated demethylation of RB at K810 impeded the interaction of RB with the protein kinase CDK4 and resulted in reduced level of phosphorylation of RB at Serine807/811 (S807/811), implicating an important role of the interplay between the demethylation and phosphorylation of RB in SAHF assembly. This study highlights the role of JMJD3 as a novel inducer of SAHF formation through demethylating RB and provides new insights into the mechanisms of cellular senescence and SAHF assembly. Cellular senescence is an irreversible process of cell cycle arrest. The senescent cells remain metabolically active but are unable to express genes required for cell proliferation. 1,2 The known causes of cellular senescence include telomere shortening, oxidative stress, DNA damage and hyperoncogenic signaling. 3 H-RasV 12 has been used as a model to induce senescence in normal cells. [4][5][6] Senescent cells are typically characterized by a large flat morphology and the expression of a senescence-associated β-galactosidase activity (SA-β-gal), and nuclei of senescence cells may remodel to form the heterochromatin structures termed the senescenceassociated heterochromatin foci (SAHF). 7 SAHF are condensed regions of DNA that correlate with transcriptionally inactive sites. 8 These heterochromatin foci are hallmarked by H3K9me3 and the incorporation of heterochromatin protein HP1, macroH2A, PML (promyelocy leukemia protein) and HMGA1 (high mobility group AT-hook 1). 7,9-11 Recently, it has been shown that repressive markers, such as H3K9me3, H3K9me2 and H3K27me3, are rearranged into the nonoverlapping structural layers in SAHF. 12-14 Changes of heterochromatin organization generate a repressive chromatin environment that prevents transcription of genes that promote growth, thereby stabilize the state of senescence. 7,15 The retinoblastoma (RB) tumor suppressor is an important senesc...

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To explore the effect of SOX2 on osteogenic differentiation of dental pulp stem cells (DPSCs) and to develop a new method for facilitating osteogenic differentiation of DPSCs. SOX2-overexpressing human DPSCs (DPSCs-SOX2) were established through retrovirus infection. Differentiation was induced with osteogenic differentiation medium and further evaluated by alkaline phosphatase (ALP) staining and qPCR. Following the differentiation procedure, the mechanism of SOX2 on osteogenic differentiation of DPSCs was analyzed using genome RNA microarray and flow cytometry. The normal DPSCs, DPSCs-vector, and DPSCs-SOX2 were capable of osteogenic differentiation after 3-4 weeks of introduction and positive for ALP staining. Compared to DPSCs and DPSCs-vector, DPSCs-SOX2 exhibited higher levels of osteogenic gene expression (ALP, collagen I, Runx2, and osterix), indicating the superiority of DPSCs-SOX2 in osteogenic differentiation. Moreover, SOX2 overexpression resulted in the activation of the Hippo signal pathway and increased expressions of the BMPs family. SOX2 promotes the osteogenic differentiation of DPSCs by regulating the osteogenic genes and BMPs family, suggesting the therapeutic potential in bone repair.