Classical activation (M1 phenotype) and alternative activation (M2 phenotype) are the two polars of microglial activation states that can produce either detrimental or beneficial effects in the central nervous system (CNS). Harnessing the beneficial properties of microglia cells by modulating their polarization states provides great potential for the treatment of Parkinson's disease (PD). However, the epigenetic mechanism that regulates microglia polarization remains elusive. Here, we reported that histone H3K27me3 demethylase Jumonji domain containing 3 (Jmjd3) was essential for M2 microglia polarization. Suppression of Jmjd3 in N9 microglia inhibited M2 polarization and simultaneously exaggerated M1 microglial inflammatory responses, which led to extensive neuron death in vitro. We also observed that the suppression of Jmjd3 in the substantia nigra (SN) in vivo dramatically caused microglial overactivation and exacerbated dopamine (DA) neuron death in 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-intoxicated mouse model of PD. Moreover, we showed that the Jmjd3 level was lower in the midbrain of aged mice, which was accompanied by an elevated level of H3K27me3 and an increased ratio of M1 to M2 markers, suggesting that aging is an important factor in switching the microglia phenotypes. Overall, our studies indicate that Jmjd3 is able to enhance the polarization of M2 microglia by modifying histone H3K27me3, and therefore it has a pivotal role in the switch of microglia phenotypes that may contribute to the immune pathogenesis of PD.

Mammalian mesenchymal stem cells (MSCs) have been shown to be strongly immunosuppressive in both animal disease models and human clinical trials. We have reported that the key molecule mediating immunosuppression by MSCs is species dependent: indoleamine 2,3-dioxygenase (IDO) in human and inducible nitric oxide synthase (iNOS) in mouse. In the present study, we isolated MSCs from several mammalian species, each of a different genus, and investigated the involvement of IDO and iNOS during MSC-mediated immunosuppression. The characterization of MSCs from different species was by adherence to tissue culture plastic, morphology, specific marker expression, and differentiation potential. On the basis of the inducibility of IDO and iNOS by inflammatory cytokines in MSCs, the tested mammalian species fall into two distinct groups: IDO utilizers and iNOS utilizers. MSCs from monkey, pig, and human employ IDO to suppress immune responses, whereas MSCs from mouse, rat, rabbit, and hamster utilize iNOS. Interestingly, based on the limited number of species tested, the iNOS-utilizing species all belong to the phylogenetic clade, Glires. Although the evolutionary significance of this divergence is not known, we believe that this study provides critical guidance for choosing appropriate animal models for preclinical studies of MSCs.

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Mesenchymal stem cells (MSCs) are believed to exert their regenerative effects through differentiation and modulation of inflammatory responses. However, the relationship between the severity of inflammation and stem cell-mediated tissue repair has not been formally investigated. In this study, we applied different concentrations of dexamethasone (Dex) to anti-CD3-activated splenocyte cultured with or without MSCs. As expected, Dex exhibited a classical dose-dependent inhibition of T-cell proliferation. Surprisingly, although MSCs also blocked T-cell proliferation, the presence of Dex unexpectedly showed a dose-dependent reversion of T-cell proliferation. This effect of Dex was found to be exerted through interfering STAT1 phosphorylation-prompted expression of inducible nitric oxide synthase (iNOS). Interestingly, inflammation-induced chemokines in MSCs was unaffected. To test the role of inflammation severity in stem cell-mediated tissue repair, we employed mice with carbon tetrachloride-induced advanced liver fibrosis and found that although MSCs alone were effective, concurrent administration of Dex abrogated the therapeutic effects of MSCs on fibrin deposition, serum levels of bilirubin, albumin, and aminotransferases, as well as T-lymphocyte infiltration, especially IFN-γ+CD4+ and IL-17A+CD4+T cells. Likewise, iNOS−/− MSCs, which produce chemokines but not nitric oxide under inflammatory conditions, are ineffective in treating advanced liver fibrosis. Therefore, inflammation has a critical role in MSC-mediated tissue repair. In addition, concomitant application of MSCs with steroids should be avoided.

Prefoldin (PFDN) is a co-chaperone protein that is primarily known for its classic cytoplasmic functions in the folding of actin and tubulin monomers during cytoskeletal assembly. Here, we report a marked increase in prefoldin subunit 1 (PFDN1) levels during the transforming growth factor (TGF)-β1-mediated epithelial-mesenchymal transition (EMT) and in human lung tumor tissues. Interestingly, the nuclear localization of PFDN1 was also detected. These observations suggest that PFDN1 may be essential for important novel functions. Overexpression of PFDN1 induced EMT and cell invasion. In sharp contrast, knockdown of PFDN1 generated the opposite effects. Overexpression of PFDN1 was also found to induce lung tumor growth and metastasis. Further experiments showed that PFDN1 overexpression inhibits the expression of cyclin A. PFDN1 suppressed cyclin A expression by directly interacting with the cyclin A promoter at the transcriptional start site. Strikingly, cyclin A overexpression abolished the above PFDN1-mediated effects on the behavior of lung cancer cells, whereas cyclin A knockdown alone induced EMT and increased cell migration and invasion ability. This study reveals that the TGF-β1/PFDN1/cyclin A axis is essential for EMT induction and metastasis of lung cancer cells.

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We report on the InAs quantum dots (QDs) laser in the 1.55μm wavelength region grown by gas source molecular-beam epitaxy. The active region of the laser structure consists of fivefold-stacked InAs QD layers embedded in the InGaAsP layer. Ridge waveguide lasers were processed and continuous-wave mode operation was achieved between 20 and 70°C, with characteristic temperature of 69K. High internal quantum efficiency (56%) and low infinite length threshold current density (128A∕cm2 per QD layer) was obtained for the as-cleaved devices at room temperature. The lasing wavelength range between 1.556 and 1.605μm can be covered by varying the laser cavity length.