The M variant of encephalomyocarditis (EMC) 1 virus produces a diabetes-like syndrome in mice by infecting and destroying pancreatic beta cells (1-3). The severity of the diabetes correlates with the degree of virus-induced beta cell damage (4, 5). Only certain inbred strains of mice develop diabetes, and susceptibility to EMC virusinduced diabetes is inherited as an autosomal recessive trait (2, 6-8). The genetic factors controlling susceptibility operate at the level of the beta cell, and whether a particular strain of mouse develops diabetes appears to be related to differences in the permissiveness of beta cells to infection with EMC virus (9, 10).Previous experiments (5) showed that when mice were inoculated with a high concentration of mouse-passaged EMC virus (10 8 plaque-forming units [PFU]), fewer animals developed diabetes than when inoculated with a low concentration of the same virus (10 ~ PFU). Moreover, the diabetogenic capacity of the virus was markedly diminished after passage in mouse fibroblast cultures, but was restored when passaged in mice. This raised the possibility that the stock pool of EMC virus was made up of two populations of virus: one that had a tropism for beta cells and produced diabetes and the other that did not have a tropism for beta cells and was nondiabetogenic (5).The present investigation was initiated to see, first, whether our stock pool of the M variant of EMC virus was made up of a mixture of diabetogenic and nondiabetogenic virus and, second, whether the nondiabetogenic virus inhibited the development of diabetes. Materials and MethodsMice. Unless otherwise indicated, SJL/J male mice, 5-6 wk old, obtained from The Jackson Laboratory, Bar Harbor, Maine, were used in all experiments. Animals were inoculated with virus by the intraperitoneal route.Pancreatic Beta Cell Cultures. Pancreata were aseptically removed from suckling SJL/J mice, and beta cell cultures were prepared as described previously (9). The cultures were refed at 2-d intervals, and at 6 d the monolayers were used to passage virus. Staining of the monolayers with fluorescein isothiocyanate-labeled antibody to insulin indicated that 40-70% of the cells were beta cells (9).Virus. The M variant of EMC virus (1), prepared as described elsewhere, was passaged five J Abbrev.iations used in this paper: EMC, encephalomyocarditis; FITC, fluorescein isothiocyanate; IRI, immunoreactive insulin; PFU, plaque-forming units; SME, secondary mouse embryo; VSV, vesicular stomatitis virus.

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Reovirus type 3, passaged in pancreatic beta-cell cultures, produced an insulitis when inoculated into 1- to 2-week-old mice. By means of a double-label antibody technique, in which we used fluorescein-labeled antibody to reovirus and rhodamine-labeled antibody to insulin, reovirus antigens were found in beta cells. By electron microscopy, viral particles in different stages of morphogenesis were observed in insulin-containing beta cells but not glucagon-containing alpha cells. The infection resulted in destruction of beta cells, reduction in the insulin content of the pancreas, and alteration in the host's capacity to respond normally to a glucose tolerance test.

Crosstalk of signaling pathways play crucial roles in cell proliferation, cell differentiation, and cell fate determination for development. In the case of ventx1.1 in Xenopus embryos, both BMP-4/Smad-1 and FGF/Xbra signaling induce the expression of neural repressor ventx1.1. However, the details of how these two pathways interact and lead to neural inhibition by ventx1.1 remain largely unknown. In the present study, Xbra directly bound to the ventx1.1 promoter region and inhibited neurogenesis in a Ventx1.1-dependent manner. Furthermore, Smad-1 and Xbra physically interacted and regulated ventx1.1 transcription in a synergistic fashion. Xbra and Smad-1 interaction cooperatively enhanced the binding of an interacting partner within the ventx1.1 promoter and maximum cooperation was achieved in presence of intact DNA binding sites for both Smad-1 and Xbra. Collectively, BMP-4/Smad-1 and FGF/Xbra signal crosstalk cooperate to activate the transcription of neural repressor ventx1.1 in Xenopus embryos. This suggests that the crosstalk between BMP-4 and FGF signaling negatively regulates early neurogenesis by synergistic activation of ventx1.1 in Xenopus embryos.

Although Eph-ephrin signalling has been implicated in the migration of cranial neural crest (CNC) cells, it is still unclear how ephrinB transduces signals regulating this event. We provide evidence that TBC1d24, a putative Rab35-GTPase activating protein (Rab35 GAP), complexes with ephrinB2 via the scaffold Dishevelled (Dsh) and mediates a signal affecting contact inhibition of locomotion (CIL) in CNC cells. Moreover, we found that, in migrating CNC, the interaction between ephrinB2 and TBC1d24 negatively regulates E-cadherin recycling in these cells via Rab35. Upon engagement of the cognate Eph receptor, ephrinB2 is tyrosine phosphorylated, which disrupts the ephrinB2/Dsh/TBC1d24 complex. The dissolution of this complex leads to increasing E-cadherin levels at the plasma membrane, resulting in loss of CIL and disrupted CNC migration. Our results indicate that TBC1d24 is a critical player in ephrinB2 control of CNC cell migration via CIL.

The capacity of Coxsackie B3 virus to infect insulin-containing beta cells was studied in human pancreatic cell cultures. Antibody to Coxsackie B3 virus was labeled with fluorescein isothiocyanate, and antibody to insulin was labeled with rhodamine. By use of a double-label antibody technique, three populations of cells were identified: uninfected insulin-containing beta cells, which stained only with rhodamine-labeled anti-insulin antibody; Coxsackie-infected (noninsulin-containing) cells, which stained only with fluorescein-labeled anti-Coxsackie antibody; and Coxsackie-infected insulin-containing beta cells, which stained with both antibodies. Radioimmunoassay showed that intracellular immunoreactive insulin decreased rapidly beginning at 24 hours after infection, and the decrease in insulin roughly paralleled the increase in viral titer. It is concluded that, under in vitro conditions, human beta cells are susceptible to Coxsackie B3 virus.

Hydrocolloid dressings have been developed for many types of wound healing. In particular, dressing is a critical component in the successful recover of burn injuries, which causes a great number of people to not only suffer from physical but also psychological and economic anguish each year. Additionally, silk fibroin is the safest material for tissue engineering due to biocompatibility. In this study, we fabricated hydrocolloid dressings incorporating silk fibroin nanoparticles to enhance the efficacy of hydrocolloid dressing and then use this silk fibroin nanoparticle hydrocolloid dressing (SFNHD) in animal models to treat burn wounds. The structures and properties of SFN-HD were characterized using tensile strength and Cell Counting Kit-8 assay. The results indicated the structural stability and the cellular biocompatibility of the hydrocolloid dressing suggesting that SFNHD can be applied to the treatment of wounds. To demonstrate the capacity of a silk fibroin hydrocolloid dressing to treat burn wounds, we compared SFNHD to gauze and Neoderm ® , a commercially available dressing. This study clearly demonstrated accelerated wound healing with greater wound structural integrity and minimal wound size after treatment with SFNHD. These observations indicate that SFNHD may be an improvement upon current standard dressings such as Gauze and Neoderm ® for burn wounds.

During Xenopus early development, FGF signaling is involved in mesoderm formation and neurogenesis by modulating various signaling cascades. FGF-MAPK signaling induces Xbra expression, which maintains mesodermal fate through an autocatalytic-loop. Interestingly, previous reports have demonstrated that basic FGF (bFGF) treatment alone does not induce neurogenesis in ectodermal explants, even though FGF signaling inhibits BMP signaling via phosphorylation in Smad1 linker region. In addition, the overexpression of dominantnegative Xbra induces neurogenesis in ectodermal explants. However, the detailed mechanism underlying these phenomena has not yet been clarified. In this work, we showed that bFGF-Xbra signaling increased the PV.1 expression. DN-Xbra was found to decrease PV.1 expression, and the co-injection of PV.1 with DN-Xbra reduced neurogenesis in ectodermal explants. Furthermore, the knockdown of PV.1 induced neurogenesis in bFGF-treated ectodermal explants. Taken together, our results demonstrate that FGF-Xbra signaling induces PV.1 expression and that PV.1 functions as a neural repressor in the FGF-treated ectoderm. [BMB Reports 2014; 47(12): 673-678]