Mutations in the Drosophila trol gene cause cell cycle arrest of neuroblasts in the larval brain. Here, we show that trol encodes the Drosophila homolog of Perlecan and regulates neuroblast division by modulating both FGF and Hh signaling. Addition of human FGF-2 to trol mutant brains in culture rescues the trol proliferation phenotype, while addition of a MAPK inhibitor causes cell cycle arrest of the regulated neuroblasts in wildtype brains. Like FGF, Hh activates stem cell division in the larval brain in a Trol-dependent fashion. Coimmunoprecipitation studies are consistent with interactions between Trol and Hh and between mammalian Perlecan and Shh that are not competed with heparin sulfate. Finally, analyses of mutations in trol, hh, and ttv suggest that Trol affects Hh movement. These results indicate that Trol can mediate signaling through both of the FGF and Hedgehog pathways to control the onset of stem cell proliferation in the developing nervous system.

SUMMARYTheiler's murine encephalomyelitis virus (TMEV) gives rise to a biphasic disease of the central nervous system (CNS) following intracranial inoculation of susceptible strains of mice. The early phase, during the first month, resembles poliomyelitis and in the late phase the mice suffer from inflammatory demyelination reminiscent of multiple sclerosis. In order to investigate the role of helper T cells in the acute and chronic phases of the disease we depleted mice of their L3T4 T cells in vivo with rat monoclonal antibodies, prior to infection and prior to the onset of clinical signs of demyelination. Mice depleted of their helper cells failed to produce antibodies to TMEV and consequently were unable to clear virus from the CNS and died within the first month of infection. Depletion of T cells before the demyelinating phase ol" the disease resulted in a marked decrease in the incidence of disease from 77 ~ of the immunocompetent animals with clinical signs of paralysis to 36%. Immunocompetent TMEV-infected mice also developed antibodies against myelin suggesting that autoimmune mechanisms may play a role in TMEV-induced demyelination.

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The developed multisite BBB chip is expected to be used for screening drug by more accurately predicting their permeability through BBB as well as their toxicity.

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