Showing papers by "Rosario Donato published in 2001"

S100B expression in and effects on microglia.

Abstract: We evaluated the intracellular and extracellular biological role of S100B protein with respect to microglia. S100B, which belongs to the multigenic family of Ca2+-binding proteins, is abundant in astrocytes where it is found diffusely in the cytoplasm and is associated with membranes and cytoskeleton constituents. S100B protein is also secreted by astrocytes and acts on these cells to stimulate nitric oxide secretion in an autocrine manner. However, little is known about the relationship between S100B and microglia. To address this issue, we used primary microglia from newborn rat cortex and the BV-2 microglial cell line, a well-established cell model for the study of microglial properties. S100B expression was assessed by immunofluorescence in primary microglia and by RT-PCR, Western blotting, and immunofluorescence in BV-2 cells. S100B was found in microglia in the form of a filamentous network as well as diffusely in the cytoplasm and associated with intracellular membranes. S100B relocated around phagosomes during BV-2 phagocytosis of opsonized Cryptococcus neoformans. Furthermore, interferon-γ (IFN-γ) treatment caused cell shape changes and redistribution of S100B, and downregulation of S100B mRNA expression in BV-2 cells. Treatment of BV-2 cells with nanomolar to micromolar amounts of S100B resulted in increased IFN-γ–induced expression of inducible nitric oxide synthase mRNA as well as nitric oxide secretion. Taken together, these data suggest a possible role for S100B in the accomplishment/regulation of microglial cell functions. GLIA 33:131–142, 2001. © 2001 Wiley-Liss, Inc.

Prosaposin is immunolocalized to muscle and prosaptides promote myoblast fusion and attenuate loss of muscle mass after nerve injury

Abstract: Prosaposin is the precursor of the saposins and has both neurotrophic and myelinotrophic activity in vitro and in vivo. Using an antibody specific for the holoprotein, an immunocytochemical survey demonstrated intense staining of adult rat skeletal, cardiac, and smooth muscle cells. Prosaposin immunoreactivity in muscle appears dependent on innervation, as denervated adult rat skeletal muscles showed decreased immunostaining that returned to normal levels after reinnervation. TX14(A), a peptide derived from the neurotrophic sequence of prosaposin, attenuated the decline in muscle mass loss following nerve injury induced by a constricting ligature. In vitro, both L6 myoblasts and primary chick-embryo myoblasts showed similar prosaposin immunopositivity, mainly in myotubes. TX14(A) induced a threefold increase in L6 myoblast fusion during early stages of differentiation without affecting cell proliferation. The fusion process was decreased in vitro in a dose-dependent fashion by addition of a neutralizing anti-prosaposin antibody. These data suggest that, in addition to neurotrophic and myelinotrophic activities, prosaposin has myotrophic properties.