Astroglial cells are involved in directional movements of neurons such as migration of the neuronal cell body and growth of neurites. In the mammalian midbrain, medial (M) and lateral (L) radial glia and derived astrocytes differ in their ability to support neuritic growth. In previous work, we have demonstrated that the growthpermissive ability of L astrocytes and non-permissive properties of M astrocytes correlate with the respective composition of the cell surface-associated and secreted glycosaminoglycans (GAGs). Recent work also shows that the GAG-degrading enzyme heparitinase I increases the neurite growth-promoting ability of M midbrain astrocytes (Garcia-Abreu J et al. 2000 Glia 29: 260). In agreement with previous AFM studies of living glial cell lines and cells in primary culture, imaging of living L and M cells at similar load forces showed structures identified as F-actin fibers. Moreover, no systematic differences were observed between L and M pictures. By contrast, the surfaces of formaldehyde-fixed lateral (L) and medial (M) astrocytes differ by the presence of conspicuous 250 nm protrusions in the former, and of a fibrillar network in the extracellular matrix of the latter. Furthermore, we show that treatment with heparitinase I leads to disappearance of the fibrils from M cells and, consequently, to the assumption of an L-like appearance. Our results suggest that the formation of fibrils may follow from an ability to form large aggregates by association of HS carbohydrate units as has been unexpectedly detected by AFM for oligomers of polysialic acid or polysialic acid-containing carbohydrate units of N-CAM, with formation of filament bundles (Toikka J et al. 1998. J Biol Chem 273: 28557). Taken together with the functional effects of heparitinase I treatment, our present results demonstrate an important role of the extracellular matrix on the functional properties of astrocytes. They also emphasize the power and potentialities of AFM in the study of the extracellular matrix on the surface of fixed cells. - ( June 27, 2000 ) . * Supported by PRONEX/ MCT, CNPq, FAPERJ, CEPG/UFRJ. E-mail: gweissmuller@hotmail.com Aggregation of amyloid β peptide (Aβ) into fibrils and deposition as senile plaques are primarily related to neurotoxicity in Alzheimer's Disease (AD). Thus, agents interfering with aggregation may be potentially useful in preventing or decreasing Aβ toxicity. We first studied the effects of guanidine hydrochloride and temperature on the stability of fibrillar Aβ using peptides truncated at different positions. These experiments suggested that hydrophobic interactions mediated by the C-terminal portion of Aβ are important for fibril stability. Based on these results, we found two compounds capable of disaggregating amyloid fibrils at micromolar concentrations, as indicated by light scattering measurements and transmission electron microscopy. When applied to primary cultures of E18 rat hippocampal neurons, both drugs significantly reduced Aβ-induced cell death (as assayed by trypan blue ...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.