Search PubMed⌕ Search

Biomedical subjects

S Porter

Publications and source records attributed to S Porter.

At least 181 records · Page 10Linked to original sources
PubMed1986

Specific asparagine-linked oligosaccharides are not required for certain neuron-neuron and neuron-Schwann cell interactions.

To determine whether specific asparagine-linked (N-linked) oligosaccharides present in cell surface glycoproteins are required for cell-cell interactions within the peripheral nervous system, we have used castanospermine to inhibit maturation of N-linked sugars in cell cultures of neurons or neurons plus Schwann cells. Maximally 10-15% of the N-linked oligosaccharides on neuronal proteins have normal structure when cells are cultured in the presence of 250 micrograms/ml castanospermine; the remaining oligosaccharides are present as immature carbohydrate chains not normally found in these glycoproteins. Although cultures were treated for 2 wk with castanospermine, cells always remained viable and appeared healthy. We have analyzed several biological responses of embryonic dorsal root ganglion neurons, with or without added purified populations of Schwann cells, in the presence of castanospermine. We have observed that a normal complement of mature, N-linked sugars are not required for neurite outgrowth, neuron-Schwann cell adhesion, neuron-induced Schwann cell proliferation, or ensheathment of neurites by Schwann cells. Treatment of neuronal cultures with castanospermine increases the propensity of neurites to fasciculate. Extracellular matrix deposition by Schwann cells and myelination of neurons by Schwann cells are greatly diminished in the presence of castanospermine as assayed by electron microscopy and immunocytochemistry, suggesting that specific N-linked oligosaccharides are required for the expression of these cellular functions.

Alkaloids↗
PubMed1986

Schwann cells stimulated to proliferate in the absence of neurons retain full functional capability.

Schwann cells from neonatal rat sciatic nerve can be maintained and grown in culture in the absence of neurons. We are interested in substantially expanding such cultures for use in the study of Schwann cells, their growth responses, and their interactions with neurons. However, it was important to determine if expanded cell populations retained their distinguishing biological properties and their ability to differentiate when recombined with neurons. Therefore, we have compared the functional properties of extensively expanded populations of sciatic nerve Schwann cells to those of embryonic dorsal root ganglion (DRG) Schwann cells that had been briefly expanded in vitro in the continuous presence of ganglion neurons. Sciatic nerve Schwann cells were cultured and purified according to the methods of Brockes et al. (1979). A combination of crude glial growth factor and forskolin was found to act synergistically in providing maximal stimulation of Schwann cell proliferation. Sciatic nerve Schwann cells that were continuously expanded for at least 2 months were compared to Schwann cells derived from fetal dorsal root ganglia. The results indicate that the complement of secreted proteins from both cell populations, either in isolation or recombined with neurons, was essentially identical; both cell populations expressed the cell-surface antigens laminin and Ran 1 (217C antibody); after seeding onto DRG neurons, both cell populations associated with neuronal processes with the same time course; and under identical nutrient conditions, both cell populations were observed to exhibit a comparable capacity for myelination of DRG axons in vitro. Thus, methods used to establish primary cultures of rat sciatic nerve Schwann cells and to expand secondary cultures in vitro in the absence of neurons preserve basic Schwann cell functions.

Antigens, Surface↗