In:
Journal of Cell Science, The Company of Biologists, Vol. 107, No. 6 ( 1994-06-01), p. 1687-1695
Abstract:
We have produced a number of astrocytic cell lines, some of which promote abundant neurite outgrowth, some of which are poor promoters of neurite outgrowth. The critical difference between these lines lies in the extracellular matrix, cell lines that are good promoters of axon growth producing a matrix that promotes axon growth, cell lines that are poor promoters of axon growth producing a non-permissive matrix. We were unable to find any consistent correlations between promotion of axon growth and production of proteases, protease inhibitors, N-cadherin, growth cone collapsing activity, and several extracellular matrix molecules. In the present study we have compared the least permissive of our cell lines, Neu7, with the most permissive, A7. Medium conditioned by the cell lines has the same properties as the matrix, since dorsal root ganglia (DRGs) grown in conditioned medium from the Neu7 line grow axons poorly, while DRGs grown in medium conditioned by A7 or primary astrocytes grow many long axons. Since matrix produced by all the cell lines contains large amounts of laminin, we looked to see whether the cells were producing laminin-blocking activity. Medium from the Neu7 line blocked laminin, while that from the A7 and primary astrocytes did not. However, when the conditioned media were heat-treated to remove neurite-promoting activity, they all had laminin-blocking activity: the blocking activity is heat stable. The neurite-promoting properties of the conditioned media therefore probably reflect a balance between promoting molecules and blockers. The laminin-blocking activity could be reduced by treatment of the heat-treated conditioned media with trypsin, keratanase, chondrointase ABC, but not chondroitinase AC or heparitinase. Fractionation of the conditioned medium on an ion-exchange column revealed that the laminin-blocking activity was found in the sulphatelabelled fractions, which are predominantly proteoglycan. Whole Neu7 extracellular matrix was treated with enzymes, and its neurite-promoting activity could be increased by chondroitinase ABC and to a lesser extent by keratinase, but not by heparitinase. We conclude that the critical difference between matrix produced by astrocytic cell lines that promote axon growth and those that do not lies in the level of production of a dermatan/keratan sulphate proteoglycan.
Type of Medium:
Online Resource
ISSN:
0021-9533
,
1477-9137
DOI:
10.1242/jcs.107.6.1687
Language:
English
Publisher:
The Company of Biologists
Publication Date:
1994
detail.hit.zdb_id:
219171-4
detail.hit.zdb_id:
1483099-1
SSG:
12
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