Research article summary (published 13 Oct 1999):

Synapse formation and agrin expression in stratospheroid cultures from embryonic chick retina.

Full Abstract

Stratospheroids are three-dimensional cellular spheres which develop in vitro through the proliferation and differentiation of retinal neuroepithelial precursor cells. We investigated synapse formation in stratospheroids by analyzing the development of aggregates of synapse-associated molecules and of electron microscopically identifiable synaptic specializations. Our results show that the first aggregates of the GABA(A) receptor, the glycine receptor, and gephyrin appear in the inner plexiform layer after 8 days in culture simultaneously with the development of the first active zones and postsynaptic densities. In contrast, presynaptic molecules including synaptophysin could be detected in the inner plexiform layer before synaptogenesis, suggesting functions for these molecules in addition to neurotransmitter exocytosis at mature synapses. Similar to the retina in vivo, synapses were not found in the nuclear layers of stratospheroids. We also analyzed the isoform pattern, expression, and distribution of the extracellular matrix molecule agrin, a key regulator during formation, maintenance, and regeneration of the neuromuscular junction. In stratospheroids, several agrin isoforms were expressed as highly glycosylated proteins with an apparent molecular weight of approximately 400 kDa, similar to the molecular weight of agrin in the retina in vivo. The expression specifically of the neuronal isoforms of agrin was concurrent with the onset of synaptogenesis. Moreover, the neuronal agrin isoforms were exclusively found in the synapse-containing inner plexiform layer, whereas other agrin isoforms were associated also with the inner limiting membrane and with Müller glial cells. These results show that synapse formation is very similar in stratospheroids and in the retina in vivo, and they suggest an important role for agrin during CNS development. Copyright 1999 Academic Press.

Author information

Author/s: Hering, H (H); Kröger, S (S);

Affiliation: Department of Neuroanatomy, Max-Planck-Institute for Brain Research, Deutschordenstrasse 46, Frankfurt, D-60528, Germany.

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: Developmental biology (Dev Biol), published in UNITED STATES. (Language: eng)

Reference: 1999-Oct; vol 214 (issue 2) : pp 412-28

Dates: Created 1999/11/22; Completed 1999/11/22; Revised 2006/11/15;

PMID: 10525344, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Agrin - metabolism Animals Carrier Proteins - metabolism Cells, Cultured Chick Embryo Extracellular Matrix - metabolism Immunoblotting Immunohistochemistry Membrane Proteins - metabolism Microscopy, Electron Microscopy, Electron, Scanning

Microscopy, Electron, Scanning Neuroglia - metabolism Organ Culture Techniques Protein Isoforms - metabolism Receptors, GABA - metabolism Retina - embryology Reverse Transcriptase Polymerase Chain Reaction Synapses - metabolism Synaptophysin - metabolism Time Factors Vimentin - metabolism

Associated Chemicals: Agrin (0) ; Carrier Proteins (0) ; Membrane Proteins (0) ; Protein Isoforms (0) ; Receptors, GABA (0) ; Synaptophysin (0) ; Vimentin (0) ; gephyrin (0)

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