Spectrins in developing rat hippocampal cells

• Published in: Brain research. Developmental brain research 2001-07, Vol.129 (1), p.81-93
• Main Authors: Ursitti, Jeanine A., Martin, Laura, Resneck, Wendy G., Chaney, Tessa, Zielke, Carol, Alger, Bradley E., Bloch, Robert J.
• Format: Article
• Language: English
• Subjects: Age Factors; Animals; Animals, Newborn; Antibody Specificity; Axon; Axons - chemistry; Carrier Proteins - analysis; Carrier Proteins - immunology; Cell Membrane - chemistry; Cells, Cultured; Dendrite; Dendrites - chemistry; Fodrin; Hippocampus - cytology; Hippocampus - growth & development; Immunohistochemistry; Membrane domains; Microfilament Proteins - analysis; Microfilament Proteins - immunology; Neurolemma; Neurons - chemistry; Neurons - ultrastructure; Rats; Spectrin; Spectrin - analysis; Spectrin - immunology; Spine; Synapse; Synapses - chemistry
• ISSN: 0165-3806
• DOI: 10.1016/S0165-3806(01)00160-2

We studied the spectrins in developing hippocampal tissue in vivo and in vitro to learn how they contribute to the organization of synaptic and extrasynaptic regions of the neuronal plasma membrane. β-Spectrin, but not β-fodrin or α-fodrin, increased substantially during postnatal development in the hippocampus, where it was localized in neurons but not in astrocytes. Immunoprecipitations from neonatal and adult hippocampal extracts suggest that while both β-spectrin and β-fodrin form heteromers with α-fodrin, oligomers containing all three subunits are also present. At the subcellular level, β-fodrin and α-fodrin were present in the cell bodies, dendrites, and axons of pyramidal-like neurons in culture, as well as in astrocytes. β-Spectrin, by contrast, was absent from axons but present in cell bodies and dendrites, where it was organized in a loose, membrane-associated meshwork that lacked α-fodrin. A similar meshwork was also apparent in pyramidal neurons in vivo. At some dendritic spines, α-fodrin was present in the necks but not in the heads, whereas β-spectrin was present at significant levels in the spine heads. The presence of significant amounts of β-spectrin without an accompanying α-fodrin subunit was confirmed by immunoprecipitations from extracts of adult hippocampus. Our results suggest that the spectrins in hippocampal neurons can assemble to form different membrane-associated structures in distinct membrane domains, including those at synapses.