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Bergmann glial ensheathment of dendritic spines regulates synapse number without affecting spine motility

  • Jocelyn J. Lippman Bell (a1), Tamar Lordkipanidze (a1), Natalie Cobb (a1) and Anna Dunaevsky (a1)
Abstract

In the cerebellum, lamellar Bergmann glial (BG) appendages wrap tightly around almost every Purkinje cell dendritic spine. The function of this glial ensheathment of spines is not entirely understood. The development of ensheathment begins near the onset of synaptogenesis, when motility of both BG processes and dendritic spines are high. By the end of the synaptogenic period, ensheathment is complete and motility of the BG processes decreases, correlating with the decreased motility of dendritic spines. We therefore have hypothesized that ensheathment is intimately involved in capping synaptogenesis, possibly by stabilizing synapses. To test this hypothesis, we misexpressed GluR2 in an adenoviral vector in BG towards the end of the synaptogenic period, rendering the BG α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) Ca2+-impermeable and causing glial sheath retraction. We then measured the resulting spine motility, spine density and synapse number. Although we found that decreasing ensheathment at this time does not alter spine motility, we did find a significant increase in both synaptic pucta and dendritic spine density. These results indicate that consistent spine coverage by BG in the cerebellum is not necessary for stabilization of spine dynamics, but is very important in the regulation of synapse number.

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Corresponding author
Correspondence should be addressed to: Anna Dunaevsky, Developmental Neuroscience Department, Munroe-Meyer Institute, University of Nebraska Medical Center, 985960 Nebraska Medical Center, Omaha, NE 68198-5960 USA email: adunaevsky@unmc.edu
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Current address: Department of Neurology, Children's Hospital Boston and Harvard Medical School, Boston, Massachusetts 02115, USA.

Current address: Developmental Neuroscience Department, Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, NE 68198, USA.

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Neuron Glia Biology
  • ISSN: 1740-925X
  • EISSN: 1741-0533
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