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Factors affecting the morphology of radial glia
Marcin Gierdalski1, Sharon L Juliano
1Department of Anatomy, Physiology, & Genetics and Program in Neuroscience, USUHS, Bethesda, MD 20814, USA.
Abstract:
A model of cortical dysplasia results from disruption of the earliest generated neocortical cells. Injections of an antimitotic (methylazoxy methanol - MAM) into pregnant ferrets result in a constellation of effects, which include disruption of radial glia, with early differentiation in astrocytes, and impaired migration of neurons into the cortical plate. We found previously that culture of P0 MAM-treated slices with explants of normal cortical plate reorganizes the radial glia toward their normal morphology and improves migration of neurons into the cortical plate. This suggested that P0 normal cortical plate contains a 'factor' capable of providing reorganizing cues to disorganized developing cortex. The current study characterizes the biological activity in normal cortical plate by isolating fractions of different molecular weight obtained from conditioned media of organotypic cultures. The only media fraction capable of providing reorganizing activity to MAM-treated cortex was the molecular weight fraction between 30 and 50 kDa. Treatment designed to denature proteins demonstrated that the active molecular weight fraction (30-50 kDa) was not able to provide reorganizing cues when either heated or treated with Proteinase K. These data provide support for the idea that normal cortical plate of neonatal ferret contains a radialization factor that is a protein of 30-50 kDa.
Insights
Researchers identified a protein in normal neonatal ferret cortex that corrects developmental brain abnormalities. This 30-50 kDa protein factor aids in reorganizing radial glia and improving neuron migration in models of cortical dysplasia.
Area of Science:
- Neuroscience
- Developmental Biology
- Cell Biology
Background:
- Cortical dysplasia models involve disrupting early neocortical cells.
- Methylazoxy methanol (MAM) injections in pregnant ferrets disrupt radial glia and neuron migration.
- Normal neonatal ferret cortical plate can reorganize MAM-treated cortex.
Purpose of the Study:
- Characterize the biological activity in normal cortical plate.
- Isolate and identify the factor responsible for cortical reorganization.
- Determine the molecular weight and protein nature of the reorganizing factor.
Main Methods:
- Organotypic cultures of neonatal ferret cortical slices.
- Preparation of conditioned media with molecular weight fractions.
- Treatment of fractions with heat and Proteinase K to assess protein denaturation.
Main Results:
- A molecular weight fraction between 30 and 50 kDa exhibited reorganizing activity.
- Heat treatment or Proteinase K digestion abolished the reorganizing activity.
- The active factor is a protein within the 30-50 kDa range.
Conclusions:
- Normal neonatal ferret cortical plate contains a radialization factor.
- This factor is a protein with a molecular weight of 30-50 kDa.
- This protein plays a crucial role in cortical development and organization.