Cell Migration

Cell Migration

1. After mitosis

   • Cells migrate outwards
     • 1. Preplate
     • 2. Cortical plate
     • 3. Neocortex
       • 6 Layers
       • Each layer = different fuction, different neuron type

2. Migration-tracing methods

   • DiI
   • BrdU
   • Thymidine
   • Lineage analysis using retroviruses
     • Infecting one cell and studying infection in daughter cells

3. Migration characteristics

   • Direction
     • Radial
       • Up radia glia cells
     • Tangential
       • Through ganglionic eminences to cortex
         • With corticofugal axons
   • Germinal zones
     • Ventricular
     • Subventricular
   • Types of cells
     • Pyramidal cells
       • Derived from neuroepithelium of ventricular zone
       • Use radial path
     • Interneurones
       • Derived from ganglionic eminences
       • Tangential path
     • Glia
       • Subventricular zone
       • Motogenic cues

4. Guidance cues

   • Oligodendrocytes
     • Semaphorin = REPULSIVE
     • Netrin = ATTRACTIVE
   • Radial migration of neuroblasts
     • Extra-cellular / cell-surface molecules
       • Reelin
         • Controls terminal translocation
           • Activates cell adhesion molecules
       • Reelin receptors
         • Changes cell adhesiveness for neuronal layers
     • Intracellular proteins
       • Filamin
         • Actin-binding protein
       • Disabled-1 (DAB-1)
         • Regulates reelin signalling, which directs cell positioning
           • Stops migration
       • Cyclin dependent kinase
         • Factor p35 and p39 dependent kinase 5
           • Contribute to the development of oligodendrocytes and myelination
         • Regulate the cell cycle
   • Human and mouse genes
     • Integrin
     • Laminin
     • Netrin
     • Neuregulin
     • Slit (chemorepellant)

5. Reelin

   • Produced by Cajal-Retzius cells
   • Serine protease activity
     • Cleaves peptide bonds in proteins
   • Reelin Receptors
     • Very low-density lipoprotein
     • Apolipoprotein B

6. Defects

   • Lissencephaly
     • Lack of gyri and sulci
     • Causes
       • Viral infection in foetus
         • Toxoplasmosis
         • Cytomegalovirus
       • Brain ischemia
         • Lack of blood flow to foetal brain
       • Toxins
       • Radiation
       • Mutations
         • Lys 1 haploinsufficiency
           • Only one copy of gene, which doesn't produce enough dynein and nudeln proteins
         • Filamin 1 gene deficit
           • periventricular heterotopia
             • Neurons fail to migrate properly and form clumps around ventricles

Images and files in the map