Early brain development part two
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Growth cones at the tip of developing axons contain filopodia and lamellipodia that use cell-associated and diffusible molecular signals to guide axon pathfinding and growth. Cell-associated molecules like integrins and cadherins mediate interactions between growth cones and surrounding cells, while diffusible factors like netrins, semaphorins and neurotrophins act as attractants or repellents to guide axons or promote their survival. The balance of these molecular cues is crucial for proper wiring of neural circuits during early brain development.
Early brain development part two
- 1. Early brain development part two DOMINA PETRIC, MD
- 2. Growth cones Growth cone has flat lamminar type of appearance: LAMELLA PODIUM (SHEET FLOOR). FILOPODIA are processes that extend from the lamella podium. Filopodia have dynamic behavior because they have ACTINS. Growth cone is rich of mitochondria and it is very important for the axon development. HTTPS://WWW.COURSERA.ORG/LEARN/MEDICAL-NEUROSCIENCE/LECTURE: LEONARD E. WHITE, PHD, DUKE UNIVERSITY
- 3. Growht cone https://cmgm.stanford.edu HTTPS://WWW.COURSERA.ORG/LEARN/MEDICAL-NEUROSCIENCE/LECTURE: LEONARD E. WHITE, PHD, DUKE UNIVERSITY
- 4. Molecular signals for axon guidance cell-associated molecules diffusible molecules HTTPS://WWW.COURSERA.ORG/LEARN/MEDICAL-NEUROSCIENCE/LECTURE: LEONARD E. WHITE, PHD, DUKE UNIVERSITY
- 5. Cell-associated molecules Those molecules are on the surface of cells or embedded in extracellular matrix. They mediate molecular interactions between growth cones and parenchyma. Interactions with growth cone can trigger second messenger systems in growth cones that transduce extracellular signals into patterns of growth. These molecules are important for stabilizing linkages between axons and glia. HTTPS://WWW.COURSERA.ORG/LEARN/MEDICAL-NEUROSCIENCE/LECTURE: LEONARD E. WHITE, PHD, DUKE UNIVERSITY
- 6. Cell-associated molecules integrins (extracellular matrix molecules) calcium independent cell adhesion molecules (CAM) like NCAM and L1 calcium dependent cell adhesion molecules (CAM) like CADHERINS EPHRINS and EPHRIN receptors play important role in establishing neural topography HTTPS://WWW.COURSERA.ORG/LEARN/MEDICAL-NEUROSCIENCE/LECTURE: LEONARD E. WHITE, PHD, DUKE UNIVERSITY
- 7. Diffusible molecules Those molecules are secreted by target tissues. They diffuse into extracellular fluids. HTTPS://WWW.COURSERA.ORG/LEARN/MEDICAL-NEUROSCIENCE/LECTURE: LEONARD E. WHITE, PHD, DUKE UNIVERSITY
- 8. Diffusible molecules • They affect growth and survival of neurons and their processes. • TROPIC diffusible molecules guide growing axons toward or away from source. • Tropic molecules can be chemo-attractant and chemo-repellant molecules. • TROPHIC diffusible molecules promote survival and growth of neurons and their processes. • In the peripheral nervous system trophic molecules match axonal innervation with target tissue. • Production of trophic molecules is activity dependent. HTTPS://WWW.COURSERA.ORG/LEARN/MEDICAL-NEUROSCIENCE/LECTURE: LEONARD E. WHITE, PHD, DUKE UNIVERSITY
- 9. Diffusible molecules can be TROPIC: P like PATHWAY, guidance of growing axons towards or away from source. TROPHIC: H like HEALTH, nourishment, survival and growth of neurons and their processes. HTTPS://WWW.COURSERA.ORG/LEARN/MEDICAL-NEUROSCIENCE/LECTURE: LEONARD E. WHITE, PHD, DUKE UNIVERSITY
- 10. CHEMOATTRACTION CHEMOREPULSION HTTPS://WWW.COURSERA.ORG/LEARN/MEDICAL-NEUROSCIENCE/LECTURE: LEONARD E. WHITE, PHD, DUKE UNIVERSITY Tropic diffusible molecules Chemo-attractant tropic molecules Chemo-reppelant tropic molecules
- 11. Tropic diffusible molecules NETRIN/SLIT family (netrin is chemo-attractant, slit antagonises netrin) SEMAPHORINS (chemo-repellants) HTTPS://WWW.COURSERA.ORG/LEARN/MEDICAL-NEUROSCIENCE/LECTURE: LEONARD E. WHITE, PHD, DUKE UNIVERSITY
- 12. Trophic molecules (neurotrophins) and neurotrophin hypothesis NEUROTROPHIN HYPOTHESIS: in development, the survival of neurons and their axonal connections depends upon the availability of some minimal quantity of trophic factor. Target tissues synthesize and secrete a limited quantity of trophic factor. Survival of neuron and their specific connections depens upon successful competition among inputs for a limited quantity of trophic factor. HTTPS://WWW.COURSERA.ORG/LEARN/MEDICAL-NEUROSCIENCE/LECTURE: LEONARD E. WHITE, PHD, DUKE UNIVERSITY
- 13. Neurotrophins In maturity, regulated secretion of trophic factors may help shape neuronal connections in response to injury or adaptation to new patterns of neural activity. HTTPS://WWW.COURSERA.ORG/LEARN/MEDICAL-NEUROSCIENCE/LECTURE: LEONARD E. WHITE, PHD, DUKE UNIVERSITY
- 14. Neurotrophins NERVE GROWTH FACTOR (NGF) BRAIN DERIVED NEUROTROPHIC FACTOR (BDNF) NT-4/5, NT-3 HTTPS://WWW.COURSERA.ORG/LEARN/MEDICAL-NEUROSCIENCE/LECTURE: LEONARD E. WHITE, PHD, DUKE UNIVERSITY
- 15. Neurotrophins • Neurotrophin receptors are TIROSINE KINASE RECEPTORS (TRK). Results of TRK receptors can be: • cell survival • neurite outgrowth and neuronal differentiation • activity-dependent plasticity HTTPS://WWW.COURSERA.ORG/LEARN/MEDICAL-NEUROSCIENCE/LECTURE: LEONARD E. WHITE, PHD, DUKE UNIVERSITY
- 16. Neurotrophin receptor p75 p75 RhoA Neurite growth C-Jun Cell death NF-kB Cell survival HTTPS://WWW.COURSERA.ORG/LEARN/MEDICAL-NEUROSCIENCE/LECTURE: LEONARD E. WHITE, PHD, DUKE UNIVERSITY Second messengers Outcome
- 17. Literature https://www.coursera.org/learn/medical- neuroscience/lecture: Leonard E. White, PhD, Duke University https://cmgm.stanford.edu HTTPS://WWW.COURSERA.ORG/LEARN/MEDICAL-NEUROSCIENCE/LECTURE: LEONARD E. WHITE, PHD, DUKE UNIVERSITY