Module 2 Lecture 2 Flashcards
What is a morphogen?
A signaling molecule that diffuses across tissues and forms a concentration gradient.
How do morphogens affect neural development?
They regulate cell fate by triggering specific molecular and cellular responses based on their concentration.
List five key morphogens involved in nervous system development.
Retinoic Acid (RA), Fibroblast Growth Factor (FGF), Wnt, Bone Morphogenic Protein (BMP), Sonic Hedgehog (Shh).
What is the role of Retinoic Acid (RA) in neural development?
RA regulates anterior-posterior patterning and promotes neuronal differentiation.
What is the role of Fibroblast Growth Factor (FGF)?
FGF controls proliferation and regionalization of neural tissue.
What is the role of Wnt signaling in neural development?
Wnt is essential for dorsal-ventral patterning and neural tube closure.
What is the role of Bone Morphogenic Protein (BMP) in neural development?
BMP promotes epidermal fate but is antagonized by Noggin and Chordin to induce neural fate.
What is the role of Sonic Hedgehog (Shh)?
Shh patterns the ventral neural tube and is crucial for motor neuron differentiation.
What is a neural organizer?
A group of cells that release morphogens to direct neural development.
Name three key neural organizers.
Notochord, Roofplate & Floorplate, Somites.
How does the notochord influence neural development?
It secretes Shh to pattern the ventral neural tube and induce motor neuron identity.
How do the roofplate and floorplate contribute to neural patterning?
They secrete BMP (roofplate) and Shh (floorplate) to establish dorsal-ventral polarity.
What are BMP antagonists?
Noggin and Chordin.
What is the function of Noggin and Chordin?
They inhibit BMP signaling, allowing neural tissue to form instead of epidermis.
What is the function of Hox genes?
They establish anterior-posterior segmentation and control neuromere identity.
How are Hox genes organized?
They are clustered into four groups and expressed in a temporal-spatial pattern along the A-P axis.
What is neurogenesis?
The process of generating neurons from neural stem cells (NSCs).
When does neurogenesis occur?
It primarily occurs during embryonic development but continues in the SVZ and hippocampus postnatally.
What is symmetric division in neurogenesis?
A cell divides to produce two identical progenitors, expanding the neural progenitor pool.
What is asymmetric division in neurogenesis?
A cell divides to produce one progenitor and one differentiated neuron or intermediate progenitor.
What is direct neurogenesis?
Radial glial cells directly generate neurons.
What is indirect neurogenesis?
Radial glial cells first produce intermediate progenitors, which divide further before generating neurons.
How do neurons migrate in the developing cortex?
Neurons migrate in an inside-out manner, with deeper layers forming first.
What is the role of radial glial cells in neuronal migration?
They act as scaffolds that guide neurons to their final positions.
Which extracellular matrix (ECM) proteins regulate neuronal migration?
Reelin, Laminin, Integrins.
What is the function of LIS1 in neuronal migration?
It regulates the cytoskeleton to ensure proper neuronal positioning.
What is tangential migration?
Neurons migrate parallel to the brain surface instead of radially.
Which neurons undergo tangential migration?
Interneurons from the medial ganglionic eminence (MGE) to the cortex.
What is the rostral migratory stream (RMS)?
A pathway through which neuroblasts migrate to the olfactory bulb and differentiate into interneurons.
What is gliogenesis?
The formation of glial cells from neural progenitors.
How does gliogenesis timing compare to neurogenesis?
Gliogenesis starts after neurogenesis but continues postnatally.
What are the three main types of glial cells?
Astrocytes, Oligodendrocytes, Ependymal cells.
What is the function of astrocytes?
They regulate synaptic function, blood-brain barrier integrity, and neural homeostasis.
What is the function of oligodendrocytes?
They myelinate CNS axons, increasing conduction velocity.
What is the function of ependymal cells?
They line the ventricles and produce cerebrospinal fluid (CSF).
When does myelination begin?
Shortly after glial proliferation increases, progressing rapidly during the first postnatal year.
What is the order of myelination across different pathways?
Sensory pathways myelinate first, followed by motor pathways, then association areas.
What are the four major cellular processes in early nervous system development?
Proliferation, Differentiation (neurogenesis & gliogenesis), Migration, Myelination.
How do inductive signals define CNS regions?
They establish broad patterning domains that transcription factors refine into specific cell fates.
What is the GABAergic switch in postnatal interneurons?
GABAergic interneurons transition from excitatory to inhibitory function due to chloride channel regulation.
How does cell cycle exit influence neuronal differentiation?
Cells that exit earlier form deep-layer neurons, while late-exiting cells form superficial-layer neurons.
What is the relationship between neural proliferation and differentiation?
Proliferation expands the progenitor pool, while differentiation commits cells to specific neuronal or glial fates.
What determines whether a neural stem cell undergoes neurogenesis or gliogenesis?
Transcription factor signaling: proneural genes (e.g., Neurogenin) promote neurogenesis, while gliogenic factors (e.g., Sox9, NFIA) drive gliogenesis.
Which transcription factors promote neurogenesis?
Neurogenin, Mash1, and Pax6.
Which transcription factors promote gliogenesis?
Sox9 and NFIA.
What is the function of integrins in neuronal migration?
They mediate cell adhesion to the extracellular matrix (ECM), allowing neurons to move effectively.
Which key molecular signal attracts migrating interneurons during tangential migration?
SDF1 (stromal-derived factor 1).
What are intermediate progenitors, and how do they contribute to neurogenesis?
Intermediate progenitors are transit-amplifying cells that undergo limited divisions before differentiating into neurons, increasing neuronal output.
How does LIS1 mutation affect neuronal migration?
It disrupts microtubule function, leading to lissencephaly (smooth brain).
What is the function of neuregulin in cortical layer formation?
Neuregulin regulates the specification and differentiation of cortical layers.
Which brain structure generates oligodendrocytes during gliogenesis?
The oligodendrocyte precursor cells (OPCs) arise from the ventral ventricular zone (VZ) of the spinal cord and brain.
How does myelination enhance synaptic plasticity?
By modulating the timing of action potentials and optimizing neurotransmission.
What is the relationship between radial glial cells and ependymal cells?
Radial glial cells give rise to ependymal cells, which remain in the ventricular lining postnatally.
What role does reelin play in cortical development?
Reelin guides neurons during migration, ensuring proper layer formation in the cerebral cortex.
Why do late-born neurons migrate past earlier-born neurons in the cortex?
The inside-out migration pattern ensures that deeper cortical layers form first, followed by superficial layers.
How does the timing of cell cycle exit affect neuronal fate?
Early-exiting cells become deep-layer neurons, while late-exiting cells form upper-layer neurons.
Which signaling molecule is critical for neural tube closure?
Wnt signaling plays a key role in neural tube closure and dorsal-ventral patterning.
How does the extracellular matrix (ECM) contribute to neural migration?
The ECM provides structural support and signaling cues, including Reelin, Laminin, and Integrins.
