transcription factors

bio348 exam #2

En

• Cerebellum development

• Segmentation of the epidermis in Drosophila

• No engrailed: deformed cerebellum

  • Can be rescued w/ Drosophila engrailed

Shh

Specifies ventral cell fates (high Shh = ventral) Secreted by floor plate/notochord, which are ventral Attractive force that brings axons closer to FP

BMP

• Promote neural differentiation

• High BMP = dorsal

• Act as a repellant to push axons away from RP

Wnt

Establishes anterior (rostral) - posterior (caudal)

Otx2

• Less Wnt

• Anterior/rostral

• Dopaminergic

Gbx2

• High Wnt

• Posterior/caudal

• Serotonergic

FGF

• Secreted from isthmus

• Neural patterning

• Neurogenesis

• Neuron survival

• Growth of axons

PDGFRα

Protein expressed in OPC

Hox

Specific combination of Hox expression determines neuronal subtype specification

HoxB1

• Controls the identity and projection of hindbrain MNs

• Lack of HoxB1 expression = no longer make cells specified in rhombomere 4; acquire rhombomere 2 identity

Emx2

High Emx2 inhibits Pax6 (less anterior, more posterior)

Pax6

• Establish cells in the anterior (motor)

• Pax6 mutant has an increase in visual cortex (shrinkage of anterior cells and expansion of cells with posterior identity)

Olig2/Nkx2.2/Foxa2

Ventral domains Motor neuron and floor plate regions

bHLH repressors, Hes1 and Hes5

Maintain radial glial identity of a cell; repress neuronal fate

NRG1

• Expressed highly in immature neurons

• Bind to ErbB on RGC → maintain radial glial (progenitor) identity

Nkx2.1

Interneuron production

Sox10

• Expressed in neural crest cells

• Required for differentiation of peripheral glial cells

• In mutants, MN are generated, but Schwann cells are not

RC-1

Cells expressing this marker begin to express GFAP

GFAP

Increase in GFAP → astrocyte proteins → astrocytes

OPC

• Generated ventrally (influenced by Shh), then migrate tangentially to disperse throughout developing spinal cord → will later myelinate axons 

• Reside in cluster of cells in the pMN domain

Nkx6.1

Makes up pMN, p3 and p2 domains Controls development of motor neurons

Par

Mediate reorganization of the cytoskeleton Localized to soma and tips of neurites  Without Par, no clear distinction between axonal and dendritic processes

BMP7

• Growth cone attracted to it

• Growth cone turned towards signal once activated 

• State-dependent signaling → attraction early on, repels later in development

Agrin

• Induces AchR clustering in muscle cell (interactions with Musk receptor)

• Mutant with no agrin: AchRs are too dispersed and axons are not very organized

• Double-mutant: OE of musk rescues Ach clustering