SIGNAL TRANSDUCTION PATHWAYS Flashcards
______
Critical in cell growth, differentiation, and survival. Mutations can lead to cancer.
_____
Genes that promote cell division and survival. When mutated, they can become ____, leading to cancer.
In neural crest cells, the RTK pathway activates the ____, leading to the production of pigment cells like melanoblasts and cells of the pigmented retina.
RTK (Receptor Tyrosine Kinase) Pathway
Proto-Oncogenes
oncogenes
microphthalmia transcription factor (Mitf)
RTK (Receptor Tyrosine Kinase) Pathway Mechanism:
____ A hormone or paracrine factor binds to the receptor.
____ Binding causes the receptor to change shape.
____The receptor phosphorylates itself on ____residues.
____ The ____ serve as docking sites for proteins that relay the signal into the cell.
Ligand Binding
Conformational Change
Autophosphorylation
tyrosine
Signal Transduction
phosphorylated tyrosines
RTK (Receptor Tyrosine Kinase) Pathway Steps 13:
- Ligand Binding
- RTK Dimerization
- RTK Autophosphorylation
- Adaptor Protein Binding
5 .GNRP Binding
- GNRP activates Ras (G protein)
- Ras-GDP→Ras-GTP
- (GAP Recycles Ras)
- Active Ras activates Raf
. - Raf phosphorylates MEK
- MEK phosphorylates ERK
- ERK phosphorylates transcription factors
- Transcription factors regulate gene expression.
_____
It is very important in regulation of human fetal bone growth. Important in immune function, growth, and milk production. Mutations can lead to diseases like dwarfism.
JAK-STAT Pathway
Components:
____ Non-receptor tyrosine kinases.
____ Family of transcription factors.
JAK (Janus Kinase)
STAT (Signal Transducers and Activators of Transcription)
JAK (Janus Kinase) mechanism (4):
Ligand binding induces receptor dimerization and JAK activation.
JAK phosphorylates STAT proteins.
Phosphorylated STATs dimerize and translocate to the nucleus.
STATs bind DNA and regulate gene expression.
____
Vital for development of vertebrate limbs and neural differentiation.
Hedgehog Pathway
Hedgehog pathway mechanism (3):
Mechanism:
- Binding of Hedgehog protein to its receptor, Patched, releases the inhibition on Smoothened.
- Smoothened activates the Gli family of transcription factors.
- Gli proteins regulate gene expression.
Hedgehog pathway:
One remarkable feature of Hedgehog signal transduction pathway is the importance of ____.
is critical for the catalytic cleavage of ____.
The Patched protein that binds sonic hedgehog also needs it in order to function.
cholesterol
sonic hedgehog protein
Hedgehog family
___ Sertoli cells of the testes
___ gut and cartilage
___ important in embryo development
desert hedgehog (dhh)
indian hedgehog (ihh)
sonic hedgehog (shh)
____
Involved in cell proliferation, differentiation, and polarity. Important in organogenesis and stem cell maintenance.
Wnt
Wnt mechanism (3)
Wnt proteins bind to Frizzled receptors.
Activation of Disheveled, which inhibits GSK-3, leading to stabilization of β-catenin.
β-catenin enters the nucleus and regulates gene expression.
____ - vertebrates + invertebrates
____ characterized in humans
Frizzled gene family
____ found in vertebrates
30 Wnt genes
19 Wnts
10 frizzled genes
Wnt/ β-catenin (Canonical) Pathway components:
Components:
____ A cytoplasmic protein that is activated upon Wnt binding.
____ A tumor suppressor protein that forms a complex with GSK-3 to target β-catenin for degradation.
____ It prevents β-catenin dissociation from APC.
____ A key signaling molecule that, when stabilized, enters the nucleus to influence gene expression.
_____Transcription factors in the nucleus that interact with β-catenin to regulate gene expression.
Dishevelled (Dvl)
Adenomatous Polyposis Coli (APC)
Glycogen Synthase Kinase 3 (GSK-3)
β-catenin
LEF/TCF
_____
highly conserved cell signaling system present in most multicellular organisms. It plays a critical role in cell differentiation, proliferation, and apoptosis.
sensory hair cells, branched arterial networks
Tissue growth and cancer, cell death and tumor suppression
involved in the formation of numerous
vertebrate organs such as kidney, pancreas, and heart
In the vertebrate eye, the interactions between Notch and its ligands regulate which cells become optic neurons and which become glial cells.
Notch pathway
