Signal-transduction pathway (G) Flashcards
Where in the cell are transcription factors activated?
Nucleus or cytosol
What do positive growth factors do?
Stimulate cell division
What do growth-inhibiting factors do?
Inhibit cell division
What does GPCR ligand stand for?
G-protein coupled receptor ligand
What happens if there is unbalance between positive and negative regulators?
It induces an abnormal cell signalling and promote cancer
Where is the non receptor tyrosine kinase based receptor found?
In the cytoplasm
What does the non receptor tyrosine kinase based receptor do?
Modulates the intracellular signal
What kind of kinase receptors are there?
Tyrosine
Serine
Threonine
Where are notch ligands often found?
On stem cells
Where are the receptors for nuclear hormones found?
In the cytoplasm as they are hydrophobic so they can pass plasma membranes
What does EGF stand for?
Epidermal growth factor
Why is the epidermal growth factor receptor important?
As it stimulates proliferation of most cells
What does NGF stand for?
Nerve growth factor
What does PDGF stand for?
Platelet derived growth factor receptor
What does FGF stand for?
Fibroblast growth facter
What does VEGF stand for?
Vascular endothelial growth factor
Name the 6 most important tyrosine kinase receptors
EGF
NGF
Insulin
PDGF
FGF
VEGF
Name the 4 receptors in the HER family
EGFR (HER1)
HER2
HER3
HER4
What is EGFR a target for?
Treatment of colon cancer
What are the ligands for EGFR?
EGF
TGFX
Amphiregulin
HB-EGF
Betacellulin
What are the ligands for HER2?
No specific ligands
What does HER2 often act as?
A dimer part
What are the ligands for HER3?
Hergulin
What are the ligands for HER4?
Hergulin
Betacellulin
NRG2
NRG3
What does DAG stand for?
Diaglyglycerol
What can PLCbeta and PLCgamma break PIP2 into?
IP3 and DAG
What does PLCbeta stand for?
phospholipase C- beta
What does PLCgamma stand for?
Phospholipase C- gamma
What is DAG the physiological activator of?
PKC
What does sIP3 determine? and how?
An increase in free intracellular calcium as it induces calcium to be released from the ER
Why is calcium a useful second messenger?
As the concentration outside the cell is high and the concentration inside the cell is low
What is the concentration of calcium outside the cell?
1.8mM
What happens if GAP is absent?
RAS is constantly activated causing constant proliferation
How many tumors have RAS mutations?
30%
Which is the only inhibiting growth factor you need to remember?
TGFbeta
What does RTK stand for?
Receptor for tyrosine kinase
Process for JAK and STAT pathway
Binding to the cytokine
JAK phosphorylates the receptor
STAT binds to the phosphorylated tyrosine, become a dimer and moves to the nucleus
What does JAK phosphorylate?
The tail of the receptor in the intracellular compartment
What are cytokines involved in?
Inflammation
What do cytokines regulate?
The most important pathways in immunology
What is transduction of cytokine receptors mediated by?
JAK
What does mTOR stand for?
Mammalian target of rapamycin
What is mTOR activated by?
Phosphorylation by G-protein Rheb
What does mTOR control?
The anabolic process, cell growth and proliferation
What kind of kinase is mTOR?
Serine/threonine kinase
How many complexes can mTOR exist in?
2
What is mTORC 1 involved in?
Protein synthesis (more involved in cancer than mTORC2)
What is mTORC 2 involved in?
Phosphorylation of AKT and cytoskeletal organisation
What kind of drugs often inhibit mTORC?
Immunosuppressive drugs
Which mTORC does rapamycin inhibit?
mTORC1
Which drug that inhibits mTORC is used to improve transplantations?
Rad001
In how many percent of tumors is p53 either inactive or mutated?
50-60%
What can inactivate p53?
AKT
When is p53 degraded?
When it binds to MDM2
What happens when MDM2 is phosphorylated?
It moves to the nucleus and binds to p53 which then is degraded in the proteasome
What kind of mutation in p53 causes tumors?
Point mutation
What causes the point mutation in p53 that leads to cancer?
Smoke
Easy tell tale sign that lung cancer is due to smoking
Point mutation in p53
What can happen if MDM2 is over expressed?
Tumors
How does AKT play an anti-apoptotic role?
By controlling survival genes and death genes
What kind of molecule is AKT?
Kinase
What kind of molecule is PTEN?
Phosphatase
Name a tumor supressor gene phosphatase and tensin homolog
PTEN
Is PTEN active or inactive in cancer?
Inactive (which leads to the pathway constantly being active)
Name 2 survival genes
BCI-2
BCI-xl
Name a death gene
Bax
What kind of molecule is PI3K?
Kinase
What 3 subclasses is PI3K divided into?
Structure
Regulation
Lipid substrate specificity
What are class I PI3Ks?
Heterodimeric proteins
Name 2 class I PI3Ks
p110 (catalytic subunit)
p85 (regulatory subunit, primarily involved in the pathogenesis of human cancer)
What does it mean that PI3K is a photo-oncogene
It is normally present in the cell
What happens when PI3K is mutated?
It becomes and oncogene and is in cancer
What is the phosphorylation of AKT important in?
Cell growth
Metabolism
Survival
What does PI3K phosphorylate ?
PIP2 into PIP3
Name 3 important transcription factors
AP-1
E2F
CMyc
What does the stimulation of B-Raf increase?
Expression of C-jun and C-fos which up regulates AP-1-Regulated gene transcription
Name the 3 RAS (rat sarcoma) int eh family of GTPase
KRas (kirsten RAS)
NRas (neuroblastoma Ras)
HRas (Harvey Ras)
In which of the 3 Ras do most mutations occur?
KRas
Which of the 3 Ras are viruses?
KRas
HRas
How many percent of tumors have Ras mutation?
30%
What happens if GAP is absent?
Continuos proliferation
What activates RAS?
SOS
How is RAS activated?
It is phosphorylated, turning GDP into GTP
What does activated RAS