18 Signal transduction Flashcards
What are 3 receptor superfamilies?
- ligand-gated ion channels
- kinase linked receptors
- G protein-coupled receptors
What happens to blood glucose level after eating?
increases
What senses the blood glucose level?
pancreatic beta cell
what happens after the pancreatic beta cell detects an increase in blood glucose?
insulin secretion
What is the role of insulin signaling?
- drop blood glucose level is only a byproduct
- Insulin gives signal to other cells its time to absorb glucose from the blood, for cell growth, proliferation, development etc by signalling a bunch of other things
- PIP3 activates other players for growth proliferation and oncogenesis
What is the R residue in phospholipid?
Inositol
How does PIP2 become PIP3?
PI3K adds a phosphate
what happens if theres a mutation in InR
growth defect (donohue syndrome)
What do growth factor affect?
GF can affect both cell proliferation and migration dependent on different signaling pathways
what is RTK?
receptor tyrosine kinases
What are RTK ectodomains like? what do they do
they are highly variables structures - bind to a variety of liagnds
What is the transmembrane domain of RTK for?
transmembrane domain for the anchorage on the plasmamembrane
what do all domains of RTK have in common?
all have a common cytoplasmic tyrosine kinase domain
what happens if RTK is dysregulated?
often involved in tumor pathogenesis
In what ways can RTK be affected to become cancerous?
- overexpression of RTK - recog more ligands
- activating mutations - RTK lose control and activate downstream players all the time
- ligand dysregulation (ligand overexpression) - all cells recog this receptor and cancer cells use this ligand to activate
What are the steps of RTK activation?
- ligands bind to RTK
- RTK undergoes conformational changes
- ligand-bound RTKs make dimers
- RTK dimer phosphorylates each other
- Phosphorylated RTKs recruit downstream players
what does abnormal activation of RTKs cause?
cancer
What is the leading cause of death in hk?
cancer 32%
increasing every year
Why does a tumor occur?
- Human body has lots of cells (30 trillion cells)
- 1% (300 billion) cells divide every day
- around one mutation occurs per cell division
- body accumulates 300 billion mutations/day
- smoking, UV exposure, infection, increases mutation rates
- mutations = protooncogenes -> oncogenes -> tumor (cancer)
- 1/3 may have cancer in their lifetime
Did ancient egyptians suffer from cancer?
yes
what are the modern treatments for cancer?
cant cure completely
goal: complete elimination of tumors
Why is it difficult to eliminate cancer?
- heterogeneous cancer cells (lots of diff ones, vary slightly)
- caner therapies cant target all
- and tumor cells that do survive regrow and accumulate more mutations
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How can the insulin signaling pathway turn into a tumor?
what is the autocrine signaling loop in cancer?
Autocrine signaling refers to a form of cell communication where a cell produces signals (such as hormones or growth factors) that bind to receptors on its own surface, influencing its own behavior
tumor cells can acquire the ability to generate a ligand for a growth factor receptor that they also express
what is a constitutively active signal?
A constitutively active signal refers to a signaling pathway that is continuously active without the need for external stimuli or signals.
How can GF elicit a constitutively active signal?
mutation affecting structure of overexpression
what are 2 methods cancer cells emply to activate RTK signaling?
amplification and mutation
