18 Signal transduction

Question 1

What are 3 receptor superfamilies?

Answer 1

• ligand-gated ion channels
• kinase linked receptors
• G protein-coupled receptors

Question 2

What happens to blood glucose level after eating?

Answer 2

increases

Question 3

What senses the blood glucose level?

Answer 3

pancreatic beta cell

Question 4

what happens after the pancreatic beta cell detects an increase in blood glucose?

Answer 4

insulin secretion

Question 5

What is the role of insulin signaling?

Answer 5

• 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

Question 6

What is the R residue in phospholipid?

Answer 6

Inositol

Question 7

How does PIP2 become PIP3?

Answer 7

PI3K adds a phosphate

Question 8

what happens if theres a mutation in InR

Answer 8

growth defect (donohue syndrome)

Question 9

What do growth factor affect?

Answer 9

GF can affect both cell proliferation and migration dependent on different signaling pathways

Question 10

what is RTK?

Answer 10

receptor tyrosine kinases

Question 11

What are RTK ectodomains like? what do they do

Answer 11

they are highly variables structures - bind to a variety of liagnds

Question 12

What is the transmembrane domain of RTK for?

Answer 12

transmembrane domain for the anchorage on the plasmamembrane

Question 13

what do all domains of RTK have in common?

Answer 13

all have a common cytoplasmic tyrosine kinase domain

Question 14

what happens if RTK is dysregulated?

Answer 14

often involved in tumor pathogenesis

Question 15

In what ways can RTK be affected to become cancerous?

Answer 15

1. overexpression of RTK - recog more ligands
2. activating mutations - RTK lose control and activate downstream players all the time
3. ligand dysregulation (ligand overexpression) - all cells recog this receptor and cancer cells use this ligand to activate

Question 16

What are the steps of RTK activation?

Answer 16

1. ligands bind to RTK
2. RTK undergoes conformational changes
3. ligand-bound RTKs make dimers
4. RTK dimer phosphorylates each other
5. Phosphorylated RTKs recruit downstream players

Question 17

what does abnormal activation of RTKs cause?

Answer 17

cancer

Question 18

What is the leading cause of death in hk?

Answer 18

cancer 32%
increasing every year

Question 19

Why does a tumor occur?

Answer 19

• 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

Question 20

Did ancient egyptians suffer from cancer?

Answer 20

yes

Question 21

what are the modern treatments for cancer?

Answer 21

cant cure completely

goal: complete elimination of tumors

Question 22

Why is it difficult to eliminate cancer?

Answer 22

• 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
  *

Question 23

How can the insulin signaling pathway turn into a tumor?

Answer 23

Question 24

what is the autocrine signaling loop in cancer?

Answer 24

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

Question 25

what is a constitutively active signal?

Answer 25

A constitutively active signal refers to a signaling pathway that is continuously active without the need for external stimuli or signals.

Question 26

How can GF elicit a constitutively active signal?

Answer 26

mutation affecting structure of overexpression

Question 27

what are 2 methods cancer cells emply to activate RTK signaling?

Answer 27

amplification and mutation