Exam 2 - More Signaling Flashcards
What is somatotropin?
Growth hormone
Where is somatotropin produced?
Anterior pituitary
Through what does somatotropin act?
Via growth hormone receptor
Where is IGF-1 made?
Liver
What 4 things does somatotropin affect growth of?
- Liver
- Bone
- Adipose tissue
- Skeletal muscle
How is GH used in children?
Supplemented for GH deficiency
How do body builders use GH?
To decrease body fat
How is GH used in aging populations?
To decrease loss of muscle mass
What is the IC structure of the GH receptor?
Dimer
What pathway does GH utilize?
MAPK and Jak/STAT
What is the end result of GH using the MAPK pathway?
Cell division/chondrocytes and bone growth during childhood
What is the end result of GH using the Jak/STAT pathway?
IGF-1 production in the liver and growth of liver and other tissues
What are the levels of IGF-1 in Great Danes vs. Chihuahuas?
High in Danes, Low in Chihuahuas
What is special about IGF-1 haplotypes in small breeds?
Impact IGF-1’s signal for production of GH; less GH is made than in larger breeds
What occurs in mouse models with elevated GH levels?
Gigantism
What occurs in mouse models with GH insensitivity?
Liver is unable to read signal to GH receptor.
What type of mutation does the Ames dwarf mouse have that leads to it being GH-deficient?
Loss-of-function
- Pituitary TF mutant
When GH signaling decreases, what happens to lifespan?
Increases
What does IGF-1 promote survival of when related to bovine somatotropin?
Mammary alveolar cells
What 3 things does recombinant BST do?
- Increases IGF-1 production in liver
- Increases survival of mammary alveoli
- Increases production over course of lactation
What are the side effects of rBST?
Can cause increased mastitis in cows and pregnancy issues if the cow gets pregnant another time
What makes cAMP?
Adenylyl cyclase
What does cAMP activate?
PKA
What does PKA do?
Phosphorylates and activates many proteins
What is cAMP hydrolyzed to?
AMP
What facilitates ATP –> cAMP?
Adenylyl cyclase
What facilitates cAMP –> AMP?
cAMP phosphodiesterase (PDE)
How is PKA activated?
cAMP binds to PKA regulatory subunits, catalytic subunits become active
What does adrenaline stimulate in the muscle?
Glycogen breakdown
What does glucagon stimulate in the liver?
Glycogen breakdown
What stimulates the muscle to break down glycogen?
adrenaline
What stimulates the liver to break down glycogen?
glucagon
What stimulates the heart to increase HR and force of contraction?
adrenaline
What does adrenaline stimulate in the heart?
Increased HR and force of contraction
What releases cholera toxin?
Vibrio cholerae
What does CTX catalyze in the cell?
Covalent modification of G protein
How does CTX act to increase the concentration of cAMP in the cell?
Activates adenylyl cyclase
What do elevated cAMP and PKA levels open in the cell in response to CTX?
Chloride (CFTR) channel
What ultimately causes watery diarrhea in someone with cholera?
Loss of Cl- and water from the cell
What is the therapeutic approach for cholera?
Enkephalin (opioid)
Where is adrenaline/epinephrine produced?
Adrenal medulla
Where does adrenaline bind?
GPCRs (adrenergic receptors)
What does adrenaline lead to in the alpha-1 pathway?
Vasoconstriction of GI and periphery blood vessels
What does adrenaline lead to in the alpha-2 pathway?
GI sphincter innervation and constriction
What happens to adenylyl cyclase, cAMP, and smooth muscle in the alpha-2 adrenaline pathway?
Adenylyl cyclase activates
cAMP increases
Smooth muscle contracts
What happens to adenylyl cyclase, cAMP, and smooth muscle in the beta adrenaline pathway?
Adenylyl cyclase activates
cAMP increases
Smooth muscle relaxes
What does adrenaline lead to in the beta pathway?
Increased HR, open airways (heart and bronchioles)
What is special about the way caffeine enters a cell?
It is lipid and water soluble so can enter the cell without binding to a receptor
Caffeine is a neuro_____.
stimulant
What does caffeine inhibit and what results?
Inhibits PDE, resulting in increased cAMP concentration, increased PKA activity (increased HR)
What are 2 ways to increase [cAMP]?
- Activate adenylyl cyclases (GPCR activation)
2. Inhibit PDE
