Metabolic Homeostasis #23

Question 1

the function of AMP-dependent protein Kinase (AMPK)

Answer 1

activates ATP -generating processes

inhibits ATP- consuming processes

Question 2

Structure of AMPK

Answer 2

is an alpha-beta-gamma heterotrimer
the alpha contains Ser/Thr172 protein kinase domain
the gamma contains sites for allosteric activation by AMP or inhibition by ATP

Question 3

when is AMPK activated?

Answer 3

when it is phosphorylated

Question 4

the major AMPK in the body is

Answer 4

the liver kinase LKB1

Question 5

adenylate kinase perfoms?

Answer 5

2ADP–>

Question 6

AMPK function in the heart

Answer 6

it affects the PFK-2/FBPase-2 enzymes that affect F2,6P concentration.

Question 7

AMPK inhibits which 3 reactions in the liver

Answer 7

lipogenesis
gluconeogenesis
glycogen synthesis

Question 8

how does AMPK dependent phosphorylation inhibit FA biosynthesis

Answer 8

by stopping acetyl-coA carboxylase

Question 9

how does AMPK dependent phosphorylation inhibit cholesterol biosynthesis

Answer 9

by stopping HMG-coA reductase

Question 10

how does AMPK dependent phosphorylation inhibit glycogen synthesis

Answer 10

by stopping glycogen synthase

Question 11

AMPK promotes which 2 processes in skeletal muscle?

Answer 11

FA oxidation

Glucose uptake

Question 12

how does AMPK promote FA oxidation

Answer 12

AMPK inhibits acetyl-coA carboxylase. This means a decrease in malonyl-coA. This means an increase in activity of carnitine acyltransferase 1. Therefore an increase in acyl-coA entry into mitochondria

Question 13

how does AMPK increase glucose uptake in skeletal muscle?

Answer 13

by increasing expression of GLUT4, thus facilitating insulin independent entry of glucose into cells

Question 14

how does AMPK dependent phosphorylation inhibit lipolysis in adipocytes

Answer 14

it phosphorylate hormone sensitive lipase in adipose tissue, this inhibits the lipase. Therefore less TAG are broken into FA. Thus a decrease of FA in bloodstream. This help prevent buildup of intracellular free FA –> soapy

Question 15

how does adiponectin affect AMPK

Answer 15

it is a protein hormone synthesized by adipocytes.
it shows in the blood stream as homotrimers LMW, homoexmers MMW, aggregates HMW, and proteolytic fragments.
When it binds to its receptors on the liver and muscle cells it stimulates the phosphorylation of AMPK. Thus acting to increase insulin sensitivity

Question 16

decreased adiponectin is associated with

Answer 16

insulin resistance. This is because adiponectin increases insulin sensitivity

Question 17

why does the blood concentration of adiponectin decrease with increases adipose tissue?

Answer 17

because of increases production of tumor necrosis factor alpha, which is a growth factor that decreases expression and secretion of adiponectin from adipocytes

Question 18

leptin

Answer 18

is a protein hormone, synthesized and secreted by adipose cells, it decreases appetite. It is called the satiety hormone. encoded by OB gene in mice

Question 19

neuropeptide Y

Answer 19

is synthesized and releases in the hypothalamus, it increases appetite

Question 20

how is NY secretion inhibited?

Answer 20

by insulin and leptin binding on hypothalamus

Question 21

in obese humans leptin ….

Answer 21

leptin resistance is present, thus increases levels are associated with high fat levels.

Question 22

ghrelin

Answer 22

is an appetite stimulating peptide secreted by an empty stomach

Question 23

PYY

Answer 23

is an appetite suppressing hormone released by GI tract

Question 24

when glucose levels are low, how do muscle cells get their energy fill?

Answer 24

by switching to FA metabolism

Question 25

the livers reserve of glycogen is exhausted after how many hours?

Answer 25

in 40 hrs

Question 26

after glycogen is exhausted how does the body get glucose?

Answer 26

by gluconeogenesis

Question 27

diabetes type 1

Answer 27

lack/functional deficiencies of pancreatic B cells

Question 28

what 2 substances increase AMPK activity

Answer 28

metformin and thiazolidinediones, they inhibit gluconeogenesis in liver and increase glucose uptake by muscle. they increase AMP/ATP ratio and decrease insulin resistance by activating peroxisome proliferator activated receptor-Y. Which induces synthesis of adiponectin and activation of AMPK. this causes decreased lipolysis and FA export–> decreased insulin resistance

Question 29

restinin in mice

Answer 29

blocks the action of insulin on adipocytes