atherosclerosis Flashcards
Things that can cause vascular damage leading to atherosclerosis
High cholseterol Turbulent blood flow Shearing forces sdLDL oxLDL
Chronic Inflammation, possibly some viruses, C. pneumonia
Cholesterol uptake transporters in the intestine
proximal jejunum
NPC1
NPC1L1
ER transporter of cholesterol
ACAT
forms cholesterol esters from cholesterol acyl coa cholesterol transport protein.
What transcription factor regulates liver synthesis and export of cholesterol?
LXR
Liver X Receptor
What regulates Bile acid uptake in the ileum?
IBAT
IBABP
Ilial bile acit transporter
ileal bile acid binding protein
both are FXR regulated
Which HDL is taken back up by the liver?
HDL 2
What regulates cholestrol synthesis?
HMG-CoA reductase
What regulates bile/cholesterol transport into the bile canaliculi?
ABC transporters,
ABCA1
ABCG1
BSEP
What does LXR do
LXR stimulates bile acid synthesis,
by activating 7-alpha-hydroxylase
Increases ABCA1, ABCG1 activity, increased bile transport
Activaters CETP
Cholesterol Ester transfer protein,
Increasing cholesterol transfer into HDLs
Mutations in CETP increase atherosclerosis, and increasing activity increases Cholesterol clearance
What do insigs do?
INSIGs bind to SCAPs and prevent them from activating sterol synthesis.
What does FXR do?
Increases BSEP activity, increased Bile salt export pump.
Increases SHP activity, which inhibits LXR
How is cholesterol synthesis induced by low cholesterol, in the liver?
SREBP-2, an ER-integral membrane protein
SREBP-2 binds to SCAP in the ER membrane,
SREBP-2-SCAP complex moves to the golgi and is cleaved
SREBP-2 is cleaved into fragments which go to the nucleus and bind DNA SRE, inducing increases HMG-CoA synthesis.
Low cholesterol also increases LDL-receptor expression to obtain fats.
How is Cholesterol taken up by peripheral cells?
By the LDL receptor
How is cholesterol exretyed by peripheral cells?
by ABCA1
ABCG1,5,8
Into HDLs
Under control of the LXR transcription factor.
Antithrombotic mediators of endothelial cells
PGI2
ADP