Ch 32 736-741

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Questions and Answers

What is the best-characterized lipoprotein receptor that specifically recognizes apoB-100 and apo E?

LDL receptor (correct)

VLDL receptor

LRP receptor

Macrophage scavenger receptor

Where is the LDL receptor gene located?

Chromosome 6

Chromosome 3

Chromosome 12

Chromosome 19 (correct)

What is the LDL receptor composed of?

Seven different regions

Five different regions

Eight different regions

Six different regions (correct)

What is the LDL-binding region of the LDL receptor composed of?

A cysteine-rich sequence of 40 residues Signup and view all the answers

What type of side chains bind ionic calcium in the LDL-binding region of the LDL receptor?

Acidic side chains Signup and view all the answers

What process was involved in assembling the gene for the LDL receptor?

Exon shuffling Signup and view all the answers

Which enzyme catalyzes β-hydroxylation at carbon 11 in the synthesis of steroid hormones?

P450C17 (CYP17) Signup and view all the answers

Which carrier is responsible for carrying thyroid hormones?

Thyroid-binding globulin (TBG) Signup and view all the answers

What is the precursor of the protease plasmin that degrades fibrin, a major component of blood clots?

Apolipoprotein(a) Signup and view all the answers

Which enzyme is involved in the transfer of electrons from NADPH through electron transfer protein intermediates to molecular oxygen in the synthesis of steroid hormones?

Cytochrome P450 (CYP) enzymes Signup and view all the answers

What is the physiological function of lipoprotein(a)?

Inhibits plasminogen activation and fibrinolysis Signup and view all the answers

Which lipoprotein is essentially an LDL particle that is covalently bound to apolipoprotein(a)?

Lipoprotein(a) Signup and view all the answers

Which receptor recognizes a broader spectrum of ligands, including apoE and remnants produced by the digestion of triacylglycerols?

LRP-1 Signup and view all the answers

What can lead to multifactorial mechanisms responsible for increased serum LDL cholesterol levels?

Glycation Signup and view all the answers

Which region of the LDL receptor is specifically related to ligand release?

Region A Signup and view all the answers

What can mutations in the LDL receptor gene lead to?

Elevated LDL cholesterol levels Signup and view all the answers

Where is LRP-1 abundant in the cell membranes?

Liver, brain, and placenta Signup and view all the answers

What is the impact of insulin on the number of LRP-1 receptors on the cell surface?

Increases Signup and view all the answers

What is the initial visible sign of atherosclerosis in the vessel lumen?

Fatty streaks Signup and view all the answers

Which cells transform into macrophages under the influence of chemoattractant cytokines secreted by vascular cells?

Monocytic cells Signup and view all the answers

What is the primary function of HDL, also known as 'good cholesterol'?

Accepts free cholesterol from peripheral tissues and helps lower blood cholesterol levels Signup and view all the answers

Which factor is not considered a risk factor for atherosclerosis?

Elevated HDL levels Signup and view all the answers

What is involved in the modification of LDL in atherosclerosis?

Oxidative damage, particularly of polyunsaturated fatty acyl groups Signup and view all the answers

Which treatment option is effective for reducing blood cholesterol levels?

Atorvastatin Signup and view all the answers

Which of the following is a potential consequence of foam cell accumulation in atherosclerosis?

Microscopic separations between endothelial cells Signup and view all the answers

What is the role of high intraluminal shear forces in atherosclerosis?

Induce macrophages to secrete additional metalloproteinases Signup and view all the answers

What is the effect of postmenopausal hormone replacement therapy (HRT) on LDL and HDL levels?

Decreases LDL and increases HDL levels Signup and view all the answers

What is the role of Proprotein convertase subtilisin-like kexin type 9 (PCSK9) in regulating LDL receptor levels?

Gain of function mutations cause hypercholesterolemia Signup and view all the answers

What is the effect of statins on LDL receptor synthesis?

Activates SREBP-2, which upregulates LDL receptor synthesis Signup and view all the answers

What is the impact of patients with elevated VLDL or LDL and low HDL levels?

Predisposed to atherosclerosis and have a high incidence of heart attacks and strokes Signup and view all the answers

Study Notes

Atherosclerosis, HDL, LDL, and Drug Targets

Macrophages can replicate and express scavenger receptors, binding and internalizing oxidatively modified fatty acids within LDLs, forming foam cells.
Foam cell accumulation causes microscopic separations between endothelial cells, leading to platelet adhesion and aggregation, potentially causing thrombus formation.
As the plaque matures, a fibrous cap forms over its expanding "roof," partially occluding the vascular lumen.
Vascular smooth muscle cells migrate to the subintimal space, secreting plaque matrix material and metalloproteinases that thin the fibrous cap, leading to rupture and acute thrombus formation.
Plaques that rupture contain focal areas of calcification, induced by oxidized sterols and TGF-β, promoting bone-like formation.
Patients with elevated VLDL or LDL and low HDL levels are predisposed to atherosclerosis and have a high incidence of heart attacks and strokes.
Physical activity and estrogen administration can increase HDL levels, recommended for heart disease prevention.
Postmenopausal hormone replacement therapy (HRT) decreases LDL and increases HDL levels but may increase the rate of atherosclerotic vascular disease.
Proprotein convertase subtilisin-like kexin type 9 (PCSK9) regulates LDL receptor levels, with gain of function mutations causing hypercholesterolemia and nonfunctional variants resulting in lower LDL levels.
Statins work partly by activating SREBP-2, which upregulates LDL receptor synthesis and PCSK9, and clinical trials using monoclonal antibodies against PCSK9 have shown significant LDL level reductions.
High intraluminal shear forces in plaque's thinning areas induce macrophages to secrete additional metalloproteinases, contributing to plaque rupture and thrombus formation.
Cholesterol is the precursor of all five classes of steroid hormones, synthesized in various organs and transported through the blood complexed with serum proteins.

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Description

Test your knowledge of atherosclerosis, HDL, LDL, and drug targets with this quiz. Explore the mechanisms of plaque formation, the role of cholesterol levels, and the impact of drugs and lifestyle on heart disease prevention.