Rethinking reverse cholesterol transport

September 12, 2001

The protective role of HDL, the so-called "good cholesterol," has been attributed to its ability to transport cholesterol to the liver, where it can be incorporated into the bile and eventually excreted. Two players in this pathway have received particular attention: One, the phospholipid/cholesterol transporter ABCA1, is required for the synthesis of HDL, as seen in humans and mice with ABCA1 mutations, who are almost entirely lacking in this lipoprotein species. The other, the cell surface HDL receptor SR-BI, is expressed in hepatocytes and other cell types that consume large amounts of HDL cholesterol. Consistent with the commonly accepted model of reverse cholesterol transport, hepatic overexpression of SR-BI increases cholesterol levels in the bile, whereas deletion of the SR-BI gene dramatically reduces biliary cholesterol secretion. Now, however, a surprising report from Groen et al. shows that mice lacking a functional ABCA1 gene secrete normal levels of cholesterol through the bile, despite the nearly complete absence of plasma HDL. The authors note that another mouse line with low HDL levels, this one lacking the HDL apolipoprotein apoA-I, is also capable of normal biliary cholesterol clearance. As the authors suggest, these findings may force the field to reexamine whether HDL plays a major role in this hepatobiliary route of reverse cholesterol transport. Alternatively, it may be that hepatic uptake of cholesterol packaged in some other form, perhaps as VLDL, increases to compensate for the absence of HDL in these systems.
-end-


JCI Journals

Related Cholesterol Articles from Brightsurf:

Cholesterol's effects on cellular membranes
The findings have far-reaching implications in the general understanding of disease, the design of drug delivery methods, and many other biological applications that require specific assumptions about the role of cholesterol in cell membranes.

Autism-cholesterol link
Study identifies genetic link between cholesterol alterations and autism.

Microbes might manage your cholesterol
Researchers discover a link between human blood cholesterol levels and a gene in the microbiome that could one day help people manage their cholesterol through diet, probiotics, or entirely new types of treatment.

Experimental cholesterol-lowering drug effective at lowering bad cholesterol, study shows
Twice-yearly injections of an experimental cholesterol-lowering drug, inclisiran, were effective at reducing low-density lipoprotein (LDL) cholesterol, often called bad cholesterol, in patients already taking the maximum dose of statin drugs, according to data of the ORION-10 trial presented Saturday, Nov.

Rethinking how cholesterol is integrated into cells
Cholesterol is best known in connection with cardiovascular disease, but cholesterol is also vital for many fundamental processes in the body.

Seed oils are best for LDL cholesterol
Using a statistical technique called network meta-analysis, researchers have combined the results of dozens of studies of dietary oils to identify those with the best effect on patients' LDL cholesterol and other blood lipids.

Cholesterol leash: Key tethering protein found to transport cellular cholesterol
Cholesterol is an essential component of living organisms, but the mechanisms that transport cholesterol inside the cell are poorly understood.

New way to treat cholesterol may be on the horizon
A breakthrough discovery by scientists at Houston Methodist Research Institute could change the way we treat cholesterol.

How low should LDL cholesterol go?
New analysis shows that in a high-risk population, achieving ultra-low LDL cholesterol levels, down to <10 mg/dL, safely results in additional lowering of risk of cardiovascular events.

Does boosting 'good' cholesterol really improve your health?
A new review addresses the mysteries behind 'good' HDL cholesterol and why boosting its levels does not necessarily provide protection from cardiovascular risk for patients.

Read More: Cholesterol News and Cholesterol Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.