Cells refine palm fat into olive oil
Study provides the first precise insight into important remodeling
processes in adipose tissue

Date:
April 3, 2023
Source:
University of Bonn
Summary:
For more than 50 years, it has been suspected that fat cells
constantly remodel the lipids they store. Researchers have now
demonstrated this process directly for the first time using culture
cells. Among other things, the study shows that the cells quickly
eliminate harmful fatty acids. They refine others into molecules
that can be used more effectively. In the long term, this turns
the components of palm fat into the building blocks of high-quality
olive oil, for example.


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FULL STORY ==========================================================================
Fat molecules serve as energy storage for fat cells. They consist
of three fatty acids attached to a backbone of glycerol. They are
therefore also called triglycerides. It has long been suspected that
molecules do not remain unchanged during their storage period. Instead,
they are regularly broken down and reassembled -- a process called "triglyceride cycling." But is this assumption even true, and if so:
What would that be good for? "Until now, there has been no real answer
to these questions," explains Prof. Dr. Christoph Thiele of the LIMES
Institute at the University of Bonn. "It's true that there has been
indirect evidence of this permanent reconstruction for the past 50
years. However, direct evidence of this has so far been lacking."

==========================================================================
The problem: To prove that triglycerides are broken down, and fatty
acids modified and reincorporated into new molecules, one would need to
track their transformation as they travel through the body. Yet there
are thousands of different forms of triglycerides in each cell. Keeping
track of individual fatty acids is therefore extremely difficult.

Label makes fatty acids unmistakable "However, we have developed a
method that allows us to attach a special label to fatty acids, making
them unmistakable," says Thiele. His research group labeled various
fatty acids in this way and added them in a nutrient medium to mouse
fat cells. The mouse cells then incorporated the labeled molecules
into triglycerides. "We were able to show that these triglycerides do
not remain unchanged, but are continuously degraded and remodeled: Each
fatty acid is split off about twice a day and reattached to another fat molecule," the researcher explains.

But why is that? After all, this conversion costs energy, which is
released as waste heat -- what does the cell get out of it? Until now, it
was thought that the cell needed this process to balance energy storage
and supply. Or perhaps it is simply a way for the body to generate
heat. "Our results now point to a completely different explanation,"
Thiele explains. "It's possible that in the course of this process,
the fats are converted to what the body needs." Poorly utilizable fatty
acids would consequently be refined into higher-quality variants and
stored in this form until they are needed.

Fatty acids consist largely of carbon atoms, which hang one behind the
other like the carriages of a train. Their length can be very different:
Some consist of only ten carbon atoms, others of 16 or even more. In
their study, the researchers produced three different fatty acids and
labeled them. One of them was eleven, the second 16 and the third 18
carbon atoms long. "These chain lengths are typically found in food as
well," Thiele explains.

Short fatty acids are eliminated, long ones "improved" Labeling
allowed the researchers to track exactly what happens to the fatty
acids of different lengths in the cell. This showed that the fatty
acids consisting of eleven carbon atoms were initially incorporated into triglycerides. After a short time, however, they were split off again and channeled out of the cell. After two days, they were no longer detectable.

"Such shorter fatty acids are poorly usable by cells and can even damage
them," says Thiele, who is also a member of the Cluster of Excellence ImmunoSensation2. "Therefore, they are disposed of quickly." In contrast,
the 16- and 18-atom fatty acids remained in the cell, although not
in their original fat molecules. They were also gradually chemically
modified, for example by additional carbon atoms being inserted. In the original fatty acids, the carbon atoms were moreover linked with single
bonds -- roughly like a human chain in which neighbors join hands. Over
time, this sometimes developed into double bonds -- as if revelers at
a party were doing a conga.

The fatty acids that are formed in this process are called
unsaturated. They are better utilizable for the body.

"Overall, in this way the cells produce fatty acids that are more
beneficial to the organism than those that we had originally supplied
with the nutrient solution," Thiele emphasizes. In the long term, this
results for instance in the formation of oleic acid, a component of high-quality olive oil, from palmitate, such as that contained in palm
fat. However, the cell cannot change the fatty acids as long as they are
inside the fat molecule. They must first be split off, then modified,
and finally tacked back on. Thiele: "Without triglyceride cycling,
there is also no fatty acid modification." Adipose tissue can therefore improve triglycerides. If we eat and store food with unfavorable fatty
acids, they do not have to be released in that state again when we are
hungry. What we get back contains fewer "short" fatty acids, more oleic
acid (instead of palmitate) and more of the important arachidonic acid
(instead of linoleic acid). "Nevertheless, we should take care in our diet
to consume high-quality dietary fats as much as possible," the researcher stresses. Because the refinement never works 100 percent. In addition,
some of the fatty acids are not stored but used directly in the body. In
the next step, the researchers now want to test whether the same processes occur in human adipose tissue as in individual mouse fat cells in the
test tube. They also want to find out which enzymes make cycling work.

* RELATED_TOPICS
o Health_&_Medicine
# Dietary_Supplements_and_Minerals # Cholesterol #
Triglycerides # Obesity
o Plants_&_Animals
# Genetics # Molecular_Biology # Cell_Biology # Food
* RELATED_TERMS
o Olive_oil o Saturated_fat o Lipid o Unsaturated_fat o
DNA_repair o Mediterranean_diet o Omega-3_fatty_acid o
Bone_marrow

========================================================================== Story Source: Materials provided by University_of_Bonn. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Klaus Wunderling, Jelena Zurkovic, Fabian Zink, Lars Kuerschner,
Christoph Thiele. Triglyceride cycling enables modification
of stored fatty acids. Nature Metabolism, 2023; DOI:
10.1038/s42255-023-00769-z ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/04/230403133457.htm

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