It
remains to be seen were this will take us, but it remains clear that
our ignorance is unchallenged when it come to understanding the
pathways leading to obesity. What is suddenly clear is that aberrant
pathways could exist and be very subtle.
What
is clear though is that exercise directly induces the conversion of
storage fat into fuel fat. This is helpful in that it supports
directly the causation argument for exercise. We actually needed
that as we had empirical results suggesting as much but no direct
argument outside of gobblety gook. Now we have a driven transition
into fuel that may even be tracked.
It
sometimes astonishes that this late in the day we are still making
primary observations of the cellular life of our bodies. What do we
know?
By Darren
Quick
23:50 July 12, 2012
A newly-discovered
third type of fat cell could be a target in the fight against obesity
(Photo: Shutterstock)
The existence of two
different types of fat – or adipose tissue – in mammals has long
been known: white fat, which stores calories and in excess results
in obesity, and brown fat, which burns calories to generate energy
and heat. Now scientists at the Dana-Farber Cancer Institute have
confirmed the existence of a third, genetically distinct type of fat
called “beige fat,” which they say is a potential therapeutic
target for treating obesity.
A 2008 paper out of
the Dana-Farber lab of Bruce Spiegelman, PhD, had proposed the
existence of a third type of fat cell, and now Spiegelman and his
team have become the first to isolate them and determine beige fat’s
unique genetic profile. They found that beige fat shares much in
common with brown fat. Both have the ability to burn large amounts of
calories as they both contain energy-burning organelles called
mitochondria, which contain iron and are responsible for the cells’
brown and beige hues.
"The therapeutic
potential of both kinds of brown fat cells is clear," the
authors say in their study, "as genetic manipulations in mice
that create more brown or beige fat have strong anti-obesity and
anti-diabetic actions."
However, unlike brown
fat cells, which express high levels of a protein called UCP1 that is
required by mitochondria to burn calories and generate heat, beige
fat cells normally express low levels of UCP1. But this changes in
response to cold or certain hormones, with beige fat cells able to
turn on high levels of UCP1, thereby enabling them to burn calories
almost as effectively as brown fat.
One of the hormones
that specifically targets beige fat cells to trigger high levels of
UCP1 is irisin, which is expressed by muscle cells during exercise.
Earlier this year, Spiegelman reported that irisin mimics some of the
results of a workout by prompting the transformation of white
fat into brown fat. He says this new research indicates that irisin
actually stimulates white fat to produce beige fat.
Spiegelman also found
that unlike brown fat cells, which are created from stem cell
precursors that also produce muscle cells, beige fat forms within
deposits of white fat cells from beige cell precursors. The beige
fat cells are found in scattered pea-sized deposits beneath the skin
near the collarbone and along the spine in adults. The team’s
research also found that deposits found in adult humans by three
research groups in 2009 and identified as brown fat are actually
beige fat cells.
It’s unclear whether
other research teams that have previously reported success in
activating brown fat – one using a protein called PRDM16 and
another by reducing the production of a naturally-produced
endocannabinoid in the brain – were actually related to beige
fat cells instead. However, given the new research’s claims as to
how beige fat cells are formed, it seems likely that UC San Francisco
researchers' recent discovery of a switch that turns white fat
cells into brown was actually turning them into brown fat cells.
Dana-Farber has
licensed the team’s discoveries about irisin to biotech company
Ember Therapeutics, which plans to develop the hormone as a therapy
for obesity and diabetes.
The team’s research
appears in the journal Cell.
No comments:
Post a Comment