To understand where fat comes from, you have to start with a skinny mouse. By using such a creature, and observing the growth of fat after injections of different kinds of immature cells, scientists at the Howard Hughes Medical Institute and Rockefeller University have discovered an important fat precursor cell that may in time explain how changes in the numbers of fat cells might increase and lead to obesity.
The finding, published online in this week's issue of the journal Cell, could also have implications for understanding how fat cells affect conditions such as diabetes and cardiovascular disease.
"The identification of white adipocyte progenitor cells provides a means for identifying factors that regulate the proliferation and differentiation of fat cells," says senior author Jeffrey Friedman, who is the Marilyn M. Simpson Professor at Rockefeller and a Howard Hughes Medical Institute investigator.
Obesity, a major public health problem in the United States and increasingly in much of the Western world, results, in part, from an increase in the mass and number of white fat cells. Because white fat cells are post-mitotic, meaning that they cannot divide, scientists have hypothesized that a population of fat precursor cells must exist in the fat depot in order to produce new fat cells. But identifying these fat precursor cells has been difficult.
With the assistance of researchers in Rockefeller's Flow Cytometry Resource Center, first author Matt Rodeheffer, a postdoctoral associate in Friedman's Laboratory of Molecular Genetics, used a cell sorting technique called fluorescence-activated cell sorting, or FACS, to search for cell populations that could produce fat in cell cultures and identified two such populations.
To determine if these cells could develop into fat cells in living animals, Rodeheffer injected these cell populations into the fat depots of a genetically engineered mouse, developed at NIH, called fatless, which lacks white fat and mimics a condition in humans called lipodystrophy that also results in diabetes.
Rodeheffer found that only one of the isolated cell populations, which express the CD24 cell-surface marker protein, produced fat tissue in the fatless mouse. This population normally represents only .08 percent of the non-adipocyte population in adipose tissue.
An imaging assay recently developed by co-author Kivanç Birsoy, a graduate student in Friedman's laboratory, enabled Rodeheffer to observe the CD24-expressing cells form fat in a living animal. Birsoy's technique uses another animal strain called the leptin-luciferase mouse, in which the visibly detectable marker luciferase is expressed under the control of the promoter of the gene that produces the hormone leptin. In this mouse strain the luciferase marker gene only switches on in mature fat cells, and provides a non-invasive way of watching immature fat cell precursors develop into mature fat cells in a living animal over time.
"I injected the CD24+ cells - which represent a very small population of cells in normal adipose tissue - into a site where the fat would normally develop in the fatless mouse, and I found that a normal sized fat depot forms at the site of injection," says Rodeheffer.
Rodeheffer also found that the injection of the fat-producing cells corrects the fatless mouse's diabetes, and the fat cells secrete adipocyte-specific signaling proteins called cytokines. Both of these results confirm that the cells produced in the fatless mouse are functional fat cells.
"This finding gives us a better understanding of the basic biology of adipose tissue and opens the door for us and for other researchers to be able to study these cells in living animals and determine the molecular factors that regulate formation of adipose tissue," says Rodeheffer. "We then can potentially study how the growth and differentiation of these cells are regulated in obesity and determine whether or not the molecular events that are involved in the regulation of adipose tissue are contributing factors to other pathologies, such as diabetes and cardiovascular disease, that are associated with obesity and metabolic syndrome."
Joseph Bonner | Newswise Science News
Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
17.01.2017 | Earth Sciences
17.01.2017 | Materials Sciences
17.01.2017 | Architecture and Construction