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Researchers have discovered a protein that could be used in the fight against obesity. The researchers have demonstrated that the protein inhibits the conversion of white fat into brown fat. Disabling this protein in mice led to weight loss despite a high-fat diet.
White Fat, Brown Fat
Last month, I also wrote an article discussing brown fat and provided a brief explanation of it:
Humans have two types of body fat. White fat stores energy in large ‘droplets’ formed by triglycerides (a compound of glycerol and three fatty acids). Brown fat is formed by smaller ‘droplets’ and a large number of mitochondria, the powerhouses of a cell. These mitochondria contain iron that gives the brown color. The powerhouses provide high combustion, raising body temperature. Brown fat primarily serves as a regulator of body temperature during cold conditions. While white fat primarily stores fatty acids, brown fat is responsible for burning them.
The conversion of white adipose tissue into brown fat, also known as ‘browning,’ is an area in which science is increasingly interested as an aid in weight loss. In last month’s article, I wrote about a fat-burning patch that applies medication to promote this process locally. Unfortunately, however, not yet in humans.
Researchers from the Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC) have now gained more insight into the process of browning. The findings were published last week in
Nature Communications [1]. They collaborated with the academic hospital in Salamanca and researchers from the Universidad de Extremadura and the Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CiMUS) in Santiago de Compostela.
The team analyzed samples of adipose tissue from obese patients at the hospital in Salamanca. They discovered that these samples contained elevated levels of the protein MKK6. Further analysis of the protein then showed that it inhibits the conversion of white adipose tissue into brown fat. According to Dr. Sabio, their research shows that overweight individuals lose the ability to activate brown fat (higher combustion) and to convert white fat into brown fat. As a result, they are unable or less able to lose weight using brown fat.
Their study indicates that this inability to convert white fat into brown fat is caused by increased levels of MKK6. Through animal experiments, the team demonstrated that MKK6 prevents this conversion. Mice lacking the MKK6 protein have more brown fat and are therefore protected against obesity by converting excess energy into heat.
They also demonstrated that disabling MKK6 in mice, after they had already become obese, stopped further weight gain and even led to weight loss during a high-fat diet.
Protection Against Diabetes
The researchers also examined the extent to which these mice with disabled MKK6 were protected against the development of diabetes (during a high-fat diet).
The mice showed higher glucose tolerance and insulin sensitivity. The higher glucose tolerance corresponded to an increased insulin concentration with increased blood sugar.
The mice with the disabled protein thus had a lower blood sugar level and responded better to high blood sugar by producing insulin, which was then better responded to. All indications of a reduced risk of diabetes.
References
- Nuria Matesanz, Edgar Bernardo, Rebeca Acín-Pérez, Elisa Manieri, Sonia Pérez-Sieira, Lourdes Hernández-Cosido, Valle Montalvo-Romeral, Alfonso Mora, Elena Rodríguez, Luis Leiva-Vega, Ana Victoria Lechuga-Vieco, Jesús Ruiz-Cabello, Jorge L. Torres, Maria Crespo-Ruiz, Francisco Centeno, Clara V. Álvarez, Miguel Marcos, Jose Antonio Enríquez, Ruben Nogueiras, Guadalupe Sabio. MKK6 controls T3-mediated browning of white adipose tissue. Nature Communications, 2017; 8 (1) DOI: 10.1038/s41467-017-00948-z
