Babies get their adorable chubbiness from brown fat, which keeps them warm. However, until 2009, scientists thought we lost this healthy tissue as we age. Since its discovery in adults, brown fat has been studied as potential treatment for obesity and other health-related issues. Now a team at Boston University has sequenced the genes of different fat types and discovered that white fat cells may be turned brown through several different mechanisms, also by way of an experimental chemotherapy drug.
White fat is the more common type of adipose tissue which is used to store excess energy.
Brown fat contains more mitochondria, iron-rich organelles that burn glucose and lipids rapidly to generate body heat and create energy, helping to fight obesity and associated health risks.
Conversion of white fat into brown fat:
Previous studies have found methods to increase the growth of healthy brown fat, or how existing white fat can be converted into high fish oil diets or blocking certain proteins in the body. This process of conversion is called “beigeing”. The genetically distinct type of fat produced is called as beige fat. Boston University scientists looked to a diabetes drug called Avandia, in the process of wanting to replicate Brown fat. The drug Avandia has not been shown to improve the function of white fat, rather cause weight and heart problems in some people.
The ideal thing would be to have a drug that does all the good things Avandia does, without the side effects,” says Stephen Farmer, senior author of the study. “A lot of research now is focusing on what exactly the ‘beigeing’ fat is, how it functions, and how we can activate it.”
The project:
To study the process, the team experimented with two groups of mice: 1. Healthy ones, 2. Mice that were fed upon high-fat, high-calorie diet. Then, these mice have divided again into a control group, 3other groups that received different drugs:
- Avandia
- Experimental Chemotherapy drug- Roscovitine
- CL-316,243, which mimics how the body responds to external cold, a factor that’s previously been linked to improved brown fat growth
Eight weeks later, of these three leads, only the mice given Roscovitine showed any improvements, including lower blood glucose levels, reduced weight gain and increased levels of beige fat, without any ill effects.
Looking for other potential avenues of treatment, the researchers went on to analyze the genes of the different types of fat. By using transgenic mice whose fat cells glowed different colors – red for white fat, and green for brown – the team was able to separate and study the cells. They found that the brown fat cells could be divided into three genetically distinct types, according to how they were produced. Naturally-occurring brown cells had one genetic pattern, while those created through cold had another, and those induced by either Avandia or Roscovitine were different again.
The team calls these types of brown cells classic brown, beige and bright, respectively. Why they have different genetic patterns is still unknown, and they appear to include genes not normally associated with fat. But although only one of the drugs had positive effects, the research does suggest that multiple methods, including drugs, could be used to induce brown fat.