Researchers use CRISPR-Cas9 to successfully target brown fat

Fat is an essential component of life, however too much fat leads to numerous health issues. Investigating the role played by fat or adipose tissue is significant to get a better understanding of obesity and other problems. However, structural variations of the fat cells and their distribution throughout the body make it challenging.

Fat cells are different from other cells in that they lack unique cell surface receptors and only account for a minority of the cells within fat tissue.”

Steven Romanelli PhD, Department of Molecular & Integrative Physiology, University of Michigan Medical School

Steven Romanelli is a former member in the lab of Ormand MacDougald PhD.

Romanelli, MacDougald, and coworkers demonstrated a breakthrough utilizing CRISPR-Cas9, a tool that revolutionized molecular biological research, whose use in the analysis of adipose tissue had been elusive. The study was published in the Journal of Biological Chemistry.

The biggest challenge in terms of adipose research to date has been that if you want to study a gene’s function, you have to commit a considerable amount of time, resources, and money into developing a transgenic mouse.”

Steven Romanelli PhD, Department of Molecular & Integrative Physiology, University of Michigan Medical School

According to Romanelli, the conventional way of developing mouse models includes breeding mice with the desired mutation to introduce or delete the genes of interest, and this could take more than a year and tens of thousands of dollars.

CRISPR-Cas9 brought in changes to this process. This gene-editing technique comprises an enzyme named Cas9 which breaks strands of DNA and a piece of RNA that pilots the Cas9 enzyme to the desired site in the genome for editing.

This tool is packed into a harmless virus for delivery to the cells under investigation. The tool was utilized to successfully examine the liver, heart, neurons, and skin cells to name a few. However, this tool was never used on a certain type of adipose cells called brown fat.

With this technique, the researchers successfully targeted brown fat, a specialized adipose tissue employed to produce heat and safeguard core body temperature.

What we’ve been able to do is take that whole process and distill it into anywhere from two weeks to a month to generate a transgenic mouse, reducing the cost to less than $2,000. Not only does it reduce time and cost, it democratizes the research so that any lab that is familiar with molecular biology techniques can adopt this method and do it themselves.”

Steven Romanelli PhD, Department of Molecular & Integrative Physiology, University of Michigan Medical School

The researchers also used the technique to remove multiple genes simultaneously, which facilitates the understanding of vital molecular pathways.

With the adeno-associated virus CRISPR-Cas9 components, the scientists could knock out the UCP1 gene that determines brown adipose and allows it to produce heat, in adult mice. The researchers found that the knockout mice could adapt to the gene loss and retain their body temperature in cold conditions, indicating the presence of other pathways in temperature homeostasis.

Romanelli remarks that these initial results are exploratory, however, the technique indicates a vital step forward in investigating fat.