06:19pm Friday 20 October 2017

How fasting helps fight fatty liver disease

 Jointly with colleagues from Helmholtz Zentrum München, scientists at the German Cancer Research Center in Heidelberg have new information on what happens at the molecular level when we go hungry. In cooperation with the German Center for Diabetes Research they were able to show that upon deprivation of food a certain protein is produced that adjusts the metabolism in the liver.

The growing number of overweight people has long been one of modern society’s pressing issues. In particular the resulting metabolic diseases such as type 2 diabetes and corresponding secondary conditions can have serious consequences for health. Can a reduced intake of calories help to whip the metabolism back into shape?

This is the question that Adam J. Rose at the German Cancer Research Center (DKFZ) Heidelberg and Stephan Herzig at the Helmholtz Zentrum München, wanted to answer. “Once we understand how fasting influences our metabolism we can attempt to bring about this effect therapeutically,” Rose states.

Stress molecule reduces the absorption of fatty acids in the liver

In the current study, the scientists looked for liver cell genetic activity differences that were caused by fasting. With the help of so-called transcript arrays, they were able to show that especially the gene for the protein GADD45β was often read differently depending on the diet: the greater the hunger, the more frequently the cells produced the molecule, whose name stands for ‘Growth Arrest and DNA Damage-inducible’. As the name says, the molecule was previously associated with the repair of damage to the genetic information and the cell cycle, rather than with metabolic biology.

Subsequent simulation tests showed that GADD45β is responsible for controlling the absorption of fatty acids in the liver. Mice who lacked the corresponding gene were more likely to develop fatty liver disease. However when the protein was restored, the fat content of the liver normalized and also sugar metabolism improved. The scientists were able to confirm the result also in humans: a low GADD45β level was accompanied by increased fat accumulation in the liver and an elevated blood sugar level.

“The stress on the liver cells caused by fasting consequently appears to stimulate GADD45β production, which then adjusts the metabolism to the low food intake,” Herzig summarizes. The researchers now want to use the new findings for therapeutic intervention in the fat and sugar metabolism so that the positive effects of food deprivation might be translated for treatment.

An interview with Stephan Herzig is available at:
https://vimeo.com/164214586

Jessica Fuhrmeister, Annika Zota, Tjeerd P. Sijmonsma, Oksana Seibert, Sahika Cıngır, Kathrin Schmidt, Nicola Vallon, Roldan M de Guia, Katharina Niopek, Mauricio Berriel Diaz, Adriano Maida, Matthias Blüher, Jürgen G. Okun, Stephan Herzig und Adam J. Rose: Fasting-induced liver GADD45β restrains hepatic fatty acid uptake and improves metabolic health, EMBO Molecular Medicine 2016, DOI: 10.15252/emmm.201505801

The German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) with its more than 3,000 employees is the largest biomedical research institute in Germany. At DKFZ, more than 1,000 scientists investigate how cancer develops, identify cancer risk factors and endeavor to find new strategies to prevent people from getting cancer. They develop novel approaches to make tumor diagnosis more precise and treatment of cancer patients more successful. The staff of the Cancer Information Service (KID) offers information about the widespread disease of cancer for patients, their families, and the general public. Jointly with Heidelberg University Hospital, DKFZ has established the National Center for Tumor Diseases (NCT) Heidelberg, where promising approaches from cancer research are translated into the clinic. In the German Consortium for Translational Cancer Research (DKTK), one of six German Centers for Health Research, DKFZ maintains translational centers at seven university partnering sites. Combining excellent university hospitals with high-profile research at a Helmholtz Center is an important contribution to improving the chances of cancer patients. DKFZ is a member of the Helmholtz Association of National Research Centers, with ninety percent of its funding coming from the German Federal Ministry of Education and Research and the remaining ten percent from the State of Baden-Württemberg.


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