New findings – Diabetes
Post doc Ingvild Aukrust and researcher Lise Bjørkhaug Gundersen presented new findings in January 2013. They have led a study that have discovered a previously unknown protein; SUMO protein (Small Ubiquitin -like Modifier), that may affect the regulation of insulin.
Dextrose or Glucose is the main source of energy in the body. Glucose is stored as glycogen in the liver and muscles and is released into the bloodstream when the body needs it. Insulin is necessary for glucose to enter the cells when additional energy is needed. In the pancreas there exist a separate sensor that can sense the level of glucose in the blood and mediate an increase in the secretion of insulin when glucose levels are high, and stop insulin secretion when glucose levels are low. This glucose sensor is called glukokinase.
If an individual has a mutation in the gene encoding glukokinase, that individual develops hereditary diabetes (of type MODY2). One longterm goal has been to find drugs that can stimulate glukokinase so that insulin secretion increases. Such drugs could be used in the treatment of both MODY2 and type 2 diabetes.
At the KG Jebsen Center for Diabetes Research, Department of Clinical Medicine 2 , University of Bergen and Haukeland University Hospital, researcher have now identified a specific factor that can affect the sensor glukokinase. This factor is called SUMO and is short for Small Ubiquitin -like Modifier. Experiments have shown that the glucose sensor glukokinase is stimulated when SUMO intereacts. Glucokinase interaction with SUMO also causes the sensor to be less susceptible to degradation by other proteins, and can therefore function longer. The findings may be of significance for the development of drugs directed at treating MODY2 and type 2 diabetes.
This work will in March 2013 be published in the Journal of Biological Chemistry, a prestigious journal in medical biochemistry and one of the most cited biomedical research journals in the world.
Postdoctoral Ingvild Aukrust and researcher Lise Bjørkhaug has led the study and professor Pål Rasmus Njølstad has been the coordinator. In addition, a number of scientists and physicians from the Department of Biomedicine, University of Bergen, and Harvard Medical School, Boston, USA participated. The study reflects a successful national and international collaboration where the University of Bergen and Haukeland University Hospital have been central in this work.
The work is supported by Helse Vest, Innovest, the Research Foundation KG Jebsen and the University of Bergen.
Ingvild Aukrust*, Lise Bjørkhaug*, Maria Negahdar, Janne Molnes, Bente B. Johansson, Yvonne Müller, Wilhelm Hass, Steven P. Gygi, Oddmund Søvik, Torgeir Flatmark, Rohit N. Kulkarni, and Pål R. Njølstad: SUMOylation of pancreatic glucokinase regulates its cellular stability and activity.
Journal of Biological Chemistry, online 7. Januar 2013 (doi:10.1074/jbc.M112.393769/PMID: 23297408). *These have contributed equally.