The article has been published in the Journal of Clinical Investigation (JCI). GGTase-I is found in all cells but is particularly important for the function of so-called CAAX proteins in inflammatory cells. GGTase-I attaches a cholesterol-like fatty acid on the CAAX proteins.
Researchers previously believed that this fatty acid played an important role in activating the proteins and could contribute to the functioning of inflammatory cells. There are now medicines that include substances that suppress the activity of GGTase-I with the aim of stopping the CAAX proteins from working. These substances are already being clinically tested on cancer patients, and researchers have also wondered whether they could be used to alleviate inflammatory disorders such as rheumatoid arthritis.
However, treatment with substances that inhibit GGTase-I has often been non-specific, making it difficult for researchers to assess the real potential of GGTase-I as a drug target.
“We therefore developed genetic strategies in transgenic mice to switch off the gene that codes for GGTase-I,” says PhD student Omar Khan who is heading up the study along with professor Martin Bergö and co-worker docent/consultant Maria Bokarewa from the Institute of Medicine. “This allowed us to investigate whether a complete blockade of GGTase-I can inhibit the development of inflammatory disorders and whether there are any side-effects.”
However, the results were quite the opposite of what the researchers were expecting. Instead of inhibiting inflammation, the deficiency of GGTase-I in macrophages (a common type of inflammatory cell) led to the mice developing chronic inflammation with cartilage and bone erosion in the joints, very similar to rheumatoid arthritis in humans.
“We had to reassess the role that GGTase-I plays in the function of CAAX proteins, and found that one group of CAAX proteins could not only function quite normally in macrophages that didn’t have any GGTase-I, but even increased in number and activity. This led to hyper-activation of the macrophages, which produced large quantities of inflammatory substances and, in turn, led to arthritis in the mice.”
GGTase-I acts on over 50 different CAAX proteins. The study shows that just one of these proteins – RAC1 – appears to be behind the disorder. This means that one function of GGTase-I is to suppress the activity of RAC1 and protect mice from developing arthritis. The results suggest that medicines that inhibit GGTase-I might actually induce arthritis instead of providing a cure. This will be important information for the ongoing clinical trials with GGTase-I inhibitors in cancer patients.
“The study has also resulted in an effective and simple genetic mouse model for arthritis that can be used to study the effect of new medicines and identify the mechanisms involved in the development of the disorder,” says Khan. “The next step is to try to decide whether and how GGTase-I and RAC1 are implicated in arthritis in humans.”CAAX PROTEINS
Docent/consultant Maria Bokarewa, Institute of Medicine, Sahlgrenska Academy, tel: +46 (0)31 342 4021, mobile: +46 (0)70 651 3292, e-mail: email@example.comBibliographic data
Authors: Omar M. Khan, Mohamed X. Ibrahim, Ing-Marie Jonsson, Christin Karlsson, Meng Liu, Anna-Karin M. Sjogren, Mikael Brisslert, Sofia Andersson, Claes Ohlsson, Lillemor Mattsson Hultén, Maria Bokarewa and Martin O. Bergo
Helena Aaberg | idw
Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory
How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy