Human brain and the potato: Similarities within the mitochondrial ion channels

Membranes surrounding the mitochondria contain proteins controlling the movement of ions, called the ion channels. Research conducted by scientists from the Nencki Experimental Biology Institute of the Polish Academy of Sciences in Warsaw (Nencki Institute) and the Institute of Molecular Biology and Biotechnology at the Adam Mickiewicz University (IBMiB UAM) in Poznan showed that certain types of mitochondrial potassium channels in potato cells are identical with respect to their structure and function as their counterparts in the mitochondria of neurons in mammalian brain.

Mitochondria, the energy centres of cells, are organelles a few micrometres in length. They are present inside eukaryotic cells (cells with a nucleus) and their number ranges from a few hundred to a few thousand. Mitochondria are responsible for important life functions as, among other, they produce a chemical compound called adenosine triphosphate (ATP), which is the main carrier of chemical energy in cells. Its fundamental importance is highlighted by the fact that each day a human being transforms ATP in the amount comparable to the mass of its entire body.

Ion channels are proteins which allow the flow of large quantities of certain type of ions in a controlled manner. In the membranes surrounding either the cells or the mitochondria, there are channels specializing in transport of potassium, sodium, calcium or chlorine ions. Scientists from Nencki Institute and IBMiB UAM investigated mitochondrial potassium channels controlled by ATP as well as calcium ions.

"The problem with ion channels in the mitochondrial membranes is that they really should not exist at all. Modern models of energy production in the cell indicate that channels in mitochondrial membranes would lower the effectiveness of the process. But since the channels do exist, they must have provided significant evolutionary advantage. We, therefore, face the following question: when in the history of life on Earth has this advantage played a role?," comments Prof. Adam Szewczyk from Nencki Institute, co-investigator.

Ion channels are opened and closed by specific activators or blockers. An example of a blocker affecting human cellular mitochondria is iberiotoxin, present also in the scorpion venom. Measurements of the current flowing through the potassium channels in the mitochondria of potatoes, taken at Nencki Institute, have shown that these proteins not only have a similar function as mammalian mitochondrial channels, but also react to the same toxins. "This is extraordinary. Proteins responsible for the transport of potassium ions seem to be evolutionary preserved it the mitochondria," concludes Prof. Wiesława Jarmuszkiewicz from the IBMiB UAM.

Ion channel research may have great medical significance. Drugs affecting mitochondrial ion channels could significantly limit the effects of heart attacks and strokes. However, introducing a new drug to the market is a very expensive and long process. For this reason the effects of mitochondrial ion channel research will likely first impact the cosmetics industry.

The Nencki Institute of Experimental Biology PAS intends to begin long term collaboration with Dr. Irena Eris Cosmetic Laboratory. They have jointly submitted a project under the INNOTECH initiative implemented by the National Centre for Research and Development. By studying protective substances affecting mitochondrial potassium channels they hope to develop new dermocosmetics. "If everything goes as planned, in a couple of years everyone will be able to try a new dermocosmetic product and appreciate the benefits of mitochondrial basic research," concludes Prof. Szewczyk.

The Nencki Institute of Experimental Biology of the Polish Academy of Sciences has been established in 1918 and is the largest non-university centre for biological research in Poland. Priority fields for the Institute include neurobiology, neurophysiology, cellular biology and biochemistry and molecular biology -- at the level of complexity from tissue organisms through cellular organelles to proteins and genes. There are 31 labs at the Institute, among them modern Laboratory of Confocal Microscopy, Laboratory of Cytometry, Laboratory of Electron Microscopy, Behavioural and Electrophysiological Tests. The Institute is equipped with state-of-the-art research equipment and modernized animal house, where lab animals are bred, also transgenic animals, in accordance with the highest standards. Quality of experiments, publications and close ties with the international science community, place the Institute among the leading biological research centres in Europe.