Energy for Cell Division
Freiburg, Nov 07, 2014
At the beginning of mitosis (M phase), the mitochondrial protein Tom6 is phosphorylated: It is modified to enable an increased import of proteins. This improves the performance of the mitochondria. Image: Meisinger Research Group
When a cell divides, it passes through a sequence of complex events. As the power plants of the cell, mitochondria are the main source of energy for these processes: They convert food into energy the cell can use. Together with a German-French research team, the Freiburg biochemist Dr. Angelika Harbauer and the Freiburg biochemistry professor Chris Meisinger have discovered a signaling path that links these two key tasks, cell division and energy conversion. The researchers published their findings in the journal Science. In the future, their work could help scientists to better understand the formation of tumors.
When a cell divides, its genetic information is copied and distributed among the resulting daughter cells in a complex process known as mitosis. This process is controlled by a particular kind of proteins, so-called cyclin-dependent kinases. As their name suggests, these proteins are regulated by cyclins. These are other proteins that are periodically formed and again broken down during the various phases of the cell cycle. The mitochondria are main source of energy for all of these processes.
In experiments on baker’s yeast, Harbauer discovered that a cyclin-dependent kinase phosphorylates a mitochondrial protein at the beginning of mitosis, meaning that the kinase modifies the protein to activate it. The mitochondrial protein is a component of the protein entry gate of the mitochondria: It imports nearly all of the proteins that serve a function in the mitochondria. As Harbauer demonstrated, the cell cycle–dependent modification of the protein entry gate leads to an increased import of proteins. This improves the performance of the mitochondria in their role as the power plants of the cell, thus ensuring that enough energy is available for a complex event like cell division. If this modification of the protein entry gate can no longer take place, the process of cell division – and ultimately also growth – is slowed down.
“We also find the modification discovered in the yeast in humans. It thus seems quite likely that this new signaling path also links the performance of the cellular power plants and cell division in human cells,” says Meisinger, who now plans to analyze these mechanisms in tumor tissues. The performance of the cellular power plants is greatly reduced in many forms of cancer. The newly discovered signaling path could therefore be a key to elucidating the relationship between dysregulated cell division and the mitochondria.
Chris Meisinger is a research group leader at the Institute of Biochemistry and Molecular Biology and a member of the Cluster of Excellence BIOSS Centre for Biological Signalling Studies. Angelika Harbauer is a member of Meisinger’s research group at the Institute of Biochemistry and Molecular Biology.
Original publication:
Angelika Harbauer, Magdalena Opalińska, Carolin Gerbeth, Josip Herman, Sanjana Rao, Birgit Schönfisch, Bernard Guiard, Oliver Schmidt, Nikolaus Pfanner and Chris Meisinger (2014). Cell Cycle-Dependent Regulation of Mitochondrial Preprotein Translocase. Science. DOI: 10.1126/science.1261253.
Contact:
Prof. Dr. Chris Meisinger
Institute of Biochemistry and Molecular Biology
BIOSS Centre for Biological Signalling Studies
University of Freiburg
Phone: +49 (0)761/203-5287
E-Mail: chris.meisinger@biochemie.uni-freiburg.de
Click here for a printable version (pdf) of the press release.