Researchers Discover Three Pathways Regulating Gates to Mitochondria

Researchers have discovered three signalling pathways that regulate the gates to the cell's powerhouses, also known as mitochondria.

Mitochondria were long thought to be structures that acted relatively independent from the cell. However, in a new study published in the journal Cell Metabolism, researchers outline three signalling paths the cells use to control the mitochondria's process.

Using baker's yeast, the scientists identified three enzymes that regulate the movement of proteins into the mitochondria.

The discovery, according to Dr. Chris Meisinger, a professor at the University of Freiburg and the study's lead researcher, could have widespread implications.

"Our work lays an important foundation for investigating signalling pathways like these in humans and determining what role they play in the development of illnesses," he said in a statement. "In [tumor] cells the mitochondrial energy metabolism is dysregulated, and it is possible that this reprogramming is conveyed over these newly discovered signalling paths."

Mitochondria represent a cell within the cell, separated by its own membrane and containing its own genome. Most mitochondrial proteins, however, are read off from the DNA in the nucleus, and need to be precisely sorted and then possibly transferred through the outer mitochondrial membrane, also known as the TOM complex. Like a nightclub bouncer, receptors like Tom22 decide which proteins can enter and which can't.

The gate, the researchers further discovered, is regulated by cellular proteins. They were able to prove that these so-called kinases can determine just how permeable that gate is by connecting a phosphate to the precursor of the protein Tom22.

The catalyst is sugar glucose, which means the cell is able to adjust the energy metabolism in the mitochondrion based on environmental shifts: when there is ample glucose, the pores allow fewer proteins necessary for energy production through, for example. When this happens, the cell is able to obtain its energy from the cytosol.

According to the press release detailing the discovery: "One of the kinases is even embedded directly in the outer membrane, right next to the TOM complex. Up to now, only few protein kinases have been found in mitochondria."