How to protect cells from selfish mitochondrial DNA

April 20, 2017, Lomonosov Moscow State University
Structure of the human mitochondrial genome. Credit: Wikipedia/CC BY-SA 3.0

Using yeast cells as a model, scientists from the A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University investigated the mechanisms that allow cells to protect themselves from invasion of selfish mitochondrial DNA molecules. The findings were published in the Journal of Cell Science.

The information on the structure and functioning of a cell is encoded in its DNA. While most of this information is encoded in nuclear DNA, a small but essential part is stored separately in mitochondrial DNA (mtDNA). The main role of mitochondria is to convert energy into ATP—the "molecular currency" of a cell. Mitochondrial DNA encodes some of the proteins involved in mitochondrial function. Selfish mitochondrial DNA emerge as a result of mutations. Such mtDNA molecules usually contain large deletions. These mtDNA molecules do not contain information necessary for mitochondrial operation, but have a competitive advantage over functional mtDNA molecules—being shorter than the normal mtDNA, selfish mtDNA molecules are able to replicate faster than the normal ones. As a result, eventually selfish mtDNAs replace functional mtDNA molecules. The accumulation of selfish mtDNA molecules in the can impair mitochondria functioning and induce pathologies. In their work the scientists investigated potential strategies to protect cells from selfish mtDNA clonal expansion.

Dmitry Knorre, a senior researcher at the A.N. Belozersky Institute of Physico-Chemical Biology, the corresponding author of the study shares: "We have crossed containing different (normal and selfish) variants of mtDNA and observed the results of their "competition". This experiment was possible because diploid yeast cells, in contrast to mammalian zygotes, inherit mtDNAs from both gametes (parents)."

The biologists have found out that the uncouplers of oxidative phosphorylation (namely, compounds, which decrease the efficiency of mitochondrial energy conversion) change the results of this "competition" in favor of functional mtDNA. Notably, this effect of uncouplers could be observed only in those cells, where mitochondria could divide into separate fragments and undergo intracellular digestion.

Dmitry Knorre says: "We've found that uncouplers stimulate the mitochondrial turnover in the cells. However, this effect is well pronounced only in zygotes but not in haploid yeast cells. Perhaps, the digestion of non-functional mitochondria is an evolutionary conserved mechanism protecting organisms from invasion of selfish mtDNA during sexual reproduction."

In their research, the scientists have used fluorescence microscopy and electron microscopy and also molecular biology techniques.

The biologists are going to continue studying mitochondria degradation mechanisms at different stages of the yeast life cycle. They want to find out how the cellular molecular machinery of "mitochondria digestion" recognizes bad mtDNAs hidden by two membrane layers and how the cell decides whether to eliminate this mitochondrion or not.

Explore further: For veterans with Gulf War Illness, an explanation for the unexplainable symptoms

More information: Iuliia E. Karavaeva et al, Mitochondrial depolarization in yeast zygotes inhibits clonal expansion of selfish mtDNA, Journal of Cell Science (2017). DOI: 10.1242/jcs.197269

Related Stories

Study unlocks more about cancer

February 10, 2015

Ground-breaking research from Griffith University on the Gold Coast has some scientists wondering if the entire study of cellular biology needs to be adjusted.

Cell-free circulating mtDNA identifies Parkinson's disease

December 10, 2015

(HealthDay)—Cell-free circulating mitochondrial DNA (ccf-mtDNA) from cerebrospinal fluid (CSF) is reduced in patients with Parkinson's disease (PD), according to research published in the December issue of the Annals of ...

Recommended for you

The changing shape of DNA

May 24, 2018

The shape of DNA can be changed with a range of triggers including copper and oxygen—according to new research from the University of East Anglia.

Universal pH regulated assembly of DNA nanostructures

May 23, 2018

DNA, the carrier of genetic information, has become established as a highly useful building material in nanotechnology. One requirement in many applications is the controlled, switchable assembly of nanostructures. In the ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.