We get our DNA from our parents. However, the exceptional fact puzzled scientists: Most animals, including humans, get their mitochondrial DNA only from their mothers. When a sperm meets an egg, the father’s mitochondrial DNA is destroyed, so only the mother’s DNA is passed on.
A new study by CU Boulder scientists explains the reason behind it. It suggests that when the process goes wrong, and some of the father’s mitochondrial DNA gets into the developing embryo, it can cause long-term issues in adults, like problems with the brain, behavior, and reproduction.
A study in roundworms is helping scientists understand some mitochondrial disorders. These disorders affect the body’s energy production and impact about 1 in 5,000 people. The research suggests that a simple vitamin, vitamin K2, might help prevent or treat these disorders.
Senior author Ding Xue emphasized the importance of quickly removing paternal mitochondria during early development and expressed hope for new treatments for related human diseases.
Mitochondrial DNA can be inherited from fathers, not just mothers
Mitochondria are like cellular batteries that create ATP, the energy source for almost all cell functions. They have their DNA, which is usually inherited only from the mother. In 2016, Xue published a critical study explaining how paternal mitochondria are eliminated through a process called “paternal mitochondria elimination (PME),” which has been observed in worms, rodents, and humans.
Xue said, “It could be humiliating for a guy to hear, but it’s true. Our stuff is so undesirable that evolution has designed multiple mechanisms to ensure it is cleared during reproduction.”
Some researchers believe sperm mitochondria may be worn out and damaged after competing to reach the egg, which could be harmful if passed on. Xue and his team investigated what happens when these paternal mitochondria don’t self-destruct, using C. elegans, a tiny worm with a simple body structure.
They found they couldn’t completely stop the elimination process, which shows how strong it is, but they could delay it by about 10 hours. This delay led to lower ATP levels, which resulted in impaired thinking, activity changes, and reproduction issues in the worms.
Not your mom’s genes: Mitochondrial DNA can come from dad
However, when they treated the worms with a form of vitamin K2 called MK-4, known for bone health, it restored ATP levels and improved memory, activity, and reproduction in the adult worms.
Scientists noted, “There are only a few documented cases in which paternal mitochondrial DNA might have been found in human adults. One 28-year-old man had trouble breathing, weak muscles, and could not tolerate exercise. Another paper describes 17 members of three unrelated multi-generational families who had fatigue, muscle pain, speech delays, and neurological symptoms.”
“More research is needed in larger animals, but Xue suspects that in some cases, as with the worms, a mere delay in PME could fuel hard-to-diagnose human diseases.”
“If you have a problem with ATP, it can impact every stage of the human life cycle.”
Journal Reference:
- Hu Zhang, Yunan Zhu, Ding Xue. Moderate embryonic delay of paternal mitochondrial elimination impairs mating and cognition and alters the behaviors of adult animals. Science Advances. DOI: 10.1126/sciadv.adp8351
