Stress hits every one of us, like when the Heartbleed virus makes you have to go back and reset all of your online passwords. Recent evidence has already linked the DNA methylation and histone alterations left behind by stressful events to transgenerational epigenetic inheritance, but now, scientists from the Brain Research Institute in Switzerland have observed the first causative case of newly changed ncRNAs patterns being passed on to offspring in mammals.
Here’s what went down when the team traumatized some mice early in life:
- Transcriptomic alterations in the blood, brains, and sperm of their mice, no big surprise there.
- Offspring of the stressed out fathers inherited altered miRNA expression, along with the behavioral and metabolic changes that went with them.
- To put the causative icing on the cake, ready to go wild-type oocytes were injected with a molecular payload of sperm RNAs from traumatized males. The sperm’s small non-coding RNAs reproduced the behavioral and metabolic phenotypes in the unrelated offspring.
- These effects persisted until the 3rd generation.
Overall, this research letter is a nifty little example of how epigenetic marks from life’s experiences can be inherited across generations at the molecular level and go on to influence complex brain traits, like behavior. So it looks like there is much more to come from the study of how RNA-dependent processes contribute to the transmission of acquired traits in mammals, especially those complex ones. Senior author Isabelle Mansuy concludes that “With the imbalance in microRNAs in sperm, we have discovered a key factor through which trauma can be passed on” and shares her insight that the effect may be “…part of a chain of events that begins with the body producing too much stress hormones.”
Learn more about how the epigenome influences behavior across generations in Nature Neuroscience, May 2014