Mechanism for passing on epigenetic memories

Mechanism for passing on epigenetic memories

According to epigenetics -- the study of inheritable changes in gene expression not directly coded in our DNA -- our life experiences may be passed on to our children and our children's children. Studies on survivors of traumatic events have suggested that exposure to stress may indeed have lasting effects on subsequent generations. But how exactly are these genetic "memories" passed on?

A new study pinpoints the precise mechanism that turns the inheritance of environmental influences "on" and "off." The research, published in Cell reveals the rules that dictate which epigenetic responses will be inherited, and for how long.

Small RNA molecules -- short sequences of RNA that regulate the expression of genes -- are among the key factors involved in mediating this kind of inheritance. The team had previously identified a "small RNA inheritance" mechanism through which RNA molecules produced a response to the needs of specific cells and how they were regulated between generations.

Most inheritable epigenetic responses in C.elegans worms were found to persist for only a few generations. This created the assumption that epigenetic effects simply "petered out" over time, through a process of dilution or decay.

The scientists discovered that specific genes, which they named "MOTEK" (Modified Transgenerational Epigenetic Kinetics), were involved in turning on and off epigenetic transmissions.

"We discovered how to manipulate the transgenerational duration of epigenetic inheritance in worms by switching 'on' and 'off' the small RNAs that worms use to regulate genes," said the senior author. "These switches are controlled by a feedback interaction between gene-regulating small RNAs, which are inheritable, and the MOTEK genes that are required to produce and transmit these small RNAs across generations.

"The feedback determines whether epigenetic memory will continue to the progeny or not, and how long each epigenetic response will last."

Although their research was conducted on worms, the team believes that understanding the principles that control the inheritance of epigenetic information is crucial for constructing a comprehensive theory of heredity for all organisms, humans included.

"We are now planning to study the MOTEK genes to know exactly how these genes affect the duration of epigenetic effects," said first author of the paper. "Moreover, we are planning to examine whether similar mechanisms exist in humans."

https://www.aftau.org/weblog-medicine--health?=&storyid4704=2261&ncs4704=3

Edited

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