A new scientific study reveals an innovative genetic mechanism that allows neurons to alter their identity, function and behavior in response to environmental stimuli.
Using the nematode ‘Caenorhabditis elegans’ as a modelresearchers frompart of the Superior Council for Scientific Investigations (CSIC) of Spain, discovered that an epigenetic mechanism acts like a lock that blocks the ability of neurons to capture serotonin, a neurotransmitter that regulates mood in humans, thus modifying their identity and functions.
This lockthe researchers highlighted, it can be unlocked when the environment requires it, modifying the animal’s behavior.
The discovery is fundamental to understanding how the nervous system of organisms adapts to the environment and offers a new avenue for investigating disorders such as depression, anxiety and autism.
The CSIC explained that all cells in an organism share the same genetic information (DNA)from which different cell types with specific functions emerge (skin, liver, neurons, etc.).
Genes and the environment interact to modulate cellular identity and function through epigenetic changes, a system that determines how the cell interprets DNA to function in a specific way.
Now the work describes how this mechanism regulates the response to the neurotransmitter serotonin in a simple animal model, managing to alter the identity of neurons and their behavior through small changes in genes in response to the environment.
The study used a small nematode worm (Caenorhabditis), a “living laboratory” widely used in biology and biomedicine to understand the functioning of the nervous system, as it has 302 neurons, each of which was identified individually.
“neurons with VC identity have the potential to capture serotonin”
In the laboratory led by Nuria Flames at IBV-CSIC, researchers analyzed a specific type of neuron in this animal (VC), which shows signs of something unexpected: the ability to capture serotonin, a neurotransmitter involved in the animal’s behavior and internal states.
“In the species ‘Caenorhabditis elegans’, neurons with VC identity have the potential to capture serotonin, but do not do so due to repression by epigenetic mechanisms,” explained Flames.
“A mechanism called histone methylation acts as a lock that blocks the mod-5/SERT gene, responsible for capturing serotonin from the environment. This is why these neurons do not present a serotonergic phenotype, the biological signature that allows a neuron to capture serotonin”, he highlighted.
The research team found that, in several species of the genus ‘Caenorhabditis’, this lock was broken during evolution.
“These species have acquired a new ‘enhancer’ that activates the mod-5/SERT gene in VC neurons, escaping epigenetic repression and allowing them to capture serotonin in an intense and stable way,” explained Flames.
Furthermore, the simple transfer of this enhancer to other species, such as ‘C. elegans’, is sufficient to activate the mod-5/SERT gene in its VC neurons.
“A single regulatory component is sufficient to alter the identity and function of neurons”, summarized the CSIC researcher.
To the team’s surprise, in some species this change also occurs if required by the worm’s environment.
“Although under normal conditions ‘C. elegans’ VC neurons repress serotonin reuptake, under specific conditions the epigenetic block is unblocked and these neurons become serotonergic, which alters egg-laying behavior. Their neuronal identity therefore has a plastic character. It depends on the environment”revealed Andrea Millán Trejo, scientist at IBV-CSIC and the IBV associated unit at the Príncipe Felipe Research Center (CIPF), and first author of the study.
