Parental biases influence brain

The body's tendency to silence the expression of one parental allele in favor of the other -- a practice known as genomic imprinting -- is much more widespread than scientists have believed, according to a new genome-wide study in mice, published online this week in linkurl:Science.;http://www.sciencemag.org/ The study found that the number of genes in mouse brains with a bias toward either the maternal or paternal allele is thirteen times higher than previously thought. Kessa LigerroWikimedia

| 3 min read

Register for free to listen to this article
Listen with Speechify
0:00
3:00
Share
The body's tendency to silence the expression of one parental allele in favor of the other -- a practice known as genomic imprinting -- is much more widespread than scientists have believed, according to a new genome-wide study in mice, published online this week in linkurl:Science.;http://www.sciencemag.org/ The study found that the number of genes in mouse brains with a bias toward either the maternal or paternal allele is thirteen times higher than previously thought.
Kessa Ligerro
Wikimedia Commons
"Overall, the results tell us that imprinting is a major mode of epigenetic regulation," said study author linkurl:Catherine Dulac;http://golgi.harvard.edu/faculty/faculty_profile.php?f=catherine-dulac at Harvard University. In addition, she and her colleagues argue that understanding imprinting in the brain may shed light on sex-specific brain diseases. Genomic imprinting is a type of epigenetic regulation, in which chemical reactions cause changes in gene expression without altering the underlying DNA. Over the last ten years, many researchers have tried brute-force methods like microarrays to determine the number of imprinted genes, said linkurl:Michael O'Neill,;http://www.mcb.uconn.edu/fac.php?name=oneillmj a molecular biologist at the University of Connecticut who was not involved in the research. "This is the best, most comprehensive study I've seen thus far," he said. "They can see very subtle parental biases, which you can't typically see with other methods." Prior to this study, only around 100 imprinted genes had been identified -- most either stumbled over or found on a case-by-case basis. Of those 100 genes, the majority are involved in embryonic development, but the second most frequent phenotype is brain function. Dulac and her colleagues decided to take a closer look at the role of imprinted genes in the brain by deep sequencing the RNA from the brains of mice using a high-resolution sequencing technology and comparing the expression patterns to the RNA of the parental mice. By doing so, they identified over 1,300 protein-coding genes where a maternal or paternal allele is preferentially expressed. "One hundred genes is a pretty marginal phenomenon," said Dulac. "But 1,300! That's a lot." And that was just the beginning of the surprises, Dulac told The Scientist. In addition to the sheer quantity of imprinted genes they identified, the team was surprised to find that genomic imprinting commonly varies among brain regions and between sexes. For example, in a region of the hypothalamus involved in the control of maternal and mating behavior, females had three times more imprinted genes than males. They also found that Interleukin 18, a gene linked with sex-specific diseases in the brain, is subject to complex parental imprinting effects. Finally, while analyzing both embryonic and adult mouse brains, they found that there is a preferential expression of maternal genes in the developing brain and the opposite -- a major paternal contribution -- in the adult brain. That implies that genomic imprinting is a dynamic process, which can change at some point during development. The results confirm a linkurl:1996 study;http://www.ncbi.nlm.nih.gov/pubmed/8861727 of chimeric mice that suggested maternal genes are especially important for brain development, said Dulac. DNA methylation is the best-recognized method of genomic imprinting, but it is likely not the only one, O'Neill added. "I would guess, that with so many imprinted genes showing subtle and dynamic parent-of-origin effects, we're seeing a different type of imprinting may not involve differential methylation," said O'Neill. "We may be seeing a cohort of genes with a completely different imprinting mechanism. That's really cool too." C. Gregg et al. "High Resolution Analysis of Parent-of-Origin Allelic Expression in the Mouse Brain," Science, published online July 8, 2010, doi:10.1126/science.1190830. C. Gregg et al. "Sex-Specific Parent-of-Origin Allelic Expression in the Mouse Brain," Science, published online July 8, 2010, doi:10.1126/science.1190831.
**__Related stories:__***linkurl:A new master switch in brain?;http://www.the-scientist.com/blog/display/57542/
[1st July 2010]*linkurl:Methylation and imprinting;http://www.the-scientist.com/article/display/20680/
[13th September 2002]*linkurl:Cancer epigenetics enters the mainstream;http://www.the-scientist.com/article/display/15539/
[20th June 2005]
Interested in reading more?

Become a Member of

The Scientist Logo
Receive full access to more than 35 years of archives, as well as TS Digest, digital editions of The Scientist, feature stories, and much more!
Already a member? Login Here

Meet the Author

  • Megan Scudellari

    This person does not yet have a bio.
Share
3D illustration of a gold lipid nanoparticle with pink nucleic acid inside of it. Purple and teal spikes stick out from the lipid bilayer representing polyethylene glycol.
February 2025, Issue 1

A Nanoparticle Delivery System for Gene Therapy

A reimagined lipid vehicle for nucleic acids could overcome the limitations of current vectors.

View this Issue
Enhancing Therapeutic Antibody Discovery with Cross-Platform Workflows

Enhancing Therapeutic Antibody Discovery with Cross-Platform Workflows

sartorius logo
Considerations for Cell-Based Assays in Immuno-Oncology Research

Considerations for Cell-Based Assays in Immuno-Oncology Research

Lonza
An illustration of animal and tree silhouettes.

From Water Bears to Grizzly Bears: Unusual Animal Models

Taconic Biosciences
Sex Differences in Neurological Research

Sex Differences in Neurological Research

bit.bio logo

Products

Photo of a researcher overseeing large scale production processes in a laboratory.

Scaling Lentiviral Vector Manufacturing for Optimal Productivity

Thermo Fisher Logo
Collage-style urban graphic of wastewater surveillance and treatment

Putting Pathogens to the Test with Wastewater Surveillance

An illustration of an mRNA molecule in front of a multicolored background.

Generating High-Quality mRNA for In Vivo Delivery with lipid nanoparticles

Thermo Fisher Logo
Tecan Logo

Tecan introduces Veya: bringing digital, scalable automation to labs worldwide