Nav: Home

Scientists identify genetic mechanism involved in how females inherit traits

February 20, 2019

As many know, females have two X chromosome while males have one X and one Y chromosome.

Perhaps less known is that female cells randomly and permanently shut off one of the X chromosomes during embryonic development through a process called X chromosome inactivation, or XCI.  Just how XCI occurs has remained unclear -- until now.

New research performed on mouse female embryonic stem cells by scientists at the University of California, Riverside, traces the origin of XCI to an RNA splicing mechanism.

Occurring in every human cell and almost all human genes, RNA splicing copies and pastes genetic fragments scattered among the genome to create a meaningful or functional genetic message.

In the case of XCI, the researchers found that a special splicing event occurs prior to XCI and in association with the X chromosome chosen for inactivation, but not with the other X chromosome. This special splicing event happens in "Xist," a gene expressed only in females and the inactive X chromosome.

Scientists have accepted Xist induction at the onset of XCI as the molecular trigger for initiating XCI, but how Xist is induced is not entirely clear. Also unknown is how Xist remains repressed prior to XCI. The new study shows that Xist is largely unspliced, thus unfunctional, before XCI. Upon differentiation of embryonic stem cells, Xist becomes spliced, and thus functional to kick-start subsequent events to induce XCI.

Study results appear in the journal Nucleic Acids Research.

"XCI ensures that females express similar dosages of X chromosome gene products as males do," said Sika Zheng, an assistant professor of biomedical sciences in the UCR School of Medicine, who led the research. "This inactivation ensures, too, that, like males, females have a balanced expression between the X chromosome and autosomes -- chromosomes that are not sex chromosomes."

Zheng explained that XCI happens in every female, and its regulation influences whether a daughter inherits a trait from her father or her mother. It also determines females' susceptibility to various diseases, such as Fragile X syndrome and Rett syndrome.

"The splicing mechanism is fundamental to understanding trait inheritance in females," he said. "If we could manipulate which X chromosome to inactivate through splicing, we might be able to alter females' expression of their genetic traits and their susceptibility to diseases without altering their genomes. Regulating Xist transcription has been at the center of this research field for a long time. Our discovery should draw scientists' attention to splicing."
The research was funded by the National Institutes of Health. Zheng was joined in the study by Cheryl Stork, first author of the research paper, as well as Zhelin Li and Lin Lin.

University of California - Riverside

Related Embryonic Stem Cells Articles:

New insights into mechanisms regulating gene expression in embryonic stem cells
Researchers from Turku, Finland, have discovered new information about the mechanisms which maintain gene activity in human embryonic stem cells.
New tools to study the origin of embryonic stem cells
Researchers at Karolinska Institutet have identified cell surface markers specific for the very earliest stem cells in the human embryo.
Scientists approve the similarity between reprogrammed and embryonic stem cells
Researchers from the Vavilov Institute of General Genetics, Research Institute of Physical Chemical Medicine and Moscow Institute of Physics and Technology (MIPT) have concluded that reprogramming does not create differences between reprogrammed and embryonic stem cells.
Drug makes stem cells become 'embryonic' again
If you want to harness the full power of stem cells, all you might need is an eraser -- in the form of a drug that can erase the tiny labels that tell cells where to start reading their DNA.
Oncogene controls stem cells in early embryonic development
Many animal species delay the development of their embryos to ensure that their offspring is born at a favorable time.
Are embryonic stem cells and artificial stem cells equivalent?
Harvard Stem Cell Institute (HSCI) researchers at Massachusetts General Hospital and Harvard Medical School have found new evidence suggesting some human induced pluripotent stem cells are the 'functional equivalent' of human embryonic stem cells, a finding that may begin to settle a long running argument.
UCSF researchers control embryonic stem cells with light
UCSF researchers have for the first time developed a method to precisely control embryonic stem cell differentiation with beams of light, enabling them to be transformed into neurons in response to a precise external cue.
Protein plays unexpected role in embryonic stem cells
A protein long believed to only guard the nucleus also regulates gene expression and stem cell development.
Nuclear transfer appears superior for creating embryonic stem cells
Scientists at Oregon Health & Science University have found that a process called 'somatic cell nuclear transfer' is much better and more accurate at reprogramming human skin cells to become embryonic stem cells -- capable of transforming into any cell type in the body -- than an alternative process that produces cells similar to embryonic stem cells, but with many more epigenetic abnormalities.
Embryonic stem cells offer new treatment for multiple sclerosis
A novel approach to treating multiple sclerosis using human embryonic stem cells appears to offer better treatment results than stem cells derived from human adult bone marrow, scientists in the University of Connecticut's Technology Incubation Program say.

Related Embryonic Stem Cells Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Failure can feel lonely and final. But can we learn from failure, even reframe it, to feel more like a temporary setback? This hour, TED speakers on changing a crushing defeat into a stepping stone. Guests include entrepreneur Leticia Gasca, psychology professor Alison Ledgerwood, astronomer Phil Plait, former professional athlete Charly Haversat, and UPS training manager Jon Bowers.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".