Close X
Thursday, November 28, 2024
ADVT 
Health

Decoded: What 'Silences' X Chromosome In Girls

Darpan News Desk IANS, 11 Jan, 2016 11:00 AM
    Nearly every girl and woman on Earth carries two X chromosomes in each of her cells -- but one of them does (mostly) nothing. Do you know why?
     
    That is because it has been silenced, keeping most of its DNA locked up and unread like a book in a cage, scientists led by an Indian-American researcher from the University of Michigan Medical School have revealed.
     
    A wide range of relatively rare diseases - as well as relatively common conditions such as autism, haemophilia and muscular dystrophy - are linked to problems with genes found on the X chromosome.
     
    The findings could help lead to new ways of fighting diseases linked to X chromosomes in girls and women -- the kind that occur when the X chromosome that does get read has misprints and defects.
     
    The team found that a known molecule called “Xist RNA” is insufficient to silence the X chromosome.
     
    "Xist is widely believed to be both necessary and sufficient for X silencing," said team leader Sundeep Kalantry.
     
    "We, for the first time, show that it is not sufficient and there have to be other factors - on the X-chromosome itself that activate 'Xist' and then cooperate with 'Xist RNA' to silence the X-chromosome,” he elaborated.
     
    In the future, it may be possible to change the level of these other factors in cells and turn on the healthy, silenced copy of a gene that lies on the inactive X-chromosome, Kalantry added.
     
    Although most genes on the inactive X chromosome are fully silenced, a handful of the genes on the inactive X are, in fact, active.
     
    It is this set of X-inactivation “escapees” that the research team was focused on.
     
    Since the “escapee” genes are expressed from both the active and the inactive X-chromosomes in females, they produce more gene product in female cells than in male cells which only have a single X.
     
    According to Kalantry, it is this higher “dose” in females that triggers X-inactivation selectively in females; the lower dose in males is insufficient.
     
    "That means that if researchers can determine exactly which factors cause X-inactivation to occur, they could find ways to affect the activity of genes on the X chromosomes - specifically, genes involved in certain diseases.” the authors noted.
     
    Many of them have an impact on an individual's thinking and memory capacity, and other aspects of cognition and intelligence.
     
    "In females, we could envision 'reawakening' a healthy copy of an X-linked gene on the inactive X chromosome, by modulating the dose of these so-called escapee genes and ameliorating the effects of the unhealthy copy," Kalantry explained.
     
    Unfortunately, this approach probably won't help males with X-linked diseases, because they only have a single X chromosome in each cell and inactivating it would be harmful.
     
    The new paper appeared in the journal Proceedings of the National Academy of Sciences.

    MORE Health ARTICLES

    Indian American Team Makes Gene-Editing Tool Simpler

    Indian American Team Makes Gene-Editing Tool Simpler
    A team of Indian American researchers has developed a user-friendly resource to make the powerful gene-editing tool more friendly.

    Indian American Team Makes Gene-Editing Tool Simpler

    Why Indians At Higher Risk Of Diabetes

    Compared to those in the developed world, middle classes in India and other developing countries are more susceptible to Type-2 diabetes, obesity and cardiovascular diseases, thanks to their undernourished ancestors, says a study.

    Why Indians At Higher Risk Of Diabetes

    Some SSRIs may raise birth defects risk when taken early in pregnancy: study

    Some SSRIs may raise birth defects risk when taken early in pregnancy: study
    TORONTO — A large new study by U.S. and Canadian researchers suggests the use of some anti-depressant drugs early in pregnancy may be linked to an increased risk of birth defects in the child.

    Some SSRIs may raise birth defects risk when taken early in pregnancy: study

    Why Women Live Longer Than Men?

    Why Women Live Longer Than Men?
    Explaining why women live longer than men across the world, vulnerability to heart disease is the biggest culprit behind a surge in higher death rates for men during the 20th century, says a study.

    Why Women Live Longer Than Men?

    Beware, High Heels May Hurt Your Feet

    Beware, High Heels May Hurt Your Feet
    While high heels may help you put the best fashion foot forward, their prolonged use may be a step backward for the health of your feet, new research says.

    Beware, High Heels May Hurt Your Feet

    Extracurricular Sports Make Kids More Attentive, Finds A Canadian Study

    Extracurricular Sports Make Kids More Attentive, Finds A Canadian Study
    Regular, structured extra-curricular sports help children develop self-regulation and stay focused in the classroom as they grow up, says a study.

    Extracurricular Sports Make Kids More Attentive, Finds A Canadian Study