Navigation Links
Aurora B answers an XIST-ential question
Date:8/24/2009

Early in development, mammalian female cells counteract their double dose of X chromosomes by coating one of them with a large RNA named XIST. The RNA binds to the same X chromosome from which it is transcribed and initiates a series of events leading to the chromosome's permanent silencing. In the August 24, 2009 issue of the Journal of Cell Biology (www.jcb.org), Hall et al. exploit the fact that XIST temporarily dissociates from the X chromosome during mitosis and find that Aurora B kinase helps regulate the RNA's chromatin binding.

Although more than 10 years have passed since XIST was shown to paint the inactivated X (Xi) chromosome, little is known of how the 14-kb, noncoding transcript binds its target. "We know it doesn't just bind the DNA, but no specific binding proteins have been identified," says lead author Lisa Hall. Biochemical approaches to finding protein partners may have been hampered by XIST's large size and tight association with the X chromosome, making it hard to extract the RNA complex and study it in vitro. So Hall, together with colleagues in Jeanne Lawrence's laboratory at the University of Massachusetts Medical School, took an in vivo approachmimicking the events that cause XIST to drop off the Xi in early prophase.

Hall and colleagues found that treating cells with an inhibitor of protein phosphatase 1 (PP1) caused XIST to be released from the Xi in interphase cells. PP1 usually keeps the kinase Aurora B in check until the start of mitosis, so the team wondered whether XIST's premature release was driven by increased Aurora B activity. XIST was no longer released in interphase cells if PP1 and Aurora B were both inhibited. Moreover, inhibiting Aurora B with either drugs or a specific siRNA caused XIST to be retained on the Xi even in mitotic cells.

Lawrence says that the team was excited to identify Aurora B as a regulator of XIST. Their previous studies had suggested that a broader chromatin organizer might control XIST binding, particularly during cancer when the regulation of XIST and the Xi often goes awry. Aurora B fits the bill perfectly as it localizes to the chromosome arms at prophase, phosphorylates several chromatin proteins including histone H3, and is frequently activated in cancer cells.

It remains unclear exactly how Aurora B promotes XIST's loss from the Xi. "There are probably multiple places that XIST anchors to chromatin," says Lawrence. "In order to release it, you have to modify multiple points." Further studies on the mitotic loss of XIST should help identify these different anchor points and determine how they are modified to promote or block RNA binding.

XIST may, in fact, represent a broader class of noncoding RNAs that associate with and regulate heterochromatin. "We hope that manipulating binding in vivo provides a new way to study RNAchromatin interactions that other labs will build on," says Lawrence. "It will be interesting to determine if these other RNAs mirror the behavior of XIST and are controlled by the same mechanism."


'/>"/>

Contact: Rita Sullivan
news@rupress.org
212-327-8603
Rockefeller University Press
Source:Eurekalert  

Related biology news :

1. New supercomputer to reel in answers to some of Earths problems
2. Grant to fund answers about St. Johns River
3. MIT: No easy answers in evolution of human language
4. Fungus genome yielding answers to protect grains, people and animals
5. Recent news reports of sweetener reformulations raise questions about motivations
6. Work of Field Museum scientist addresses question of chance in evolution
7. Ecologists question effects of climate change on infectious diseases
8. Mountain on Mars may answer big question
9. New models question old assumptions about how many molecules it takes to control cell division
10. Similar survival rates for Pacific salmon in Fraser, Columbia Rivers raises new questions
11. Study of polar dinosaur migration questions whether dinosaurs were truly the first great migrators
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Aurora B answers an XIST-ential question
(Date:4/5/2017)... , April 5, 2017 Today ... announcing that the server component of the HYPR platform ... for providing the end-to-end security architecture that empowers biometric ... HYPR has already secured over 15 million users ... including manufacturers of connected home product suites and physical ...
(Date:4/4/2017)...   EyeLock LLC , a leader of iris-based ... Patent and Trademark Office (USPTO) has issued U.S. Patent ... an iris image with a face image acquired in ... 45 th issued patent. "The ... the multi-modal biometric capabilities that have recently come to ...
(Date:3/30/2017)... LOS ANGELES , March 30, 2017  On ... Hack the Genome hackathon at ... This exciting two-day competition will focus on developing health ... experience. Hack the Genome is ... has been tremendous. The world,s largest companies in the ...
Breaking Biology News(10 mins):
(Date:10/10/2017)... ... October 10, 2017 , ... Dr. Bob Harman, founder ... local San Diego Rotary Club. The event entitled “Stem Cells and ... had 300+ attendees. Dr. Harman, DVM, MPVM was joined by two human doctors: ...
(Date:10/10/2017)... Calif. , Oct. 10, 2017 SomaGenics ... from the NIH to develop RealSeq®-SC (Single Cell), expected ... for profiling small RNAs (including microRNAs) from single cells ... Program highlights the need to accelerate development of approaches ... "New techniques for measuring levels ...
(Date:10/10/2017)... PA (PRWEB) , ... October 10, 2017 , ... ... year’s recipients of 13 prestigious awards honoring scientists who have ... presented in a scheduled symposium during Pittcon 2018, the world’s leading conference and ...
(Date:10/9/2017)... ... October 09, 2017 , ... The award-winning American Farmer ... first quarter 2018. American Farmer airs Tuesdays at 8:30aET on RFD-TV. , With ... with the challenge of how to continue to feed a growing nation. At the ...
Breaking Biology Technology: