Featured Research

from universities, journals, and other organizations

New Understandings In Circadian Rhythms

Date:
May 22, 2009
Source:
Dartmouth College
Summary:
Geneticists have made new inroads into understanding the regulatory circuitry of the biological clock that synchronizes the ebb and flow of daily activities.

Dartmouth Medical School geneticists have made new inroads into understanding the regulatory circuitry of the biological clock that synchronizes the ebb and flow of daily activities, according to two studies published May 15.

Research on the relationship between clocks and temperature, reported in Cell, offers insight into a longstanding puzzle of temperature compensation: why the 24-hour circadian rhythm does not change with temperature when metabolism is so affected.

A related study, in Molecular Cell, tracks a clock protein in action, mapping hundreds of highly choreographed modifications and interactions to provide the first complete view of regulation across a day.

The new work adds clarity to the molecular underpinnings of circadian clocks, the finely tuned cellular timekeepers that drive most organisms. Circadian systems are biological oscillators that orchestrate activities through an elaborate network of interactive proteins and feedback loops. All clocks rely on transfer of phosphate groups, called phosphorylation, to clock proteins for setting the 24-hour cycle.

Both studies looked at phosphorylation of the frequency (FRQ) clock protein, a central feedback cog in the fungal clock system. They build on the research of team leaders, Drs. Jay Dunlap and Jennifer Loros, who have documented the workings of FRQ and most other components in the Neurospora clock.

"The Cell paper describes how the cell uses phosphorylation of a clock protein to keep the period length of the cycle close to the same across a range of temperatures. This phenomenon, called temperature compensation, is one of the few canonical properties of rhythms that still lack molecular description," said Dunlap.

"The one in Molecular Cell describes collaborative work with Dr. Scott Gerber in the Norris Cotton Cancer Center. We used mass spectrometry to follow the degree of phosphorylation of over 75 sites on the FRQ clock protein across the day. Most proteins have one or a few phosphorylations, so following these across time is a major technical achievement as well as being informative for the clock biology."

In Cell, the researchers suggest a new role for the clock-associated enzyme, casein kinase (CK)2 as a key control for temperature compensation. Pursuing two uncharacterized circadian protein mutants shown to affect compensation in an unusual way, the investigators identified different subunits of the same enzyme, CK2.

They developed new ways to manipulate the genome and showed, by controlling expression, that the level of CK2 dictates the form of compensation through the phosphorylation of the clock protein FRQ. The property is unique to CK2 and shared with none of the other similar enzymes implicated in clock function.

Coauthors in addition to Dunlap, professor of genetics and Loros, professor of biochemistry and of genetics, are Arun Mehra, Mi Shi, Christopher L. Baker, Hildur V. Colot.

The second study traced protein interactions throughout the cycles to demonstrate how phosphorylation controls circadian rhythm. Using a heavy isotope labeling method and quantitative mass spectrometry, the researchers pinpointed a near record number of modifications on FRQ and described how each appears and disappears over the day.

Moreover, their methods facilitated the identification of interacting proteins to track and correlate changes in the core circadian network. They determined the clusters and locations of known sites, and through mutational analysis identified novel functional domains to create a dynamic view of a clock protein in action.

Co-authors with Dunlap, Loros, and Gerber, an assistant professor of genetics, are Christopher L. Baker,1 and Arminja N. Kettenbach.

The work was supported by National Institutes of Health grants from the National Institute of General Medical General Medical Sciences.


Story Source:

The above story is based on materials provided by Dartmouth College. Note: Materials may be edited for content and length.


Cite This Page:

Dartmouth College. "New Understandings In Circadian Rhythms." ScienceDaily. ScienceDaily, 22 May 2009. <www.sciencedaily.com/releases/2009/05/090515120744.htm>.
Dartmouth College. (2009, May 22). New Understandings In Circadian Rhythms. ScienceDaily. Retrieved October 1, 2014 from www.sciencedaily.com/releases/2009/05/090515120744.htm
Dartmouth College. "New Understandings In Circadian Rhythms." ScienceDaily. www.sciencedaily.com/releases/2009/05/090515120744.htm (accessed October 1, 2014).

Share This



More Health & Medicine News

Wednesday, October 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Ebola Cases Keep Coming for Monrovia's Island Hospital

Ebola Cases Keep Coming for Monrovia's Island Hospital

AFP (Oct. 1, 2014) A look inside Monrovia's Island Hospital, a key treatment centre in the fight against Ebola in Liberia's capital city. Duration: 00:34 Video provided by AFP
Powered by NewsLook.com
Ebola Puts Stress on Liberian Health Workers

Ebola Puts Stress on Liberian Health Workers

AP (Oct. 1, 2014) The Ebola outbreak is putting stress on first responders in Liberia. Ambulance drivers say they are struggling with chronic shortages of safety equipment and patients who don't want to go to the hospital. (Oct. 1) Video provided by AP
Powered by NewsLook.com
Doctors Reassure Public Ebola Patient Won't Cause Outbreak

Doctors Reassure Public Ebola Patient Won't Cause Outbreak

Newsy (Sep. 30, 2014) After the announcement that the first U.S. patient had been diagnosed with Ebola, doctors were quick to say a U.S. outbreak is highly unlikely. Video provided by Newsy
Powered by NewsLook.com
TX Hospital Confirms Patient Admitted With Ebola

TX Hospital Confirms Patient Admitted With Ebola

AP (Sep. 30, 2014) Medical officials from Texas Health Presbyterian Hospital confirm they are treating a patient with the Ebola virus, the first case found in the US. (Sept. 30 Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins