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Texas A&M researchers find new mechanism for circadian rhythm
October 21, 2009Molecules that may hold the key to new ways to fight cancer and other diseases have been found to play an important role in regulating circadian rhythm, says Liheng Shi, a researcher in Texas A&M's Department of Veterinary Integrative Biosciences.
Circadian rhythm is the roughly 24-hour cycle of physiological activities of humans, animals and even bacteria, Shi explains.
He and colleagues have had their research, currently focusing on the circadian rhythm in chickens' eyes, published in the "Journal of Biological Chemistry." Chicken eyes have a lot in common with human eyes.
"The prefix 'photo-' in photoreceptors means light, and photoreceptors in animals' eyes receive light signals and then translate them into signals that their brain can understand, and that is how they see," he explains.
Shi notes there are two kinds of photoreceptors - cone photoreceptors and rod photoreceptors, named for the shape they resemble.
Some channels that scientists call L-VGCCs are important to the circadian rhythm in chickens' eyes. These channels are important because they are the pathways through which messages go in and out of photoreceptors, and these messages are crucial to the proper functioning of the eye.
A group of proteins (L-VGCCα1C) carries the messages in and out. At night, they get more work done than during the day to "prepare chickens' eyes for another day's busy work" and "tell various parts of the eye to adjust to the darkness," explains Shi, who holds a post-doctoral position under the mentorship of Gladys Ko, one of the coauthors of the article.
These proteins are controlled by messengers called mRNA, and they are especially active, raising the question of why, he says.
"There must be an explanation," Shi says, "and we found a possible answer."
The answer lies in a sibling of the messenger named microRNA-26a, a "small guy" in the RNA family.
"During the day, the 'naughty small guy' crawls onto the back of his brother mRNA, so his brother cannot concentrate on his work," the Texas A&M researcher explains. "At night, however, he lets his brother go, so his brother focuses on his work and gets more work done."
He advises not to "look down" on the mRNA. "If they quite their job, the chicken may become blind," Shi adds. "Besides regulating circadian rhythm, the microRNA family also influence cancer development, cell division, heart disease, and so on."
"What we know about microRNAs is probably only a tip of the iceberg," the Texas A&M postdoc says. "As we get to know more about them, these small guys may be able to help us diagnose and treat many diseases."
Texas A&M University
"The prefix 'photo-' in photoreceptors means light, and photoreceptors in animals' eyes receive light signals and then translate them into signals that their brain can understand, and that is how they see," he explains.
Shi notes there are two kinds of photoreceptors - cone photoreceptors and rod photoreceptors, named for the shape they resemble.
Some channels that scientists call L-VGCCs are important to the circadian rhythm in chickens' eyes. These channels are important because they are the pathways through which messages go in and out of photoreceptors, and these messages are crucial to the proper functioning of the eye.
A group of proteins (L-VGCCα1C) carries the messages in and out. At night, they get more work done than during the day to "prepare chickens' eyes for another day's busy work" and "tell various parts of the eye to adjust to the darkness," explains Shi, who holds a post-doctoral position under the mentorship of Gladys Ko, one of the coauthors of the article.
These proteins are controlled by messengers called mRNA, and they are especially active, raising the question of why, he says.
"There must be an explanation," Shi says, "and we found a possible answer."
The answer lies in a sibling of the messenger named microRNA-26a, a "small guy" in the RNA family.
"During the day, the 'naughty small guy' crawls onto the back of his brother mRNA, so his brother cannot concentrate on his work," the Texas A&M researcher explains. "At night, however, he lets his brother go, so his brother focuses on his work and gets more work done."
He advises not to "look down" on the mRNA. "If they quite their job, the chicken may become blind," Shi adds. "Besides regulating circadian rhythm, the microRNA family also influence cancer development, cell division, heart disease, and so on."
"What we know about microRNAs is probably only a tip of the iceberg," the Texas A&M postdoc says. "As we get to know more about them, these small guys may be able to help us diagnose and treat many diseases."
Texas A&M University
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Hydrogen Peroxide's Link to Living Cells
If a circadian rhythm is like an orchestra - the united expression of the rhythms of millions of cells - a common chemical may serve as the conductor, or at least as the baton.
The food-energy cellular connection revealed
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Chemotherapy for breast cancer is associated with disruption of sleep-wake rhythm in women
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Genetic pathway responsible for link between body clock disturbance and worsening arthritis
The genes that regulate human circadian rhythm, or 'the body clock', are significantly disturbed in individuals with arthritis.
Biological Timekeeper Studies Reveal New Temperature Regulator and Track Clock Protein across a Day
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.
Constant sunlight linked to summer suicide spike
Suicide rates in Greenland increase during the summer, peaking in June. Researchers writing in the open access journal BMC Psychiatry speculate that insomnia caused by incessant daylight may be to blame.
A Biological Basis for the 8-Hour Workday?
The circadian clock coordinates physiological and behavioral processes on a 24-hour rhythm, allowing animals to anticipate changes in their environment and prepare accordingly. Scientists already know that some genes are controlled by the clock and are turned on only one time during each 24-hour cycle.
Missing or mutated 'clock' gene linked to vascular disease
The circadian clocks that set the rhythmic motion of our bodies for wakeful days and sleepy nights can also set us up for vascular disease when broken, Medical College of Georgia researchers say.
School-based intervention is a promising model for improving adolescent sleep habits
A study in the March 1 issue of the journal SLEEP shows that a school-based sleep intervention is a promising model for addressing adolescent sleep problems, given its high retention rate, cost-effectiveness and potential for promoting healthy sleep knowledge and practice.
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