Posts tagged gene
Articles and news from the latest research reports.
Dopamine-receptor gene variant linked to human longevity
A variant of a gene associated with active personality traits in humans seems to also be involved with living a longer life, UC Irvine and other researchers have found.
This derivative of a dopamine-receptor gene – called the DRD4 7R allele – appears in significantly higher rates in people more than 90 years old and is linked to lifespan increases in mouse studies.
Robert Moyzis, professor of biological chemistry at UC Irvine, and Dr. Nora Volkow, a psychiatrist who conducts research at the Brookhaven National Laboratory and also directs the National Institute on Drug Abuse, led a research effort that included data from the UC Irvine-led 90+ Study in Laguna Woods, Calif. Results appear online in The Journal of Neuroscience.
The variant gene is part of the dopamine system, which facilitates the transmission of signals among neurons and plays a major role in the brain network responsible for attention and reward-driven learning. The DRD4 7R allele blunts dopamine signaling, which enhances individuals’ reactivity to their environment.
People who carry this variant gene, Moyzis said, seem to be more motivated to pursue social, intellectual and physical activities. The variant is also linked to attention-deficit/hyperactivity disorder and addictive and risky behaviors.
“While the genetic variant may not directly influence longevity,” Moyzis said, “it is associated with personality traits that have been shown to be important for living a longer, healthier life. It’s been well documented that the more you’re involved with social and physical activities, the more likely you’ll live longer. It could be as simple as that.”
Numerous studies – including a number from the 90+ Study – have confirmed that being active is important for successful aging, and it may deter the advancement of neurodegenerative diseases, such as Alzheimer’s.
Prior molecular evolutionary research led by Moyzis and Chuansheng Chen, UC Irvine professor of psychology & social behavior, indicated that this “longevity allele” was selected for during the nomadic out-of-Africa human exodus more than 30,000 years ago.
In the new study, the UC Irvine team analyzed genetic samples from 310 participants in the 90+ Study. This “oldest-old” population had a 66 percent increase in individuals carrying the variant relative to a control group of 2,902 people between the ages of 7 and 45. The presence of the variant also was strongly correlated with higher levels of physical activity.
Next, Volkow, neuroscientist Panayotis Thanos and their colleagues at the Brookhaven National Laboratory found that mice without the variant had a 7 percent to 9.7 percent decrease in lifespan compared with those possessing the gene, even when raised in an enriched environment.
While it’s evident that the variant can contribute to longevity, Moyzis said further studies must take place to identify any immediate clinical benefits from the research. “However, it is clear that individuals with this gene variant are already more likely to be responding to the well-known medical adage to get more physical activity,” he added.
'Maternal gene' identified in mice
Researchers from The Rockefeller University in New York found that mice engineered to suppress the gene spent less time licking, nursing and retrieving their pups compared with a control group.
The findings, published in the Proceedings of the National Academy of Sciences, suggest the single gene could be responsible for motivating mothers to protect, feed and raise their young, the scientists said.
Previous studies have found that a brain region called the medial preoptic area controls aggression, sexual receptivity and maternal care in mice. In the new study, scientists artificially lowered the levels of the chemical in the medial preoptic area of female mice, to examine how they functioned without it.
They found that the mice spent less time caring for their pups but that their levels of aggression remained unchanged. Dr Ana Ribiero, who led the study, said: “The main finding of this paper is manipulation of a specific gene in a specific group of neurons (nerve cells) can drastically alter the expression of a complete, biologically crucial behaviour.” The effects were “remarkably specific” to maternal care because even related behaviours, such as aggression, remained unchanged, she added.
![Research teams from The University of Texas Health Science Center at Houston (UTHealth) and Paris, France have discovered a gene defect linked to a cluster of systemic complications, including life-threatening thoracic aortic disease and intracranial aneurysms. The new syndrome is similar, but distinct from known syndromes such as Marfan and Loeys-Dietz syndrome.
Read more: Researchers Discover Gene Defect for New Syndrome
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Research teams from The University of Texas Health Science Center at Houston (UTHealth) and Paris, France have discovered a gene defect linked to a cluster of systemic complications, including life-threatening thoracic aortic disease and intracranial aneurysms. The new syndrome is similar, but distinct from known syndromes such as Marfan and Loeys-Dietz syndrome.
Read more: Researchers Discover Gene Defect for New Syndrome
Gene Linked to Facial, Skull and Cognitive Impairment Identified
ScienceDaily (July 5, 2012) — A gene whose mutation results in malformed faces and skulls as well as mental retardation has been found by scientists.
They looked at patients with Potocki-Shaffer syndrome, a rare disorder that can result in significant abnormalities such as a small head and chin and intellectual disability, and found the gene PHF21A was mutated, said Dr. Hyung-Goo Kim, molecular geneticist at the Medical College of Georgia at Georgia Health Sciences University.
The scientists confirmed PHF21A’s role by suppressing it in zebrafish, which developed head and brain abnormalities similar to those in patients. “With less PHF21A, brain cells died, so this gene must play a big role in neuron survival,” said Kim, lead and corresponding author of the study published in The American Journal of Human Genetics. They reconfirmed the role by giving the gene back to the malformed fish — studied for their adeptness at regeneration — which then became essentially normal. They also documented the gene’s presence in the craniofacial area of normal mice.
While giving the normal gene unfortunately can’t cure patients as it does zebrafish, the scientists believe the finding will eventually enable genetic screening and possibly early intervention during fetal development, including therapy to increase PHF21A levels, Kim said. It also provides a compass for learning more about face, skull and brain formation.
The scientists zeroed in on the gene by using a distinctive chromosomal break found in patients with Potocki-Shaffer syndrome as a starting point. Chromosomes — packages of DNA and protein — aren’t supposed to break, and when they do, it can damage genes in the vicinity.
"We call this breakpoint mapping and the breakpoint is where the trouble is," said Dr. Lawrence C. Layman, study co-author and Chief of the MCG Section of Reproductive Endocrinology, Infertility and Genetics. Damaged genes may no longer function optimally; in PHF21A’s case it’s about half the norm.
"When you see the chromosome translocation, you don’t know which gene is disrupted," Layman said. "You use the break as a focus then use a bunch of molecular techniques to zoom in on the gene." Causes of chromosomal breaks are essentially unknown but likely are environmental and/or genetic, Kim said.
Little was known about PHF21A other than its role in determining how tightly DNA is wound in a package with proteins called histones. How tightly DNA is wound determines whether proteins called transcription factors have the access needed to regulate gene expression, which is important, for example, when a gene needs to be expressed only at a specific time or tissue. PHF21A is believed to primarily work by suppressing other genes, for example, ensuring that genes that should be expressed only in brain cells don’t show up in other cell types, Kim said.
Next steps include using PHF21A as a sort of geographic positioning system to identify other “depressor” genes it regulates then screening patients to look for mutations in those genes as well. “We want to find other people with different genes causing the same problem,” Layman said, and they suspect the genes PHF21A interacts with or regulates are the most likely suspects. It’s too early to know what percentage of Potocki-Shaffer syndrome patients have the PHF21A mutation, Kim noted. “Now that we know the causative gene, we can sequence the gene in more patients and see if they have a mutation,” Layman said.
They also want to look at less-severe forms of mental deficiency, including autism, for potentially milder mutations of PHF21A. More than a dozen of the 25,000 human genes are known to cause craniofacial defects and mental retardation, which often occur together, Kim said.
Source: Science Daily