Monthly Archives: February 2014

PUBLIC RELEASE DATE:

4-Feb-2014

Contact: Lisa Newbern lisa.newbern@emory.edu 404-727-7709 Emory Health Sciences

Following another's gaze or looking in the direction someone is pointing, two examples of receptive joint attention, is significantly heritable according to new study results from researchers at the Yerkes National Primate Research Center, Emory University. Determining such communicative cues are significantly heritable means variation in this ability has a genetic basis, which led the researchers to the vasopressin receptor gene, known for its role in social bonding.

The study results, which are published in Scientific Reports, give researchers insight into the biology of disorders in which receptive joint attention is compromised, such as autism spectrum disorders (ASD), and may ultimately lead to new diagnosis and treatment strategies.

According to Yerkes researchers Larry Young, PhD, and Bill Hopkins, PhD, co-authors of the study, receptive joint attention is important for developing complex cognitive processes, including language and theory of mind, and poor joint attention abilities may be a core feature in children with or at risk of developing ASD.

Young is division chief of Behavioral Neuroscience and Psychiatric Disorders at Yerkes, director of the Center for Translational Social Neuroscience (CTSN) at Emory and William P. Timmie Professor in the Emory University School of Medicine Department of Psychiatry and Behavioral Sciences. Yerkes researcher Hopkins is also a core faculty member in the Neuroscience Institute of Georgia State University and newly named science director of the Iowa Primate Learning Sanctuary.

Young and Hopkins led a collaborative team of researchers from Yerkes, the CTSN, the Neuroscience Institute at Georgia State University and the University of Texas M.D. Anderson Cancer Center. They studied chimpanzees to determine the extent to which the animals follow gaze or pointing by a human.

"We used chimpanzees in this behavioral study because their receptive joint attention abilities are well documented and their closeness to humans makes the study results the most likely to be generalizable to humans," says Hopkins.

Young's previous research in which he showed the vasopressin receptor gene was necessary for remembering individuals (or social memories) and for social bonding in male rodents was key to designing the current study. According to Young, variation in the length of a stretch of repetitive DNA, known as junk DNA, in the control region of the vasopressin receptor gene predicted if a male prairie vole was likely to form monogamous bonds with a mate. Human-based studies suggest that a similar repetitive element, referred to as RS3, in the control region of the human vasopressin receptor gene predicts romantic relationship quality and generosity.

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Gene that influences receptive joint attention in chimpanzees gives insight into autism

Researchers used blood platelets and bone marrow cells to deliver potentially curative gene therapy to mouse models of the human genetic disorder Hurler syndrome -- an often fatal condition that causes organ damage and other medical complications.

Scientists from Cincinnati Children's Hospital Medical Center and the National Institute of Neurological Disorders and Stroke (NINDS) report their unique strategy for treating the disease the week of Feb. 3-7 in Proceedings of the National Academy of Sciences (PNAS).

Researchers were able to genetically insert into the cells a gene that produces a critical lysosomal enzyme (called IDUA) and then inject the engineered cells into mice to treat the disorder. Follow up tests showed the treatment resulted in a complete metabolic correction of the disease, according to the authors.

"Our findings demonstrate a unique and somewhat surprising delivery pathway for lysosomal enzymes," said Dao Pan, PhD, corresponding author and researcher in the Division of Experimental Hematology and Cancer Biology at Cincinnati Children's. "We show proof of concept that platelets and megakaryocytes are capable of generating and storing fully functional lysosomal enzymes, which can lead to their targeted and efficient delivery to vital tissues where they are needed."

The mice tested in the study modeled human Hurler syndrome, a subset of disease known as mucopolysaccharidosis type I (MPS I), one of the most common types of lysosomal storage diseases. MPS I is a lysosomal storage disease in which people do not make an enzyme called lysosomal alpha-L-iduronidase (IDUA).

IDUA helps break down sugar molecules found throughout the body, often in mucus and fluids around joints, according to the National Library of Medicine/National Institutes of Health. Without IDUA, sugar molecules build up and cause organ damage. Depending on severity, the syndrome can also cause deafness, abnormal bone growth, heart valve problems, joint disease, intellectual disabilities and death.

Enzyme replacement therapy can be used to treat the disease, but it is only temporary and not curative. Bone marrow transplant using hematopoietic stem cells also has been tested on some patients with mixed results. The transplant procedure can carry severe risks and does not always work.

Pan and her colleagues -- including Roscoe O. Brady, MD, a researcher at NINDS -- report that using platelets and megakaryocytes for gene therapy is effective and could reduce the risk of activating cancer-causing oncogenes in hematopoietic stem cells.

The authors said tests showed that human megakaryocytic cells were capable of overexpressing IDUA, revealing their capacity for potential therapeutic benefit. While engineering megakaryocytes and platelets for infusion into their mouse models of Hurler, the scientists report they were able to release IDUA directly into amply sized extracellular spaces or inside micro-particles as the cells matured or activated. The cells were able to produce and package large amounts of functional IDUA and retained the capacity to cross-correct patient cells.

After infusing mouse models of Hurler with the genetically modified cells, researchers said this led to long-term normalization of IDUA levels in the animal's blood with versatile delivery routes and on-target preferential distribution to the liver and spleen. The treatment led to a complete metabolic correction of MPS I in most peripheral organs of the mice.

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Gene therapy may be possible cure for Hurler syndrome: Mouse Study

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Newswise PHILADELPHIA All creatures great and small, including fruitflies, need sleep. Researchers have surmised that sleep in any species -- is necessary for repairing proteins, consolidating memories, and removing wastes from cells. But, really, sleep is still a great mystery.

The timing of when we sleep versus are awake is controlled by cells in tune with circadian rhythms of light and dark. Most of the molecular components of that internal clock have been worked out. On the other hand, how much we sleep is regulated by another process called sleep homeostasis, however little is known about its molecular basis.

In a study published in eLIFE, Amita Sehgal, PhD, professor of Neuroscience at the Perelman School of Medicine, University of Pennsylvania, and colleagues, report a new protein involved in the homeostatic regulation of sleep in the fruitfly, Drosophila. Sehgal is also an investigator with the Howard Hughes Medical Institute (HHMI).

The researchers conducted a screen of mutant flies to identify short-sleeping individuals and found one, which they dubbed redeye. These mutants show a severe reduction in the amount of time they slumber, sleeping only half as long as normal flies. While the redeye mutants were able to fall asleep, they would wake again in only a few minutes.

The team found that the redeye gene encodes a subunit of the nicotinic acetylcholine receptor. This type of acetylcholine receptor consists of multiple protein subunits, which form an ion channel in the cell membrane, and, as the name implies, also binds to nicotine. Although acetylcholine signaling -- and cigarette smoking -- typically promote wakefulness, the particular subunit studied in the eLIFE paper is required for sleep in Drosophila.

Levels of the redeye protein in the fly oscillate with the cycles of light and dark and peak at times of daily sleep. Normally, the redeye protein is expressed at times of increasing sleep need in the fly, right around the afternoon siesta and at the time of night-time sleep. From this, the team concluded that the redeye protein promotes sleep and is a marker for sleepiness suggesting that redeye signals an acute need for sleep, and then helps to maintain sleep once it is underway.

In addition, cycling of the redeye protein is independent of the circadian clock in normal day:night cycles, but depends on the sleep homeostat. The team concluded this because redeye protein levels are upregulated in short-sleeping mutants as well as in wild-type animals following sleep deprivation. And, mutant flies had normal circadian rhythms, suggesting that their sleep problems were the result of disrupted sleep/wake homeostasis.

Ultimately the team wants to use the redeye gene to locate sleep homeostat neurons in the brain. We propose that the homeostatic drive to sleep increases levels of the redeye protein, which responds to this drive by promoting sleep, says Sehgal. Identification of molecules that reflect sleep drive could lead to the development of biomarkers for sleep, and may get us closer to revealing the mystery of the sleep homeostat.

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New Fruitfly Sleep Gene Promotes the Need to Sleep