(Press-News.org) ORLANDO, Fla., April 5, 2011 – Not all cholesterol is bad. Every cell requires it for growth – they either have to get cholesterol somewhere or they die. In a new study published April 6 in the journal Cell Metabolism, researchers from Sanford-Burnham Medical Research Institute (Sanford-Burnham) and their collaborators found that a protein sensor known to balance cholesterol sources can also access a previously underappreciated cellular fat storage depot.
The sensor, called sterol regulatory element-binding protein 2 (SREBP-2), monitors cellular cholesterol levels and responds to low levels by switching on genes that allow the cell to either 1) take up more from the bloodstream or 2) manufacture more from cholesterol building blocks inside the cell. Now, Sanford-Burnham's Timothy Osborne, Ph.D., and his team have uncovered a third cholesterol source also controlled by SREBP-2: fat droplets stored inside the cell itself.
"We were searching the mouse liver cell genome to find DNA sequences specifically bound by SREBP-2," said Dr. Osborne, director of the Metabolic Signaling and Disease Program in Sanford-Burnham's Diabetes and Obesity Research Center. "First we were surprised that SREBP-2 binds very close to the genes it regulates – that's not typical. Second, we were surprised to find that in addition to genes related to fat metabolism and cholesterol balance, SREBP-2 also binds and activates genes responsible for autophagy."
When times get tough, autophagy is the cell's way of recycling its own old or damaged parts. Dr. Osborne and his team found that SREBP-2 uses autophagy as a way to liberate cholesterol stored by some cells in fat droplets. (Here they looked at liver cells, which have large fat droplets. In contrast, other cell types – neurons, for example – aren't known to store fat.) When cholesterol was limited, autophagy genes were switched on and fat droplets were joined by autophagosomes (bags of enzymes the cell deploys for self-destruction). As a result, more cholesterol was available for cells to repair membranes, burn as energy or drive other life-sustaining processes.
The role of SREBP-2 in autophagy and cholesterol generation was confirmed using cells engineered to lack the protein. Facing cholesterol shortage, SREBP-2-deficient cells were unable to switch on autophagy genes and autophagosomes did not form as readily as they did in normal cells.
"This study identified a key regulatory step that determines how cells decide whether they have sufficient stored fat, or whether new fat needs to be produced internal cellular sources or obtained from the environment," Dr. Osborne said. "Genetic or environmental conditions that interfere with this regulatory step could lead to diseases such as obesity or cardiovascular disease."
###
This study was funded by the National Heart, Lung and Blood Institute and the National Library of Medicine, both parts of the National Institutes of Health, and the National Science Foundation. For more information about Sanford-Burnham research, visit our blog (http://beaker.sanfordburnham.org) or follow us on Twitter (http://twitter.com/SanfordBurnham).
Original paper
Seo Y-K, Jeon T-I, Chong HK, Biesinger J, Xie X, Osborne TF. Genome-wide localization of SREBP-2 in hepatic chromatin predicts a role in autophagy. Cell Metabolism. April 6, 2011.
About Sanford-Burnham Medical Research Institute
Sanford-Burnham Medical Research Institute is dedicated to discovering the fundamental molecular causes of disease and devising the innovative therapies of tomorrow. Sanford-Burnham, with operations in California and Florida, is one of the fastest-growing research institutes in the country. The Institute ranks among the top independent research institutions nationally for NIH grant funding and among the top organizations worldwide for its research impact. From 1999 – 2009, Sanford-Burnham ranked #1 worldwide among all types of organizations in the fields of biology and biochemistry for the impact of its research publications, defined by citations per publication, according to the Institute for Scientific Information. According to government statistics, Sanford-Burnham ranks #2 nationally among all organizations in capital efficiency of generating patents, defined by the number of patents issued per grant dollars awarded.
Sanford-Burnham utilizes a unique, collaborative approach to medical research and has established major research programs in cancer, neurodegeneration, diabetes, and infectious, inflammatory, and childhood diseases. The Institute is especially known for its world-class capabilities in stem cell research and drug discovery technologies. Sanford-Burnham is a nonprofit public benefit corporation. For more information, please visit www.sanfordburnham.org.
Cellular feast or famine
2011-04-06
ELSE PRESS RELEASES FROM THIS DATE:
Nourishing NYC and Women in Need, Inc. Collaborating To Improve Health And Nutrition For Those In-need
2011-04-06
Women in Need, Inc., and Nourishing NYC are pleased to announce Community Healthy Eating and Nutrition Classes for those in-need in April 2011. In response to the scarcity of nutrition education within parts of New York City, Nourishing NYC and Women in Need, Inc., will be offering a nutrition class free to those in-need on April 6th to help families and individuals that suffer disproportionately from poverty, obesity, and diabetes.
On April 6th, Nourishing NYC will be sending nutrition volunteers to Women in Need, Inc., The goal of the day is to teach women and families ...
Newsbriefs from the April issue of the journal Chest
2011-04-06
WATER PIPE SMOKING AS HARMFUL AS CIGARETTE SMOKING
Two new studies confirm the serious health effects caused by water pipe smoking (WPS), including reduced lung function and other cardiorespiratory conditions. In one study, researchers from the State University of New York at Buffalo found that, compared with people who do not smoke, WPS was associated with a significant reduction in lung function, equivalent to cigarette smoking. In a second study, Israeli researchers found that during a single 30-minute smoking session, WPS was associated with an increase in blood pressure, ...
Face time with a female aids males bent on monkey business
2011-04-06
New Haven, Conn. – Male monkeys looking for a good time might benefit from spending a bit longer getting to know a potential mate, according to a new study published online in the scientific journal Proceedings of the Royal Society B.
The time males spend around a prospective mate might be the key to detecting subtle sexual signals that show which females are fertile and which are not, according to the study, co-authored by an international team of biologists and psychologists.
"The results of this study shed new light on the role that experience can play in reading ...
Get Ready for Ratcliff Bailey! New Album "Deuce" Released
2011-04-06
240 song collaborations, a Viking Radio Artist of the Year Award, and a second, new CD titled 'Deuce' - these are some of the musical duo, Ratcliff Bailey, have under their belt. And they're just starting.
Ratcliff Bailey is an unassuming duo, but they're a dynamo when it comes to producing music. Their tracks have been featured on many Internet sites and on over 70 stations in the US, the UK, France, Spain, Norway, Australia, Canada, and Argentina! They're prolific, hard working, and talented to boot. They call Ashland, Kentucky and Ironton, Ohio as home, and Ratcliff ...
Tony Succar Releases "THRILLER", A Tropical Tribute to the "KING OF POP"
2011-04-06
In a fitting tribute to "The King Of Pop", virtuoso Peruvian Percussionist/Arranger/Producer TONY SUCCAR and his group Mixtura announce the launch of "THRILLER", the first single off of their upcoming album."
Without a doubt, Michael Jackson, "The King of Pop", has influenced artists of all generations. Selling over 50 million copies, "THRILLER", is considered by ROLLING STONE MAGAZINE, and the NATIONAL ASSOCIATION OF RECORD MERCHANDISERS as one of the greatest albums of all time. The impact that Michael's voice, charisma, and creative energy has had on Pop music and ...
Reef diversity no insurance against human threats
2011-04-06
In a large collaborative analysis publishing tomorrow in the online, open access journal PLoS Biology, 55 scientists from 49 nations document that the capability of reef fish systems to produce biomass and deliver goods and services to humanity, is functionally linked to the number of species; functioning increases as biodiversity increases. However, mounting pressures from growing human populations is tampering with this functioning of the reef fish communities, especially in the most diverse reefs. The extent of this distress was shown to be widespread and likely to worsen ...
Rejuvenating electron microscopy
2011-04-06
By modifying a protein from a plant that is much favored by science, researchers at the University of California, San Diego School of Medicine and colleagues have created a new type of genetic tag visible under an electron microscope, illuminating life in never-before-seen detail. Led by Nobel laureate Roger Tsien, PhD, Howard Hughes Medical Institute investigator and UCSD professor of pharmacology, chemistry and biochemistry, a team of scientists radically re-engineered a light-absorbing protein from the flowering cress plant Arabidopsis thaliana. When exposed to blue ...
Study shows that modern surgery for scoliosis has good long-term outcomes
2011-04-06
Teenagers who undergo spine fusion for scoliosis using the newest surgical techniques can expect to be doing well 10 years after surgery, according to a Hospital for Special Surgery study published online ahead of print in the [TK issue] of the journal Spine. Researchers had thought that the surgery would cause damage to the spine just below the fused discs, but the study showed that this was not the case.
"Fusion for adolescent idiopathic scoliosis using the newer generation spine implants appears to spare junctional disc degeneration and allows patients ten years out ...
Starting periods before the age of 10 increases risk of lung complaints in future
2011-04-06
Women who suffer from asthma or poor lung function as adults generally started their periods at the age of 10 or before. This is the conclusion of a European research study with Spanish participation, which shows that this trend is more common in southern Europe, and particularly affects women from large families.
"Adult women who had their first menstruation at the age of 10 or earlier have significantly lower lung capacity than women who had their first period at 13", Ferenc Macsali, lead author of the study and a researcher at the Haukeland Hospital in Bergen (Norway), ...
Overseas doctors more likely to face serious GMC action
2011-04-06
General Medical Council (GMC) decisions about doctors who qualified outside the UK are more likely to have far reaching consequences (high impact decisions), finds research published on bmj.com today.
The authors, led by Professor Charlotte Humphrey from King's College London, say there is no clear reason why overseas doctors do worse in GMC fitness to practise processes than their UK-trained peers.
Humphrey argues that perhaps "real differences exist in fitness to practise between groups of doctors who are referred to the GMC" or "that the GMC processes tend to ...