Molecular and Cell Biology Laboratory
Andrew Dillin, Pioneer Developmental Chair and a professor in the Molecular and Cell Biology Laboratory, uses the tiny roundworm Ceanorhabditis elegans to study the process of aging by looking at a hormone that is most widely recognized for its role in diabetes among humans: insulin. The insulin signaling pathway in worms is not only almost identical to that found in humans, but Dillin discovered that insulin also controls many physiological aspects in the worm's body, including reproduction and aging. In humans, interfering with insulin/IGF-1 signaling to generate a life-prolonging benefit would lead to type 2 diabetes and possibly cancer. In worms, larval development and reproduction are affected along with longevity.
Some of Dillin's earlier research had hinted at the possibility to genetically manipulate one element of the pathway without disrupting its additional functions, this led him to search for "specificity" factors that may control how and if insulin and IGF-1 impact a wide range of target genes. Recently, he and his team pinpointed a protein specifically responsible for extending lifespan and youthfulness without disrupting the worms' response to some forms of stress, development and fertility controlled by the insulin signaling pathway.
Additionally, Dillin is interested in age-onset neurodegenerative diseases. Like most neurodegenerative diseases, Alzheimer's disease usually appears late in life, raising the question of whether it is a direct and disastrous consequence of aging or if the toxic protein aggregates that cause the disease simply take a long time to form. He discovered that the harmful beta amyloid aggregates accumulate when aging impedes two molecular clean-up crews from getting rid of these toxic species.
"Aging is the single biggest risk factor for most human diseases, ranging from arthritis and cancer to diabetes and neurodegenerative disease. Our goal is to unravel the basic molecular mechanisms that drive the aging process, which will allow us to promote healthy aging for humankind."
Beyond age 65, the number of people with Alzheimer's disease doubles every five years. Centenarians, however, seem to escape most common age-related diseases, including the ravages of Alzheimer's. One of the telltale signs of Alzheimer's disease is the buildup of toxic clumps of beta amyloid plaques in the brain. Beta amyloid production probably occurs in all brains, but healthy cells clear away excess amounts. Brains of people with Alzheimer's disease, by contrast, are unable to control beta amyloid accumulation. The same is true for Alzheimer's mouse models, which are genetically engineered to overproduce beta amyloid.
To determine whether modulating the aging process could influence the onset of Alzheimer's, a team of investigators in Dillin's lab slowed the aging process in an Alzheimer's mouse model by lowering the activity of the IGF-1 signaling pathway– a highly conserved pathway that plays a crucial role in regulating lifespan and youthfulness across many species and is linked to extreme longevity in humans. Mice with reduced IGF-1 signaling live up to 35 percent longer than normal mice, and some very long-lived humans carry mutations in components of the IGF-1 pathway.
Dillin's group then employed a battery of behavioral tests to find out whether it was simply the passage of time or aging per se that determined the onset of the disease. Chronologically old but biologically young animals appeared nearly normal in the tests long after age-matched, normal-aging Alzheimer's mice exhibited severe impairments. When Dillin and his team looked at their brains, however, they found that those of the long-lived mice were riddled with highly compacted plaques.
These results clearly support the emerging theme that the plaques have a protective function and that as mice age, they become less efficient at stashing toxic beta amyloid fibrils in tightly packed aggregates. This work validates the hypothesis that genetic and pharmacologic changes to create a healthy lifespan can greatly reduce the onset of some of the most devastating diseases afflicting mankind.
Left to right:
Back row: Thomas Heimbucher, Daniel De Magalhaes Filho, Erik Kapernick, Juan Valenzuela, Derek Joyce, Nate Baird, Will Mair, Ian Nicastro, Siler Panowski, David Vilchez, Pete Douglas
Front row: Hyun-Eui Kim, Deepti Wilkinson, Jenni Durieux, Nessa Morantte, Virginia Butel-Murillo, Rebecca Taylor, Kristen Berendzen, Celine Riera, Gina Artale
Front row: Andy Dillin
Cohen E, Bieschke J, Perciavalle RM, Kelly JW, Dillin A. Opposing Activities Protect Against Age Onset Proteotoxicity. Science. 2006.
Wolff S, Ma H, Burch D, Maciel GA, Hunter T, Dillin A. SMK-1, an essential regulator of DAF-16-mediated longevity. Cell. 124(5):1039-53; 2006.
Raices M, Maruyama H, Dillin A, Karlseder J. Uncoupling of longevity and telomere length in C. elegans. PLoS Genet. (3):30; 2005.
Dillin, A., Hsu, A., Arantes-Oliveira, N., Lehrer-Graiwer, J., Hsin, H., Fraser, A. G., Kamath, R. V., Ahringer, J., Kenyon, C. Lifelong Rates of Behavior and Aging Specified by Respiratory Chain Activity During Development. Science. 298(5602):2398-401; 2002.
Dillin, A., Crawford, D. K., Kenyon C. Timing requirements for insulin signaling in C. elegans. Science. 298:830-4; 2002.
Arantes-Oliveira N, Apfeld J, Dillin A, Kenyon C. Regulation of life-span by germ-line stem cells in C. elegans. Science. 295(5554):502-5; 2002.
Salk News Releases
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April 15, 2011
When less is more: how mitochondrial signals extend lifespan
January 6, 2011
Delaying the aging process protects against Alzheimer's disease
December 10, 2009
Climbing the ladder to longevity: critical enzyme pair identified
June 24, 2009
Salk scientists selected as Howard Hughes Medical Institute investigators
May 27, 2008
Salk researchers discover first gene that specifically links calorie restriction to longevity
May 2, 2007
New research points toward mechanism of age-onset toxicity of Alzheimer's protein
August 10, 2006
For the first time: longevity modulated without disrupting life-sustaining function
March 14, 2006
Tiny roundworm's telomeres help scientists to tease apart different types of aging
August 5, 2005
Awards and Honors
- McKnight Neurosciences of Brain Disorders Award (2007)
- Ellison Medical Foundation Award (2004-2008)
- Larry L. Hillblom Junior Faculty Award (2003-2006)
- American Diabetes Association Junior Faculty Award (2004-2006)
- Damon Runyon-Walter Winchell Postdoctoral Fellowship, UC San Francisco (1999-2002)
Hungering for longevity–Salk scientists identify the confluence of aging signals
February 9, 2011
Substantial evidence suggests that lifespan is increased if an organism restricts its daily calorie intake, a spartan regime that some say works by just making life seem longer. A team of scientists from the Salk Institute of Biological Studies has discovered a molecular switch flipped by hunger that could not only make longevity more appetizing but identify drug targets for patients with aging-related diseases such as type II diabetes or cancer. Read more>>
Delaying the aging process protects against Alzheimer's disease
September 9, 2010
Aging is the single greatest risk factor for Alzheimer's disease. In their latest study, researchers at the Salk Institute for Biological Studies found that simply slowing the aging process in mice prone to develop Alzheimer's disease prevented their brains from turning into a neuronal wasteland. Read more>>