image: Altered fasting metabolism may contribute to the increased longevity of Snell dwarf mice (bottom). view more
Credit: Terry Combs
Fat Hormone may Contribute to Longevity
Both humans and mice that manage to live to a ripe, old age show a clear change in their glucose metabolism, but it's unclear whether this change alone can increase lifespan. Using a mouse model of longevity, Terry Combs and colleagues report that changes in metabolism can indeed increase longevity. They demonstrated that long-lived Snell dwarf mice burn less glucose and more fatty acids during periods of fasting, and as a result produce fewer free radicals.
The key to this switch may be adiponectin, a hormone produced by fat cells that helps lower glucose production and stimulates cells to use fat for energy instead. The researchers found that Snell mice had three times as much adiponectin in their blood as control mice; Snell mice also had fewer triglycerides in their cells, indicative of higher fat metabolism.
The benefit of burning fats instead of glucose for energy is that it produces fewer oxygen radicals which can damage cells and exacerbate the effects of aging. Confirming this, Combs and colleagues found far less free radical damage, measured as the frequency of a chemical modification on protein known as carbonyl groups, in Snell mice than controls.
Article: “Low utilization of circulating glucose after food withdrawal in Snell dwarf mice” by Natasha L. Brooks, Chad M. Trent, Carl F. Raetzsch, Kevin Flurkey, Gunnar Boysen, Michael T. Perfetti, Yo-Chan Jeong, Simon Klebanov, Kajal B. Patel, Valerie R. Khodush, Lawrence L. Kupper, David Carling, James A. Swenberg, David E. Harrison, and Terry P. Combs
CORRESPONDING AUTHOR: Terry Combs, Department of Nutrition, University of North Carolina; 919-966-7235, terrycombs@unc.edu
Unraveling the Silky Spider Web
Web-making spiders employ a host of silk glands to synthesize a variety of silk filaments with different mechanical properties. Although it is widely believed that the aciniform glands are one such silk factory, there has been no hard evidence linking aciniform-derived proteins and silk –until now. Craig Vierra and colleagues found that the aciniform gland in the Black Widow manufactures and extrudes a previously unidentified protein that is a component of multiple types of silk.
Vierra and colleagues used mass spectroscopy to analyze the protein content of two types of silk: the variety used for egg cases and the one used to wrap up prey. In both types they uncovered a thin protein fiber with a similar structure to another known silk protein called AcSp1. When they examined the expression of this new protein, termed AcSp1-like protein, in different silk glands, they found that mRNA levels were present at 1000-fold higher concentration in the aciniform gland compared to other glands.
The researchers note this finding is intriguing since it shows that aciniform silk fibers are not made for one specific task but rather get integrated into multiple silk types. They plan to further characterize the mechanics of aciniform silk, but they propose that this thin fiber acts like twine to hold thicker silk fibers together.
ARTICLE: “Aciniform spidroin: A constituent of egg case sacs and wrapping silk fibers from the black widow spider, Latrodectus Hesperus” by Keshav Vasanthavada, Xiaoyi Hu, Arnold M. Falick, Coby LaMattina, Anne M.F. Moore, Patrick R. Jones, Russell Yee, Ryan Reza, Tiffany Tuton, and Craig A. Vierra
CORRESPONDING AUTHOR: Craig Vierra, Department of Biological Sciences, University of the Pacific; 209-946-3024, cvierra@pacific.edu
The American Society for Biochemistry and Molecular Biology is a nonprofit scientific and educational organization with over 11,900 members in the United States and internationally. Most members teach and conduct research at colleges and universities. Others conduct research in various government laboratories, nonprofit research institutions and industry. The Society’s student members attend undergraduate or graduate institutions.
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Journal
Journal of Biological Chemistry