Showing posts with label diet. Show all posts
Showing posts with label diet. Show all posts
Monday, February 13, 2012
High calorie diet and memory
I just heard about the latest research connecting memory loss with a high calorie diet and thought I’d check it out. An abstract of the scientific work was presented at the American Academy of Neurology annual meeting on February 12, 2012. The team, led by Dr. Yonas Geda, evaluated the dietary intake and cognitive status of over 1200 70 - 89 year old patients over 1 year. No participants had dementia at the onset of the study. Based on their total caloric intake per day, patients were divided into one of three groups - low, middle, or high calorie diets. Those in the high calorie intake group (>2143 to 6000 calories per day) had doubled their chances of developing Mild Cognitive Impairment (MCI), a pre-dementia condition. To see the abstract, visit http://www.aan.com/globals/axon/assets/9279.pdf. It will be interesting to read the full paper when it is published.
Wednesday, August 17, 2011
HDAC4 regulates fasting/feeding states
Many studies have shown that the control of lipid (fat) stores during fasting and feeding states is largely dependent on SIRT1 and FoxO activity. This latest study investigates the role of these proteins in obesity and adds another level of regulation to the mix.
Using a drosophila model, Wang et. al. (Cell 145:596-606) provide evidence that the serine/threonine salt-inducible kinase (SIK) 3 controls lipid storage or lipolysis in a HDAC4/FoxO dependent manner. During feeding, insulin activates SIK3 (its mammalian homolog is SIK2), phosphorylates HDAC4, which prevents its activation and subsequent movement to the nuclear compartment. This inhibits the deacetylation and activation of FoxO and ultimately increases lipid storage. Under fasting conditions, SIK3 activity is inhibited, HDAC4 remains in an active, dephosphorylated state where it can easily translocate to the nucleus. In the nucleus, HDAC4 deacetylates and activates FoxO to increase lipolysis as a mechanism to provide energy to the starving organism. When the organism re-feeds, FoxO is acetylated via the action of p300 and CBP and HDAC4 is re-phosphorylated. Therefore, HDAC4 activity is a critical regulator of fasting or feeding states.
This pathway is not limited to drosophila. Using a mouse hepatocyte cell line, Wang et. al. confirm their findings in mammals, suggesting a universality of this mechanism.
n3 science communications, llc
Using a drosophila model, Wang et. al. (Cell 145:596-606) provide evidence that the serine/threonine salt-inducible kinase (SIK) 3 controls lipid storage or lipolysis in a HDAC4/FoxO dependent manner. During feeding, insulin activates SIK3 (its mammalian homolog is SIK2), phosphorylates HDAC4, which prevents its activation and subsequent movement to the nuclear compartment. This inhibits the deacetylation and activation of FoxO and ultimately increases lipid storage. Under fasting conditions, SIK3 activity is inhibited, HDAC4 remains in an active, dephosphorylated state where it can easily translocate to the nucleus. In the nucleus, HDAC4 deacetylates and activates FoxO to increase lipolysis as a mechanism to provide energy to the starving organism. When the organism re-feeds, FoxO is acetylated via the action of p300 and CBP and HDAC4 is re-phosphorylated. Therefore, HDAC4 activity is a critical regulator of fasting or feeding states.
This pathway is not limited to drosophila. Using a mouse hepatocyte cell line, Wang et. al. confirm their findings in mammals, suggesting a universality of this mechanism.
n3 science communications, llc
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