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Figure 3. Trehalose Treatment Does Not Extend the Lifespan of Lmna -/- mice . Abstract
Figure 3. Trehalose Treatment Does Not Extend the Lifespan of Lmna-/- mice.
. It has been widely shown that increased mammalian target of rapamycin (mTOR) activation inhibits autophagy. Autophagy is a major cellular pathway that degrades and clears used and dysfunctional materials through lysosomal clearance. Agents such as rapamycin and its analogs inhibit the mTOR pathway which has been shown to increase lifespan. The activation of autophagic clearance is widely thought to be one of the mechanisms by which lifespan is extended. Trehalose is a disaccharide that is known to increase autophagy. We used Lmna-/- mice which are deficient in the lmna gene and consequently have elevated mTOR levels. Given this information, we decided to test whether autophagy is the primary reason mTOR inhibition infers longevity. We will do this through the administration of trehalose to the Lmna-/- mice. Our hypothesis is that trehalose will independently activate autophagy, and therefore increase the lifespan of the Lmna-/- mice.
Figure 1. Treatment of Lmna-/- mice with Trehalose
Figure 2. Lmna-/- were treated with 2% Trehalose (in drinking water) and lifespan was monitored. There is no significant difference in lifespan of mice treated with trehalosevs water control (Median lifespan: Water = 59 days, Trehalose = 61 days)
The Activation of autophagy by the disaccharide, Trehalose, in Lmna-/- miceMichael V. Gross, Katherine H. Schreiber, Chen-Yu Liao, Brian K. KennedyThe Buck Institute for Research on Aging, Novato, CA 94945
Figure 1. Heart (A) or liver (B) samples were isolated from trehalose or control treated mice. Samples were homogenized and analyzed by Western Blot Analysis. The activation of Autophagy was examined by LC3 staining and mTOR activation was monitored by the phosphorylation of S6 and phosphorylation of NDRG-1. Autophagy was not detected in hearts or livers isolated from Lmna +/+ or Lmna -/- treated with trehalose.
• Delivery: IP vs. Water
• Look in other tissues(brain is what’s been published on
• Activate autophagy by other methods: Autophagy activating peptides
Figure 2. Body weights of Lmna -/- mice treated with Trehalose.
• 2% Trehalose treatment in water in not sufficient to activate autophagy in wild-type or lmna-/- mice
• 2% Trehalose in water does not extend the lifespan of Lmna-/- mice
• The 2% treatment of Trehalose also does not effect the bodyweights of the Lmna-/- mice
Mammalian Target of Rapamycin, also known as mTOR, is a serine threonine protein kinase that regulates many functions of the cell such as glucose homeostasis, lipid regulation and cell growth and proliferation(1). Chronically elevated mTOR levels have been implicated in multiple diseases such as diabetes, obesity, depression and certain cancers(2). Rapamycin and its variants are a class of immunosuppressant compounds that target mTOR and inhibit its function. These drugs are currently approved for immunosuppressive purposes, such as transplant rejection, and various cancers. These compounds come with a significant set of side effects which greatly limit the use for alternative indications and generally avoided outside of its approved indications.
One important effect of mTOR excitation is its inhibition of autophagy. Autophagy is the cell function where when a cell is dying the cell essentially degrades unnecessary components using lysosomes(3). Given Rapamycin’sinhibitive effect on mTOR, this trend is reversed and autophagy is activated. Although the activation of autophagy is widely thought to be a negative consequence, this process is thought to be a key malfunction in many chronic diseases, leading to the formation of aggregates and potentially cell death. It is for this reason the administration of Rapamycinhas been hypothesized to be beneficial and lengthen lifespan. To test the effect of autophagy on lifespan, we used Lmna-/- mice that were missing the Lmnagene that codes for A-type lamins. LaminA is a critical matrix protein involved in nuclear stability. We also used Trehalose, a disaccharide and also a know activator of autophagy to activate autophagy without effecting the mTOR levels(4). Removal of the Lmnagene displays an accelerated aging phenotype causing multiple diseases such as dystrophies of skeletal muscle and fat, dilated cardiomyopathy and progeria-like syndromes. In addition to this these Lamin deficient mice have elevated mTOR levels which makes them perfect to test Rapamycinand other mTOR inhibitors on.
1. Zoncu, R. Whitehead institute, Nature Reviews, Vol. 12 (2010)
2. Ramos, F.J. Science Translational medicine,ISSR 1946-6242 (2012)
3. Sarkar, S. Journal of Biological Chemistry. Vol. 282, number 8 (2007)
4. Tanaka, M. Nature Medecine, Vol. 10, Number 2(2004)
Mice Treated with water, Trehalose, or sucrose. The body weight of these mice were kept over the span of 40 days. The mice were monitored routinely and their body weight was regularly checked.