Showing posts with label autophagy. Show all posts
Showing posts with label autophagy. Show all posts

February 9, 2012

We all know that exercise is good for our bodies, and when we hear people talking about it in the media, the benefits are discussed in big-picture terms. A recent paper describes the effects of exercise at the cellular level, and gives me new motivation to get my ass in gear. Well, after I finish this heart-shaped Dunkin’ Donut (don’t give me that smug look…you know it’s delicious).

Autophagy is the process in which a cell metabolizes its own organelles and proteins. Autophagy takes place in the lysosome at a normal rate to rid the cell of old organelles, but is induced at higher rates in response to cellular stress to allow the cell to adjust to changing nutritional needs. A recent study finds that exercise can induce autophagy in muscle cells. In this paper, He and colleagues tracked autophagy in mice after they ran on treadmills. As seen in the images above, the number of autophagosomes (green dots) in the tibialis anterior muscle was higher in mice after 80 minutes of exercise (right), compared to before the exercise (left). Mice with a genetic mutation that prevented exercise-induced autophagy had lower endurance for exercise and had altered glucose metabolism. These fascinating findings provide us with a cellular understanding of how exercise prolongs life and protects our bodies from diseases such as diabetes and cancer.

ResearchBlogging.orgHe, C., Bassik, M., Moresi, V., Sun, K., Wei, Y., Zou, Z., An, Z., Loh, J., Fisher, J., Sun, Q., Korsmeyer, S., Packer, M., May, H., Hill, J., Virgin, H., Gilpin, C., Xiao, G., Bassel-Duby, R., Scherer, P., & Levine, B. (2012). Exercise-induced BCL2-regulated autophagy is required for muscle glucose homeostasis Nature, 481 (7382), 511-515 DOI: 10.1038/nature10758
Adapted by permission from Macmillan Publishers Ltd, copyright ©2012

December 16, 2010

It is natural to hypothesize that similar processes in the cell may use the same proteins to do the job. So, it is very satisfying to the scientists who identify these proteins and add another piece to the cellular puzzle.

Lysosomes are organelles that break down the cell’s waste material, which reach lysosomes from a few pathways. Endocytosis is the uptake of material from the outside surface of the cell, and this material gets shuttled through different vesicles, some of which lead to lysosomes. Authophagy is the process in which a cell’s own components are transported to lysosomes in double-membrane vesicles for degradation. A recent paper identifies the mechanism of two proteins, called Rubicon and PLEKHM1, that play a role in both endocytosis and authophagy through their interaction with Rab7, a well-known small GTPase that is found on both late endosomes and lysosomes. Images show endosomes (left column, green in merged) and PLEKHM1 (middle column, purple in merged) with different Rab7 mutants. In cells with wild-type Rab7 or a Rab7 QL mutant, PLEKHM1 was localized to endosomes (white in merged indicates colocalization). In the dominant-negative Rab7 TN mutant, PLEKHM1 could not localize to endosomes.

ResearchBlogging.orgTabata, K., Matsunaga, K., Sakane, A., Sasaki, T., Noda, T., & Yoshimori, T. (2010). Rubicon and PLEKHM1 Negatively Regulate the Endocytic/Autophagic Pathway via a Novel Rab7-binding Domain Molecular Biology of the Cell, 21 (23), 4162-4172 DOI: 10.1091/mbc.E10-06-0495