mTOR is a protein in our body involved with cellular growth, metabolism, and energy usage. Through each of these processes, cells are able to grow and function based on nutrient levels and growth signals. There are two mTOR complexes that regulate different processes in the body: mTORC1 and mTORC2.

mTORC1 is activated by insulin, amino acids, oxygen, stress, energy, and growth factors. It can promote cell growth through the inhibition of catabolic processes or activation of anabolic processes. Catabolism requires energy to break down substances into smaller molecules for use or waste, whereas anabolic processes use energy to build up substances into larger molecules for use. The activation of mTORC1 leads to protein and fat buildup, energy metabolism, and autophagy. Autophagy is the body’s process of recycling and reusing old or damaged cell parts.^[1]

mTORC2 responds to growth factors and plays a role in regulating cell survival, cellular metabolism, and the cell’s cytoskeleton.^[1] Cell survival is dependent on whether the cell is damaged or injured in any way. The cytoskeleton of the cell provides a framework for the cell shape and helps cell movement, much like the bone skeleton does for the human body, as well as playing a key role in many internal cellular functions such as transport and reproduction.

Together, both mTOR complexes serve to sense and respond to changes in the availability of cellular nutrients. In environments with high nutrients, mTOR will increase cell growth and metabolism due to availability of energy. In environments with low nutrients, mTOR will decrease cell growth and metabolism due to the lack of energy sources available.^[1]

Since this protein is directly involved in cellular growth and metabolism, it plays an important role in cancer, where mTOR signaling is disrupted. This, in turn, leads to cancer cell growth and survival, and therefore potentially to tumor formation and growth.^[1]

Aging is a risk factor for many diseases, and is also related to mTOR processing, specifically mTORC1. Recall that mTORC1 is involved in autophagy. This process of recycling and reusing old and damaged cell parts is a key component in the aging process. Since mTOR processing decreases with age, autophagy decreases as well. This can lead to the buildup of dead and damaged cells. However, the evidence for mTOR directly affecting aging is limited to animal studies; more studies will need to be done in humans to establish its applicability to us.^[2]