Stress
Stress is a warning signal. It is like setting off a fire alarm or dialling an emergency phone number. The point is to trigger a reaction which, in the best of cases, will set things right again. We have all sensed stress at various times in our lives and, if we are attentive, our bodies react by firing off different signals: muscle stiffness, fatigue, headaches, indigestion... Though we may instinctively think of stress as something which emerges from external sources - such as busy timetables, relationships, disease or starvation - stress can also arise from sources within us. In fact, living organisms recognised the benefits of stress as a warning signal long before the word existed. One example are mitochondria. Mitochondria are small organelles whose major role is to produce biological energy, otherwise known as ATP. Consequently, healthy mitochondria are paramount to life. If, for one reason or another, they become malfunctional, they may choose to trigger off what is known as an 'integrated stress response', or ISR. This indicates to the cell that they need help, and the cell will do its best to fix the situation. A key protein involved in activating mitochondrion-induced ISR is known as 'death ligand signal enhancer', or DELE1.
