From old to new - autophagy is the recycling process of our cells. Autophagy ensures that damaged components, aggregated proteins and pathogens are eliminated and can be used for new construction. The process of autophagy plays an essential role in health.
In this glossary entry you will find everything you need to know about autophagy. We present the current state of knowledge of research and explain what is behind the term autophagy. You can read in this article what effect the process has on the body and what diseases autophagy is associated with. We will also show you how to stimulate autophagy.
the essentials in brief
- Autophagy is a cellular process in which proteins and organelles are broken down and their components are recycled. The process strikes the balance between breaking down old components and producing new ones.
- Autophagy plays an important role in our immune system, the protection of nerve cells and is associated with various diseases. Autophagy is central to the health of the body.
- Autophagy can be influenced with the help of exercise, fasting and certain foods.
Glossary entry: The term autophagy explained in detail
In the following section we have summarized the most important information about autophagy for you. In addition to a detailed definition, we will show you how autophagy works and how it affects our body and diseases. We also explain which methods you can use to promote autophagy.
After reading this glossary entry, you will know everything you need to know about autophagy.
What is autophagy?
Autophagy is a eukaryotic cell recycling process. He is responsible for the recycling of breakdown products, the breakdown of cytoplasmic proteins, macromolecules and organelles (1). Recycling provides new building blocks and energy for cell renewal and homeostasis (cellular balance) (2).
Autophagy is critical for cell survival and maintenance.
Autophagy plays an important role in cellular stress. It supports the body with nutrient deficiencies and accumulations of pathogens and damaged organelles.
Autophagy also protects the body from infectious organisms (3).
How does autophagy work?
Autophagy is constantly happening in our body. However, some factors can additionally stimulate autophagy. These are, for example, aggregation of proteins, starvation (nutrient deficiency), low energy, hypoxia (lack of oxygen supply) and pathogen infections.
Autophagy takes place in small parts of our body – the cells. Proteins, pathogens, cells and organelles are broken down by autophagosomes and lysosomes and then recycled. (Image source: National Cancer Institute / unsplash)
When autophagy is activated, a regulated process starts. Cytoplasmic material is stored in double-membrane vesicles (autophagosomes). It is then broken down by fusion with lysosomes and made available for further processing (4).
What does autophagy do in the body?
Autophagy affects many different areas of our body. In this list (5) we have compiled some tasks of autophagy:
- promotes regeneration and cell health
- recycling of residual proteins
- Provides energy and building blocks for cells
- removes toxic proteins associated with neurodegenerative diseases
In the sections below, we explain how autophagy affects the immune system and lifespan in detail.
Autophagy is part of both the innate and adaptive immune responses. It is one of the most important responses to cellular stress (6). The processes allow the immune system to break down viruses, bacteria and foreign proteins within the cell.
In addition, autophagy affects the presentation of antigens to certain cells (7).
There are some pathogens that have evolved mechanisms to defend against or exploit autophagy (8).
Defective or decreased autophagic activity can contribute to infectious diseases, chronic inflammatory diseases, and autoimmune diseases (9).
Inflammation-related diseases of the metabolism can also result. These include diabetes and obesity. They are related to insulin resistance (10).
There is much debate about the effect of autophagy on lifespan.
It is known that autophagy decreases with age (11).
A 2015 study shows that autophagy can counteract age-related accumulation of damaged organelles and proteins (12).
In addition, autophagy is associated with diseases that often occur in an older age group. By preventing these diseases, autophagy also increases lifespan.
What diseases is autophagy associated with?
So far, there have mostly been insufficient studies on autophagy. In vitro studies and animal experiments are often carried out.
The scientific evidence suggests that autophagy is linked to certain diseases. Below we summarize some information about diseases.
In a neurodegenerative disease, nerve cells gradually die off. Consequences of this irrevocable process are failures that affect body and mind. Examples are Parkinson's disease and Alzheimer's disease (13).
Autophagy is neuroprotective by eliminating harmful forms of proteins (14).
Research is investigating connections between neurodegenerative diseases and autophagy. Neurodegenerative diseases are related to deposits of proteins in cells. In autophagy, the body removes these proteins (15).
Defective autophagy often leads to neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease or Huntington's disease (16).
Cancer is a common disease and there is a lot of research on the subject. The effect of autophagy on cancer is also being studied. However, the research is still in its infancy.
Studying the effect of autophagy on cancer is not easy because the effect is difficult to measure.
The effect of autophagy on cancer can be both positive and negative.
There is some evidence that autophagy inhibits tumor initiation but aids cancer progression. Researchers therefore assume that as the cancer progresses, inhibition of autophagy could be an effective therapy (17).
Another study found that the effect of autophagy on cancer depends on several factors. The effect can be either neutral, tumor-suppressive or tumor-promoting. Influencing factors are nutrient availability, stress in the microenvironment, and the immune system (18).
It is therefore difficult to make a precise statement about the effect of autophagy on cancer.
Autophagy may be linked to a common genetic cause of liver disease, α1-antitrypsin deficiency. This disease manifests itself in chronic inflammation and carcinogenesis (tumor development). The cause is a point mutation in the gain-of-function in α1-antitrypsin Z.
This mutation disrupts normal protein folding and can lead to aggregated polymers. Autophagy is known to degrade such aggregation. Research is ongoing to better understand the mechanism behind it (19).
A 2008 study examined the effect of autophagy on muscles. According to this study, autophagy can eliminate disease-causing proteins that are part of various muscle diseases.
These include (19):
- Miyoshi myopathy
- sporadic myositis of the inclusion body
- Type 2B limb girdle muscular dystrophy.
Various researchers from the USA and France were able to determine in a study that autophagy can be an important pathological reaction to cardiac stress.
In cardiovascular diseases, autophagy can have both positive and negative effects (20).
People with coronary artery disease and hypertension often have cardiac stresses such as ischemia and pressure overload (19).
What promotes autophagy?
Autophagy is a recycling process that is ongoing. In certain situations, such as cellular stress and nutrient deficiencies, autophagy is additionally activated.
Fasting, exercise and certain foods are under discussion to promote autophagy. In the following sections we explain the respective methods and their effects in more detail.
The impact of fasting on autophagy is a much debated topic. Science is constantly researching to better understand the mechanisms behind it.
A study published in 2018 showed that both fasting and calorie restriction can increase autophagy.
Thus, food deprivation can induce autophagy in many tissues and organs (21).
Scientists in another study found in vitro that fasting and nutrient deprivation enhanced autophagy sequestration of and other organelles. Essential nutrients are recycled in the process (22).
Exercise is an important factor that can promote health. Moderate sport is considered to be particularly health-promoting.
Various studies indicate that exercise can induce autophagy. Among other things, exercise has an influence on the autophagy of the cerebral cortex (23) and skeletal muscles (24).
Not only can exercise induce autophagy, but autophagy may also contribute to the beneficial metabolic effects of exercise (25).
Certain foods can have an impact on autophagy and boost it. In the following table we have listed a small selection of the most important foods that can support autophagy:
|Coffee||Both natural and decaffeinated coffee were able to induce autophagy in a study in mice. The effect appears to be independent of the caffeine content and probably dependent on polyphenols (26).|
|turmeric||play a crucial role in cellular stress responses such as autophagy. Scientific research shows the importance of polyphenolic compounds such as curcumin (part of turmeric) for l function and structure (27).|
|green tea||A component in green tea, epigallocatechin gallate (EGCG), may increase liver autophagy. This promotes the formation of autophagosomes, increases lysosomal acidification and accelerates the flow into the liver cells (28).|
|ketogenic diet||On a ketogenic diet, ketone bodies are formed. Studies in vitro showed that ketone bodies can stimulate chaperone-mediated autophagy (CMA). CMA is induced by oxidizing substrates or affecting substrate proteins during prolonged starvation (29).|
|spermidine||The natural polyamine spermidine can stimulate autophagy. In addition, spermidine appears to reduce mortality from cardiovascular disease and cancer. However, research in this area is still in its infancy (30).|
You should be aware that autophagy can have both positive and negative effects. It is important that you have a balanced diet. In this way you not only support autophagy, but also other important components and mechanisms of your body.
Autophagy is an important cellular process that can affect the entire body. This recycling process can have positive effects on neurodegeneration, the immune system, muscles and longevity. Both positive and negative effects can be seen in cancer and cardiovascular diseases.
If you want to boost your autophagy, you should therefore be well informed about the possible consequences. Fasting, exercise, and certain foods can stimulate autophagy. When it comes to this topic, you should always keep in mind that research is still in its infancy and no safe conclusions can be drawn from it. Further investigations are necessary.
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- Corazzari, M., Fimia, GM, Lovat, P. & Piacentini, M. (2013, October 1). Why is autophagy important for melanoma? Molecular mechanisms and therapeutic implications. ScienceDirect.
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- Siqueira M, Ribeiro RM, & Travassos LH (2018). Autophagy and Its Interaction With Intracellular Bacterial Pathogens. Frontiers in immunology, 9, 935.
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- NS Castrejón-Jiménez, K Leyva-Paredes, JC Hernández-González, JC Luna-Herrera, & BE García-Pérez (2015). The role of autophagy in bacterial infections. Bioscience Trends, 9(3), 149-159.
- Lenzen-Schulte, M. & Zylka-Menhorn, V. (2016). Autophagy: “self-mutilation” as a survival strategy. German Medical Journal.
- Levine B, Mizushima N, & Virgin HW (2011). Autophagy in immunity and inflammation. Nature, 469(7330), 323-335.
- Leidal, AM, Levine, B., & Debnath, J. (2018). Autophagy and the cell biology of age-related disease. Nature cell biology, 20(12), 1338-1348.
- Madeo F, Zimmermann A, Maiuri MC, & Kroemer G (2015). Essential role for autophagy in life span extension. The Journal of clinical investigation, 125(1), 85-93.
- JPND research. (no year). What are neurodegenerative diseases?
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- Menzies, FM, Fleming, A, & Rubinsztein, DC (2015). Compromised autophagy and neurodegenerative diseases. Nature reviews. Neuroscience, 16(6), 345-357.
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- Levine, B., & Kroemer, G. (2008). Autophagy in the pathogenesis of disease. Cell, 132(1), 27-42. https://doi.org/10.1016/j.cell.2007.12.018
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- Bagherniya, M., Butler, AE, Barreto, GE, & Sahebkar, A. (2018). The effect of fasting or calorie restriction on autophagy induction: A review of the literature. Aging research reviews, 47, 183-197.
- Kim, I., & Lemasters, JJ (2011). l degradation by autophagy (mitophagy) in GFP-LC3 transgenic hepatocytes during nutrient deprivation. American journal of physiology. Cell physiology, 300(2), C308-C317.
- He C, Sumpter R Jr & Levine B (2012). Exercise induces autophagy in peripheral tissues and in the brain. Autophagy, 8(10), 1548-1551. https://doi.org/10.4161/auto.21327
- Brandt N, Gunnarsson TP, Bangsbo J, & Pilegaard H (2018). Exercise and exercise training-induced increase in autophagy markers in human skeletal muscle. Physiological reports, 6(7), e13651.
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- Pietrocola F, Malik SA, Mariño G, Vacchelli E, Senovilla L, Chaba K, Niso-Santano M, Maiuri MC, Madeo F, & Kroemer G. (2014). Coffee induces autophagy in vivo. Cell cycle (Georgetown, Tex.), 13(12), 1987-1994.
- de Oliveira, MR, Jardim, FR, Setzer, WN, Nabavi, SM, & Nabavi, SF (2016). Curcumin, l biogenesis, and mitophagy: Exploring recent data and indicating future needs. Biotechnology advances, 34(5), 813-826.
- Zhou J, Farah BL, Sinha RA, Wu Y, Singh BK, Bay BH, Yang CS, & Yen PM (2014). Epigallocatechin-3-gallate (EGCG), a green tea polyphenol, stimulates hepatic autophagy and lipid clearance. Plos one, 9(1), e87161.
- Finn, PF, & Dice, JF (2005). Ketone bodies stimulate chaperone-mediated autophagy. The Journal of biological chemistry, 280(27), 25864-25870.
- Madeo F, Bauer MA, Carmona-Gutierrez D, & Kroemer G (2019). Spermidine: a physiological autophagy inducer acting as an anti-aging vitamin in humans?. Autophagy, 15(1), 165-168.