Tag Archives: Autophagy

Cell cleanup and your lifespan

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Friends,

Every few days our houses and desks get cluttered up and we need to clean them. A Similar process happens in our cells. In this VERITAS article we will study this very interesting topic and we will see how this cleanup process is related to old age diseases and how cancer researchers are using this process to fight the disease. We will also learn a very interesting fact: we can live longer by eating less!

 This article is based on a very interesting article that I read in the “Scientific American”.

 Before we start let’s understand some concepts:

 1) Cytoplasm: This is the fluid that fills a cell. The organelles of the cell ( eg nucleus, mitochondria etc) float around in the cytoplasm.

 2) Mitochondria: These are the cell’s power centers i.e they generate chemical energy that helps the cell survive. They also  control the cell’s growth and the cell’s death.

 3)Lysosome: These are the cell’s suicide bags. These organelles have “digestive juices” that can digest any other organelle of the cell. So this organelle has the ability to destroy any other part of the cell and then releasing its raw material for reuse.

The fluid the fills the cell i.e the cytoplasm gets filled with unwanted stuff/waste over a period of time. This is similar to the clutter that accumulates on our desks.  In order to keep the cell functioning properly this clutter has to be removed. This is done by a process called autophagy.

This is how the process of autophagy happens: A double layered membrane called phagophore surrounds any malfunctioning organelle
or any unwanted material in the cytoplasm. This double layered membrane surrounding the organelle moves to the lysosome and joins with it.
So now the phagophore + the “to be destroyed” organelle merge with the lysosome. The enzymes of the lysosome breakdown the organelle and
release its chemical building blocks for reuse by the cell. This is how a malfunctioning organelle or any other unwanted clutter in the cell is
destroyed.

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This process is important in all cells but in some cells like neurons it is extremely important. The reason why I say this is because most cells
are created and destroyed by another process known as apoptosis. However neurons stay with us throughout life. So it is extremely important
that they stay in perfect shape by constantly cleaning up any clutter that may have accumulated in them.

 Autophagy also plays a role in fighting diseases: if an infection causing organism enters the cell, the cell starts the autophagy program and tries
to destroy the organism. However disease carrying organisms also have a strategy to fight autophagy. Some organisms when surrounded by the
phagophore membrane make sure that it never fuses with the lysosome. So these organisms use the phagophore membrane to multiply!

Autophagy also works during starvation: if a cell is denied nutrients it has the ability to eat the less useful parts of itself in order to survive the period of starvation. So the cell tries to survive even if it means eating a part of itself. Autophagy becomes more active during periods of starvation.

 Now let’s talk about Cancer. Autophagy prevents cancer. If autophagy was not present the cell would become full of clutter and malfunctioning
organelles. These could cause the cell’s nucleus to malfunction thus causing uncontrolled reproduction which is Cancer. However sometimes
Cancer cells use autophagy to save themselves: if cells inside a cancerous mass are denied nutrients then the cell starts the autophagy process
and eats parts of itself to survive for longer periods of time.

 Several old age brain diseases are caused by a lack of effective autophagy. For example in Alzheimer’s disease neurons of the patient become full of clutter called ceroid( a dark yellow substance). This causes memory loss.  If autophagy was enhanced then these neurons will be cleaned of this material and memory will not suffer.

Scientists are trying to counter Cancer , Alzheimer’s disease and some infections by somehow controlling the amount of autophagy that happens in the diseased cells.

Autophagy also has a role in determining the lifespan of an individual. Several old age diseases like cancer and the degeneration of the brain are related to the efficiency of autophagy that reduces as we become older. We need to find ways to boost autophagy throughout our lives. One suggestion is to eat less. We have seen that restricted food supply enhances autophagy. Starved cells try and eat any thing they find in the cell and that could prevent cancer and mind degeneration.  So as you get older try and restrict your diet- it is good for your body and also your mind.

We worry about a lot of stuff around us but have we ever imagined how our building blocks deal with life. It is a battlefield at the level of our cells- they work so hard so that the larger animal can enjoy life. Life is a very complicated thing: at the level of our consciousness to the level of the smallest cell. It is beautiful and enormously complicated machinery that makes most decisions without us even knowing about them!

Kanwar

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Go, wondrous creature! mount where Science guides:
Go, measure earth, weigh air, and state the tides:
Instruct the planets in what orbs to run,
Correct old time and regulate the Sun;

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Veritas by Kanwarpreet Grewal is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.