Zombie Gene in Elephants: All the living organisms are made up of cells. During the whole life of an individual these cells divide and with each cycle of cell division,
There carries a risk of mutation which may change the normal cell to become an abnormal cancerous cells and in turn cause that cell to divide more frequently without differentiating into specific body cell.
Elephants are huge animals carrying trillions and trillions of cells which increases their chance of getting cancer. But a recent studies shows that elephants maybe protected from the deadly disease due to the possession of some special genes in their genome. Elephants have an extra copy of two cancer-fighting genes: p53 and LIF6.
How it all started?
Humans and other animals carry a set of tumor suppressor gene known as p53 which protects the cells of body from mutating. The gene products recognizes the anomaly in the DNA duplication and causes the cell carrying the damaged DNA to die by apoptosis.
However, the researchers from the University of Chicago and University of Utah, working separately, came to discover that elephants carry 20 copies of p53 gene, which makes the body cells more prone to protection from any mutation.
Vincent Lynch from the University of Chicago explained that the genes in the cells are always subjected to division. Sometimes, mistakes during the division causes the genes to become non-functional; such genes regarded as pseudogenes. These are often called as dead genes.
While studying the p53 genes and its products in elephants, Lynch came to uncover that a former pseudogene called Leukemia Inhibitory Factor 6 (LIF6) came back from death and was switched-on. The LIF6 protein causes the cancerous cells to die by making holes in the mitochondria; the powerhouse of the cell. Damage to mitochondria results in the death of cancerous or mutated cells.
“Hence, zombie,” said Lynch. “This dead gene came back to life. When it gets turned on by damaged DNA, it kills that cell, quickly. This is beneficial, because it acts in response to genetic mistakes, errors made when the DNA is being repaired. Getting rid of that cell can prevent a subsequent cancer.”
The LIF6 has peculiar evolutionary history. Almost all the animals possess LIF genes which have one function or the other. The human cells also carries a copy of LIF gene that is responsible for sending and receiving the signals from one cell or the other.
But the exception in case of elephants lies in the number of these genes. The elephants have almost 10 copies of these LIF genes. However out of all the LIF genes, only one LIF6 gene came back to life.
To find out more about the re-activation of LIF6 gene, researchers are now interested in studying the DNA extracted from fossils. Mastodons and mammoths also owned LIF6 gene and this caused the researchers and scientist to think that they have a common ancestry with the elephants of today.
“There are lots of stories like LIF6 in the elephant genome, and I want to know them all.” –Lynch.