Scientists in Czechia uncover how the liver regenerates in “one of the most significant discoveries”
It has long been known that the liver can regenerate. A new study now shows how: scientists in Czechia have discovered that the liver uses ammonia – highly toxic under normal conditions – and converts it into the amino acid glutamine, which drives rapid cell division and allows the organ to repair itself.
An international team of researchers, led by the Biotechnology Institute of the Czech Academy of Sciences, published their study on liver regeneration in the prestigious journal Nature Communications. The study’s lead author, Jiří Neužil, commented:
“I want to start by saying that what we are talking about is one of the most significant discoveries our laboratory has made in its twenty years of existence.
"We are not showing why the liver regenerates, but we are showing something new: that toxic ammonia, which is produced in large amounts in the body (for example when proteins are broken down), and is normally detoxified and removed, is absolutely key during liver regeneration.”
The liver is one of the largest organs in the human body and its normal functions are manifold, including filtering blood and producing bile to aid digestion. Under normal conditions, ammonia is converted into urea in the liver through the so-called urea cycle and excreted by the kidneys. It thus makes sure that blood ammonia levels remain low, as even slight increases are harmful to the central nervous system.
During liver regeneration, however, the organ handles ammonia completely differently. As Neužil explains:
“Our research shows that after a portion of the liver is removed, a series of reactions that normally convert ammonia into urea, which is excreted as a harmless substance, slow down or stop. During regeneration, ammonia is instead used to produce the amino acid glutamine.”
Glutamine is essential for producing DNA and RNA during rapid cell division. During regeneration, liver tissue converts ammonia into the necessary glutamine through complex chemical reactions. The study thus reveals how a harmful substances can become vital for growth.
Incredible as it may seem, Neužil describes just how great the liver’s regenerative capacity is:
“The liver can regenerate so completely that even if up to ninety percent is removed, the remaining ten percent is enough to restore full function.”
This growth occurs at a pace faster than most cancerous tumours, yet unlike tumours, it stops once the liver reaches its original size. While the study may give new insights into how tumours grow, since cancers often use similar metabolic switches, scientists don't yet fully understand why the liver stops growing and tumours don't.
“From what we know, no tumour grows as fast as a regenerating liver. We know which genes play important roles in the regulation of growth in livers, but the main signal telling the liver to stop growing remains unknown.”
The research team who made this incredible discovery in liver biology includes scientists not only form Czechia but also from the USA, Portugal, Korea, and New Zealand.
