Gene that controls regeneration of head and brain discovered
4 May 2010
Biologists at The University of Nottingham have discovered the
gene that enables the planarian worm to regenerate its whole head and
brain.
The discovery could point to ways to regenerate old or damaged
human organs and tissues.
The research led by Dr Aziz Aboobaker, a Research Councils UK
Fellow in the School of Biology shows for the first time that a gene
called 'Smed-prep' is essential for correctly regenerating a head
and brain in planarian worms. The study has been published in the
open access journal PLoS Genetics.
Planarian worms
Planarian worms are non-parasitic flatworms from 1-20mm long that
are found in saltwater, freshwater and terrestrial environments.
They have an amazing ability to regenerate body parts, including a
head and brain, following amputation. The worms contain adult stem
cells that are constantly dividing and can become all of the missing
cell types. They also have the right set of genes working to make
this happen exactly as it should so that when they re-grow body
parts they end up in the right place and have the correct size,
shape and orientation.
Dr Aboobaker said: “These amazing worms offer us the opportunity
to observe tissue regeneration in a very simple animal that can
regenerate itself to a remarkable extent and does so as a matter of
course.
“We want to be able to understand how adult stem cells can work
collectively in any animal to form and replace damaged or missing
organs and tissues. Any fundamental advances in understanding from
other animals can become relevant to humans surprisingly quickly.
“If we know what is happening when tissues are regenerated under
normal circumstances, we can begin to formulate how to replace
damaged and diseased organs, tissues and cells in an organised and
safe way following an injury caused by trauma or disease. This would
be desirable for treating Alzheimer’s disease, for example. With
this knowledge we can also assess the consequences of what happens
when stem cells go wrong during the normal processes of renewal —
for example in the blood cell system where rogue stem cells can
result in Leukaemia.”
Smed-prep is necessary for the correct differentiation and
location of the cells that make up a planarian worm’s head. It is
also sufficient for defining where the head should be located on the
worm. The team have found that although the presence of Smed-prep is
vital so that the head and brain are in the right place, the worm
stem cells can still be persuaded to form brain cells as a result of
the action of other unrelated genes. But even so, without Smed-prep
these cells do not organise themselves to form a normal brain.
Daniel Felix, a graduate student who carried out the experimental
work said: “The understanding of the molecular basis for tissue
remodelling and regeneration is of vital importance for regenerative
medicine. Planarians are famous for their immense power of
regeneration, being able to regenerate a new head after
decapitation. With the homeobox gene Smed-prep, we have
characterised the first gene necessary for correct anterior fate and
patterning during regeneration.”