It is a speedy and
comprehensive method for determining the function of genes and hence could
greatly improve our understanding of a wide range of diseases and conditions,
such as heart disease, liver disease and cancer.
This method uses
stem cells with a single set of chromosomes, instead of the two sets found in
most cells, to reveal what causes the "circuitry" of stem cells to be
rewired as they begin the process of their differentiation into other cell
types. In Embryonic stem cells ,there is a particular gene circuitry which
retains their original, undifferentiated state,making them self-renewing.Dismantling
of this circuitry is what leads to conversion of stem cells to other cell types
.This process is known as cell differentiation. However, mechanism behind this
process was not clearly understood.
Researchers from the
University of Cambridge Welcome Trust-MRC Stem Cell Institute have developed a
technique which can explain many factors which are responsible for cell
differentiation, including many that were previously unknown.
Cells in mammals
contain two sets of chromosomes : one is maternal while the other paternal. This
can lead to many challenges in studying the function of genes, since each cell contains two copies of each gene,
determining the link between a genetic change and its physical effect, or
phenotype, is immensely complex. According to Dr Martin Leeb,, who led the
research, in collaboration with Professor Austin Smith, conventionally work is
done gene by gene, and in the past people would have spent most of their
careers looking at one mutation or one gene. Today, the process is a bit
faster, but it's still a methodical gene by gene approach, especially in case
of organisms with two sets of chromosome.
Embryonic stem cells with a single set of
chromosomes, known as haploid stem cells were generated by Dr Leeb using unfertilized mouse eggs. These haploid cells show all of the
same characteristics as stem cells with two sets of chromosomes, and retain the
same full developmental potential, making them a powerful tool for determining
how the genetic circuitry of mammalian development functions. Researchers have
used transposons or "jumping
genes",to make mutations in nearly all genes. The effect of a mutation can
be seen immediately in haploid cells because there is no second gene copy.
Additionally, since embryonic stem cells can convert into almost any cell type,
the haploid stem cells can be used to investigate any number of conditions in
any number of cell types. Mutations with important biological effects can then
rapidly be traced to individual genes by next generation DNA sequencing.
This is a
revolutionary tool for unraveling how gene circuits operate and many other
biological questions.
