Scientists discover a new link between growth control switch and insulin in fruitflies


The protein DOR controls the maturation of adult flies depending on availability of nutrients

The
protein DOR activates a number of genes that larvae of the fruitfly
Drosophila
melanogaster

need in order to transform into adult flies, scientists at IRB
Barcelona have discovered. During this process, called metamorphosis,
the flies’ cells receive a number of signals which instruct them to
grow and mature into their final shape and size. Working with
fruitfly larvae, IRB Barcelona researcher Victor Francis has shown
for the first time that the protein DOR plays a role in the pathway
of the hormone ecdysone to make the transformation complete. The
study was led by Antonio Zorzano, coordinator of the IRB Barcelona’s
Molecular Medicine Programme and Professor at the University of
Barcelona, and by Aurelio Teleman, from the German Cancer Research
Center in Heidelberg, Germany, and was published in the journal
Current
Biology
.

One
of the molecules that governs metamorphosis of fruitfly larvae is a
steroid hormone called 20-hydroxyecdysone (20E). During larvae
development 20E binds to a protein receptor found in the nucleus of
cells and controls the genes that determine the shape and size of the
fly. By studying flies lacking the protein – the first time that
this protein has been studied in vivo – they determined that DOR
binds to its receptor to control the protein’s function and
activate the genes responsible for the insect’s development.

One
of the factors that controls metamorphosis is the presence of
nutrients that a fly uses to obtain energy. The scientists
demonstrated that insulin, which promotes energy consumption, uses
DOR to inactivate ecdysone, which has the opposite effect and
promotes enery procurement. A clear example of the relationship
between mechanisms of insulin and ecdysone in mammal cells is that
diabetic rats have altered DOR. The opposing functions of these two
pathways suggest that they must achieve a balance in order for the
larvae to develop correctly, and open new possibilities for the study
of human diabetes.

Reference
article:


dDOR
is an EcR coactivator that forms a feed-forward loop connecting
insulin and ecdysone signaling
Vıctor
A. Francis, Antonio Zorzano and Aurelio A. Teleman.
Current
Biology (2010) [DOI: 10.1016/j.cub.2010.08.055]