Protein signal is crucial for accurate control of insect size

May 04, 2012
This image shows the left-right asymmetry of an adult fly deficient in dilp8. Credit: Maria Dominguez, Instituto de Neurociencias, Alicante

Two independent groups of researchers have identified a hormone that is responsible for keeping the growth and development of insects on track. The results, which are reported in the journal Science, suggest that Dilp8 provides an important signal to slow body growth and delay insect development. This braking effect is an essential part of normal development since it allows sufficient time for tissues to form and the correct body size, proportions and symmetry to be achieved.

"The important question about the control of animal size is knowing when to stop," said EMBO Member Maria Dominguez, lead author of one of the papers and Professor at the Institute of Neurosciences in Alicante, Spain. "To achieve the required precision in the control of growth, organs within the body of an insect must be capable of sensing their own size and communicating their dimensions to other organs in the body and to the ." She added: "Our work with suggests that growing organs and tissues produce a secreted peptide known as Dilp8. This hormone coordinates the growth rate of different organs in the body and is capable of delaying important developmental steps such as . In healthy flies, this additional time is essential to ensure that functional tissues are established and for organs to reach normal size. It also ensures that organs maintain perfect ."

Dominguez and collaborators examined tumours in the eye discs of Drosophila, parts of the insect body that go on to generate fully formed eyes in mature adult flies. Developing flies often adjust growth and the timing of metamorphosis to compensate for the disturbance induced by tumours or injury. The researchers wanted to investigate if a shared molecular signal was responsible for these observations. "Our work identifies Dilp8 as a signal that communicates the growth status of tissues as well as local responses to recovery from injury and cancer," said Dominguez.

EMBO Member Pierre Léopold and collaborators from the Institute of Biology Valrose at the University of Nice, France, identified the same protein using a different experimental approach. "We used a genome-wide RNA interference approach to look for Drosophila gene candidates that might be involved in coupling growth with the timing of development. Out of 11,000 genes that we tested in our genetic screen, only one was able, upon silencing, to rescue the delay in development induced by conditions that perturb tissue growth. This candidate gene corresponded to dilp8, which is exactly same gene identified by Dominguez and collaborators."

The expression of the dilp8 gene reduces tissue growth, which suggests that in addition to its role in preventing the hormonal induction of metamorphosis, dilp8 could act by slowing the growth of healthy tissues to stay synchronized with slow-growing tissue.

Until now, little information at the molecular level has been available about how organ growth is monitored and coordinated with the timing of development in insects and other complex organisms. Dilp8 appears to be part of the molecular machinery that helps tissues to grow and develop at the right pace.

Explore further: Molecular gate that could keep cancer cells locked up

More information: Science 4 May 2012: Vol. 336 no. 6081 pp. 579-582. doi: 10.1126/science.1216735

Science 4 May 2012: Vol. 336 no. 6081 pp. 582-585 doi: 10.1126/science.1216689

Related Stories

Regulatory process for organ scaling discovered

Oct 25, 2011

A new study has shed light on the process by which fruit flies develop with their body proportions remaining constant. The study, conducted by the research group of Professor Markus Affolter at the Biozentrum of the University ...

The brain grows while the body starves

Aug 04, 2011

When developing babies are growth restricted in the womb, they are typically born with heads that are large relative to their bodies. The growing brain is protected at the expense of other, less critical organs. Now, researchers ...

p53 determines organ size

Dec 15, 2010

In studies conducted on the fruit fly, researchers at IRB Barcelona (Spain) headed by ICREA Professor Marco Milan have revealed that organs have the molecular mechanisms to control their proportions. In this process the protein ...

Recommended for you

Molecular gate that could keep cancer cells locked up

Jul 31, 2014

In a study published today in Genes & Development, Dr Christian Speck from the MRC Clinical Sciences Centre's DNA Replication group, in collaboration with Brookhaven National Laboratory (BNL), New York, ...

The 'memory' of starvation is in your genes

Jul 31, 2014

During the winter of 1944, the Nazis blocked food supplies to the western Netherlands, creating a period of widespread famine and devastation. The impact of starvation on expectant mothers produced one of the first known ...

Sugar mimics guide stem cells toward neural fate

Jul 30, 2014

Embryonic stem cells can develop into a multitude of cells types. Researchers would like to understand how to channel that development into the specific types of mature cells that make up the organs and other structures of ...

User comments : 0