[ASC-media] Putting the brakes on gene expression

Samantha Lucia s.lucia at victorchang.unsw.edu.au
Tue Nov 15 09:21:32 EST 2005

The Victor Chang Cardiac Research Institute


For immediate release 15 November 2005


Putting the brakes on gene expression


Scientists have found that gene expression is controlled much like a car by
tiny brakes called microRNA. 


These tiny brakes are central to the mechanism of embryo development,
including heart formation, and their failure could contribute to human
disease including heart defects and cancer.


The study, published today in the science journal Proceedings of the
National Academy of Sciences USA, was led by Dr Thomas Preiss from the
Victor Chang Cardiac Research Institute. Dr Preiss is also, this week,
presenting his findings at the 6th Peter Mac Cancer Symposium in Melbourne.


"Humans have roughly 30 thousand genes in each of their trillion cells. The
genes are a blue-print of how we are built, and their complex workings are
controlled and regulated to allow for proper body development and
maintenance, as well as to prevent or fight disease," Dr Preiss said.


By understanding how genes are controlled Dr Preiss and his team aim to shed
light on the development of disease and how it might be stopped, reversed
and cured. 


"Genes give all their information to large molecules, called messenger RNA
(mRNA), which oversee the synthesis of proteins that in turn go to work and
build specialised cells, tissues and organs," Dr Preiss said. 


"Surprisingly, cells express too many mRNA molecules for many genes and then
need to restrict the usage of the mRNA during protein synthesis. It's a bit
like driving your car at full-throttle while applying the brakes to hold the
speed limit.  


"Cells use tiny brakes, called microRNAs, to slow gene expression. These
tiny brakes had largely been overlooked until about five years ago, but now
hundreds of distinct microRNAs are known. It is clear that if left
unchecked, cells go on a collision course if some or all of their tiny
brakes are out of whack. In some cases this can result in unrestricted cell
growth, such as in cancer.


"We are only scratching the surface in terms of the biomedical importance of
microRNAs, but already they have been shown to be essential for stem cell
differentiation and heart development, and are major players in cancer," Dr
Preiss said.


Just how microRNAs go about controlling protein synthesis in animal cells
has until now been a mystery. "Although we've known for a while that
microRNAs have the ability to control the rate of gene expression in animal
cells by blocking the process of protein synthesis, no one knew exactly how.
We set out to discover this.


"We found that the microRNAs blocked the functions of the cap and tail
components of the mRNA, and we were further able to demonstrate a role for
the cap-binding factor eIF4E. We now understand the process a lot better.
Rather like having gone from knowing that a car has brakes to locating them
at the wheels and working out that they are disk brakes," Dr Preiss said." 


This is a significant find for biomedical sciences as it gives a better
understanding of how a major class of gene regulators functions. It is hoped
that this work will help researchers move closer to unlocking the complexity
of, and ultimately finding a cure for heart disease and cancer.


For further information and interview opportunities please contact:

Samantha Lucia

Communications and Marketing Manager, Victor Chang Cardiac Research

Tel: 61 02 8382 3415    Mobile: 0415 140 595     E-mail:
s.lucia at victorchang.unsw.edu.au



Samantha Lucia

Marketing and Communications Manager

Victor Chang Cardiac Research Institute



Ph: 61 2 8382 3415

Fax: 61 2 8382 3585

Mobile: 0415 140 595

email: s.lucia at victorchang.unsw.edu.au


Level 4, 376 Victoria Street

Darlinghurst NSW 2010


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