First published online July 10, 2003
Journal of Cell Science 116, e1603 (2003)
Copyright © 2003 The Company of Biologists Limited
Superoxide: the route to multicellularity?
Generation of reactive oxygen species (ROS) such as superoxide ions is an
important signalling mechanism in mammals and plants. Yeast and bacteria
possess systems that allow them to respond to ROS produced during oxidative
stress but do not actively produce them as messengers. So when did ROS
generation become a signalling mechanism and why? Gareth Bloomfield and
Catherine Pears suggest the answer lies at the advent of multicellularity (see
p. 3387). They show
that the social amoeba Dictyostelium, which straddles the boundary
between unicellular and multicellular life (since it can exist in either
form), can generate superoxide. The ROS is produced in response to a secreted
factor early in development during the transition to multicellularity, which
occurs when the organism runs out of food. The authors show that
low-molecular-weight superoxide scavengers or overexpression of the
superoxide-scavenging enzyme superoxide dismutase can block
Dictyostelium aggregation during the transition to multicellularity;
in addition, they find that it significantly reduces expression of genes
important for early development. Bloomfield and Pears therefore conclude that
a superoxide-dependent signal is critical for initiation of development in
Dictyostelium. They also note that ROS play important developmental
roles in animals and plants, suggesting that this mechanism might have arisen
to provide the signalling diversity that multicellularity demands.
Related articles in JCS:
- Superoxide signalling required for multicellular development of Dictyostelium
- Gareth Bloomfield and Catherine Pears
JCS 2003 116: 3387-3397.
[Abstract]
[Full Text]
