Jen Sheen talks with
ScienceWatch.com and answers a few questions about
this month's Emerging Research Front Paper in the field of
Plant & Animal Science.
Article: Role of the Arabidopsis glucose sensor
HXK1 in nutrient, light, and hormonal
Authors: Moore, B;Zhou, L;Rolland, F;Hall, Q;Cheng, WH;Liu,
Journal: SCIENCE, 300 (5617): 332-336 APR 11 2003
Addresses: Harvard Univ, Sch Med, Dept Genet, Boston, MA
Harvard Univ, Sch Med, Dept Genet, Boston, MA 02114
Massachusetts Gen Hosp, Dept Mol Biol, Boston, MA 02114
Why do you think your paper is highly
Glucose plays essential regulatory roles in gene expression, physiology,
metabolism, cell proliferation, growth, and aging, but the molecular
mechanisms underlying the glucose signal transduction pathway remain
elusive in plants and animals. This paper provides the first conclusive
genetic and biochemical evidence that a specific
hexokinase (HXK1) acts as glucose sensor and integrates nutrient, light,
and hormonal signaling to modulate plant growth, a fundamental problem
linked to many areas of plant research.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
"We have just identified novel
components of the nuclear HXK1 signaling
complex in Arabidopsis."
It has been assumed that the regulatory roles of glucose are mediated
through its metabolism, and require the catalytic activity of hexokinase or
glucokinase in yeast, plants, mammals, and humans. Our studies provide
compelling evidence that Arabidopsis HXK1 possesses dual catalytic
and sensing functions. We show that the catalytically inactive HXK1 can
still serve its sensor functions in gene expression, cell proliferation,
root and inflorescence growth, and leaf expansion and senescence, thus
demonstrating the uncoupling of glucose signaling from glucose metabolism.
Would you summarize the significance of your paper in
The paper shows that glucose, as a nutrient, has essential regulatory roles
in controlling gene expression, cell growth, and hormonal responses in
plants. The evolutionarily conserved enzyme HXK1, conventionally known to
be responsible for glucose metabolism, can also serve as a sensor to
initiate diverse glucose responses important for every aspect of plant
How did you become involved in this research and were
any particular problems encountered along the way?
I discovered that glucose is a powerful repressor of photosynthesis gene
transcription in leaf cells when I was developing a cell-based system to
facilitate the studies of gene regulation and signal transduction in
plants. Many people believed that the glucose effect is mediated through
metabolism, not signal transduction, and studies performed in isolated
plant cells are artifacts and cannot reflect true regulation in whole
Where do you see your research leading in the
We have just identified novel components of the nuclear HXK1 signaling
complex in Arabidopsis. The work opens a previously unexpected new
direction to advance our understanding of the glucose sensing and signaling
network, as well as the role of HXK1 as a master regulator of transcription
and hormonal signaling central to plant growth.
Do you foresee any social or political implications for
Our research on the fundamental and evolutionarily conserved mechanisms of
glucose sensing and signaling carried out in plants may offer new insight
into glucose regulation in humans with implications for treatment of
diabetes, obesity, cancer, and aging.
Professor of Genetics
Department of Genetics
Harvard Medical School
Department of Molecular Biology
Massachusetts General Hospital
Boston, MA, USA
see also |
Related information: view a Fast Moving Front comment by
Sheen from September 2005.
Keywords: glucose signal transduction pathway, arabidopsis
hexokinase, glucose sensor, hormonal signaling, uncoupling of glucose
signaling from glucose metabolism, gene regulation and signal
transduction in plants.