When a cell is exposed to
life-threatening conditions, the protein HSF1 (marked in green) initiates an
emergency program to prevent permanent damage to the cell. Credit: © MPI of
"Our results could also be of use
neurodegenerative diseases such as Alzheimer's or Parkinson's," hopes
Christian Loew, PhD student at the MPI of Biochemistry. The study has now been
published in the journal Cell.
When an organism is exposed to
life-threatening conditions, it sounds the alarm and a cellular emergency
program, the heat shock response, is initiated. However, the name "heat shock
response" is misleading. In the beginning of the 1960s, this form of
stress response was first observed. Scientists exposed fruit flies to
high temperatures and discovered a complex emergency program designated to
save single cells and thus the organism itself. Today researchers know that this
program is also triggered by other dangers such as radiation or
toxic substances. The terminology, however, is still in use.
During the heat shock response,
different stress proteins are synthesized. Their task is to prevent permanent
damage to the organism. "You can compare it to an emergency alert. In order to
restore the original status as soon as possible, problems and damages are
identified, counter-measures initiated and coordinated", Loew describes the
processes in the cell. In a comprehensive analysis, the Max Planck scientists
have investigated 15 000 proteins and their role in the heat shock response.
They could show that the helpers
are organized in different groups according to their tasks and disaster zones.
One group of proteins, for instance, checks whether the DNA in the nucleus is
The protein HSF1 (short for heat
shock transcription factor) is responsible for the central coordination of the
disaster management. In the moment it is activated, it calls a variety of other
proteins into action to eliminate the damages. The scientists could demonstrate
two ways in which this control centre in itself is regulated. When the crisis is
overcome, HSF1 is degraded by the cell's waste disposal system, the
proteasome. As long as there is still damage to get rid
of, another protein (Acetyltransferase EP300) prevents the degradation.
The understanding of the heat
shock response could also be of interest for neurodegenerative diseases such as
Alzheimer's or Parkinson's, so the scientists in Martinsried hope. Typical for
these diseases are massive cell damages and, thus, the excessive demand on the
cellular quality control. Nerve cells die and cannot fulfil their tasks in the
brain anymore. "A targeted activation of the
heat shock response could reduce the disease specific cell damages,"
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