October 22, 2001
Pattern of Protein Manufacture in
Hippocampus Found by Scientists at University of Pennsylvania
School of Medicine
Researchers Used Multiphoton Microscopy to Measure
Protein Translation
Scientists
at the University of Pennsylvania School of Medicine
have discovered a pattern to protein manufacture in
the hippocampus, the part of the brain devoted to making
memories.
Christy Job, PhD, a postdoctoral neurobiologist
with James H. Eberwine, PhD, Professor of Pharmacology
at Penn, measured a protein as it was being made in
structures of brain cells called dendrites. "The
patterns of electrical stimulation which make memories
are well-established, but how those memories are stored
is still unexplained," said Job. "We decided
to tackle this from a completely different angle by
looking at protein synthesis in dendrites."
Job and Eberwine grew particular cells from the hippocampus
called neurons that extend long structures (dendrites)
away from the main portion of the cell, known as the
cell body. Cell bodies store the genetic code (the DNA)
so a message, mRNA, which is made from the DNA, moves
from the cell body to dendrites.
Using a procedure known as multiphoton microscopy, Job
and Eberwine were able to measure translation of this
message into a protein that fluoresces. Multiphoton
microscopy enabled them to examine the pattern of fluorescence
across space and time.
"We thought that the rate of translation might
be different in dendrites, but not only was it exponentially
faster than translation in the cell body, it was also
faster at particular places in each dendrite,"
Eberwine said.
The research, which will be published in the journal
Proceedings of the National Academy of Science on October
23, could have important implications for other research
into how memories are stored in the brain. Neuronal
dendrites are known to pick up and convey information
in the form of electrical pulses, but they could also
store information by synthesizing proteins from mRNA
templates.
"This raises the possibility that there is a pattern
or code in the order of translation and mechanics of
the translational process that exists in these translation
sites at the dendritic level for the formation of memories,"
Eberwine said. "It could also be important for
illnesses involving memory loss or mental retardation,
such as Alzheimers and fragile X retardation."
The study was funded by the National Institutes of Health.
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Editor's note: Eberwine may be reached directly at:
215-898-0420.
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