Nature:
The enzyme
protein
kinase M-ζ (PKM-ζ) was believed to be key to
long-term memory after a series of studies showed that blocking
the enzyme in the brains of mice caused them to forget old
memories. Now, two independent studies have shown that the
connection between PKM-ζ and memory may not be as
significant as previously believed. A group led by Richard
Huganir of Johns Hopkins University in Baltimore, Maryland, and
another led by Robert Messing from the University of
California, San Francisco, independently created mice strains
in which PKM-ζ was not produced. Both groups found that
the mice showed no signs of memory impairment, either in the
forming of memories or in recalling them. Todd Sacktor of SUNY
Downstate Medical Center in New York City, who originally
discovered the apparent connection between PKM-ζ and
long-term memory, believes that related proteins may have
served the same function as PKM-ζ in the altered mice.
However, Huganir's group, which also created mice whose
PKM-ζ production could be turned off in adulthood, found
that there was no loss of memory ability in these mice either.
Although PKM-ζ has not been completely ruled out as having
a role in memory development and retention, the new studies
have shown that the system is much more complicated than it
originally appeared.
