CONTACT: JENNIFER CRONIN
2130 Medical Laboratories
Iowa City IA 52242
(319) 335-9917; fax (319) 335-8034
Release: Nov. 23, 1999
UI research helping answer questions about cystic fibrosis
IOWA CITY, Iowa -- Many times successfully attacking
a problem first requires that the attackers devise a battle plan. The individuals
must figure out how the other side operates and then how those operations
might be dismantled. That is exactly the approach a team of University of
Iowa Health Care researchers is taking with respect to bacteria that cause
chronic and serious lung infections in people with cystic fibrosis.
Results from the continuing UI efforts to understand
how the bacteria Pseudomonas aeruginosa (P. aeruginosa) lead to infection
are being published in the Nov. 23 issue of the Proceedings of the National
Academy of Sciences (PNAS).
"This is a logical extension of what has been going
on about how and why that infection is so persistent," said E. Peter Greenberg,
Ph.D., UI professor of microbiology and the study's lead investigator.
The PNAS article deals with quorum sensing -- a communication
device involving chemical signals that bacteria rely on to cause infection.
When a bacteria population reaches a certain density, quorum-sensing signals
tell the community of bacteria, known as a biofilm, to activate certain genes
that allow the bacteria to cause infection and disease.
The UI investigators wanted to identify the genes
expressed through the quorum-sensing process. Although there had been some
research into the area, the number and types of genes controlled by quorum
sensing had not been studied systemically. The UI team was able to look at
the entire gene make-up of P. aeruginosa thanks to the just-completed work
of University of Washington researchers, who have sequenced all of the bacteria's
Through their work, the UI investigators screened
most of P. aeruginosa's 7,000 genes. Of those, the researchers identified
39 genes strongly regulated by quorum sensing.
"The most important thing from this work is that it
begins to map out a network of what is regulated by quorum sensing that is
so important to infection," Greenberg said. "More and more evidence
is accumulating that suggests if we can block quorum sensing, we can incapacitate
Greenberg and his co-workers, graduate student Marvin
Whiteley and technician Kimberly Less, added that although this investigation
revealed some interesting features of gene expression by quorum sensing, it
clearly raises more questions than it answers.
Now that the UI investigators are beginning to understand
quorum sensing in P. aeruginosa at the gene level, it is feasible to address
these questions. The UI team is currently collaborating with researchers at
the University of Washington to study which genes play a role in causing infections
in animal models. In a separate, but related effort, Greenberg's lab is also
working with former UI post-doctoral fellow Matt Parsek, now at Northwestern
University, to ask which of the genes are required for biofilm maturation.
The research detailed in the PNAS article was supported
by grants from the National Science Foundation (NSF) and the National Institutes
of Health. Whiteley is supported by a NSF Research Training Grant.
University of Iowa Health Care describes the partnership
between the UI College of Medicine and the UI Hospitals and Clinics and the
patient care, medical education and research programs and services they provide.