SIGNALING FOR CYTOKINE GENE EXPRESSION IN HUMAN PMN

Project: Research project

Description

In periodontal pockets, PMN form a protective barrier between pathogenic
microorganisms and the underlying connective tissue. Their function is
crucial for host protection from infection throughout the oral cavity and
for promotion of wound healing. Mediators found at oral inflammatory sites
induce expression of a limited number of cytokine genes in PMN that
regulate inflammation, immunity, and tissue repair. For example, TNF and
GM-CSF rapidly and transiently induce IL-1Beta expression in PMN. There is
a direct correlation between transcription and relative levels of
TNF-induced IL-1Beta mRNA and protein levels in PMN. In contrast, in
fibroblasts TNF induces IL-1Beta mRVA via message stabilization.
Expression of cytokines is initiated by inducing agents that are perceived
by cell surface receptors. Clearly, there are differences between PMN and
fibroblasts in how these signals are transduced to induce IL-1Beta
expression. Although little is known about signal transduction mechanisms
regulating gene expression in PMN, protein kinase C and Ca2+ appear to be
critical for TNF induction of IL-1Beta. The objective of these studies is
to determine how receptor binding of cytokines leads to induction of
IL-1Beta transcription in PMN. IL-1Beta is worthy of study because of its
key role in regulating bone resorption, collagen degradation, immune
responses, and recruitment of inflammatory cells in periodontal disease and
other oral inflammatory disorders. GM-CSF and TNF have been chosen as
inducing agents because they are important in the regulation of
inflammation, PMN gene expression, and have been recently used in clinical
trials to modulate inflammation and immunity. Hypothesis: In PMN, the
induction of IL-1Beta transcription by TNF is primarily regulated by Ca2+
and protein kinase C, while GM-CSF induces IL-1Beta transcription via
tyrosine protein kinases and protein kinase C. These signaling pathways
play key roles in modulating inflammation by controlling transcription of
cytokine genes. This regulates the specificity, magnitude, and kindeics of
the response. Specific aim I: Determine the early events in signaling for
IL-1Beta expression by TNF and GM-CSF in human PMN by using agonists and
antagonists of signaling pathways to inhibit mRNA expression and
transcription. Specific aim II: Confirm the activation of PC and Tyrosine
protein kinase by TNF and GM-CSF and delineate the activation of downstream
signal transducers (e.g., ras-related proteins, Raf, and MAP kinase).
Specific aim III. Characterize TNF- and GM-CSF-induced IL-1Beta
transcription factors. Variation in the pattern of cytokine gene
expression in response to the same inducing agent provides the basis for a
tissue specific response. It also provides a potential target for
specifically modulating the response. Understanding the pathways that lead
to gene expression in specific cell types, like PMN, will be critical in
determining which agents may be effective and what their effects will be in
the host.
StatusFinished
Effective start/end date9/1/938/31/99

Funding

  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health

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Granulocyte-Macrophage Colony-Stimulating Factor
Cytokines
Gene Expression
Protein Kinase C
Inflammation
Immunity
raf Kinases
Periodontal Pocket
ras Proteins
Messenger RNA
Cytokine Receptors
Cell Surface Receptors
Periodontal Diseases
Protein-Tyrosine Kinases
Bone Resorption
Transducers
Connective Tissue
Wound Healing
Genes
Mouth

ASJC

  • Medicine(all)
  • Dentistry(all)