SIGNAL TRANSDUCTION MECHANISMS AND AMNION PGE2 SYNTHESIS

Project: Research project

Description

Synthesis and release of eicosanoids by amnion in response to a fetal or
maternal signal may be involved the onset of parturition in humans but
the intracellular signal transduction mechanisms that lead to eicosanoid
synthesis (the response) in amnion are ill-defined. Delineation of a
transduction mechanism requires identification of substrates that are
covalently modified, the specific modifications made and demonstration
of a cause and effect relationship. We have evidence that metabolism of
arachidonic acid switches from lipoxygenase to cyclo-oxygenase pathways
at parturition and that activation of protein kinase C (PKC) may be
involved in the transduction mechanism that stimulates PGE 2 synthesis
in amnion. PKC may phosphorylate key regulatory elements which either
control arachidonic acid mobilization or its subsequent metabolism to
eicosanoid. the elements involved in mobilization include phospholipase
enzyme activity and the phospholipase inhibitors, the lipcortins, which
have been shown to be activated or de-inhibited, respectively, by
phosphorylation. The elements involved in arachidonic acid metabolism,
about which nothing is known regarding their activity in response to
phosphorylation, include the PGH 2 synthase/PGE 2 isomerase and
lipoxygenase enzymes. We aim to: 1. Precisely identify the
lipoxygenase metabolites produced by amnion, examine if production
changes at parturition and if alterations in concentrations or activies
of lipoxygenase and PGH2 synthase/ PGE2 isomerase enzymes occur. 2.
Identify the phosphoproteins involved in the transduction mechanism,
specifically which isoform(s) of lipocortin and phospholipase are
present in amnion, their specific PKC phosphorylation sites and if
phosphorylation increases phospholipase activity and hence PG
production. Examine if phosphorylation of these isoforms occurs at
parturition and fits the criteria necessary to be part of a signal
transduction mechanism. 3. Establish the role of PKC in calcium
ionophore-stimulated amnion PGE2 synthesis and the identity of the
phosphoproteins that may be involved. 4. Determine whether putative
stimulants of amnion PGE2 synthesis e.g. EGF, TGFa, IL-1 and PAF act via
the PKC-mediated pathway outlined above. Once the transduction mechanism that controls arachidonic acid
metabolism is precisely defined then the real endogenous in vivo signal
that initiates it can be defined. The opportunities for prevention of
preterm labor at the biochemical level then become real.
StatusFinished
Effective start/end date9/1/895/31/94

Funding

  • National Institutes of Health
  • National Institutes of Health: $125,909.00
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health: $121,283.00

Fingerprint

Amnion
Dinoprostone
Signal Transduction
Protein Kinase C
Phospholipases
Prostaglandin H2
Lipoxygenase
Parturition
Prostaglandin-Endoperoxide Synthases
Prostaglandins E
Arachidonic Acid
Protein Isoforms
Phosphorylation
Annexins
Isomerases
Eicosanoids
Phosphoproteins
Enzymes
Interleukin-1
Epidermal Growth Factor

ASJC

  • Medicine(all)