# STIMULATION OF NEUTROPHIL ARACHIDONATE METABOLISM

> **NIH NIH R01** · WAKE FOREST UNIVERSITY · 1993 · $159,587

## Abstract

Arachidonic acid (AA) is the precursor of an array of potent oxidation
products eicosanoids) whose role in inflammation and hypersensitivity is
widely recognized.  Cellular AA is bound in the 2-position of membrane
phospholipids and must be released before conversion to eicosanoids.  In
neutrophils (PMN), phospholipase A2 (PLA2) appears to be the major enzyme
responsible for the release of free AA, but the specific PLA2 isozyme
involved has not been established.  In human PMN approximately half the
phospholipids are ether-linked and these subclasses are highly enriched
in AA.  It has recently been demonstrated that the ethanolamine-
containing phosphoglycerides (PE) are a major source of AA in stimulated
PMN.  On the other hand, alkyl-2-AA-sn-glycero-3-phosphocholine (alkyl-2-
AA-GPC) serves as a source of both eicosanoids and platelet activating
factor (PAF), another powerful mediator of PMN function.  It has been
assumed that PLA2 acts directly on alkyl-2-AA-GPC to initiate this
conversion.  However, the PI's laboratory recently found evidence that
hydrolysis of AA from PE results in an accumulation of 1-0-alkenyl-2-
lyso-sn-glycero-3-phosphoethanolamine (alkenyl-2-lyso-GPE) which can
trigger transfer of AA from alkyl-2-AA-GPC to alkenyl-2-lyso-GPE via a
CoA-independent transacylase reaction, thus regenerating alkenyl-2-AA-GPE
and forming alkyl-2-lyso-GPC (1yso-PAF).  The studies outlined are
designed to assess the importance of this indirect route of AA release
and PAF synthesis relative to that catalyzed by the direct action of PLA2
on alkyl-2-AA-GPC.  The transacylase will be characterized both in
membrane preparations and as the purified enzyme, if attempts to isolate
the enzyme are successful.  The substrate specificity, kinetic parameters
and protein properties of the transacylase will be examined.  In the
postulated transacylase-dependent route of AA release and PAF synthesis,
the action of PLA2 on alkenyl-2-AA-GPE plays a central role in triggering
the pathway.  Studies will be carried out to examine the hydrolysis of
exogenous and membrane-bound alkenyl-AA-GPE by PLA2 in both isolated
subcellular fractions and in permeabilized cells.  These studies will
provide information on the nature of the PLA2 responsible for the release
of AA and synthesis of PAF and will elucidate the control mechanisms
responsible for activating the enzyme upon stimulation.  Preliminary
evidence suggests that the alkyl-2-AA-GPC and alkenyl-2-AA-GPE of the
specific granules may play an important role as a source of eicosanoids
and PAF in stimulated neutrophils.  The possible role of fusion of
specific granules and plasma membrane in mobilization of these lipids
will be examined.

## Key facts

- **NIH application ID:** 3127106
- **Project number:** 2R01AI017287-12
- **Recipient organization:** WAKE FOREST UNIVERSITY
- **SAM.gov UEI:** MBU6HCLNZ431
- **Principal Investigator:** ROBERT L WYKLE
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1993
- **Award amount:** $159,587
- **Award type:** 2
- **Project period:** 1981-09-30 → 1998-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3127106

## Citation

> US National Institutes of Health, RePORTER application 3127106, STIMULATION OF NEUTROPHIL ARACHIDONATE METABOLISM (2R01AI017287-12). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3127106. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*