MECHANISMS OF PROTECTION BY GLYCINE AGAINST CELL DEATH

Project: Research project

Project Details

Description

We propose research to investigate the mechanisms of how glycine and
related amino acids prevent plasma membrane damage in energy compromised
cells. The effects of amino acids are not related to metabolism. Moreover,
they occur in spite of severe ATP depletion and break down of ion
homeostasis. Our preliminary studies show that the cellular defect in ATP
depleted cells that is specifically corrected by glycine is a unique
plasma membrane abnormality. Analysis of the dysfunction revealed that the
membrane behaves as if it is perforated by pores of molecular dimensions
with definable size exclusion limits, although it remains structurally
intact in other respects. This type of pathology is either suppressed or
aggravated by a number of other agents which have activities at inhibitory
glycine receptors in the central nervous system (CNS). The alkaloid
Strychnine and the anthelmintic Avermectin protect cells, and their
effects are additive to those of glycine. Other agents, (RU5135,
pitrazepin and thebaine) antagonize the protective effects of glycine in
a specific manner. The pharmacology of these effects suggests strongly
that the beneficial effects of glycine may be explained by its actions on
a target protein in the plasma membrane that is analogous to the CNS
glycine receptor chloride channel. According to the hypothesis, ATP
depletion leads to an unknown abnormality of the glycine receptor like
protein which is responsible for the porous membrane defect. Dose
responses to some of the pharmacological agents (Avermectin, RU5135,
pitrazepin) suggest high affinity interactions in the ATP depletion model
and point towards strategies that may be used to identify and isolate the
protein at which their effects are directed. Our objectives are threefold.
Firstly, we will characterize the glycine specific membrane defect by
functional as well as morphological techniques. Secondly, we will develop
methodology to obtain ultra pure preparations of plasma membranes.
Thirdly, we will use derivatives of Avermectin B1a to affinity label and
affinity purify plasma membrane proteins to which they may bind. We
believe that this approach will succeed in the identification and
purification of the putative target protein for glycine. The studies will
be done in a cultured kidney epithelial cell line, but will be generally
relevant to other cell types.
StatusFinished
Effective start/end date8/1/947/31/00

Funding

  • National Institutes of Health
  • National Institutes of Health: $177,435.00
  • National Institutes of Health
  • National Institutes of Health: $164,047.00
  • National Institutes of Health

ASJC

  • Medicine(all)

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