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Effects of ORG 2766, a neurotrophic ACTH4-9 analogue, in neuroblastoma cells
R Murry1, J A McLane, G Gruener
1Graduate Neuroscience Program, Loyola University Stritch School of Medicine, Maywood, Illinois 60153.
Abstract:
Treatment of Neuro2a cells with drugs known to affect the integrity of microfilaments and microtubules, as well as with a calcium ionophore produced damage to the cellular membrane that was quantifiable by measuring the release of LDH into the culture medium. Concurrent exposure of the cells to ORG 2766 was found to modulate the release of LDH in a dose- and time-dependent fashion. ORG 2766 treatment was also able to reduce the basal release of LDH into the culture medium. [table: see text] The ORG 2766-induced reduction in LDH release was not due to down-regulation of protein synthesis. The peptide produced significant increases in protein synthesis relative to control conditions at concentrations of 10(-11) to 10(-6) M with 10(-8) M being an optimal dose. SDS-PAGE and 2-D PAGE analysis showed that de novo synthesis of most polypeptides was increased by about 40%. Additionally, a family of polypeptides tentatively identified as actins appear to undergo ORG 2766-dependent post translational charge modifications. These data are consistent with the hypothesis that regulation of transcription and/or translation are mechanisms important to the neurotrophic actions of ORG 2766.
Insights
The peptide ORG 2766 protects Neuro2a cells from membrane damage by modulating lactate dehydrogenase (LDH) release. It also enhances protein synthesis, suggesting transcriptional and translational regulation underlies its neurotrophic effects.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Cellular damage can be quantified by measuring lactate dehydrogenase (LDH) release.
- Microfilaments and microtubules are crucial for cellular integrity.
Purpose of the Study:
- To investigate the effects of ORG 2766 on Neuro2a cell membrane integrity.
- To explore the mechanisms underlying the neurotrophic actions of ORG 2766.
Main Methods:
- Neuro2a cells were treated with drugs affecting cytoskeleton and a calcium ionophore.
- LDH release was measured to quantify membrane damage.
- Protein synthesis was analyzed using SDS-PAGE and 2-D PAGE.
Main Results:
- ORG 2766 modulated LDH release in a dose- and time-dependent manner, reducing basal release.
- ORG 2766 increased protein synthesis, with optimal effects at 10(-8) M.
- Actin polypeptides showed ORG 2766-dependent post-translational modifications.
Conclusions:
- ORG 2766 exhibits neuroprotective effects by preserving cell membrane integrity.
- Regulation of transcription and/or translation are likely mechanisms for ORG 2766's neurotrophic activity.