Programmed Cell Death 4 (PDCD4): A Novel Player in Ethanol-Mediated Suppression of Protein Translation in Primary Cortical Neurons and Developing Cerebral Cortex
Article first published online: 3 JUL 2012
Copyright © 2012 by the Research Society on Alcoholism
Alcoholism: Clinical and Experimental Research
Volume 37, Issue 1, pages 96–109, January 2013
How to Cite
Narasimhan, M., Rathinam, M., Riar, A., Patel, D., Mummidi, S., Yang, H.-S., Colburn, N. H., Henderson, G. I. and Mahimainathan, L. (2013), Programmed Cell Death 4 (PDCD4): A Novel Player in Ethanol-Mediated Suppression of Protein Translation in Primary Cortical Neurons and Developing Cerebral Cortex. Alcoholism: Clinical and Experimental Research, 37: 96–109. doi: 10.1111/j.1530-0277.2012.01850.x
- Issue published online: 4 JAN 2013
- Article first published online: 3 JUL 2012
- Manuscript Accepted: 3 APR 2012
- Manuscript Received: 16 FEB 2012
- Biomedical Laboratory Research and Development Service of the Veterans Affairs Office of Research and Development. Grant Number: 1I01BX000975
- NIH. Grant Number: RO1AI043279
- Protein Synthesis;
- Primary Cortical Neurons;
- Cerebral Cortex
Prenatal exposure to ethanol (EtOH) elicits a range of neuro-developmental abnormalities, microcephaly to behavioral deficits. Impaired protein synthesis has been connected to pathogenesis of EtOH-induced brain damage and abnormal neuron development. However, mechanisms underlying these impairments of protein synthesis are not known. In this study, we illustrate the effects of EtOH on programmed cell death protein 4 (PDCD4), a tumor and translation repressor.
Primary cortical neurons (PCNs) were treated with 2.5 and 4 mg/ml EtOH for different time points (4 to 24 hours), and PDCD4 expression was detected by Western blotting. Protein synthesis was determined using [35S] methionine incorporation assay. Methyl cap pull-down assay was performed to establish the effect of EtOH on association of eukaryotic initiation factor 4A (eIF4A) with capped mRNA. Luciferase assay was performed to determine the in vivo translation. A 2-day acute 5-dose binge model with EtOH (4 g/kg body wt, 25% v/v) was performed in Sprague–Dawley rats at 12-hour intervals and analyzed for PDCD4, eIF4A, and eIF4A–methyl cap association.
EtOH increased PDCD4 expression in a time- and dose-dependent manner in PCNs, which inhibited the association of eIF4A with methyl cap. EtOH and ectopic PDCD4 expression suppressed in vivo translation in PCNs and RNAi targeting of PDCD4 blocked the inhibitory effect of EtOH on protein synthesis. In utero exposure of pregnant rats to EtOH resulted in a significant increase in PDCD4 in fetal cerebral cortex along with the inhibition of methyl cap–associated eIF4A, compared with isocaloric controls. Increased PDCD4 also occurred in pooled fractions of remaining brain regions.
Our data, for the first time, illustrate that PDCD4 mediates inhibitory effects of EtOH on protein synthesis in PCNs and developing brain.