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Programmed Cell Death 4 ( PDCD 4): A Novel Player in Ethanol‐Mediated Suppression of Protein Translation in Primary Cortical Neurons and Developing Cerebral Cortex
Author(s) -
Narasimhan Madhusudhanan,
Rathinam Marylatha,
Riar Amanjot,
Patel Dhyanesh,
Mummidi Srinivas,
Yang HsinShen,
Colburn Nancy H.,
Henderson George I.,
Mahimainathan Lenin
Publication year - 2013
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/j.1530-0277.2012.01850.x
Subject(s) - in vivo , ectopic expression , microbiology and biotechnology , protein biosynthesis , translation (biology) , apoptosis , chemistry , biology , biochemistry , messenger rna , gene
Background Prenatal exposure to ethanol ( E t OH ) elicits a range of neuro‐developmental abnormalities, microcephaly to behavioral deficits. Impaired protein synthesis has been connected to pathogenesis of E t OH ‐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 E t OH on programmed cell death protein 4 ( PDCD 4), a tumor and translation repressor. Methods Primary cortical neurons ( PCN s) were treated with 2.5 and 4 mg/ml E t OH for different time points (4 to 24 hours), and PDCD 4 expression was detected by Western blotting. Protein synthesis was determined using [ 35 S] methionine incorporation assay. Methyl cap pull‐down assay was performed to establish the effect of E t OH 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 E t OH (4 g/kg body wt, 25% v/v) was performed in S prague– D awley rats at 12‐hour intervals and analyzed for PDCD 4, eIF 4 A , and eIF 4 A –methyl cap association. Results E t OH increased PDCD 4 expression in a time‐ and dose‐dependent manner in PCN s, which inhibited the association of eIF 4 A with methyl cap. E t OH and ectopic PDCD 4 expression suppressed in vivo translation in PCN s and RNA i targeting of PDCD 4 blocked the inhibitory effect of E t OH on protein synthesis. In utero exposure of pregnant rats to E t OH resulted in a significant increase in PDCD 4 in fetal cerebral cortex along with the inhibition of methyl cap–associated eIF 4 A , compared with isocaloric controls. Increased PDCD 4 also occurred in pooled fractions of remaining brain regions. Conclusions Our data, for the first time, illustrate that PDCD 4 mediates inhibitory effects of E t OH on protein synthesis in PCN s and developing brain.