Differential effects of PDCD4 depletion on protein synthesis in myoblast and myotubes

BMC Cell Biology

Research Article

Dhanshri Kakade¹  Naomi Maeda¹  Nushaba Islam¹  Olasunkanmi A J Adegoke¹ 

[1] School of Kinesiology & Health Science and Muscle Health Research Centre, York University, 4700 Keele Street, M3J 1P3, Toronto, Ontario, Canada;

关键词: PDCD4;    mRNA translation;    S6K1;    Protein synthesis;    Skeletal muscle;   

DOI  :  10.1186/1471-2121-15-2

 received in 2013-11-01, accepted in 2014-01-04,  发布年份 2014

来源: Springer

【 摘 要 】

BackgroundReduced muscle mass is a hallmark of metabolic diseases like diabetes and cancer. The mammalian (mechanistic) target of rapamycin complex 1/S6 kinase 1 (mTORC1/S6K1) pathway is critical to the regulation of muscle protein synthesis and mass but its mechanism of action is not completely understood.ResultsUsing L6 myotubes, we characterized the regulation of programmed cell death 4 (PDCD4), a recently described substrate of S6K1. The abundance, but not Ser67 phosphorylation, of PDCD4 was sensitive to amino acid and serum deprivation: values in starved cells were 4.5X of control (P < 0.001). Refeeding had opposite effects. Growth factors, compared to amino acids, appeared more critical in regulating PDCD4 abundance. Furthermore, inhibition of mTORC1 or the proteasome prevented the refeeding-associated decrease in PDCD4 abundance. Amino acid and serum deprivation significantly increased PDCD4 binding to eIF4A (P < 0.05); this was reversed during refeeding. PDCD4 depletion by RNA interference had no significant effect on phenylalanine incorporation into myotube mixed proteins in control cells but further suppressed (30%) this measure in nutrient-deprived cells (P < 0.0005). This was not observed in myoblasts. In starved myotubes, PDCD4 depletion further reduced the association of eIF4G with eIF4E.ConclusionOur data suggest that in myotubes, PDCD4 abundance is sensitive to nutritional manipulation in an mTORC1 and proteasome depended manner. Furthermore, the role of PDCD4 in regulating protein synthesis appears dependent on the developmental state of the cell.

【 授权许可】

Unknown   
© Kakade et al.; licensee BioMed Central Ltd. 2014. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.