Translation initiation is known to be regulated by the binding of eukaryotic initiation factor 4E (eIF4E) by binding proteins (4EBPs), and there is evidence that amino acid deprivation and other cellular stresses upregulate 4EBP1 expression. To pursue the question of whether diets limited in an essential amino acid lead to induction of 4EBP1 expression in vivo, diets that varied in methionine and cystine content were fed to rats for 7 days, and 4EBP1 mRNA and protein levels and 4EBP1 phosphorylation state were determined. Total 4EBP1 mRNA and protein abundance increased in liver of rats with severely deficient intakes of sulfur amino acids (0.23% or 0.11% methionine without cystine) but not in animals with a less restricted intake of sulfur amino acids (0.11% methionine plus 0.35% cystine) but a similarly restricted intake of total diet (53 to 62% of control). The amount of 4EBP1 binding activity (α + β forms) was elevated in liver of rats fed sulfur amino acid-deficient diets, whereas the hyperphosphorylation of 4EBP1 was not affected by dietary treatment. Results suggest that changes in total 4EBP1 expression should be considered when examining mechanisms that attenuate protein synthesis during amino acid deficiency states. 1. Introduction Regulation of protein synthesis in eukaryotic cells occurs primarily at the initiation step of mRNA translation, during which ribosomal subunits are recruited to the mRNA through the action of eukaryotic initiation factors (eIFs). The regulation of mRNA translation initiation plays critical roles in the regulation of cell division, differentiation, growth, survival, and apoptosis, and dysregulation of translation initiation is associated with cancer, obesity, insulin resistance, and impaired responses to various stress situations [1–7]. The two best understood mechanisms for regulation of mRNA translation initiation are the regulation of formation of the ternary complex, which consists of the methionine-charged initiator tRNA, eIF2, and GTP, and the regulation of assembly of the eIF4F complex, which involves the association of the mRNA 5′ cap-binding protein eIF4E with eIF4G and eIF4A. Phosphorylation of the alpha subunit of eIF2 (eIF2α) blocks ternary complex formation, thereby blocking formation of the 43S preinitiation complex and suppressing global translation. Mammals have four eIF2α kinases that are activated by different types of cellular stress, including the unfolded protein response and amino acid deprivation, such that downstream effects of eIF2α phosphorylation are shared among different stress-response
References
[1]
O. Le Bacquer, E. Petroulakis, S. Paglialunga et al., “Elevated sensitivity to diet-induced obesity and insulin resistance in mice lacking 4E-BP1 and 4E-BP2,” Journal of Clinical Investigation, vol. 117, no. 2, pp. 387–396, 2007.
[2]
Y. Martineau, R. Azar, C. Bousquet, and S. Pyronnet S, “Anti-oncogenic potential of the eIF4E-binding proteins,” Oncogene, vol. 32, no. 6, pp. 671–677, 2012.
[3]
G. Armengol, F. Rojo, J. Castellví et al., “4E-binding protein 1: a key molecular “funnel factor” in human cancer with clinical implications,” Cancer Research, vol. 67, no. 16, pp. 7551–7555, 2007.
[4]
Nasr, F. Robert, J. A. Porco Jr., W. J. Muller, and J. Pelletier, “eIF4F suppression in breast cancer affects maintenance and progression,” Oncogene, vol. 32, no. 7, pp. 861–871, 2012.
[5]
Y. Shi, S. I. Taylor, S.-L. Tan, and N. Sonenberg, “When translation meets metabolism: multiple links to diabetes,” Endocrine Reviews, vol. 24, no. 1, pp. 91–101, 2003.
[6]
S. Yamaguchi, H. Ishihara, T. Yamada et al., “ATF4-mediated induction of 4E-BP1 contributes to pancreatic β cell survival under endoplasmic reticulum stress,” Cell Metabolism, vol. 7, no. 3, pp. 269–276, 2008.
[7]
B. M. Zid, A. N. Rogers, S. D. Katewa et al., “4E-BP extends lifespan upon dietary restriction by enhancing mitochondrial activity in Drosophila,” Cell, vol. 139, no. 1, pp. 149–160, 2009.
[8]
M. Holcik and N. Sonenberg, “Translational control in stress and apoptosis,” Nature Reviews Molecular Cell Biology, vol. 6, no. 4, pp. 318–327, 2005.
[9]
H. P. Harding, I. Novoa, Y. Zhang et al., “Regulated translation initiation controls stress-induced gene expression in mammalian cells,” Molecular Cell, vol. 6, no. 5, pp. 1099–1108, 2000.
[10]
J.-I. Lee, J. E. Dominy Jr., A. K. Sikalidis, L. L. Hirschberger, W. Wang, and M. H. Stipanuk, “HepG2/C3A cells respond to cysteine deprivation by induction of the amino acid deprivation/integrated stress response pathway,” Physiological Genomics, vol. 33, no. 2, pp. 218–229, 2008.
[11]
A. K. Sikalidis, J.-I. Lee, and M. H. Stipanuk, “Gene expression and integrated stress response in HepG2/C3A cells cultured in amino acid deficient medium,” Amino Acids, vol. 41, no. 1, pp. 159–171, 2011.
[12]
J. Shan, M.-C. Lopez, H. V. Baker, and M. S. Kilberg, “Expression profiling after activation of amino acid deprivation response in HepG2 human hepatoma cells,” Physiological Genomics, vol. 41, no. 3, pp. 315–327, 2010.
[13]
A.-C. Gingras, B. Raught, S. P. Gygi et al., “Hierarchical phosphorylation of the translation inhibitor 4E-BP1,” Genes and Development, vol. 15, no. 21, pp. 2852–2864, 2001.
[14]
C. C. Thoreen, L. Chantranupong, H. R. Keys, T. Wang, N. S. Gray, and D. M. Sabatini, “A unifying model for mTORC1-mediated regulation of mRNA translation,” Nature, vol. 485, no. 7396, pp. 109–113, 2012.
[15]
I. Mothe-Satney, D. Yang, P. Fadden, T. A. J. Haystead, and J. C. Lawrence Jr., “Multiple mechanisms control phosphorylation of PHAS-I in five (S/T)P sites that govern translational repression,” Molecular and Cellular Biology, vol. 20, no. 10, pp. 3558–3567, 2000.
[16]
X. Wang, A. Beugnet, M. Murakami, S. Yamanaka, and C. G. Proud, “Distinct signaling events downstream of mTOR cooperate to mediate the effects of amino acids and insulin on initiation factor 4E-binding proteins,” Molecular and Cellular Biology, vol. 25, no. 7, pp. 2558–2572, 2005.
[17]
K. Tsukiyama-Kohara, F. Poulin, M. Kohara et al., “Adipose tissue reduction in mice lacking the translational inhibitor 4E-BP1,” Nature Medicine, vol. 7, no. 10, pp. 1128–1132, 2001.
[18]
K. Tsukiyama-Kohara, S. M. Vidal, A.-C. Gingras et al., “Tissue distribution, genomic structure, and chromosome mapping of mouse and human eukaryotic initiation factor 4E-binding proteins 1 and 2,” Genomics, vol. 38, no. 3, pp. 353–363, 1996.
[19]
F. Poulin, A.-C. Gingras, H. Olsen, S. Chevalier, and N. Sonenberg, “4E-BP3, a new member of the eukaryotic initiation factor 4E-binding protein family,” Journal of Biological Chemistry, vol. 273, no. 22, pp. 14002–14007, 1998.
[20]
C. C. Chen, J. C. Lee, and M. C. Chang, “4E-BP3 regulates eIF4E-mediated nuclear mRNA export and interacts with replication protein A2,” FEBS Letters, vol. 586, no. 16, pp. 2260–2266, 2012.
[21]
R. Azar, A. Alard, C. Susini, C. Bousquet, and S. Pyronnet, “4E-BP1 is a target of Smad4 essential for TGFΒ-mediated inhibition of cell proliferation,” The EMBO Journal, vol. 28, no. 22, pp. 3514–3522, 2009.
[22]
B. S. Balakumaran, A. Porrello, D. S. Hsu et al., “MYC activity mitigates response to rapamycin in prostate cancer through eukaryotic initiation factor 4E-binding protein 1-mediated inhibition of autophagy,” Cancer Research, vol. 69, no. 19, pp. 7803–7810, 2009.
[23]
P. D. Lu, C. Jousse, S. J. Marciniak et al., “Cytoprotection by pre-emptive conditional phosphorylation of translation initiation factor 2,” The EMBO Journal, vol. 23, no. 1, pp. 169–179, 2004.
[24]
M. Rolli-Derkinderen, F. Machavoine, J. M. Baraban, A. Grolleau, L. Beretta, and M. Dy, “ERK and p38 inhibit the expression of 4E-BP1 repressor of translation through induction of Egr-1,” Journal of Biological Chemistry, vol. 278, no. 21, pp. 18859–18867, 2003.
[25]
R. Azar, S. Najib, H. Lahlou, C. Susini, and S. Pyronnet, “Phosphatidylinositol 3-kinase-dependent transcriptional silencing of the translational repressor 4E-BP1,” Cellular and Molecular Life Sciences, vol. 65, no. 19, pp. 3110–3117, 2008.
[26]
S. S. Palii, C. E. Kays, C. Deval, A. Bruhat, P. Fafournoux, and M. S. Kilberg, “Specificity of amino acid regulated gene expression: analysis of genes subjected to either complete or single amino acid deprivation,” Amino Acids, vol. 37, no. 1, pp. 79–88, 2009.
[27]
A. K. Sikalidis and M. H. Stipanuk, “Growing rats respond to a sulfur amino acid-deficient diet by phosphorylation of the α subunit of eukaryotic initiation factor 2 heterotrimeric complex and induction of adaptive components of the integrated stress response,” The Journal of Nutrition, vol. 140, no. 6, pp. 1080–1085, 2010.
[28]
M. S. Kilberg, J. Shan, and N. Su, “ATF4-dependent transcription mediates signaling of amino acid limitation,” Trends in Endocrinology and Metabolism, vol. 20, no. 9, pp. 436–443, 2009.
[29]
P. J. Bagley and M. H. Stipanuk, “Rats fed a low protein diet supplemented with sulfur amino acids have increased cysteine dioxygenase activity and increased taurine production in hepatocytes,” The Journal of Nutrition, vol. 125, no. 4, pp. 933–940, 1995.
[30]
Y. Hosokawa, S. Niizeki, H. Tojo, I. Sato, and K. Yamaguchi, “Hepatic cysteine dioxygenase activity and sulfur amino acid metabolism in rats: possible indicators in the evaluation of protein quality,” The Journal of Nutrition, vol. 118, no. 4, pp. 456–461, 1988.
[31]
M. K. Gaitonde Jr., “A spectrophotometric method for the direct determination of cysteine in the presence of other naturally occurring amino acids,” Biochemical Journal, vol. 104, no. 2, pp. 627–633, 1967.
[32]
J. E. Dominy Jr., J. Hwang, and M. H. Stipanuk, “Overexpression of cysteine dioxygenase reduces intracellular cysteine and glutathione pools in HepG2/C3A cells,” American Journal of Physiology. Endocrinology and Metabolism, vol. 293, no. 1, pp. E62–E69, 2007.
[33]
C. Cereser, J. Guichard, J. Drai et al., “Quantitation of reduced and total glutathione at the femtomole level by high-performance liquid chromatography with fluorescence detection: application to red blood cells and cultured fibroblasts,” Journal of Chromatography B, vol. 752, no. 1, pp. 123–132, 2001.
[34]
T. A. Gautsch, J. C. Anthony, S. R. Kimball, G. L. Paul, D. K. Layman, and L. S. Jefferson, “Availability of eIF4E regulates skeletal muscle protein synthesis during recovery from exercise,” American Journal of Physiology. Cell Physiology, vol. 274, no. 2, pp. C406–C414, 1998.
[35]
S. R. Kimball, R. L. Horetsky, and L. S. Jefferson, “Implication of eIF2B rather than eIF4E in the regulation of global protein synthesis by amino acids in L6 myoblasts,” Journal of Biological Chemistry, vol. 273, no. 47, pp. 30945–30953, 1998.
[36]
M. Balage, S. Sinaud, M. Prod'Homme et al., “Amino acids and insulin are both required to regulate assembly of the eIF4E·eIF4G complex in rat skeletal muscle,” American Journal of Physiology. Endocrinology and Metabolism, vol. 281, no. 3, pp. E565–E574, 2001.
[37]
J. Escobar, J. W. Frank, A. Suryawan, H. V. Nguyen, and T. A. Davis, “Amino acid availability and age affect the leucine stimulation of protein synthesis and eIF4F formation in muscle,” American Journal of Physiology. Endocrinology and Metabolism, vol. 293, no. 6, pp. E1615–E1621, 2007.
[38]
A. Suryawan, R. M. Torrazza, M. C. Gazzaneo et al., “Enteral leucine supplementation increases protein synthesis in skeletal and cardiac muscles and visceral tissues of neonatal pigs through mTORC1-dependent pathways,” Pediatric Research, vol. 71, no. 4, pp. 324–331, 2012.
[39]
T. Matsumura, Y. Morinaga, S. Fujitani, K. Takehana, S. Nishitani, and I. Sonaka, “Oral administration of branched-chain amino acids activates the mTOR signal in cirrhotic rat liver,” Hepatology Research, vol. 33, no. 1, pp. 27–32, 2005.
[40]
S. R. Kimball, R. A. Orellana, P. M. J. O'Connor et al., “Endotoxin induces differential regulation of mTOR-dependent signaling in skeletal muscle and liver of neonatal pigs,” American Journal of Physiology. Endocrinology and Metabolism, vol. 285, no. 3, pp. E637–E644, 2003.
[41]
I. Novoa, Y. Zhang, H. Zeng, R. Jungreis, H. P. Harding, and D. Ron, “Stress-induced gene expression requires programmed recovery from translational repression,” The EMBO Journal, vol. 22, no. 5, pp. 1180–1187, 2003.
[42]
H. Chen, Y.-X. Pan, E. E. Dudenhausen, and M. S. Kilberg, “Amino acid deprivation induces the transcription rate of the human asparagine synthetase gene through a timed program of expression and promoter binding of nutrient-responsive basic region/leucine zipper transcription factors as well as localized histone acetylation,” Journal of Biological Chemistry, vol. 279, no. 49, pp. 50829–50839, 2004.
[43]
Z. Mounir, J. L. Krishnamoorthy, S. Wang et al., “Akt determines cell fate through inhibition of the PERK-eIF2α phosphorylation pathway,” Science Signaling, vol. 4, no. 192, article ra62, 2011.
[44]
N. H. Kwon, T. Kang, J. Y. Lee et al., “Dual role of methionyl-tRNA synthetase in the regulation of translation and tumor suppressor activity of aminoacyl-tRNA synthetase-interacting multifunctional protein-3,” Proceedings of the National Academy of Sciences of the United States of America, vol. 108, no. 49, pp. 19635–19640, 2011.
[45]
J. R. Murguía and R. Serrano, “New functions of protein kinase Gcn2 in yeast and mammals,” IUBMB Life, vol. 64, no. 12, pp. 971–974, 2012.
[46]
V. Carraro, A.-C. Maurin, S. Lambert-Langlais et al., “Amino acid availability controls TRB3 transcription in liver through the GCN2/EIF2a/ATF4 pathway,” PLoS One, vol. 5, no. 12, Article ID e15716, 2010.
[47]
J. Shan, M.-C. Lopez, H. V. Baker, and M. S. Kilberg, “Expression profiling after activation of amino acid deprivation response in HepG2 human hepatoma cells,” Physiological Genomics, vol. 41, no. 3, pp. 315–327, 2010.
