Regulation of the 14-3-3-binding protein p39 by growth factors and nutrients in rat PC12 pheochromocytoma cells
Open Access
- 1 December 2002
- journal article
- Published by Portland Press Ltd. in Biochemical Journal
- Vol. 368 (2), 565-572
- https://doi.org/10.1042/bj20020838
Abstract
Unstimulated PC12 pheochromocytoma cells contain many proteins that bound to 14-3-3s in competition with a 14-3-3-binding peptide. Additional proteins, including one of 39kDa (p39), became capable of binding to 14-3-3s in phosphatidylinositol 3-kinase-dependent responses to epidermal growth factor or nerve growth factor in vivo. The growth factor regulation was unaffected by inhibitors of the mitogen- or stress-activated protein kinase pathways, or by glucose starvation, but was blocked by amino acid starvation and only partially blocked by rapamycin. p39 in extracts of unstimulated, nutrient-fed cells, but not nutrient-starved cells, was able to bind to 14-3-3s after phosphorylation by protein kinase B (PKB) in vitro. Nutrient starvation did not affect the growth factor-stimulated activation of PKB in vivo. Either cycloheximide (CHX) or the cysteine protease inhibitor, MG132, restored the responsiveness of p39 to growth factors in nutrient-starved cells. In contrast, MG132 could not replace amino acids in supporting the growth factor-stimulated phosphorylation of two downstream targets of mTOR (mammalian target of rapamycin), namely eukaryotic initiation factor 4E binding protein 1 (4E-BP1) and p70 S6 kinase. CHX permitted complete growth factor-stimulated phosphorylation of both 4E-BP1 and p70 S6 kinase in nutrient- starved cells; however, unlike p39, phosphorylation of these proteins was blocked by rapamycin. These findings implicate PKB (or an enzyme with similar specificity) in the growth factor-triggered phosphorylation of p39. In addition, amino acidstarvation induces a CHX- and MG132-sensitive pathway that targets p39 and appears to be distinct from the mechanism of regulation of 4E-BP1 and p70 S6 kinase.Keywords
This publication has 35 references indexed in Scilit:
- 14-3-3 proteins: regulation of subcellular localization by molecular interferenceCellular Signalling, 2000
- Peptide and Protein Library Screening Defines Optimal Substrate Motifs for AKT/PKBPublished by Elsevier BV ,2000
- Mammalian Target of Rapamycin-dependent Phosphorylation of PHAS-I in Four (S/T)P Sites Detected by Phospho-specific AntibodiesJournal of Biological Chemistry, 2000
- Regulatory 14-3-3 protein–protein interactions in plant cellsCurrent Opinion in Plant Biology, 2000
- PROTEIN AND AMINO ACID METABOLISM DURING AND AFTER EXERCISE AND THE EFFECTS OF NUTRITIONAnnual Review of Nutrition, 2000
- 14-3-3s regulate global cleavage of their diverse binding partners in sugar-starved Arabidopsis cellsThe EMBO Journal, 2000
- Glucose and amino acids modulate translation factor activation by growth factors in PC12 cellsBiochemical Journal, 2000
- Use of Kinase Inhibitors to Dissect Signaling PathwaysMethods in molecular biology (Clifton, N.J.), 1999
- Differences in fuel utilization between trout and human thrombocytes in physiological media.Journal of Comparative Physiology B, 1999
- Role and regulation of 90 kDa ribosomal S6 kinase (RSK) in signal transductionMolecular and Cellular Endocrinology, 1999