Differential Activation of ERK and JNK Mitogen-Activated Protein Kinases by Raf-1 and MEKK
09 Dec 1994-Science (American Association for the Advancement of Science)-Vol. 266, Iss: 5191, pp 1719-1723
TL;DR: These results demonstrate the existence of two distinct Ras-dependent MAPK cascades--one initiated by Raf-1 leading to ERK activation, and the other initiated by MEKK leading to JNK activation.
Abstract: Growth factors activate mitogen-activated protein kinases (MAPKs), including extracellular signal-regulated kinases (ERKs) and Jun kinases (JNKs). Although the signaling cascade from growth factor receptors to ERKs is relatively well understood, the pathway leading to JNK activation is more obscure. Activation of JNK by epidermal growth factor (EGF) or nerve growth factor (NGF) was dependent on H-Ras activation, whereas JNK activation by tumor necrosis factor alpha (TNF-alpha) was Ras-independent. Ras activates two protein kinases, Raf-1 and MEK (MAPK, or ERK, kinase) kinase (MEKK). Raf-1 contributes directly to ERK activation but not to JNK activation, whereas MEKK participated in JNK activation but caused ERK activation only after overexpression. These results demonstrate the existence of two distinct Ras-dependent MAPK cascades--one initiated by Raf-1 leading to ERK activation, and the other initiated by MEKK leading to JNK activation.
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TL;DR: The effects of dominant-interfering or constitutively activated forms of various components of the JNK-p38 and ERK signaling pathways demonstrated that activation of JNK and p38 and concurrent inhibition of ERK are critical for induction of apoptosis in these cells.
Abstract: Apoptosis plays an important role during neuronal development, and defects in apoptosis may underlie various neurodegenerative disorders. To characterize molecular mechanisms that regulate neuronal apoptosis, the contributions to cell death of mitogen-activated protein (MAP) kinase family members, including ERK (extracellular signal-regulated kinase), JNK (c-JUN NH2-terminal protein kinase), and p38, were examined after withdrawal of nerve growth factor (NGF) from rat PC-12 pheochromocytoma cells. NGF withdrawal led to sustained activation of the JNK and p38 enzymes and inhibition of ERKs. The effects of dominant-interfering or constitutively activated forms of various components of the JNK-p38 and ERK signaling pathways demonstrated that activation of JNK and p38 and concurrent inhibition of ERK are critical for induction of apoptosis in these cells. Therefore, the dynamic balance between growth factor-activated ERK and stress-activated JNK-p38 pathways may be important in determining whether a cell survives or undergoes apoptosis.
5,398 citations
TL;DR: Recent studies have begun to shed light on the physiological functions of MAPK cascades in the control of gene expression, cell proliferation and programmed cell death.
Abstract: Mitogen-activated protein kinases (MAPKs) are important signal transducing enzymes, unique to eukaryotes, that are involved in many facets of cellular regulation. Initial research concentrated on defining the components and organization of MAPK signalling cascades, but recent studies have begun to shed light on the physiological functions of these cascades in the control of gene expression, cell proliferation and programmed cell death.
4,973 citations
Cites background from "Differential Activation of ERK and ..."
...and can provide a means for one MAPK cascade to activate other signalling pathway...
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TL;DR: Experiments with PC12 cells suggest that the duration of ERK activation is critical for cell signaling decisions, and the extracellular signal-regulated kinase (ERK-regulated) MAPK pathway may be sufficient for these cellular responses.
4,628 citations
Cites background from "Differential Activation of ERK and ..."
...It is now clear that Ras is required for the Raf/Mek/ERK pathway, for PI3-kinase activation (Rodriguez-Viciana et al., 1994), and for a MAPK pathway involving MEKK-1 and the Jun kinases (Lange- Carter and Johnson, 1994; Minden et al., 1994)....
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...It involves Ras, MEKK-1, a dual-specificity kinase (SEK1), and the MAPK Jun kinase (JNKs/SAPKs) (Hibi et al., 1993; Minden et al., 1994; Sanchez et al., 1994; Yan et al., 1994)....
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TL;DR: Nonenzymatic mechanisms that impact MAP kinase functions and findings from gene disruption studies are highlighted and particular emphasis is on ERK1/2.
Abstract: Mitogen-activated protein (MAP) kinases comprise a family of ubiquitous proline-directed, protein-serine/threonine kinases, which participate in signal transduction pathways that control intracellular events including acute responses to hormones and major developmental changes in organisms. MAP kinases lie in protein kinase cascades. This review discusses the regulation and functions of mammalian MAP kinases. Nonenzymatic mechanisms that impact MAP kinase functions and findings from gene disruption studies are highlighted. Particular emphasis is on ERK1/2.
4,040 citations
TL;DR: This review focuses on the biochemical components and regulation of mammalian stress-regulated mitogen-activated protein kinase (MAPK) pathways, and the nuclear factor-kappa B pathway, a second stress signaling paradigm.
Abstract: The molecular details of mammalian stress-activated signal transduction pathways have only begun to be dissected. This, despite the fact that the impact of these pathways on the pathology of chroni...
3,338 citations
References
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TL;DR: JNK1 is a component of a novel signal transduction pathway that is activated by oncoproteins and UV irradiation and its properties indicate that JNK1 activation may play an important role in tumor promotion.
3,232 citations
TL;DR: The kinase p54s are the principal c-Jun N-terminal kinases activated by cellular stress and tumour necrosis factor (TNF)-α, hence they are designated stress-activated protein kinases, or SAPKs.
Abstract: The mitogen-activated protein (MAP) kinases Erk-1 and Erk-2 are proline-directed kinases that are themselves activated through concomitant phosphorylation of tyrosine and threonine residues. The kinase p54 (M(r) 54,000), which was first isolated from cycloheximide-treated rats, is proline-directed like Erks-1/2, and requires both Tyr and Ser/Thr phosphorylation for activity. p54 is, however, distinct from Erks-1/2 in its substrate specificity, being unable to phosphorylate pp90rsk but more active in phosphorylating the c-Jun transactivation domain. Molecular cloning of p54 reveals a unique subfamily of extracellularly regulated kinases. Although they are 40-45% identical in sequence to Erks-1/2, unlike Erks-1/2 the p54s are only poorly activated in most cells by mitogens or phorbol esters. However, p54s are the principal c-Jun N-terminal kinases activated by cellular stress and tumour necrosis factor (TNF)-alpha, hence they are designated stress-activated protein kinases, or SAPKs. SAPKs are also activated by sphingomyelinase, which elicits a subset of cellular responses to TNF-alpha (ref. 9). SAPKs therefore define a new TNF-alpha and stress-activated signalling pathway, possibly initiated by sphingomyelin-based second messengers, which regulates the activity of c-Jun.
2,628 citations
TL;DR: This work has identified a serine/threonine kinase whose activity is stimulated by the same signals that stimulate the amino-terminal phosphorylation of c-Jun, and suggests a mechanism through which protein kinase cascades can specifically modulate the activity of distinct nuclear targets.
Abstract: The activity of c-Jun is regulated by phosphorylation. Various stimuli including transforming oncogenes and UV light, induce phosphorylation of serines 63 and 73 in the amino-terminal activation domain of c-Jun and thereby potentiate its trans-activation function. We identified a serine/threonine kinase whose activity is stimulated by the same signals that stimulate the amino-terminal phosphorylation of c-Jun. This novel c-Jun amino-terminal kinase (JNK), whose major form is 46 kD, binds to a specific region within the c-Jun trans-activation domain and phosphorylates serines 63 and 73. Phosphorylation results in dissociation of the c-Jun-JNK complex. Mutations that disrupt the kinase-binding site attenuate the response of c-Jun to Ha-Ras and UV. Therefore the binding of JNK to c-Jun is of regulatory importance and suggests a mechanism through which protein kinase cascades can specifically modulate the activity of distinct nuclear targets.
1,921 citations
TL;DR: Cl cloning and characterization of two ERK1-related kinases, ERK2 and ERK3, are described and evidence suggesting that there are additional ERK family members is provided, which may serve as intermediates that depend on tyrosine phosphorylation to activate serine/threonineosphorylation cascades.
1,853 citations
TL;DR: Evidence is presented that mitogen-activated protein-serine (MAP) kinases (pp54 and pp42/44) specifically phosphorylate these sites and that their phosphorylation positively regulates the transacting activity of c-jun.
Abstract: THE proto-oncogene c-jun is a component of the AP-1 transcription factor family involved in the mediation of nuclear events elicited by extracellular stimuli1–3. The c-jun protein is negatively regulated by phosphorylation of residues near the carboxy terminus which are dephosphorylated in response to phorbol esters4. Here we identify two serine residues in the amino terminal Al transactivation domain which are phosphorylated in response to a variety of mitogens, phorbol esters and activated ras (ref. 5). We present evidence that mitogen-activated protein-serine (MAP) kinases (pp54 and pp42/44) specifically phosphorylate these sites and that their phosphorylation positively regulates the transacting activity of c-jun. The MAP kinase enzymes pp54 and pp42/44 are regulated by tyrosine as well as serine/threonine phosphorylation6,7. MAP kinase activation of c-jun may underlie the common stimulation of this transcription factor by mitogens, growth factors and oncogenes.
1,444 citations