| 1. |
- Björkblom, Benny, et al.
(författare)
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All JNKs Can Kill, but Nuclear Localization Is Critical for Neuronal Death
- 2008
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Ingår i: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 283:28, s. 19704-19713
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Tidskriftsartikel (refereegranskat)abstract
- JNKs are implicated in a range of brain pathologies and receive considerable attention as potential therapeutic targets. However, JNKs also regulate physiological and homeostatic processes. An attractive hypothesis from the drug development perspective is that distinct JNK isoforms mediate “physiological” and “pathological” responses. However, this lacks experimental evaluation. Here we investigate the isoforms, subcellular pools, and c-Jun/ATF2 targets of JNK in death of central nervous system neurons following withdrawal of trophic support. We use gene knockouts, gene silencing, subcellularly targeted dominant negative constructs, and pharmacological inhibitors. Combined small interfering RNA knockdown of all JNKs 1, 2, and 3, provides substantial neuroprotection. In contrast, knockdown or knock-out of individual JNKs or two JNKs together does not protect. This explains why the evidence for JNK in neuronal death has to date been largely pharmacological. Complete knockdown of c-Jun and ATF2 using small interfering RNA also fails to protect, casting doubt on c-Jun as a critical effector of JNK in neuronal death. Nonetheless, the death requires nuclear but not cytosolic JNK activity as nuclear dominant negative inhibitors of JNK protect, whereas cytosolic inhibitors only block physiological JNK function. Thus any one of the three JNKs is capable of mediating apoptosis and inhibition of nuclear JNK is protective.
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| 2. |
- Tararuk, Tatsiana, et al.
(författare)
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JNK1 phosphorylation of SCG10 determines microtubule dynamics and axodendritic length
- 2006
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Ingår i: Journal of Cell Biology. - : Rockefeller University Press. - 0021-9525 .- 1540-8140. ; 173:2, s. 265-277
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Tidskriftsartikel (refereegranskat)abstract
- c-Jun NH2-terminal kinases (JNKs) are essential during brain development, when they regulate morphogenic changes involving cell movement and migration. In the adult, JNK determines neuronal cytoarchitecture. To help uncover the molecular effectors for JNKs in these events, we affinity purified JNK-interacting proteins from brain. This revealed that the stathmin family microtubule-destabilizing proteins SCG10, SCLIP, RB3, and RB3′ interact tightly with JNK. Furthermore, SCG10 is also phosphorylated by JNK in vivo on sites that regulate its microtubule depolymerizing activity, serines 62 and 73. SCG10-S73 phosphorylation is significantly decreased in JNK1−/− cortex, indicating that JNK1 phosphorylates SCG10 in developing forebrain. JNK phosphorylation of SCG10 determines axodendritic length in cerebrocortical cultures, and JNK site–phosphorylated SCG10 colocalizes with active JNK in embryonic brain regions undergoing neurite elongation and migration. We demonstrate that inhibition of cytoplasmic JNK and expression of SCG10-62A/73A both inhibited fluorescent tubulin recovery after photobleaching. These data suggest that JNK1 is responsible for regulation of SCG10 depolymerizing activity and neurite elongation during brain development.
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| 3. |
- Waetzig, Vicki, et al.
(författare)
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Concurrent protective and destructive signaling of JNK2 in neuroblastoma cells
- 2009
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Ingår i: Cellular Signalling. - : Elsevier. - 0898-6568 .- 1873-3913. ; 21:6, s. 873-880
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Tidskriftsartikel (refereegranskat)abstract
- Investigation of the c-Jun N-terminal kinases (JNKs) has mainly focused on their response to stress and their pro-apoptotic effects. In this regard, JNKs are crucial mediators of chemotherapy-induced killing of tumor cells. Importantly, however, JNKs also have physiological functions in cancer involving cell cycle regulation or oncogenesis. Hypothetically, the composition of JNK signalosomes determines the signaling outcome which, in turn, implies a multitude of different, sometimes opposing and interfering functions. In the present study, the well-characterized human neuroblastoma cell line SH-SY5Y served as a model system to separate physiological and pro-apoptotic JNK actions in the response to the cytoskeleton-interfering substances colchicine, cytochalasin D and taxol. Basically, JNKs mediated both cell death and proliferation. Using the chemical JNK inhibitor SP600125 as well as compartment-specific JNK-inhibiting constructs and dominant-negative isoform mutants, we show that the nuclear subgroup of JNK2 is the dominant effector in colchicine- and taxol-induced apoptosis, while cell cycle promotion is mediated by both cytoplasmic and nuclear JNK2. In contrast, cytochalasin D-triggered apoptosis is independent of JNK signaling. Interestingly, the data of the present study demonstrate for the first time that both cell protective (cell cycle progression) and destructive mechanisms (apoptosis) are simultaneously controlled by a single JNK isoform in the same cell system even under the influence of one stimulus. This has implications for the therapeutic application of JNK inhibitors and cytoskeleton-interfering substances in oncologic disorders.
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