Inhibition of TNF-α-Induced Neutrophil Apoptosis by Crystals of Calcium Pyrophosphate Dihydrate Is Mediated by the Extracellular Signal-Regulated Kinase and Phosphatidylinositol 3-Kinase/Akt Pathways Up-Stream of Caspase 3

OBJECTIVE: Insulin has well-known activities in controlling energy metabolism, cellular proliferation and biosynthesis of functional molecules to maintain a biological homeostasis. Recently, several studies have suggested that insulin may protect cells from apoptosis in different cell lines; however, little is known about the nature of its anti-apoptotic activity. In many clinical disorders, including type 2 diabetes mellitus, oxidative stress and the production of reactive oxygen species (ROS) is increased. With these facts as a background, we examined here whether insulin protects HepG2 cells from apoptosis by decreasing oxidative stress and, if so, which signaling steps are involved in this process. METHODS: Intracellular DNA content, the degree of nuclear condensation or poly(ADP-ribose) polymerase hydrolysis was measured to verify the occurrence of apoptotic events. Caspase-3 activity and ROS accumulation within cells were also measured. Western blot analysis was performed to identify signaling molecules activated in response to insulin. RESULTS: Serum starvation resulted in a marked accumulation of ROS, activation of caspase-3, and subsequent apoptotic cell death which were, in turn, markedly blocked by the addition of insulin. The anti-apoptotic activity of insulin was sensitive to blockade of two different signaling steps, activations of phosphatidylinositol 3-kinase (PI3 kinase) and extracellular signal-regulated protein kinase (ERK). CONCLUSION: Insulin exerts an anti-apoptotic activity by suppressing the excessive accumulation of ROS within cells through signaling pathways including stimulation of PI3 kinase and ERK in HepG2 cells.

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Interferon α Induces Nucleus-independent Apoptosis by Activating Extracellular Signal-regulated Kinase 1/2 and c-Jun NH2-Terminal Kinase Downstream of Phosphatidylinositol 3-Kinase and Mammalian Target of Rapamycin

Molecular Biology of the Cell ◽

10.1091/mbc.e07-04-0358 ◽

2008 ◽

Vol 19 (1) ◽

pp. 41-50 ◽

Cited By ~ 33

Author(s):

Theocharis Panaretakis ◽

Linn Hjortsberg ◽

Katja Pokrovskaja Tamm ◽

Ann-Charlotte Björklund ◽

Bertrand Joseph ◽

...

Keyword(s):

Apoptotic Cell ◽

Mammalian Target Of Rapamycin ◽

Target Of Rapamycin ◽

Interferon Α ◽

Dependent Manner ◽

Phosphatidylinositol 3 Kinase ◽

Extracellular Signal Regulated Kinase ◽

Extracellular Signal ◽

Induced Apoptosis ◽

Phosphatidylinositol 3

Interferon (IFN)α induces apoptosis via Bak and Bax and the mitochondrial pathway. Here, we investigated the role of known IFNα-induced signaling cascades upstream of Bak activation. By pharmacological and genetic inhibition of the kinases protein kinase C (PKC)δ, extracellular signal-regulated kinase (ERK), and c-Jun NH2-terminal kinase (JNK) in U266-1984 and RHEK-1 cells, we could demonstrate that all three enzymes are critical for the apoptosis-associated mitochondrial events and apoptotic cell death induced by IFNα, at a step downstream of phosphatidylinositol 3-kinase (PI3K) and mammalian target of rapamycin (mTOR). Furthermore, the activation of JNK was found to occur in a PKCδ/ERK-dependent manner. Inhibition of these kinases did not affect the canonical IFNα-stimulated Janus tyrosine kinase-signal transducer and activator of transcription signaling or expression of IFN-responsive genes. Therefore, enucleated cells (cytoplasts) were examined for IFNα-induced apoptosis, to test directly whether this process depends on gene transcription. Cytoplasts were found to undergo apoptosis after IFNα treatment, as analyzed by several apoptosis markers by using flow cytometry, live cell imaging, and biochemical analysis of flow-sorted cytoplasts. Furthermore, inhibition of mTOR, ERK, and JNK blocked IFNα-induced apoptosis in cytoplasts. In conclusion, IFNα-induced apoptosis requires activation of ERK1/2, PKCδ, and JNK downstream of PI3K and mTOR, and it can occur in a nucleus-independent manner, thus demonstrating for the first time that IFNα induces apoptosis in the absence of de novo transcription.

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Insulin-Like Growth Factor 1 Inhibits Extracellular Signal-Regulated Kinase to Promote Neuronal Survival via the Phosphatidylinositol 3-Kinase/Protein Kinase A/c-Raf Pathway

Journal of Neuroscience ◽

10.1523/jneurosci.5060-04.2005 ◽

2005 ◽

Vol 25 (11) ◽

pp. 2838-2852 ◽

Cited By ~ 66

Author(s):

S. Subramaniam

Keyword(s):

Growth Factor ◽

Protein Kinase ◽

Protein Kinase A ◽

Neuronal Survival ◽

Insulin Like Growth Factor ◽

Phosphatidylinositol 3 Kinase ◽

Extracellular Signal Regulated Kinase ◽

Extracellular Signal ◽

Kinase A ◽

Phosphatidylinositol 3

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Molecular mechanisms of neutrophil apoptosis (review)

Nauchno-prakticheskii zhurnal «Patogenez» ◽

10.25557/2310-0435.2018.04.5-18 ◽

2018 ◽

pp. 5-18

Author(s):

И.А. Щепеткин ◽

О.П. Буданова ◽

И.Ю. Малышев ◽

Д.Н. Аточин

Keyword(s):

Protein Kinase ◽

P38 Mapk ◽

Mitogen Activated Protein Kinase ◽

Neutrophil Apoptosis ◽

Nuclear Factor ◽

Phosphatidylinositol 3 Kinase ◽

Extracellular Signal Regulated Kinase ◽

Extracellular Signal ◽

Mitogen Activated Protein ◽

Nuclear Factor Kb

В обзоре представлены современные данные о механизмах инициации, регуляции и выполнении процесса апоптоза нейтрофилов с участием «рецепторов смерти», митохондрий, белков семейства Bcl-2, PI3-K (phosphatidylinositol 3-kinase), протеинкиназных каскадов p38 MAPK (mitogen-activated protein kinase), ERK (extracellular signal regulated kinase) и JNK (c-Jun N-terminal kinase), протеинкиназ А, В и С, сAMP, белков теплового шока, NF-kB (nuclear factor-kB), кальпаинов, каспаз и их ингибиторов, активных форм кислорода и других факторов. Предложена гипотетическая модель вовлечения апоптотических процессов в регуляцию дифференцировки и реактивности нейтрофилов. This review presented recent data on initiation, regulation, and execution of neutrophil apoptosis with participation of «death receptors», mitochondria, Bcl-2 family proteins, PI3-K (phosphatidylinositol 3-kinase), p38 MAPK (mitogen-activated protein kinase), ERK (extracellular signal regulated kinase) and JNK (c-Jun N-terminal kinase) cascades, protein kinases A, B and C, сAMP, heat shock proteins, NF-kB (nuclear factor-kB), calpains, caspases and theirs inhibitors, reactive oxygen species, and other factors. A speculative model of the apoptotic processes involvement in the regulation of neutrophil differentiation and reactivity was proposed.

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