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1.
BMC Geriatr ; 23(1): 579, 2023 09 20.
Article in English | MEDLINE | ID: mdl-37730556

ABSTRACT

BACKGROUND: Participating in groups with diverse members is associated with improved health among older adults. The study examined the relationship between diversity of group members and needed support or long-term care. METHODS: We conducted a longitudinal study for the Japan Gerontological Evaluation Study with 61,281 participants aged ≥ 65 years who were surveyed in 2013 and followed-up for six years. We assessed three dimensions of the diversity of the participating members (sex, age, and region of residence). We then graded the diversity level into four categories: level 0 (not in any group), level 1 (in a group without diversity or in a group with diversity in one of the three factors), level 2 (in a group with diversity in two of the three factors), or level 3 (in a group with diversity across all factors). We adjusted for 12 covariates using Cox hazard survival analysis models with hazard ratios (HRs) and 95% confidence intervals (CIs) estimated for the association between group members' diversity levels and needed support or long-term care. The same study was conducted when stratified by employment status at baseline. RESULTS: Participants in social participation groups with more diverse group members had a lower incidence of needed support or long-term care as compared to their counterparts. Compared to those with no participation group, HR decreased by 14% to 24% with increasing levels of diversity. The HR for the level of care needed for participants in the social participation group with high residential diversity was 0.89 (95% CI: 0.84-0.94). For participants who were currently unemployed, HR reductions ranged from 16%-28% with increasing levels of diversity compared to the non-participating group. No association was found for employed participants. CONCLUSIONS: The reason the HRs of Japanese elderly people certified as needing support or care are lower when the diversity of participating groups is higher could be owing to the presence of a variety of people and the diversification of social networks, which facilitates the building of bridging social relational capital. Public health policies that encourage participation in diverse organizations will be important in the future.


Subject(s)
Geriatrics , Plastic Surgery Procedures , Aged , Humans , Longitudinal Studies , Japan/epidemiology , Long-Term Care
2.
J Org Chem ; 87(12): 8071-8083, 2022 06 17.
Article in English | MEDLINE | ID: mdl-35652135

ABSTRACT

A range of asymmetric photochemical transformations using visible light have recently become considerably attractive. Among the various approaches, chiral Lewis acid association to enones for [2 + 2] and ortho photocycloadditions and oxadi-π-methane rearrangements have shown to be very promising. Naturally, chiral Lewis acid coordination protects one of the prochiral faces of the C═C double bond, which enables an effective enantiodifferentiation in the following bond-forming process(es). Here, we studied regio- and enantiodifferentiating [2 + 2] photocycloaddition reactions of naphthoquinone derivatives mediated by chiral oxazaborolidines. A stereochemical control was quite challenging for the 2-ene-1,4-dione substrate, as a double coordination of Lewis acid essentially cancels out the face selectivity, and a mono-coordination to each carbonyl group leads to an opposite stereochemical outcome. Furthermore, a stepwise coordination in the ground state of Lewis acid in a 1:1 fashion was practically inaccessible. We found that the excited-state decomplexation is a key to accomplish high regio- and enantioselectivities in the photocycloaddition of an ene-dione.


Subject(s)
Lewis Acids , Naphthoquinones , Lewis Acids/chemistry , Light , Stereoisomerism
3.
Clin Exp Med ; 22(2): 221-228, 2022 May.
Article in English | MEDLINE | ID: mdl-34196881

ABSTRACT

Non-small cell lung cancer (NSCLC) is a highly aggressive cancer with one of the most prevalent malignant tumors. Metastasis in NSCLC is the major cause of treatment failure and cancer-related deaths. Yes-associated protein (YAP) is a transcriptional coactivator regulated by the evolutionarily conserved Hippo signaling pathway that regulates organ size, growth, and regeneration. YAP is highly expressed in several malignant tumor types. Furthermore, YAP promotes tumor initiation and/or progression in various types of cancer. However, it is unclear whether YAP contributes to the metastasis in NSCLC and serves as a useful therapeutic target. Here, we investigated whether levels of YAP correlate with metastatic phenotype in NSCLC cells and serve as a useful therapeutic target. We found that high levels of YAP associate with high cell migration, invasion, and metastasis in NSCLC cell lines. Furthermore, YAP siRNA decreased the migration and invasion in NSCLC cells. Additionally, verteporfin, an agent used for the treatment of symptomatic polypoidal choroidal vasculopathy, decreased the expression of YAP and inhibited migration, invasion, and metastasis in NSCLC cells. Thus, the study suggests that targeting YAP may present a new avenue to develop therapeutics against metastasis in NSCLC and that verteporfin has potential molecular therapeutic strategy for the treatment of metastatic NSCLC.


Subject(s)
Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , Carcinoma, Non-Small-Cell Lung/pathology , Cell Line, Tumor , Cell Proliferation , Gene Expression Regulation, Neoplastic , Humans , Lung Neoplasms/drug therapy , Lung Neoplasms/genetics , Lung Neoplasms/pathology , Signal Transduction , Verteporfin/pharmacology , Verteporfin/therapeutic use , YAP-Signaling Proteins
4.
J Am Chem Soc ; 136(39): 13534-7, 2014 Oct 01.
Article in English | MEDLINE | ID: mdl-25236858

ABSTRACT

Functional group tolerance is one of the important requirements for chemical reactions, especially for the synthesis of complex molecules. Herein, we report a mild, general, and functional group tolerant intramolecular hydroamination of unactivated olefins using a Co(salen) complex, an N-fluoropyridinium salt, and a disiloxane reagent. This method, which was carried out at room temperature (or 0 °C), afforded three-, five-, six-, and seven-membered ring nitrogen-containing heterocyclic compounds and was compatible with diverse functional groups.


Subject(s)
Alkenes/chemistry , Amines/chemical synthesis , Cobalt/chemistry , Heterocyclic Compounds/chemistry , Organometallic Compounds/chemistry , Amination , Amines/chemistry , Catalysis , Molecular Structure
5.
J Am Chem Soc ; 135(28): 10306-9, 2013 Jul 17.
Article in English | MEDLINE | ID: mdl-23819774

ABSTRACT

A unique Markovnikov hydroalkoxylation of unactivated olefins with a cobalt complex, silane, and N-fluoropyridinium salt is reported. Further optimization of reaction conditions yielded high functional group tolerance and versatility of alcoholic solvent employed, including methanol, i-propanol, and t-butanol. Use of trifluorotoluene as a solvent made the use of alcohol in stoichiometric amount possible. Mechanistic insight into this novel catalytic system is also discussed. Experimental results suggest that catalysis involves both carbon radical and carbocation intermediates.


Subject(s)
Alcohols/chemical synthesis , Alkenes/chemistry , Carbon/chemistry , Alcohols/chemistry , Catalysis , Cobalt/chemistry , Free Radicals/chemistry , Molecular Structure , Organometallic Compounds/chemistry , Pyridinium Compounds/chemistry , Silanes/chemistry
6.
J Cell Biochem ; 110(4): 1022-37, 2010 Jul 01.
Article in English | MEDLINE | ID: mdl-20564202

ABSTRACT

Stress-induced Sapk/Jnk signaling is involved in cell survival and apoptosis. Recent studies have increased our understanding of the physiological roles of Jnk signaling in embryonic development. However, still unclear is the precise function of Jnk signaling during gastrulation, a critical step in the establishment of the vertebrate body plan. Here we use morpholino-mediated knockdown of the zebrafish orthologs of the Jnk activators Mkk4 and Mkk7 to examine the effect of Jnk signaling abrogation on early vertebrate embryogenesis. Depletion of zebrafish Mkk4b led to abnormal convergent extension (CE) during gastrulation, whereas Mkk7 morphants exhibited defective somitogenesis. Surprisingly, Mkk4b morphants displayed marked upregulation of wnt11, which is the triggering ligand of CE and stimulates Jnk activation via the non-canonical Wnt pathway. Conversely, ectopic activation of Jnk signaling by overexpression of an active form of Mkk4b led to wnt11 downregulation. Mosaic lineage tracing studies revealed that Mkk4b-Jnk signaling suppressed wnt11 expression in a non-cell-autonomous manner. These findings provide the first evidence that wnt11 itself is a downstream target of the Jnk cascade in the non-canonical Wnt pathway. Our work demonstrates that Jnk activation is indispensable for multiple steps during vertebrate body plan formation. Furthermore, non-canonical Wnt signaling may coordinate vertebrate CE movements by triggering Jnk activation that represses the expression of the CE-triggering ligand wnt11.


Subject(s)
Gastrula , Gene Expression Regulation, Developmental , MAP Kinase Kinase 4/metabolism , Signal Transduction , Wnt Proteins/genetics , Zebrafish Proteins/genetics , Zebrafish/embryology , Animals , Base Sequence , Cloning, Molecular , DNA Primers , Reverse Transcriptase Polymerase Chain Reaction , Transcription, Genetic
7.
Stem Cells Dev ; 19(11): 1723-34, 2010 Nov.
Article in English | MEDLINE | ID: mdl-20412016

ABSTRACT

Many studies have shown that it is possible to use culture conditions to direct the differentiation of murine embryonic stem (ES) cells into a variety of cell types, including cardiomyocytes and neurons. However, the molecular mechanisms that control lineage commitment decisions by ES cells remain poorly understood. In this study, we investigated the role of the 3 major mitogen-activated protein kinases (MAPKs: extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38) in ES cell lineage commitment and showed that the p38 MAPK-specific inhibitor SB203580 blocks the spontaneous differentiation of ES cells into cardiomyocytes and instead induces the differentiation of these ES cells into neurons. Robust p38 MAPK activity between embryoid body culture days 3 and 4 is crucial for cardiomyogenesis of ES cells, and specific inhibition of p38 MAPK activity at this time results in ES cell differentiation into neurons rather than cardiomyocytes. At the molecular level, inhibition of p38 MAPK activity suppresses the expression of bmp-2 mRNA, whereas treatment of ES cells with bone morphogenetic protein 2 (BMP-2) inhibits the neurogenesis induced by SB203580. Further, luciferase reporter assays and chromatin immunoprecipitation experiments showed that BMP-2 expression in ES cells is regulated directly by the transcription factor myocyte enhancer factor 2C, a well-known substrate of p38 MAPK. Our findings reveal the molecular mechanism by which p38 MAPK activity in ES cells drives their commitment to differentiate preferentially into cardiomyocytes, and the conditions under which these same cells might develop into neurons.


Subject(s)
Bone Morphogenetic Protein 2/metabolism , Embryonic Stem Cells/physiology , Myocytes, Cardiac/physiology , Myogenic Regulatory Factors/metabolism , Neurons/physiology , p38 Mitogen-Activated Protein Kinases/metabolism , Animals , Bone Morphogenetic Protein 2/genetics , Cell Differentiation/physiology , Cell Lineage , Cells, Cultured , Embryonic Stem Cells/cytology , Enzyme Inhibitors/metabolism , Humans , Imidazoles/metabolism , MEF2 Transcription Factors , Mice , Myocytes, Cardiac/cytology , Myogenic Regulatory Factors/genetics , Neurons/cytology , Pyridines/metabolism , Transcription, Genetic , p38 Mitogen-Activated Protein Kinases/genetics
8.
Biol Pharm Bull ; 32(6): 999-1003, 2009 Jun.
Article in English | MEDLINE | ID: mdl-19483305

ABSTRACT

Pax6 genes are highly conserved and important for eye development. Vertebrates predominantly produce two alternatively spliced Pax6 isoforms, Pax6 and Pax6-5a. Pax6-5a differs from Pax6 by the presence of 14 additional amino acids encoded by exon 5a. These additional amino acids occur in the Pax6 paired domain and thus influence its DNA-binding properties. However, little is known about Pax6-5a's physiological functions. Here we establish murine embryonic stem (ES) cell lines in which expression of either the human Pax6 or Pax6-5a isoform is negatively controlled by tetracycline. We report that, in contrast to Pax6 expression, Pax6-5a expression strongly induces ES cells to differentiate into neurons. Moreover, using DNA microarray analysis, we have identified the transcription factor basic helix loop-helix domain containing, class b2 (bHLHb2) in Pax6-5a-expressing ES cells. Our Pax6 isoform-expressing ES cell lines may serve as useful models for identifying Pax6-regulated genes that are important for neurogenesis and/or eye development.


Subject(s)
Cell Differentiation/drug effects , Embryonic Stem Cells/cytology , Eye Proteins/physiology , Homeodomain Proteins/physiology , Neurons/cytology , Paired Box Transcription Factors/physiology , Repressor Proteins/physiology , Animals , Cell Line , Embryonic Stem Cells/drug effects , Embryonic Stem Cells/metabolism , Eye Proteins/biosynthesis , Homeodomain Proteins/biosynthesis , Humans , Immunoblotting , Immunoprecipitation , Mice , Microscopy, Confocal , Neurons/drug effects , Neurons/metabolism , Oligonucleotide Array Sequence Analysis , PAX6 Transcription Factor , Paired Box Transcription Factors/biosynthesis , Plasmids , Protein Isoforms/biosynthesis , Protein Isoforms/physiology , Repressor Proteins/biosynthesis , Reverse Transcriptase Polymerase Chain Reaction , Tetracycline
9.
J Biochem ; 145(3): 345-54, 2009 Mar.
Article in English | MEDLINE | ID: mdl-19106158

ABSTRACT

SP600125 is used as a specific inhibitor of c-Jun N-terminal kinase (JNK). We initially aimed to examine physiological roles of JNK in mast cells that play a central role in inflammatory and immediate allergic responses. We found that Fc receptor for IgE (FcepsilonRI)-induced degranulation (serotonin release) and cytokine gene expression [interleukin (IL)-6, tumour necrosis factor-alpha and IL-13] in bone marrow-derived mast cells, were almost completely inhibited by SP600125. However, the time course of FcepsilonRI-induced JNK activation did not correlate with that of serotonin release. Furthermore, FcepsilonRI-induced degranulation and cytokine gene expression were not impaired in a JNK activator, MKK7-deficient mast cells, in which JNK activation was lost. These results indicate that the inhibitory effects by SP600125 are not due to impaired JNK activation. Instead, we found that SP600125 markedly inhibited the FcepsilonRI-induced activation of phosphatidylinositol 3-kinase (PI3K) and Akt, the same as a PI3K inhibitor, wortmannin. Finally, we found that SP600125 specifically inhibits delta form of p110 catalytic subunit (p110delta) of PI3K. Thus, SP600125 exerts its influence on mast cell functions by inhibiting the kinase activity of PI3K, but not JNK.


Subject(s)
Anthracenes/pharmacology , Cell Degranulation/drug effects , Cytokines/genetics , Mast Cells/enzymology , Phosphoinositide-3 Kinase Inhibitors , Receptors, IgE/metabolism , Signal Transduction/drug effects , Animals , Bone Marrow Cells/cytology , Bone Marrow Cells/drug effects , Bone Marrow Cells/enzymology , Calcium Signaling/drug effects , Class I Phosphatidylinositol 3-Kinases , Cytokines/metabolism , Enzyme Activation/drug effects , Gene Expression Regulation/drug effects , Intracellular Signaling Peptides and Proteins/metabolism , Isoenzymes/metabolism , JNK Mitogen-Activated Protein Kinases/metabolism , MAP Kinase Kinase 7/deficiency , MAP Kinase Kinase 7/metabolism , Mast Cells/drug effects , Mast Cells/physiology , Mice , Protein-Tyrosine Kinases/metabolism , Receptors, Purinergic P1/metabolism , Syk Kinase , src-Family Kinases/metabolism
10.
Circ J ; 73(3): 575-9, 2009 Mar.
Article in English | MEDLINE | ID: mdl-19075525

ABSTRACT

We had the unique opportunity of following the electrocardiographic (ECG) course of a 13-year-old male with sinus dysfunction and atrial flutter who subsequently developed a Brugada-type ECG pattern associated with sick sinus syndrome at 25 years old. Family history showed that the patient's mother and maternal grandfather suddenly died while sleeping at night. When the patient was 13 years old, he lost consciousness after running a marathon. The patient was diagnosed with sinus dysfunction and atrial flutter, and he underwent pacemaker implantation at 15 years old. ECG examinations performed between 13 and 20 years old showed incomplete right bundle branch block and ST elevation with early depolarization. On ECG examinations performed when the patient was 21 years old and thereafter, the V(2) lead always showed a saddleback-type ST elevation. At 25 years old, the late potential was positive and the electrophysiological study induced ventricular fibrillation. A challenge test with pilsicainide showed remarkable ST elevation by the V(2) lead. The 24-h Holter ECG monitoring showed remarkable ST elevation after eating a snack and during night time when the patient was asleep. The patient was diagnosed with Brugada syndrome and an implantable cardioverter-defibrillator was implanted. Genetic analysis did not reveal mutation of the SCN5A gene.


Subject(s)
Brugada Syndrome/diagnosis , Electrocardiography, Ambulatory , Sick Sinus Syndrome/diagnosis , Adolescent , Adult , Age Factors , Brugada Syndrome/therapy , Defibrillators, Implantable , Humans , Male , Sick Sinus Syndrome/therapy , Sleep
11.
J Biol Chem ; 279(3): 1621-6, 2004 Jan 16.
Article in English | MEDLINE | ID: mdl-14585831

ABSTRACT

SAPK/JNK, which belongs to the family of mitogen-activated protein kinase (MAPK), is activated by many types of cellular stresses or extracellular signals and is involved in embryonic development, immune responses, and cell survival or apoptosis. However, the physiological roles of SAPK/JNK in the signaling of stress-induced apoptosis are still controversial. To evaluate the precise function, SAPK/JNK-inactivated mouse embryonic stem (ES) cells were generated by disrupting genes of the MAPK activators, SEK1 and MKK7. Although SAPK/JNK activation by various stresses was completely abolished in sek1(-/-) mkk7(-/-) ES cells, apoptotic responses including DNA fragmentation and caspase 3 activation still occurred normally, which displays a sharp contrast to apaf1(-/-) ES cells exhibiting profound defects in the mitochondria-dependent apoptosis. These normal apoptotic responses without SAPK/JNK activation were also observed in fibroblasts derived from sek1(-/-) mkk7(-/-) ES cells. Instead, interleukin-1 beta (IL-1 beta)-induced IL-6 gene expression was greatly suppressed in sek1(-/-) mkk7(-/-) fibroblasts. These results clearly show that SAPK/JNK activation is responsible for the inflammatory cytokine-induced gene expression but not essentially required for the mitochondria-dependent apoptosis at least in ES or fibroblast-like cells, which are prototypes of all cell lineages.


Subject(s)
Apoptosis , Mitochondria/physiology , Animals , Cells, Cultured , Embryo, Mammalian/cytology , Enzyme Activation , Hot Temperature , Interleukin-1/pharmacology , Interleukin-6/genetics , MAP Kinase Kinase 7 , Mice , Mitogen-Activated Protein Kinase Kinases/physiology , Mitogen-Activated Protein Kinases/physiology , Stem Cells/cytology , Stem Cells/enzymology , p38 Mitogen-Activated Protein Kinases
12.
J Biol Chem ; 278(19): 16595-601, 2003 May 09.
Article in English | MEDLINE | ID: mdl-12624093

ABSTRACT

Stress-activated protein kinase/c-Jun NH(2)-terminal kinase (SAPK/JNK), belonging to the mitogen-activated protein kinase family, plays an important role in stress signaling. SAPK/JNK activation requires the phosphorylation of both Thr and Tyr residues in its Thr-Pro-Tyr motif, and SEK1 and MKK7 have been identified as the dual specificity kinases. In this study, we generated mkk7(-/-) mouse embryonic stem (ES) cells in addition to sek1(-/-) cells and compared the two kinases in terms of the activation and phosphorylation of JNK. Although SAPK/JNK activation by various stress signals was markedly impaired in both sek1(-/-) and mkk7(-/-) ES cells, there were striking differences in the dual phosphorylation profile. The severe impairment observed in mkk7(-/-) cells was accompanied by a loss of the Thr phosphorylation of JNK without marked reduction in its Tyr-phosphorylated level. On the other hand, Thr phosphorylation of JNK in sek1(-/-) cells was also attenuated in addition to a decreased level of its Tyr phosphorylation. Analysis in human embryonic kidney 293T cells transfected with a kinase-dead SEK1 or a Thr-Pro-Phe mutant of JNK1 revealed that SEK1-induced Tyr phosphorylation of JNK1 was followed by additional Thr phosphorylation by MKK7. Furthermore, SEK1 but not MKK7 was capable of binding to JNK1 in 293T cells. These results indicate that the Tyr and Thr residues of SAPK/JNK are sequentially phosphorylated by SEK1 and MKK7, respectively, in the stress-stimulated ES cells.


Subject(s)
JNK Mitogen-Activated Protein Kinases , MAP Kinase Kinase 4 , Mitogen-Activated Protein Kinase Kinases/physiology , Stem Cells/physiology , Animals , Cells, Cultured , Enzyme Activation/genetics , Gene Expression Regulation, Developmental , MAP Kinase Kinase 7 , Mice , Mutation , Phosphorylation , Signal Transduction/genetics
13.
J Neurochem ; 83(1): 150-6, 2002 Oct.
Article in English | MEDLINE | ID: mdl-12358738

ABSTRACT

L-type calcium channel antagonists, nimodipine and nifedipine, were tested for effects on the survival of purified rat motoneurons in culture. They showed significant activity, with maximum survival at 30 microm after 3 days in culture as high as 75%, which was comparable to the maximum effect obtained with brain-derived neurotrophic factor, a potent neurotrophic factor for rat motoneurons. It was also found that depolarizing conditions with a high potassium concentration (30 mm) were toxic to motoneurons. This toxicity was blocked by co-treatment with nimodipine. These results implicate a pre-existing calcium burden through calcium channels in motoneurons; they may offer further insights into understanding the selective death of motoneurons and have therapeutic implications in amyotrophic lateral screlosis.


Subject(s)
Calcium Channel Blockers/pharmacology , Calcium/toxicity , Motor Neurons/drug effects , Nifedipine/pharmacology , Nimodipine/pharmacology , Animals , Brain-Derived Neurotrophic Factor/pharmacology , Calcium/metabolism , Calcium Channels, L-Type/drug effects , Calcium Channels, L-Type/metabolism , Cell Survival/drug effects , Cells, Cultured , Motor Neurons/cytology , Motor Neurons/metabolism , Neuroprotective Agents/pharmacology , Potassium/toxicity , Rats , Sodium Channel Blockers , Tetrodotoxin/pharmacology
14.
Dev Biol ; 250(2): 332-47, 2002 Oct 15.
Article in English | MEDLINE | ID: mdl-12376107

ABSTRACT

Mice lacking the stress-signaling kinase SEK1 die from embryonic day 10.5 (E10.5) to E12.5. Although a defect in liver formation is accompanied with the embryonic lethality of sek1(-/-) mice, the mechanism of the liver defect has remained unknown. In the present study, we first produced a monoclonal antibody specifically recognizing murine hepatoblasts for the analysis of liver development and further investigated genetic interaction ofsek1 with tumor necrosis factor-alpha receptor 1 gene (tnfr1) and protooncogene c-jun, which are also responsible for liver formation and cell apoptosis. The defective liver formation in sek1(-/-) embryos was not protected by additionaltnfr1 mutation, which rescues the embryonic lethality of mice lacking NF-kappaB signaling components. There was a progressive increase in the hepatoblast cell numbers of wild-type embryos from E10.5 to E12.5. Instead, impaired hepatoblast proliferation was observed in sek1(-/-) livers from E10.5, though fetal liver-specific gene expression was normal. The impaired phenotype in sek1(-/-) livers was more severe than in c-jun(-/-) embryos, and sek1(-/-) c-jun(-/-) embryos died more rapidly before E8.5. The hepatoblast proliferation required no hematopoiesis, since liver development was not impaired in AML1(-/-) mice that lack hematopoietic functions. Stimulation of stress-activated protein kinase/c-Jun N-terminal kinase by hepatocyte growth factor was attenuated in sek1(-/-) livers. Thus, SEK1 appears to play a crucial role in hepatoblast proliferation and survival in a manner apparently different from NF-kappaB or c-Jun.


Subject(s)
Liver/embryology , MAP Kinase Kinase 4 , Mitogen-Activated Protein Kinase Kinases/metabolism , Mitogen-Activated Protein Kinases/metabolism , NF-kappa B/metabolism , Animals , Antibodies, Monoclonal , Antigens, CD/genetics , Antigens, CD/metabolism , Apoptosis , Biomarkers , Cell Count , Cell Division , Enzyme Activation/drug effects , Female , Gene Expression , Hematopoiesis , Hepatocyte Growth Factor/pharmacology , JNK Mitogen-Activated Protein Kinases , Liver/cytology , Liver/metabolism , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Mitogen-Activated Protein Kinase Kinases/deficiency , Mitogen-Activated Protein Kinase Kinases/genetics , Mitogen-Activated Protein Kinases/deficiency , Mitogen-Activated Protein Kinases/genetics , Models, Biological , Pregnancy , Receptors, Tumor Necrosis Factor/deficiency , Receptors, Tumor Necrosis Factor/genetics , Receptors, Tumor Necrosis Factor/metabolism , Receptors, Tumor Necrosis Factor, Type I , Signal Transduction , Stem Cells/cytology , Stem Cells/metabolism
15.
J Biol Chem ; 277(1): 366-71, 2002 Jan 04.
Article in English | MEDLINE | ID: mdl-11694531

ABSTRACT

Ultraviolet (UV) irradiation stimulates stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), which is a member of the mitogen-activated protein kinase (MAPK) superfamily and implicated in stress-induced apoptosis. UV also induces the activation of another MAPK member, extracellular signal-regulated kinase (ERK), which is typically involved in a growth-signaling cascade. However, the UV-induced signaling pathway leading to ERK activation, together with the physiological role, has remained unknown. Here we examined the molecular mechanism and physiological function of UV-induced ERK activation in human epidermoid carcinoma A431 cells that retain a high number of epidermal growth factor (EGF) receptors. UV-induced ERK activation was accompanied with the Tyr phosphorylation of EGF receptors, and both responses were completely abolished in the presence of a selective EGF receptor inhibitor (AG1478) or the Src inhibitor PP2 and by the expression of a kinase-dead Src mutant. On the other hand, SAPK/JNK activation by UV was partially inhibited by these inhibitors. UV stimulated Src activity in a manner similar to the ERK activation, but the Src activation was insensitive to AG1478. UV-induced cell apoptosis measured by DNA fragmentation and caspase 3 activation was enhanced by AG1478 and an ERK kinase inhibitor (U0126) but inhibited by EGF receptor stimulation by the agonist. These results indicate that UV-induced ERK activation, which provides a survival signal against stress-induced apoptosis, is mediated through Src-dependent Tyr phosphorylation of EGF receptors.


Subject(s)
Apoptosis , ErbB Receptors/metabolism , Mitogen-Activated Protein Kinases/radiation effects , Ultraviolet Rays , src-Family Kinases/physiology , Animals , Cell Line , Enzyme Activation/radiation effects , Mice , Mitogen-Activated Protein Kinases/metabolism , Phosphorylation
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