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Energy adaptive response during parthanatos is enhanced by PD98059 and involves mitochondrial function but not autophagy induction
No full textParthanatos is a programmed necrotic demise characteristic of ATP (adenosine triphosphate) consumption due to NAD(+) (nicotinamide adenine dinucleotide) depletion by poly(ADP-ribose) polymerase 1 (PARP1)-dependent poly(ADP-ribosyl)ation on target proteins. However, how the bioenergetics is adaptively regulated during parthanatos, especially under the condition of macroautophagy deficiency, remains poorly characterized. Here, we demonstrated that the parthanatic inducer N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) triggered ATP depletion followed by recovery in mouse embryonic fibroblasts (MEFs). Notably, Atg5(-/-) MEFs showed great susceptibility to MNNG with disabled ATP-producing capacity. Moreover, the differential energy-adaptive responses in wild-type (WT) and Atg5(-/-) MEFs were unequivocally worsened by inhibition of AMP-activated protein kinase (AMPK), sirtuin 1 (SIRT1), and mitochondrial activity. Importantly, Atg5(-/-) MEFs disclosed diminished SIRT1 and mitochondrial activity essential to the energy restoration during parthanatos. Strikingly, however, parthanatos cannot be exasperated by bafilomycin A1 and MNNG neither provokes microtubule-associated protein 1A/1B-light chain 3 (LC3) lipidation and p62 elimination, suggesting that parthanatos does not induce autophagic flux. Intriguingly, we reported unexpectedly that PD98059, even at low concentration insufficient to inhibit MEK, can promote mitochondrial activity and facilitate energy-restoring process during parthanatos, without modulating DNA damage responses as evidenced by PARP1 activity, p53 expression, and gamma H2AX (H2A histone family, member X (H2AX), phosphorylated on Serine 139) induction. Therefore, we propose that Atg5 deficiency confers an infirmity to overcome the energy crisis during parthanatos and further underscore the deficits in mitochondrial quality control, but not incapability of autophagy induction, that explain the vulnerability in Atg5-deficient cells. Collectively, our results provide a comprehensive energy perspective for an improved treatment to alleviate parthanatos-related tissue necrosis and disease progression and also provide a future direction for drug development on the basis of PD98059 as an efficacious compound against parthanatos. (C) 2013 Elsevier B.V. All rights reserved
A polarized Ca2+, diacylglycerol and STIM1 signalling system regulates directed cell migration
No full textCa2+ signals control cell migration by regulating forward movement and cell adhesion. However, it is not well understood how Ca2+-regulatory proteins and second messengers are spatially organized in migrating cells. Here we show that receptor tyrosine kinase and phospholipase C signalling are restricted to the front of migrating endothelial leader cells, triggering local Ca2+ pulses, local depletion of Ca2+ in the endoplasmic reticulum and local activation of STIM1, supporting pulsatile front retraction and adhesion. At the same time, the mediator of store-operated Ca2+ influx, STIM1, is transported by microtubule plus ends to the front. Furthermore, higher Ca2+ pump rates in the front relative to the back of the plasma membrane enable effective local Ca2+ signalling by locally decreasing basal Ca2+ Finally, polarized phospholipase C signalling generates a diacylglycerol gradient towards the front that promotes persistent forward migration. Thus, cells employ an integrated Ca2+ control system with polarized Ca2+ signalling proteins and second messengers to synergistically promote directed cell migration
Ca2+ Signaling in Cytoskeletal Reorganization, Cell Migration, and Cancer Metastasis
No full textProper control of Ca2+ signaling is mandatory for effective cell migration, which is critical for embryonic development, wound healing, and cancer metastasis. However, how Ca2+ coordinates structural components and signaling molecules for proper cell motility had remained elusive. With the advance of fluorescent live-cell Ca2+ imaging in recent years, we gradually understand how Ca2+ is regulated spatially and temporally in migrating cells, driving polarization, protrusion, retraction, and adhesion at the right place and right time. Here we give an overview about how cells create local Ca2+ pulses near the leading edge, maintain cytosolic Ca2+ gradient from back to front, and restore Ca2+ depletion for persistent cell motility. Differential roles of Ca2+ in regulating various effectors and the interaction of roles of Ca2+ signaling with other pathways during migration are also discussed. Such information might suggest a new direction to control cancer metastasis by manipulating Ca2+ and its associating signaling molecules in a judicious manner
Pyrrolidinyl caffeamide against ischemia/reperfusion injury in cardiomyocytes through AMPK/AKT pathways
No full textBackground: Coronary heart disease is a leading cause of death in the world and therapy to reduce injury is still needed. The uncoupling of glycolysis and glucose oxidation induces lactate accumulation during myocardial ischemia/reperfusion (I/R) injury. Cell death occurs and finally leads to myocardial infarction. Caffeic acid, one of the major phenolic constituents in nature, acts as an antioxidant. Pyrrolidinyl caffeamide (PLCA), a new derivative of caffeic acid, was synthesized by our team. We aimed to investigate the effect of PLCA on hypoxia/reoxygenation (H/R) in neonatal rat ventricular myocytes (NRVM) and on myocardial I/R in rats.
Results: Cardiomyocytes were isolated and subjected to 6 h hypoxia followed by 18 h reperfusion. PLCA (0.1 to 3 mu M) and metformin (30 mu M) were added before hypoxia was initiated. PLCA at 1 mu M and metformin at 30 mu M exerted similar effects on the improvement of cell viability and the alleviation of cell apoptosis in NRVM after H/R. PLCA promoted p-AMPK, p-AKT, and GLUT4 upregulation to induce a cardioprotective effect in both cell and animal model. The accumulation of cardiac lactate was attenuated by PLCA during myocardial I/R, and infarct size was smaller in rats treated with PLCA (1 mg/kg) than in those treated with caffeic acid (1 mg/kg).
Conclusions: AMPK and AKT are synergistically activated by PLCA, which lead facilities glucose utilization, thereby attenuating lactate accumulation and cell death. The cardioprotective dose of PLCA was lower than those of metformin and caffeic acid. We provide a new insight into this potential drug for the treatment of myocardial I/R injury
Novel Pyrazole Derivatives Effectively Inhibit Osteoclastogenesis, a Potential Target for Treating Osteoporosis
No full textAs human beings live longer, age-related diseases such as osteoporosis will become more prevalent. Intolerant side effects and poor responses to current treatments are observed. Therefore, novel effective therapeutic agents are greatly needed. Here, pyrazole derivatives were designed and synthesized, and their osteoclastogenesis inhibitory effects both in vitro and in vivo were evaluated. The most promising compound 13 with a 2-(dimethylamino)ethyl group inhibited markedly in vitro osteoclastogenesis as well as the bone resorption activity of osteoclasts. Compound 13 affected osteoclast's early proliferation and differentiation more than later fusion and maturation stages. In ovariectomized (OVX) mice, compound 13 can inhibit the loss of trabecular bone volume, trabecular bone number, and trabecular thickness. Moreover, compound 13 can antagonize OVX-induced reduction of serum bone resorption marker and then compensatory increase of the bone formation marker. To sum up, compound 13 has high potential to be developed into a novel therapeutic agent for treating osteoporosis in the future
Interleukin 6 confers poor prognosis of hepatocellular carcinoma through cancer stemness properties
No full textThe disintegrin, trimucrin, suppresses LPS-induced activation of phagocytes primarily through blockade of NF-kappa B and MAPK activation
No full textIn addition to antiplatelet activity, disintegrin, a small-mass RGD-containing polypeptide, has been shown to exert anti-inflammatory effects but the mechanism involved remains unclear. In this study, we report that trimucrin, a disintegrin from the venom of Trimeresurus mucrosquamatus, inhibits lipopolysaccharide (LPS)-induced stimulation of THP-1 and RAW 264.7 cells. We also investigate the underlying mechanism. Trimucrin decreased the release of proinflammatory cytokines including tumor necrosis factor alpha (TNF alpha), interleukin-6 (IL-6), nitric oxide, and reactive oxygen species (ROS), and inhibited the adhesion and migration of LPS-activated phagocytes. Trimucrin significantly blocked the expression of nuclear factor kappaB (NF-kappa B)-related downstream inducible enzymes such as inducible nitric oxide synthase (iNOS) and COX-2. In addition, its anti-inflammatory effect was associated with the decreased mitogen-activated protein kinase (MAPK) phosphorylation. Furthermore, trimucrin concentration dependently inhibited LPS-induced phosphorylation of focal adhesion kinase (FAK), PI3K, and Akt. Trimucrin also reversed the DNA-binding activity of NF-kappa B by suppressing the LPS-induced nuclear translocation of p65 and the cytosolic I kappa B release. Flow cytometric analyses showed that trimucrin bound to cells in a concentration-dependent manner. The anti-alpha V beta 3 mAb also specifically decreased the binding of fluorescein isothiocyanate (FITC)-conjugated trimucrin. Binding assays demonstrated that integrin alpha V beta 3 was the binding site for trimucrin on THP-1 and RAW 264.7 cells. In conclusion, we showed that trimucrin decreases the inflammatory reaction through the attenuation of iNOS expression and nitric oxide (NO) production by blocking MAP kinase and the NF-kappa B activation in LPS-stimulated THP-1 and RAW 264.7 cells
The synergic effect of vincristine and vorinostat in leukemia in vitro and in vivo
No full textBackground: Combination therapy is a key strategy for minimizing drug resistance, a common problem in cancer therapy. The microtubule-depolymerizing agent vincristine is widely used in the treatment of acute leukemia. In order to decrease toxicity and chemoresistance of vincristine, this study will investigate the effects of combination vincristine and vorinostat (suberoylanilide hydroxamic acid (SAHA)), a pan-histone deacetylase inhibitor, on human acute T cell lymphoblastic leukemia cells.
Methods: Cell viability experiments were determined by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, and cell cycle distributions as well as mitochondria membrane potential were analyzed by flow cytometry. In vitro tubulin polymerization assay was used to test tubulin assembly, and immunofluorescence analysis was performed to detect microtubule distribution and morphology. In vivo effect of the combination was evaluated by a MOLT-4 xenograft model. Statistical analysis was assessed by Bonferroni's t test.
Results: Cell viability showed that the combination of vincristine and SAHA exhibited greater cytotoxicity with an IC50 value of 0.88 nM, compared to each drug alone, 3.3 and 840 nM. This combination synergically induced G(2)/M arrest, followed by an increase in cell number at the sub-G(1) phase and caspase activation. Moreover, the results of vincristine combined with an HDAC6 inhibitor (tubastatin A), which acetylated alpha-tubulin, were consistent with the effects of vincristine/SAHA co-treatment, thus suggesting that SAHA may alter microtubule dynamics through HDAC6 inhibition.
Conclusion: These findings indicate that the combination of vincristine and SAHA on T cell leukemic cells resulted in a change in microtubule dynamics contributing to M phase arrest followed by induction of the apoptotic pathway. These data suggest that the combination effect of vincristine/SAHA could have an important preclinical basis for future clinical trial testing