Apopain/CPP32 cleaves proteins that are essential for cellular repair: a fundamental principle of apoptotic death

Caspase-mediated cleavage of a scaffold protein, MPRIP, yields a truncated form that is involved in repetitive bleb formation

Membrane blebbing is a hallmark of apoptotic cell death. However, the molecular mechanism that regulates this event has not been fully elucidated. To understand this underlying mechanism, we developed visualization systems suitable for spatiotemporal analysis. By monitoring the plasma membrane labeled with a fluorescent protein and reconstructing the image data as three-dimensional (3D) volumes based on the rendering technique, we observed that dying cells exhibit cycles of bleb formation at the same region of the cell surface. In addition, a Förster Resonance Energy Transfer (FRET)-based biosensor incorporating a regulatory myosin light chain (RMLC) displayed phosphorylation at the base of the retracting bleb, and dephosphorylation before re-expansion, implying the involvement of not only a kinase but also a phosphatase in the regulation of RMLC. To extend these observations, we focused on a scaffold protein, myosin phosphatase Rho interacting protein (MPRIP), which interacts with RhoA and myosin phosphatase targeting subunit 1 (MYPT1), involved in activation of Rho-associated coiled-coil kinase-I (ROCK-I) or protein phosphatase 1 (PP1), respectively. We found that MPRIP is cleaved both in dying cells and in an in vitro cleavage assay in a caspase-dependent manner. A cleaved C-terminal peptide fragment maintains the interaction with MYPT1. Cytological analysis showed that this fragment forms a complex with MYPT1 and myosin after translocating to the cytoplasm. These results suggest that this complex formation promotes the dephosphorylation of RMLC. Collectively, our study indicates that repetitive bleb formation, which is unique to apoptosis, is regulated by both phosphorylation and dephosphorylation of RMLC through MPRIP in a coordinated manner.

Alendronate sodium induces G1 phase arrest and apoptosis in human umbilical vein endothelial cells by inhibiting ROS-mediated ERK1/2 signaling

Bisphosphonates are potent bone resorption inhibitors, among which alendronate sodium (ALN) is commonly prescribed for most osteoporosis patients, but long-term application of ALN can cause bisphosphonate-related osteonecrosis of jaw (BRONJ), the pathogenesis of which remains unclear. Previous studies have suggested that bisphosphonates cause jaw ischemia by affecting the biological behavior of vascular endothelial cells, leading to BRONJ. However, the impacts of ALN on vascular endothelial cells and its mechanism remain unclear. The purpose of this work is to assess the influence of ALN on human umbilical vein endothelial cells (HUVECs) and clarify the molecular pathways involved. We found that high concentration of ALN induced G1 phase arrest in HUVECs, demonstrated by downregulation of Cyclin D1 and Cyclin D3. Moreover, high concentration of ALN treatment showed pro-apoptotic effect on HUVECs, demonstrated by increased levels of the cleaved caspase-3, the cleaved PARP and Bax, along with decreased levels of anti-apoptotic protein Bcl-2. Further experiments showed that ERK1/2 phosphorylation was decreased. Additionally, ALN provoked the build-up of reactive oxygen species (ROS) in HUVECs, leading to ERK1/2 pathway suppression. N-acetyl-L-cysteine (NAC), a ROS scavenger, efficiently promoted the ERK1/2 phosphorylation and mitigated the G1 phase arrest and apoptosis triggered by ALN in HUVECs. PD0325901, an inhibitor of ERK1/2 that diminishes the ERK1/2 phosphorylation enhanced the ALN-induced G1 phase arrest and apoptosis in HUVECs. These findings show that ALN induces G1 phase arrest and apoptosis through ROS-mediated ERK1/2 pathway inhibition in HUVECs, providing novel insights into the pathogenic process, prevention and treatment of BRONJ in individuals receiving extended use of ALN.

Quercetin and L-Arginine Ameliorated the Deleterious Effects of Copper Oxide Nanoparticles on the Liver of Mice Through Anti-inflammatory and Anti-apoptotic Pathways

The widespread use and applications of copper oxide nanoparticles (CuO NPs) in daily life make human exposure to these particles inevitable. This study was carried out to investigate the deteriorations in hepatic and serum biochemical parameters induced by CuO NPs in adult male mice and the potential ameliorative effect of L-arginine and quercetin, either alone or in combination. Seventy adult male mice were equally allocated into seven groups: untreated group, L-arginine, quercetin, CuO NPs, arginine + CuO NPs, quercetin + CuO NPs, and quercetin + arginine + CuO NPs. Treating mice with CuO NPs resulted in bioaccumulation of copper in the liver and consequent liver injury as typified by elevation of serum ALT activity, reduction in the synthetic ability of the liver indicated by a decrease in the hepatic arginase activity, and serum total protein content. This copper accumulation increased oxidative stress, lipid peroxidation, inflammation, and apoptosis as manifested by elevation in malondialdehyde, nitric oxide, tumor necrosis factor-α, the expression level of caspase-3 and bax quantified by qPCR, and the activity of caspase-3, in addition to the reduction of superoxide dismutase activity. It also resulted in severe DNA fragmentation as assessed by Comet assay and significant pathological changes in the liver architecture. The study proved the efficiency of quercetin and L-arginine in mitigating CuO NPs-induced sub-chronic liver toxicity due to their antioxidant, anti-inflammatory, and anti-apoptotic properties; ability to inhibit DNA damage; and the potential as good metal chelators. The results of histopathological analysis confirmed the biochemical and molecular studies.

Cytotoxic Activity of Herbal Medicines as Assessed in Vitro: A Review

Since time immemorial, human beings have sought natural medications for treatment of various diseases. Weighty evidence demonstrates the use of chemical methodologies for sensitive evaluation of cytotoxic potentials of herbal agents. However, due to the ubiquitous use of cytotoxicity methods, there is a need for providing updated guidance for the design and development of in vitro assessment. The aim of this review is to provide practical guidance on common cell-based assays for suitable assessment of cytotoxicity potential of herbal medicines and discussing their advantages and disadvantages Relevant articles in authentic databases, including PubMed, Web of Science, Science Direct, Scopus, Google Scholar and SID, from 1950 to 2022 were collected according to selection criteria of in vitro cytotoxicity assays and protocols. In addition, the link between cytotoxicity assay selection and different factors such as the drug solvent, concentration and exposure duration were discussed.

Sodium hydrosulfide and bone marrow derived mesenchymal stem cells combined therapy for bleomycin induced pulmonary fibrosis in rats: Implication of micro RNA-21 and Lnc GAS5

AIMS

Pulmonary fibrosis (PF) is considered as an end stage for many lung diseases. Mesenchymal stem cells (MSC) as regenerative therapy have become a remarkably valuable therapeutic strategy in different diseases. Hydrogen sulfide has been recently introduced into the medical field for its antifibrotic properties in addition to enhancement of MSC stemness and function. The aim of the present study was to investigate the ability of BM-MSC in combination with NaHS to attenuate Bleomycin induced pulmonary fibrosis was studied in rats. A special emphasis was given to miR-21 and GAS5 as important players in the development of PF.

MAIN METHODS

PF was induced in 32 Wistar male rats by single endotracheal injection of bleomycin, those were randomly divided into four groups (8 rats each): (untreated PF group) - (PF + MSC) treated group- (PF + NaHS treated group) - PF + combined (NAHS + MSC) treated group.

KEY FINDINGS

Induction of PF was associated with increased miR-21 and decreased lncRNA-GAS5 expression. Treatment with either NaHS or BM-MSC leads to an inhibitory effect on pulmonary fibrosis as evidenced by improvement of histopathological studies, pulmonary function tests, reduction of inflammatory and fibrotic markers like Hydroxyproline, TNF α, TGF-β and caspase -3 together with downregulation miR-21 and increase lncRNA-GAS5 expression.

SIGNIFICANCE

The current work revealed the inhibitory effect of combined NaHS and BM-MSC on pulmonary fibrosis with concomitant modulation of miR-21 and lncRNA-GAS5 expression.

Hybrid lipid core chitosan-TPGS shell nanocomposites as a promising integrated nanoplatform for enhanced oral delivery of sulpiride in depressive disorder therapy

Sulpiride (SUL), a benzamide derivative, acts as a multitarget drug with extensive biological properties. However, being a P-glycoprotein efflux substrate with a limited oral bioavailability imposes a challenge to its clinical efficacy. The current research explores the impact of tailored hybrid lipid-polysaccharide nanocomposites in augmenting the biological performance of SUL. Chitosan-graft-tocopherol polyethylene glycol 1000 succinate (TPGS) copolymers were synthesized and integrated as a polysaccharide shell into a SUL-loaded lipid nanocore. The optimized nanohybrids revealed a nanocore-shell structure with 110.1 nm particle size, 23.7 mV zeta potential, 85.42% encapsulation efficiency, a pH-dependent-release profile, and an acceptable mucoadhesive tendency. Employing TPGS into the chitosan backbone alleviated the cellular internalization of nanohybrids into the Caco-2 intestinal cells and hence increased the intestinal permeation and the oral bioavailability of SUL by 3.3, and 8.7-folds, respectively. Reserpine-induced depression rat model confirmed the superior antidepressant activity of nanohybrids, compared with free SUL and a marketed product. The nanohybrids exhibited 1.87- and 1.47-folds enhancement in both serotonin and dopamine levels, respectively. Additionally, nanohybrids were shown to attenuate brain oxidative stress state and SUL irritant effect on different body tissues. Overall, the newly tailored nanohybrids pave the way for an advance in the field of oral drug delivery.

Precisely Fabricated Sulpiride-Loaded Nanolipospheres with Ameliorated Oral Bioavailability and Antidepressant Activity

BACKGROUND

Sulpiride (SUL), is a selective antidopaminergic drug that had extensive biological activities. However, its sparingly aqueous solubility and limited gastrointestinal permeability lead to scanty oral bioavailability which hinders its clinical efficacy.

OBJECTIVE

SUL-loaded lipospheres (SUL-LPS) were designed to serve as an oral biocompatible nanovector for improving SUL permeability as well as conquering its low oral absorption and then in turn enhancing its antidepressant action.

METHODS

SUL-LPS were fabricated via two processing techniques namely, melt emulsification and solvent evaporation. The impact of different lipid cores, phospholipid shells together with various surfactant concentrations and types on the lipospheres properties were screened. Detailed physicochemical elucidations were performed followed by ex vivo permeation appraisal using the non-everted intestine model. The pharmacokinetic parameters of SUL-LPS, free SUL and marketed product were assessed following oral administration to healthy rats. Reserpine-induced depression rat model was used to assess the antidepressant action of SUL-LPS on which full behavioural and biochemical analysis was conducted. Safety attributes of nanoencapsulated SUL on the brain and other internal organs were evaluated.

RESULTS

The optimum LPS revealed an excellent nanosize with a narrow PdI, negative zeta potential and acceptable entrapment efficiency of 68.62 nm, 0.242, -30.4 mV and 84.12%, respectively. SUL-LPS showed a sustained release pattern and 2.1-fold enhancement in the intestinal permeation parameters with low mucin interaction. Oral pharmacokinetic appraisal exhibited that LPS provided 3.4-fold improvement in SUL oral bioavailability together with long-circulating properties, relative to the free drug. Pharmacodynamic study confirmed the superior antidepressant action of SUL-LPS as evident by 1.6 and 1.25-fold elevation in the serotonin and dopamine expressions, respectively. Meanwhile, nanotoxicological appraisal proved the biocompatibility of SUL-LPS upon repetitive oral administration.

CONCLUSION

Rationally designed lipospheres hold promising in vitro and in vivo characteristics for efficient delivery of SUL with high oral bioavailability, antidepressant activity together with a good safety profile.

Onion Extract Encapsulated on Nano Chitosan: a Promising Anticancer Agent

BACKGROUND

Onion (Allium cepa) is very rich in nutritional and pharmaceutical components, such as saponins, tannins, alkaloids, steroids, and phenols. Many recent researches approved its anticancer activity against various cancer cell lines. In this paper, we attempt to improve its anticancer activity with encapsulation on nano chitosan. On the best of our knowledge, this is considered the first study that tries to increase the anticancer activity of the onion extract on nano chitosan.

METHODS

An aqueous extract of the onion was prepared and the extract efficiency as anticancer agent was enhanced by encapsulating the extract on nano chitosan. The antioxidant capacity and the functional ingredients such as alkaloid, tannin, saponin, steroid, phenolic, and flavonoid in either the free or encapsulated one were estimated. Also, the anticancer activity of the two extracts was tested against different cell lines.

RESULTS

Encapsulation of the extract on chitosan nano particles decreased IC₅₀ in different cell lines and induced apoptosis through decreasing BCL-2 level and increasing caspase-3 and caspase-9 activity.

CONCLUSION

Onion extract encapsulated on nano chitosan can be used as protective agents from cancer, antitumor, or act synergistically with the cancer chemotherapy. This greatly participates in improving the use of natural products in cancer therapy instead of chemotherapy.

Low molecular weight silicones induce cell death in cultured cells

Women with silicone gel-filled breast implants are exposed to organosilicon compounds, in particular methylsiloxanes, as a result of ‘gel bleed’ and implant rupture. Although these silicones were originally considered to be inert, increasing evidence indicates that they can cause serious health problems. Here, we have analyzed the effects of microdroplets of the methylcyclosiloxanes, in particular D4, on the viability of cultured human cells. The exposure of Jurkat suspension and HeLa monolayer cells to D4 resulted in morphological changes of the cells. The analysis of molecular markers for apoptotic and necrotic processes not only demonstrated that caspases were activated and DNA was fragmented in Jurkat cells exposed to D4, but that also the permeability of the plasma membrane was altered. The induction of apoptotic pathways by D4 was substantiated by the inhibition of caspase activation in cells overexpressing Bcl-2. Cleavage of the caspase-3 substrate U1-70K appeared to be dependent on the D4 content and the efficiency of cleavage decreased with increasing size of the methylcyclosiloxanes (D4, D5 and D6). In addition to Jurkat cells, D4-induced U1-70K cleavage was also observed in HeLa cells, but not in HEp-2 cells. Taken together, these results indicate that D4 and, to a lesser extent, D5 can activate cell-death-related pathways in a cell type-specific fashion and suggest that this phenomenon may contribute to the development of Breast Implant Illness.

Hepatoprotective activity of depsidone enriched Cladonia rangiferina extract against alcohol-induced hepatotoxicity targeting cytochrome P450 2E1 induced oxidative damage

Alcoholic liver disease (ALD) is a broad-spectrum disorder, covering fatty liver, cirrhosis, alcoholic hepatitis and in extreme untreated condition hepatocellular carcinoma (HCC) may also develop. Cladonia rangiferina (CR) is a class of lichen having a broad spectrum of pharmacological activity. It is used like traditional natural sources in ancient times in India, China, Sri Lanka, etc. Folkloric record about CR has reported their use as an antimicrobial, antitumor, antioxidant, anti-inflammatory activities, etc. Hence, the present study was requested to ascertain the effect of the ethanolic extract of Cladonia rangiferina (CRE) on alcohol-induced hepatotoxicity. The animals were evaluated for the estimation of the liver in vivo biochemical antioxidant parameters. The liver tissues were further evaluated histopathologically and western blotting examination for localization of apoptotic gene expression that plays a pivotal role in hepatotoxicity. The results of this study reveal that CRE proves to be helpful in the treatment of alcohol-induced hepatotoxicity and oxidative stress. Results of different markers have shown that among all, CRE has demonstrated the best hepatoprotective activity. These observations say about the importance of the components of the extract. The ameliorative action of CRE in alcoholic liver damage may exist due to antioxidant, anti-inflammatory, and anti-apoptotic activities.

Liquid crystalline nanoreservoir releasing a highly skin-penetrating berberine oleate complex for psoriasis management

Aim: The current work highlighted preparation of highly penetrating liquid crystalline nanoparticulates (LCNPs) reservoir of a solubility modified berberine oleate (Brb-OL) complex for effective psoriasis management. Materials & methods: Brb-OL-loaded LCNPs (Brb-OL-LCNPs) were prepared using hydrotrope method. Results: The proposed Brb-OL-LCNPs showed a particle size of 137 ± 3.7 nm and negative ζ-potential (-38 ± -5.85 mV). Brb-OL-LCNPs showed a threefold increase in the drug accumulated within rat skin and around tenfold increase in the drug permeation compared with crude Brb. In vivo studies revealed that topical application of Brb-OL-LCNPs hydrogel significantly alleviated psoriasis symptoms and reduced the levels of psoriatic inflammatory cytokines. Conclusion: Formulating Brb-OL in the LCNPs controlled the release, retention and permeation of the drug across skin layers, which are of prime importance for psoriasis management.

Resveratrol mediated cancer cell apoptosis, and modulation of multidrug resistance proteins and metabolic enzymes

BACKGROUND

The degree of intracellular drug accumulation by specific membrane transporters, i.e., MDR1, BCRP, and MRP, and the degree of detoxification by intracellular metabolic enzymes, i.e., CYP3A4 and GST, provide control for cancer chemotherapy through diminishing the propensity of cancer cells to undergo apoptosis which in turn modulates the unresolved and complex phenomenon of multidrug resistance (MDR) for the cancer cells.

HYPOTHESIS/PURPOSE

This study dwells into the interaction details involving ABC-transporters, CYP3A4, GST and cytotoxic effects of resveratrol on different cell lines.

METHODS

Resveratrol was evaluated for its ability modulating the expression and efflux functions of P-gp /MDR1, MRP1, and BCRP in the multidrug-resistant human colon carcinoma cell line, Caco-2, and CEM/ADR5000 cells through flow cytometry and RTPCR technique.

RESULTS

The resveratrol influenced P-gp and MRP1 efflux functions whereby it increased rhodamine 123 with calcein accumulation in concentration-dependent manner (1 - 500 µM) in the Caco-2 cell lines and inhibited the effluxes of both the substrates also as concentration-dependent phenomenon (10 - 100 µM) in the p-gp overexpressing CEM/ADR5000 cells through FACS (full form). The treatment of drug-resistant Caco-2, and CEM/ADR5000 cells with doxorubicin (DOX) along with 20 µM of resveratrol in the mixture. It increased the cell sensitivity DOX towards the DOX and enhanced the cytotoxicity. The resveratrol inhibited both CYP3A4 and GST enzymatic activity in a concentration-dependent way and induced apoptosis in the resistance cell lines because of increased levels of caspase-3, -8,-6/9 and incremental phosphatidyl serine (PS) exposure as detected by flow cytometry. The treatment of Caco-2 cells with resveratrol showed significantly lower p-gp, MRP1, BCRP, CYP3A4, GST, and hPXR mRNA levels in a 48 h observation.

CONCLUSION

The result confirmed resveratrol mediated inhibition of ABC-transporters' overall efflux functions, and its expression, and apoptosis as well as metabolic enzymes GST and CYP3A4 activity.

Oral Brain-Targeted Microemulsion for Enhanced Piperine Delivery in Alzheimer's Disease Therapy: In Vitro Appraisal, In Vivo Activity, and Nanotoxicity

Alzheimer's disease (AD) is a neurodegenerative disorder that has no cure till now. Piperine (PIP) is an alkaloid characterized by memory-enhancing properties but challenging oral delivery obstacles. The objectives of this study are as follows: preparation of microemulsion (ME) as a proposed oral PIP nanocarrier for treatment of Alzheimer's disease and testing its safety on the brain and other internal organs. This study employs bioactive surfactants in the common safe doses to improve PIP targeting to the brain. Selected ME systems encompassed Caproyl 90 (oil)/Tween 80/Cremophor RH 40 (surfactant) and Transcutol HP (co-surfactant). The particle size of the prepared formulations was less than 150 nm with negative zeta potential. The in vivo results showed a superior effect of ME over free PIP. Colchicine-induced brain toxicity results showed the safety of ME on brain cells. Nevertheless, toxicological results showed a potential ME nephrotoxicity. Oral microemulsion increased PIP efficacy and enhanced its delivery to the brain resulting in better therapeutic outcome compared to the free drug. However, the toxicity of this nanosystem should be carefully taken into consideration on chronic use.

Anticancer potentiality of lignan rich fraction of six Flaxseed cultivars

The objective of our study is to highlight the therapeutic effect and mechanism of action by which purified Flaxseed hydrolysate (PFH) which is a lignan rich fraction exerts its anticancer activity on a human breast cancer cell line (T47D) and in mice bearing tumor. HPLC analysis of PFH of six flaxseed cultivars had shown that PFH of the cultivar Giza 9 (PFH-G9) contains the highest concentration of SDG (81.64 mg/g). The in vitro cytotoxic potentiality of PFH’s of six flaxseed cultivars was screened against a panel of human cancer cell lines. PFH -G9 showed the most significant cytotoxic activity against ER-receptor positive breast cell lines MCF7 and T47D with IC₅₀ 13.8 and 15.8 µg/ml, respectively. Moreover, PFH-G9 reduced the expression of the metastasis marker, 1-α, metalloproteinases and vascular endothelial growth factor (VEGF), one of the most potent stimulators of angiogenesis, while it increased the caspase-3 dependent apoptosis. Our study also showed that dietary intake of 10% of Giza 9 Flaxseeds (FS), fixed oil (FSO) or Flax meal (FSM) twice daily for 3 weeks in mice-bearing solid Ehrlich ascites carcinoma (EAC) resulted in reducing the tumor volume, the expression of estrogen, insulin growth factor, progesterone, VEGF and MMP-2, but enhanced expression of caspase-3.

Proteasome inhibitor bortezomib is a novel therapeutic agent for focal radiation-induced osteoporosis

Bone atrophy and its related fragility fractures are frequent, late side effects of radiotherapy in cancer survivors and have a detrimental impact on their quality of life. In another study, we showed that parathyroid hormone 1-34 and anti-sclerostin antibody attenuates radiation-induced bone damage by accelerating DNA repair in osteoblasts. DNA damage responses are partially regulated by the ubiquitin proteasome pathway. In the current study, we examined whether proteasome inhibitors have similar bone-protective effects against radiation damage. MG132 treatment greatly reduced radiation-induced apoptosis in cultured osteoblastic cells. This survival effect was owing to accelerated DNA repair as revealed by γH2AX foci and comet assays and to the up-regulation of Ku70 and DNA-dependent protein kinase, catalytic subunit, essential DNA repair proteins in the nonhomologous end-joining pathway. Administration of bortezomib (Bzb) reversed the loss of trabecular bone structure and strength in mice at 4 wk after focal radiation. Histomorphometry revealed that Bzb significantly increased the number of osteoblasts and activity in the irradiated area and suppressed the number and activity of osteoclasts, regardless of irradiation. Two weeks of Bzb treatment accelerated DNA repair in bone-lining osteoblasts and thus promoted their survival. Meanwhile, it also inhibited bone marrow adiposity. Taken together, we demonstrate a novel role of proteasome inhibitors in treating radiation-induced osteoporosis.-Chandra, A., Wang, L., Young, T., Zhong, L., Tseng, W.-J., Levine, M. A., Cengel, K., Liu, X. S., Zhang, Y., Pignolo, R. J., Qin, L. Proteasome inhibitor bortezomib is a novel therapeutic agent for focal radiation-induced osteoporosis.

Cerium oxide nanoparticles could ameliorate behavioral and neurochemical impairments in 6-hydroxydopamine induced Parkinson's disease in rats

BACKGROUND

Cerium oxide nanoparticles (CeO₂NPs) showed promising effects in neurodegenerative diseases including some animal models of Parkinsonism. However, the implication of CeO₂NPs in 6-hydroxydopamine (6-OHDA) induced Parkinsonism remains to be investigated.

AIM

This study was designed to assess whether CeO₂NPs treatment could alleviate neurobehavioral and neurobiochemical deficits in 6-OHDA induced neurotoxicity in rats.

MATERIAL AND METHODS

50 rats received left intrastriatal (IS) injection of either saline (control, n = 10) or 6-OHDA (n = 40). At the third week post-lesion, motor dysfunction was verified using neurobehavioral tests. Then diseased rats received intraperitoneal injection of 0.1, 0.5 or 1 mg/kg of CeO₂NPs or vehicle (10 rats each) for 3 weeks. Rats were subjected to behavioral assessments and then sacrificed for biochemical analyses of the striatum. Striatal dopamine levels, oxidative stress markers including total antioxidant capacity (TAC) and malondialdehyde (MDA), and caspase 3 activity as an apoptotic marker were assessed.

RESULTS

Different doses of CeO₂NPs variably improved motor dysfunctions induced by 6-OHDA injection in open field, Rota Rod and stepping tests. In addition, the neurobiochemical derangements were almost reversed by the 0.5 mg/kg dose of CeO₂NPs, while 0.1 mg/kg dose was not sufficient to alter biochemical measurements in the striatum. Administration of 1 mg/kg of CeO₂NPs partially ameliorated striatal dopamine and decreased apoptosis without significant effect on oxidative stress.

CONCLUSION

The present study showed a putative therapeutic role of CeO2NPs in the treatment of 6-OHDA-induced Parkinsonian rats, and suggested their antioxidant and antiapoptotic effects as possible mechanisms for elevated striatal dopamine level and improved motor performance.

The Combination of α-Tocopheryl Succinate and Sodium Selenite on Breast Cancer: A Merit or a Demerit?

α-Tocopheryl succinate (α-TOS), a mitochondria-targeting agent, induces apoptosis in malignant cells in vitro and in vivo. Selenite is a nutritional supplement that has been shown to stimulate apoptosis in cancer cells. This study was designed to investigate the cytotoxic effect of combined treatment of α-TOS and sodium selenite (SSe) in vitro and in vivo and to explore their effect on apoptosis and autophagy in breast cancer. The type of interaction between α-TOS and SSe was evaluated and levels of oxidative stress and apoptotic and autophagic markers were determined. SSe alone showed varying degrees of cytotoxicity on all the tested cell lines. Its combination with α-TOS was antagonistic in vitro in MCF7 and in vivo in mice bearing Ehrlich tumor compared to α-TOS-treated one. Combination of TOS with 2 μM of SSe increased the level of glutathione without changes in antiapoptotic markers Bcl-2 and Mcl-1 at 16 and 48 hrs. SSe decreased caspase 3 activity and protein level of caspases 7 and 9, while it increased autophagic markers beclin-1 and LC3B protein levels of MCF7 cells treated with α-TOS. In conclusion, SSe antagonizes α-TOS-induced apoptosis via inhibition of oxidative stress and promoting prosurvival machinery of autophagy.

Intranasal Piperine-Loaded Chitosan Nanoparticles as Brain-Targeted Therapy in Alzheimer's Disease: Optimization, Biological Efficacy, and Potential Toxicity

Piperine (PIP) is a phytopharmaceutical with reported neuroprotective potential in Alzheimer's disease (AD). Oral PIP delivery suffers from its hydrophobicity and pre-systemic metabolism. In this article, mono-disperse intranasal chitosan nanoparticles (CS-NPs) were elaborated for brain targeting of PIP. Formula optimization was based on particle size (PS), zeta potential (ZP), polydispersity index (PDI), % entrapment efficiency (% EE), release studies, and transmission electron microscopy. AD was induced in 48 male Wistar rats on which full behavioral and biochemical testing was conducted. Brain toxicity was assessed based on Caspase-3 assay for apoptosis and tumor necrosis factor for inflammation. Spherical NPs with optimum % EE (81.70), PS (248.50nm), PDI (0.24), and ZP (+56.30mV) were elaborated. PIP-NPs could significantly improve cognitive functions as efficient as standard drug (donpezil injection) with additional advantages of dual mechanism (Ach esterase inhibition and antioxidant effect). CS-NPs could significantly alleviate PIP nasal irritation and showed no brain toxicity. This work was the first to report additional mechanism of PIP in AD via anti-apoptosis and anti-inflammatory effects. To conclude, mucoadhesive CS-NPs were successfully tailored for effective, safe, and non-invasive PIP delivery with 20-folds decrease in oral dose, opening a gate for a future with lower AD morbidity. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:3544-3556, 2015.

Targeting glycolysis by 3-bromopyruvate improves tamoxifen cytotoxicity of breast cancer cell lines

Background

Tamoxifen is the standard endocrine therapy for ER+ breast cancer; however, many women still relapse after long-term therapy. 3-Bromopyruvate, a glycolytic inhibitor, has shown high selective anti-tumor activity in vitro, and in vivo. The aim of this study was to evaluate the possible augmentation of the effect of tamoxifen via reprograming cancer cell metabolism using 3-bromopyruvate.

Methods

An in vitro screening of antitumor activity as well as the apoptotic, anti-metastatic, and anti-angiogenic potentials of the combination therapy were carried out using different techniques on breast cancer cell lines MCF7and T47D. In addition the antitumor effect of the combined therapy was done on mice bearing tumor.

Results

Our results showed modulation in apoptosis, angiogenesis and metastatic potential by either drug alone; however, their combination has surpassed that of the individual one. Combination regimen enhanced activated caspases-3, 7 and 9, as well as oxidative stress, signified by increased malondialdehyde and decreased glutathione level. Additionally, the angiogenesis and metastasis markers, including hypoxia inducing factor-1α, vascular endothelia growth factor, and metaloproteinases-2 and 9 were decreased after using the combination regimen. These results were further confirmed by the in vivo study, which depicted a decrease in the tumor volume and angiogenesis and an increase in oxidative stress as well.

Conclusion

3-bromopyruvate could be a valuable compound when added with tamoxifen in breast cancer treatment.

Novel piperine-loaded Tween-integrated monoolein cubosomes as brain-targeted oral nanomedicine in Alzheimer's disease: pharmaceutical, biological, and toxicological studies

Alzheimer's disease (AD) is one of the most patient devastating central nervous system diseases with no curative therapy. An effective oral therapy with brain-targeting potential is required that is hampered by blood-brain barrier. Piperine (PIP) is a natural alkaloid with memory enhancing potentials. Oral PIP delivery suffers from its hydrophobicity and first-pass metabolism. In this study, novel Tween-modified monoolein cubosomes (T-cubs) were elaborated as bioactive nanocarriers for brain-targeted oral delivery of PIP. Seven liquid crystalline nanoparticles (cubosomes) were prepared testing different bioactive surfactants (Tween 80, poloxamer, and Cremophor). Full in vitro characterization was carried out based on particle size, zeta potential, polydispersity index, entrapment efficiency, and in vitro release. Morphological examination and structure elucidation were performed using transmission and polarizing microscopes. Sporadic dementia of Alzheimer's type was induced in 42 male Wistar rats on which full behavioral and biochemical testing was conducted. Brain toxicity was assessed based on Caspase-3 assay for apoptosis and tumor necrosis factor-α for inflammation. Liver and kidney toxicity studies were conducted as well. Among others, T-cubs exhibited optimum particle size (167.00±10.49 nm), polydispersity index (0.18±0.01), and zeta potential (-34.60±0.47 mv) with high entrapment efficiency (86.67%±0.62%). Cubs could significantly sustain PIP in vitro release. In vivo studies revealed T-cubs potential to significantly enhance PIP cognitive effect and even restore cognitive function to the normal level. Superiority of T-cubs over others suggested brain-targeting effect of Tween. Toxicological studies contended safety of cubs on kidney, liver, and even brain. T-cubs exhibited potential anti-inflammatory and anti-apoptotic activity of loaded PIP, indicating potential to stop AD progression that was first suggested in this article. Novel oral nanoparticles elaborated possess promising in vitro and in vivo characteristics with high safety for effective chronic treatment of AD.

Erythropoietin protects cardiomyocytes from cell death during hypoxia/reperfusion injury through activation of survival signaling pathways

Hypoxia/Reoxygenation (H/R) cardiac injury is of great importance in understanding Myocardial Infarctions, which affect a major part of the working population causing debilitating side effects and often-premature mortality. H/R injury primarily consists of apoptotic and necrotic death of cardiomyocytes due to a compromise in the integrity of the mitochondrial membrane. Major factors associated in the deregulation of the membrane include fluctuating reactive oxygen species (ROS), deregulation of mitochondrial permeability transport pore (MPTP), uncontrolled calcium (Ca²⁺) fluxes, and abnormal caspase-3 activity. Erythropoietin (EPO) is strongly inferred to be cardioprotective and acts by inhibiting the above-mentioned processes. Surprisingly, the underlying mechanism of EPO's action and H/R injury is yet to be fully investigated and elucidated. This study examined whether EPO maintains Ca²⁺ homeostasis and the mitochondrial membrane potential (ΔΨ_m) in cardiomyocytes when subjected to H/R injury and further explored the underlying mechanisms involved. H9C2 cells were exposed to different concentrations of EPO post-H/R, and 20 U/ml EPO was found to significantly increase cell viability by inhibiting the intracellular production of ROS and caspase-3 activity. The protective effect of EPO was abolished when H/R-induced H9C2 cells were treated with Wortmannin, an inhibitor of Akt, suggesting the mechanism of action through the activation Akt, a major survival pathway.

Mechanisms of apoptosis in irradiated and sunitinib-treated follicular thyroid cancer cells

The multikinase inhibitor sunitinib (S) seems to have promising potential in the treatment of thyroid cancer. We focused on the impact of S and/or irradiation (R) on mechanisms of apoptosis in follicular thyroid cancer cells. The effects of R, S and their combination were evaluated 2 and 4 days after treatment, using the human thyroid cancer cell line CGTH W-1. The transcription of genes involved in the regulation of apoptosis was investigated using quantitative real-time PCR. Western blot analyses of caspases and survivin were also performed. S elevated BAX (day 4), CASP9, CASP3, BIRC5 (day 4) and PRKACA (day 4) gene expression, whereas the mRNAs of BCL2, CASP8, PRKCA, ERK1, and ERK2 were not significantly changed. S, R and R+S clearly induced caspase-9 protein and elevated caspase-3 activity. Survivin was down-regulated at day 4 in control cells and the expression was blunted by S treatment. R+S induced survivin expression at day 2 followed by a reduction at day 4 of treatment. Sunitinib and the combined application with radiation induced apoptosis in follicular thyroid cancer cells via the intrinsic pathway of apoptosis. In addition, sunitinib might induce apoptosis via decreased expression of the anti-apoptotic protein survivin. These findings suggest the potential use of sunitinib for the treatment of poorly differentiated follicular thyroid carcinomas.

Integrated approaches for analyzing U1-70K cleavage in Alzheimer's disease

The accumulation of pathologic protein fragments is common in neurodegenerative disorders. We have recently identified in Alzheimer’s disease (AD) the aggregation of the U1-70K splicing factor and abnormal RNA processing. Here, we present that U1-70K can be cleaved into an N-terminal truncation (N40K) in ∼50% of AD cases, and the N40K abundance is inversely proportional to the total level of U1-70K. To map the cleavage site, we compared tryptic peptides of N40K and stable isotope labeled U1-70K by liquid chromatography–tandem mass spectrometry (MS), revealing that the proteolysis site is located in a highly repetitive and hydrophilic domain of U1-70K. We then adapted Western blotting to map the cleavage site in two steps: (i) mass spectrometric analysis revealing that U1-70K and N40K share the same N-termini and contain no major modifications; (ii) matching N40K with a series of six recombinant U1-70K truncations to define the cleavage site within a small region (Arg300 ± 6 residues). Finally, N40K expression led to substantial degeneration of rat primary hippocampal neurons. In summary, we combined multiple approaches to identify the U1-70K proteolytic site and found that the N40K fragment might contribute to neuronal toxicity in Alzheimer’s disease.

Glabridin mediate caspases activation and induces apoptosis through JNK1/2 and p38 MAPK pathway in human promyelocytic leukemia cells

Background

Glabridin, a prenylated isoflavonoid of G. glabra L. roots, has been associated with a wide range of biological properties such as regulation of energy metabolism, estrogenic, neuroprotective, anti-osteoporotic, and skin-whitening in previous studies. However, the effect of glabridin on tumor cells metastasis has not been clearly clarified. Here, the molecular mechanism by which glabridin anticancer effects in human promyelocytic leukemia cells was investigated.

Methodology and Principal Findings

The results showed that glabridin significantly inhibited cell proliferation of four AML cell lines (HL-60, MV4-11, U937, and THP-1). Furthermore, glabridin induced apoptosis of HL-60 cells through caspases-3, -8, and -9 activations and PARP cleavage in dose- and time-dependent manner. Moreover, western blot analysis also showed that glabridin increase phosphorylation of ERK1/2, p38 MAPK and JNK1/2 in dose- and time-dependent manner. Inhibition of p38 MAPK and JNK1/2 by specific inhibitors significantly abolished the glabridin-induced activation of the caspase-3, -8 and -9.

Conclusion

Taken together, our results suggest that glabridin induced HL-60 cell apoptosis through p38 MAPK and JNK1/2 pathways and could serve as a potential additional chemotherapeutic agent for treating AML.

Retinoic acid induces apoptosis in activated canine neutrophils

Activated neutrophils live longer, produce toxic metabolites and cause considerable tissue injury, which is central to the pathogenesis of many inflammatory conditions. Retinoids are a class of lipophilic compounds with anti-inflammatory effects. We examined the effect of retinoic acid on apoptosis in normal and activated neutrophils. Our results showed that treatment with 1 μg/ml Escherichia coli lipopolysaccharide (LPS) for 12 and 36 h delayed the spontaneous neutrophil apoptosis compared to untreated cells. But exposure of LPS-treated cells to retinoic acid (1 and 5 μM) abolished the inhibitory effects of LPS on neutrophil apoptosis in a concentration-dependent manner based on annexin V staining, Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, light and electron microscopy. These results show that retinoic acid increases apoptosis in activated canine neutrophils and this effect could enhance the resolution of inflammation in vivo.

Histone deacetylase inhibitor upregulates peroxisomal fatty acid oxidation and inhibits apoptotic cell death in abcd1-deficient glial cells

In X-ALD, mutation/deletion of ALD gene (ABCD1) and the resultant very long chain fatty acid (VLCFA) derangement has dramatically opposing effects in astrocytes and oligodendrocytes. While loss of Abcd1 in astrocytes produces a robust inflammatory response, the oligodendrocytes undergo cell death leading to demyelination in X-linked adrenoleukodystrophy (X-ALD). The mechanisms of these distinct pathways in the two cell types are not well understood. Here, we investigated the effects of Abcd1-knockdown and the subsequent alteration in VLCFA metabolism in human U87 astrocytes and rat B12 oligodendrocytes. Loss of Abcd1 inhibited peroxisomal β-oxidation activity and increased expression of VLCFA synthesizing enzymes, elongase of very long chain fatty acids (ELOVLs) (1 and 3) in both cell types. However, higher induction of ELOVL's in Abcd1-deficient B12 oligodendrocytes than astrocytes suggests that ELOVL pathway may play a prominent role in oligodendrocytes in X-ALD. While astrocytes are able to maintain the cellular homeostasis of anti-apoptotic proteins, Abcd1-deletion in B12 oligodendrocytes downregulated the anti-apototic (Bcl-2 and Bcl-xL) and cell survival (phospho-Erk1/2) proteins, and upregulated the pro-apoptotic proteins (Bad, Bim, Bax and Bid) leading to cell loss. These observations provide insights into different cellular signaling mechanisms in response to Abcd1-deletion in two different cell types of CNS. The apoptotic responses were accompanied by activation of caspase-3 and caspase-9 suggesting the involvement of mitochondrial-caspase-9-dependent mechanism in Abcd1-deficient oligodendrocytes. Treatment with histone deacetylase (HDAC) inhibitor suberoylanilide hydroxamic acid (SAHA) corrected the VLCFA derangement both in vitro and in vivo, and inhibited the oligodendrocytes loss. These observations provide a proof-of principle that HDAC inhibitor SAHA may have a therapeutic potential for X-ALD.

Viability inhibition effect of gambogic acid combined with cisplatin on osteosarcoma cells via mitochondria-independent apoptotic pathway

We previously demonstrated that gambogic acid (GA) is a promising chemotherapeutic compound for human osteosarcoma treatment. The aim of this study was to detect whether the combination of lower-dose GA (0.3 mg/L) and cisplatin (CDDP) (1 mg/L) could perform a synergistic effect on inhibiting tumor in four osteosarcoma cell lines. Our results showed that the combination between GA at lower dose and CDDP significantly exerts a synergistic effect on inhibiting the cellular viability in MG63, HOS, and U2OS cells. In contrast, an antagonistic character was detected in SAOS2 cells exposed to the combined use of lower-dose GA (0.3 mg/L) and CDDP (1 mg/L). Then, analysis of cell cycle showed the combination of both drugs significantly induced the G2/M phase arrest, without any difference relative to GA treatment alone, in MG63 cells. Flow-cytometric analysis of cell apoptosis displayed that the apoptotic rate in the combination group is higher than that in GA treatment alone in MG63, HOS, and U2OS cells. The combined use of both drugs had no effect on mitochondrial membrane potential, but promoted the apoptosis-inducing function through triggering of CDDP in the three cell lines. By measurement of mitochondrial membrane potential, the activity of caspase-3 and the expressions of caspase-8 and caspase-9, it was showed that the apoptosis-promoting effect of the combined use of both drugs could be dependent on the death receptor apoptosis pathway, not dependent on the mitochondria apoptosis mechanism. This research, for the first time, demonstrates that GA could increase the chemotherapeutic effect of CDDP in human osteosarcoma treatment through inducing the cell cycle arrest and promoting cell apoptosis.

Lentiviral-mediated p38 MAPK RNAi attenuates aldosterone-induced myocyte apoptosis

Aldosterone-induced myocyte apoptosis is an important component of cardiovascular disease. While the p38 mitogen-activated protein kinase (p38 MAPK) pathway has been shown to be crucial in myocyte apoptosis, whether aldosterone induces myocyte apoptosis through this pathway remains unclear. In the present study, three individual strands of p38 MAPK short hairpin RNA (ShRNA), delivered by lentiviral vectors (PGLV), were constructed and used to explore the role of p38 MAPK pathway activation in aldosterone-mediated myocyte apoptosis in cultured myocytes and normotensive rats. Aldosterone stimulation increased myocyte apoptosis, caspase-3 expression levels and p38 MAPK mRNA and protein expression levels in vitro and in vivo. PGLV-ShRNA3 transduction decreased aldosterone-mediated myocyte apoptosis and p38 MAPK mRNA and protein expression levels in vitro (all P<0.01). PGLV-ShRNA3 transduction significantly decreased aldosterone-mediated myocyte apoptosis, p38 MAPK mRNA and protein expression levels in normotensive rats (P<0.01, P<0.01 and P<0.05, respectively). Results from the present study suggest that aldosterone directly induces myocyte apoptosis through the p38 MAPK pathway and the gene silencing of p38 MAPK may protect cardiac myocytes from aldosterone-mediated apoptosis.

Escherichia coli lipopolysaccharide administration transiently suppresses luteal structure and function in diestrous cows

The objective was to characterize the effects of Escherichia coli lipopolysaccharide (LPS) endotoxin (given i.v.) on luteal structure and function. Seven nonlactating German Holstein cows, 5.1 ± 0.8 years old (mean ± s.e.m.), were given 10  ml saline on day 10 (ovulation=day 1) of a control estrous cycle. On day 10 of a subsequent cycle, they were given 0.5 μg/kg LPS. Luteal size decreased (from 5.2 to 3.8 cm², P≤0.05) within 24 h after LPS treatment and remained smaller throughout the remainder of the cycle. Luteal blood flow decreased by 34% (P≤0.05) within 3 h after LPS and remained lower for 72 h. Plasma progesterone (P₄) concentrations increased (P≤0.05) within the first 3 h after LPS but subsequently declined. Following LPS treatment, plasma prostaglandin (PG) F metabolites concentrations were approximately tenfold higher in LPS-treated compared with control cows (9.2 vs 0.8 ng/ml, P≤0.05) within 30 min, whereas plasma PGE concentrations were nearly double (P≤0.05) at 1 h after LPS. At 12 h after treatment, levels of mRNA encoding Caspase-3 in biopsies of the corpus luteum (CL) were increased (P≤0.05), whereas those encoding StAR were decreased (P≤0.05) in cattle given LPS vs saline. The CASP3 protein was localized in the cytoplasm and/or nuclei of luteal cells, whereas StAR was detected in the cytosol of luteal cells. In the estrous cycle following treatment with either saline or LPS, there were no significant differences between groups on luteal size, plasma P₄ concentrations, or gene expression. In conclusion, LPS treatment of diestrus cows transiently suppressed both the structure and function of the CL.

Alterations in RNA processing during immune-mediated programmed cell death

During immune-mediated death, death-inducing granzyme (Gzm) proteases concentrate in the nucleus of cells targeted for immune elimination, suggesting that nuclear processes are important targets. Here we used differential 2D proteomics of GzmA-treated nuclei to identify potential GzmA substrates. Of 44 candidates, 33 were RNA-binding proteins important in posttranscriptional RNA processing, including 14 heterogeneous nuclear ribonucleoproteins (hnRNP). Multiple hnRNPs were degraded in cells undergoing GzmA-, GzmB-, or caspase-mediated death. GzmA and caspase activation impaired nuclear export of newly synthesized RNA and disrupted pre-mRNA splicing. Expressing GzmA-resistant hnRNP A1 inhibited GzmA-mediated cell death and rescued pre-mRNA splicing, suggesting that hnRNP A1 is an important GzmA substrate. Cellular stresses are known to inhibit initiation of cap-dependent translation. Disrupting pre-mRNA processing should block further new protein synthesis and promote death by interfering with pathways induced to protect cells from death.

Functions of the poly(ADP-ribose) polymerase superfamily in plants

Poly(ADP-ribosyl)ation is the covalent attachment of ADP-ribose subunits from NAD(+) to target proteins and was first described in plants in the 1970s. This post-translational modification is mediated by poly(ADP-ribose) polymerases (PARPs) and removed by poly(ADP-ribose) glycohydrolases (PARGs). PARPs have important functions in many biological processes including DNA repair, epigenetic regulation and transcription. However, these roles are not always associated with enzymatic activity. The PARP superfamily has been well studied in animals, but remains under-investigated in plants. Although plants lack the variety of PARP superfamily members found in mammals, they do encode three different types of PARP superfamily proteins, including a group of PARP-like proteins, the SRO family, that are plant specific. In plants, members of the PARP family and/or poly(ADP-ribosyl)ation have been linked to DNA repair, mitosis, innate immunity and stress responses. In addition, members of the SRO family have been shown to be necessary for normal sporophytic development. In this review, we summarize the current state of plant research into poly(ADP-ribosyl)ation and the PARP superfamily in plants.

Latent Epstein-Barr virus can inhibit apoptosis in B cells by blocking the induction of NOXA expression

Latent Epstein-Barr virus (EBV) has been shown to protect Burkitt's lymphoma-derived B cells from apoptosis induced by agents that cause damage to DNA, in the context of mutant p53. This protection requires expression of the latency-associated nuclear proteins EBNA3A and EBNA3C and correlates with their ability to cooperate in the repression of the gene encoding the pro-apoptotic, BH3-only protein BIM. Here we confirm that latent EBV in B cells also inhibits apoptosis induced by two other agents--ionomycin and staurosporine--and show that these act by a distinct pathway that involves a p53-independent increase in expression of another pro-apoptotic, BH3-only protein, NOXA. Analyses employing a variety of B cells infected with naturally occurring EBV or B95.8 EBV-BAC recombinant mutants indicated that the block to NOXA induction does not depend on the well-characterized viral latency-associated genes (EBNAs 1, 2, 3A, 3B, 3C, the LMPs or the EBERs) or expression of BIM. Regulation of NOXA was shown to be at least partly at the level of mRNA and the requirement for NOXA to induce cell death in this context was demonstrated by NOXA-specific shRNA-mediated depletion experiments. Although recombinant EBV with a deletion removing the BHRF1 locus--that encodes the BCL2-homologue BHRF1 and three microRNAs--partially abrogates protection against ionomycin and staurosporine, the deletion has no effect on the EBV-mediated block to NOXA accumulation.

Protective effects of cyclo(L-Leu-L-Tyr) against postischemic myocardial dysfunction in guinea-pig hearts

The protective effects of cyclic dipeptides in alcoholic beverages were investigated in the perfused guinea-pig hearts subjected to ischemia and reperfusion. Subsequently, in order to determine the importance of cyclic dipeptide structure, the effects of cyclo(L-Leu-L-Tyr) (cLY) were compared with those of the newly synthesized non-cyclic dipeptides, L-Leu-L-Tyr (LY) and L-Tyr-L-Leu (YL). After reperfusion, pressure recovery (%) in the left ventricle reached a peak of over 90% in the presence of cLY (10(-6) M and 10(-5) M) (control: 22.9%). The recovery by LY and YL was significantly lower than that by cLY, and ATP levels simultaneously monitored using (31)P-NMR were already lower during the ischemic end period than those observed with cLY treatment. In perfused mitochondrial preparations, cLY significantly inhibited mitochondrial Ca(2+) ([Ca(2+)](m)) elevation in a similar way to that of the mitochondrial permeability transition pore (MPTP) inhibitor cyclosporin A. In vitro electron paramagnetic resonance (EPR) revealed that the active oxygen radicals quenching activity of cLY was greater than those of non-cyclic dipeptides. cLY inhibited caspase-3-induced apoptosis. The cyclic dipeptide structure inhibits opening of the MPTP by preventing [Ca(2+)](m) overload-induced apoptosis related to mitochondrial active oxygen radical accumulation in ischemia-reperfusion hearts.

A trigger model of apoptosis induced by tumor necrosis factor signaling

BACKGROUND

The ability of living cells to respond appropriately to apoptosis signals is crucial for the proper development and homeostasis of multicellular organisms. For example, viable cells must be stable enough to appropriately respond to apoptosis signaling so that an irreversible death program is only induced when apoptosis signaling reaches a certain threshold. Previous studies have introduced bistability models in which signaling by caspase-3 activity represents a key regulator of cell fate in response to apoptosis stimuli.

RESULTS

In this study, apoptosis induced by tumor necrosis factor (TNF) signaling is investigated, and a mathematical model without the requirement for bistability is proposed. In this model, rapid degradation of the active forms of caspases -8 and -3 are included, and TNF-signaling is found to induce a pulse of caspase-3 activation and trigger an irreversible death program. This result agrees with experimental observations. The ability of a cell to respond to, or resist, apoptosis stimuli is also discussed. Furthermore, the activation efficiencies of caspases -8 and -3 that are essential to a cell's response to extracellular apoptosis stimuli are defined. Based on the simulations performed, it is observed that activation efficiencies must be sufficiently sensitive to appropriately compromise a cell's resistance and effectiveness in response to apoptosis stimuli.

CONCLUSIONS

Our results suggest that bistability may not be a necessary condition for the induction of apoptosis by TNF signaling. Rather, a sharp increase in caspase-3 activity might be sufficient to trigger the induction of an irreversible death program. Accordingly, regulation of caspase activity and degradation of active caspases is essential for a cell's response to apoptosis stimuli.

Longevity of SLE-prone mice increased by dietary 2-mercaptoethanol via a mechanism imprinted within the first 28 days of life

In the preceding report, moderately lived-mice fed dietary 2-mercaptoethanol (2-Me) had their life extended, whereas long-lived mice were found to have the quality of life improved, but not extended, and did not develop high fat-diet obesity. In the present report, alteration of longevity of mice prone to develop spontaneous, systemic lupus erythematosus (SLE) by dietary 2-Me was determined. NZB, NZW, (NZW x NZB) F₁-hybrid, BXSB/MpJ, BXSB-Yaa+/J, MRL/MpJ and MRL/MpJ-Faslpr mice received drinking water, without or with 2-Me at concentrations of 10⁻³ or 10⁻² M. Therapeutic benefit was assessed by changes in longevity. The median survival of MRL/MpJ males was increased from 443 to 615 days and those of (NZW x NZB) F₁ and NZB males and females were increased approximately 2-fold. The most unexpected finding was that longevity of F₁ males was significantly extended irrespective of whether dietary exposure to 2-Me was initiated at 28 days of age, at 50 days of age, or initiated during gestation (and then terminated at weaning--28 days of age). Survival of F₁-hybrids in which treatment was initiated in utero or at 28 days of age was not significantly different, whereas if initiation was delayed until 50 days of age, survival was >200 days shorter. Survival of male MRL/MpJ-Fas lpr and BXSB/MpJ (Yaa-), two strains with genetically controlled accelerated SLE, was not altered by 2-Me when started at 50 days. Various alternatives are discussed regarding potential long-lasting mechanisms imprinted early in life. Even though present day treatments of rodent SLE are generally aimed at controlling specific immunological events, with or without survival benefits, or are procedures presently unsuitable for therapeutic use in humans, the findings presented herein seem worthy of clinical evaluation.

Induction of cytopathic effects and apoptosis in Spodoptera frugiperda cells by the HIV-1 Env glycoprotein signal peptide

The loss of CD4(+) T-cells in human immunodeficiency virus-infected individuals has been attributed not only to dysregulation of immune cell function but also direct and indirect killing mechanisms of both infected and bystander cells. This process proceeds through both necrotic and programmed cell death pathways. Several human immunodeficiency virus type 1 (HIV-1) gene products have been linked to the induction of cell death and apoptosis associated with virus infection. These include the Nef, Tat, Vpr, and Vpu proteins as well as the viral envelope glycoprotein. Our results now indicate that the signal peptide of HIV-1 is also involved in the induction of cytopathic effects leading to cell death. We have shown here that expression of HIV-1 gp120 or vesicular stomatitis virus G glycoprotein with the HIV-1 Env signal peptide resulted in a rapid induction of cytopathicity and cell death in S. frugiperda cells, whereas removal or replacement of the signal peptide ameliorated those effects. Further, our results show that cell death is induced, at least in part, through apoptotic pathways as characterized by evidence of nuclear condensation and DNA fragmentation, as well as by the activation of host-cell caspase activity. Our results indicate that the signal peptide of HIV-1 Env itself thus has a direct role in cellular cytotoxicity and the triggering of cell death pathways.

Cutting edge: proteolytic inactivation of poly(ADP-ribose) polymerase 1 by the Nlrp3 and Nlrc4 inflammasomes

Caspase-mediated cleavage of the DNA damage sensor poly(ADP-ribose) polymerase 1 (PARP1) is a hallmark of apoptosis. However, it remains unclear whether PARP1 is processed during pyroptosis, a specialized cell-death program that occurs upon activation of caspase-1 in inflammasome complexes. In this article, we show that activation of the Nlrp3 and Nlrc4 inflammasomes induces processing of full-length PARP1 into a fragment of 89 kDa in a stimulus-dependent manner. Macrophages deficient for caspase-1 and those lacking the inflammasome adaptors Nlrp3, Nlrc4, and ASC were highly resistant to cleavage, whereas macrophages lacking the downstream inflammasome effector caspase-7 were partially protected. A modest, but statistically significant, reduction in Nlrp3 inflammasome-induced pyroptosis was observed in PARP1 knockout macrophages. Thus, protease-mediated inactivation of PARP1 is a shared feature of apoptotic, necrotic, and pyroptotic cells.