Browse
Submit Data
Databases
API
Help

Dataset Information

22 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

A calpain-like protease inhibits autophagic cell death.

ABSTRACT: Programmed cell death (PCD) plays critical roles during development and in disease states. One form of programmed cell death utilizes autophagy--a cellular mechanism of degrading bulk cytosolic components--to destroy cells. Previously, the broad-spectrum caspase inhibitor z-Val-Ala-Asp(OMe)-fluoromethylketone (zVAD) was shown to induce autophagic cell death. The mechanism of Zvad-induced cell death was proposed to require caspase-8 inhibition. In our report, we extend these findings to show that--as is the case for apoptosis--induction of autophagic cell death in response to zVAD results in phosphatidylserine exposure prior to loss of membrane integrity. Additionally, we show that caspase-8 inhibition is insufficient to cause autophagic cell death. Rather, the activity of a calpain-like protease must also be blocked. These results reveal the existence of an autophagic PCD-inhibiting calpain-like cysteine protease.

SUBMITTER: Madden DT

PROVIDER: S-EPMC2749617 | biostudies-literature | 2007 Sep-Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

A calpain-like protease inhibits autophagic cell death.

Madden David T DT Egger Lotti L Bredesen Dale E DE

Autophagy 20070223 5

Programmed cell death (PCD) plays critical roles during development and in disease states. One form of programmed cell death utilizes autophagy--a cellular mechanism of degrading bulk cytosolic components--to destroy cells. Previously, the broad-spectrum caspase inhibitor z-Val-Ala-Asp(OMe)-fluoromethylketone (zVAD) was shown to induce autophagic cell death. The mechanism of Zvad-induced cell death was proposed to require caspase-8 inhibition. In our report, we extend these findings to show that ...[more]

PMID: 17404499

Similar Datasets

Rotenone inhibits autophagic flux prior to inducing cell death.

Project description:Rotenone, which selectively inhibits mitochondrial complex I, induces oxidative stress, α-synuclein accumulation, and dopaminergic neuron death, principal pathological features of Parkinson's disease. The autophagy-lysosome pathway degrades damaged proteins and organelles for the intracellular maintenance of nutrient and energy balance. While it is known that rotenone causes autophagic vacuole accumulation, the mechanism by which this effect occurs has not been thoroughly investigated. Treatment of differentiated SH-SY5Y cells with rotenone (10 μM) induced the accumulation of autophagic vacuoles at 6 h and 24 h as indicated by Western blot analysis for microtubule associated protein-light chain 3-II (MAP-LC3-II). Assessment of autophagic flux at these time points indicated that autophagic vacuole accumulation resulted from a decrease in their effective lysosomal degradation, which was substantiated by increased levels of autophagy substrates p62 and α-synuclein. Inhibition of lysosomal degradation may be explained by the observed decrease in cellular ATP levels, which in turn may have caused the observed concomitant increase in acidic vesicle pH. The early (6 h) effects of rotenone on cellular energetics and autophagy-lysosome pathway function preceded the induction of cell death and apoptosis. These findings indicate that the classical mitochondrial toxin rotenone has a pronounced effect on macroautophagy completion that may contribute to its neurotoxic potential.

| S-EPMC3526971 | biostudies-other

Autophagic cell death.

Project description:In this chapter we discuss methods to study autophagic cell death. A large body of evidence demonstrates that autophagy is a cell survival mechanism in response to starvation. The role of autophagy in cell death, however, has long been controversial. Recently, molecular approaches have provided direct evidence that autophagy contributes to cell death in certain contexts. We begin this chapter by outlining methods to quantify cell death, for example by assaying for cell viability. Next, we discuss methods to measure processes involved in cell death, such as caspase activation and autophagy. Finally, we discuss methods to genetically or chemically perturb autophagy to test whether autophagy is required for cell death. Together, these approaches provide a guide to investigate the relationship between autophagy and cell death.

| S-EPMC3417315 | biostudies-literature

Lapatinib induces autophagic cell death and inhibits growth of human hepatocellular carcinoma.

Project description:Lapatinib, an orally administered small-molecule tyrosine kinase inhibitor targeting epidermal growth factor receptors (EGFR) and Her2/Neu, has been widely accepted in the treatment of breast cancer. In this study, we found that lapatinib induced cytotoxicity in human hepatoma Huh7, HepG2 and HA22T cells. For the mode of cell death, we found lapatinib induced a higher percent of dead cells and a lower percent of hypodiploid cells, suggesting non-apoptotic cell death in lapatinib-treated hepatoma cells. Moreover, lapatinib-induced autophagy in hepatoma cells was confirmed by the detection of autophagic LC3-II conversion, the up-regulation of autophagy-related proteins, and the down-regulation of p62 by immunoblotting. Autophagic cell death was demonstrated by images of punctuated LC3 patterns, a higher percent of acridine orange positive cells, as well as a partial rescue of cell death by autophagy inhibitor 3-methyladenine or chloroquine. We also found massive vacuoles in lapatinib-treated hepatoma cells by electronic microscopy. In addition, the shRNA of knocked-down autophagy-related proteins rescued the hepatoma cells from lapatinib-induced growth inhibition. We also demonstrated a reduction of tumorigenesis by lapatinib in vivo. In conclusion, lapatinib induced autophagic cell death and the growth of human hepatoma cells. Our study provides potential cancer therapies by using lapatinib as a treatment for hepatoma.

| S-EPMC4148104 | biostudies-literature

The anti-apoptotic Bcl-B protein inhibits BECN1-dependent autophagic cell death.

Project description:Bcl-2 family members are key modulators of apoptosis that have recently been shown to also regulate autophagy. It has been previously reported that Bcl-2 and Bcl-X(L) bind and inhibit BECN1, an essential mediator of autophagy. Bcl-B is an anti-apoptotic member of the Bcl-2 family that possesses the four BH (Bcl-2 homology) domains (BH1, BH2, BH3 and BH4) and a predicted C-terminal trans-membrane domain. Although the anti-apoptotic properties of Bcl-B are well characterized, its physiological function remains to be established. In the present study, we first established that Bcl-B interacts with the BH3 domain of BECN1. We also showed that Bcl-B overexpression reduces autophagy triggered by a variety of pro-autophagic stimuli. This impairment of autophagy was closely related to the capacity of Bcl-B to bind to BECN1. Importantly, we have demonstrated that Bcl-B knockdown triggers autophagic cell death and sensitizes cells to amino acid starvation. The cell death induced by Bcl-B knockdown was partially dependent on components of the autophagy machinery (LC3; BECN1; ATG5). These findings reveal a new role of Bcl-B in the regulation of autophagy.

| S-EPMC3405843 | biostudies-other

Activation of DRD5 (dopamine receptor D5) inhibits tumor growth by autophagic cell death.

Project description:Dopamine agonists such as bromocriptine and cabergoline have been successfully used in the treatment of pituitary prolactinomas and other neuroendocrine tumors. However, their therapeutic mechanisms are not fully understood. In this study we demonstrated that DRD5 (dopamine receptor D5) agonists were potent inhibitors of pituitary tumor growth. We further found that DRD5 activation increased production of reactive oxygen species (ROS), inhibited the MTOR pathway, induced macroautophagy/autophagy, and led to autophagic cell death (ACD) in vitro and in vivo. In addition, DRD5 protein was highly expressed in the majority of human pituitary adenomas, and treatment of different human pituitary tumor cell cultures with the DRD5 agonist SKF83959 resulted in growth suppression, and the efficacy was correlated with the expression levels of DRD5 in the tumors. Furthermore, we found that DRD5 was expressed in other human cancer cells such as glioblastomas, colon cancer, and gastric cancer. DRD5 activation in these cell lines suppressed their growth, inhibited MTOR activity, and induced autophagy. Finally, in vivo SKF83959 also inhibited human gastric cancer cell growth in nude mice. Our studies revealed novel mechanisms for the tumor suppressive effects of DRD5 agonists, and suggested a potential use of DRD5 agonists as a novel therapeutic approach in the treatment of different human tumors and cancers.

| S-EPMC5584849 | biostudies-literature

Astaxanthin Inhibits Autophagic Cell Death Induced by Bisphenol A in Human Dermal Fibroblasts.

Project description:Astaxanthin, a natural antioxidant carotenoid, is a nutrient with diverse health benefits, given that it decreases the risk of oxidative stress-related diseases. In the present study, we investigate the functional role of astaxanthin during autophagic cell death induced by the estrogenic endocrine-disrupting chemical bisphenol A (BPA) in normal human dermal fibroblasts (NHDF). BPA significantly induced apoptotic cell death and autophagy in NHDF. Autophagic cell death evoked by BPA was significantly restored upon a treatment with astaxanthin (10 μM) via the inhibition of intracellular reactive oxygen species (ROS) production. Astaxanthin inhibited the phosphorylation of extracellular signal-regulated kinases (ERK) stimulated by ROS production, but it did not influence the activation of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) in BPA-treated NHDF. Astaxanthin abrogated the ERK-mediated activation of nuclear factor-kappa B (NF-κB), which is responsible for the mRNA expression of LC3-II, Beclin-1, Atg12, and Atg14 during apoptotic cell death induced by BPA. These results indicate that astaxanthin is a pharmacological and nutritional agent that blocks the skin fibroblastic autophagic cell death induced by BPA in human dermal fibroblasts.

| S-EPMC8389241 | biostudies-literature

EZH2 inhibits autophagic cell death of aortic vascular smooth muscle cells to affect aortic dissection.

Project description:Enhancer of zeste homolog 2 (EZH2), a methyltransferase that di- and tri-methylates lysine-27 of histone H3, largely functions as a transcriptional repressor, and plays a critical role in various kinds of cancers. Here we report a novel function of EZH2 in regulating autophagic cell death (ACD) of vascular smooth muscle cells (VSMCs) that affect aortic dissection (AD). Inhibition of EZH2 activity by UNC1999 or knockdown EZH2 resulted in VSMC loss, while overexpression of EZH2 facilitated VSMC growth, and these effects of EZH2 on VSMCs were independent of proliferation and apoptosis. Interestingly, more autophagic vacuoles and increased LC3II protein levels were identified in VSMCs with EZH2 inhibition or deficiency. Moreover, when compared with counterparts, chloroquine alone, or chloroquine with rapamycin treatment led to more LC3II accumulation in EZH2 inhibited or knockdown VSMCs, which indicated that EZH2 negatively regulated autophagosome formation. In conjunction to this, ATG5 and ATG7 protein levels were remarkably increased in EZH2 inhibited or deficient VSMCs, and ATG5 or ATG7 knockdown virtually rescued VSMC loss induced by EZH2 inhibition or knockdown. In addition, we found that the MEK-ERK1/2 signaling pathway, but not AMPK?, mTOR, or AKT pathway, is responsible for the impact of EZH2 on ACD of VSMCs. Additionally, the adverse effects of EZH2 inhibition or knockdown on VSMCs were largely reversed by PD98059, an inhibitor of MEK1. More importantly, decreased EZH2 expression levels in the aortic wall of patients with AD indicated its contribution to VSMC loss and AD occurrence. Overall, these findings revealed that EZH2 affects ACD of VSMCs and the pathologic process of AD via regulating ATG5 and ATG7 expression and MEK-ERK1/2 signaling. Our hitherto unrecognized findings indicate that EZH2 activation has therapeutic or preventive potential for AD.

| S-EPMC5833461 | biostudies-literature

Autophagic activity in neuronal cell death.

Project description:As post-mitotic cells with great energy demands, neurons depend upon the homeostatic and waste-recycling functions provided by autophagy. In addition, autophagy also promotes survival during periods of harsh stress and targets aggregate-prone proteins associated with neurodegeneration for degradation. Despite this, autophagy has also been controversially described as a mechanism of programmed cell death. Instances of autophagic cell death are typically associated with elevated numbers of cytoplasmic autophagosomes, which have been assumed to lead to excessive degradation of cellular components. Due to the high activity and reliance on autophagy in neurons, these cells may be particularly susceptible to autophagic death. In this review, we summarize and assess current evidence in support of autophagic cell death in neurons, as well as how the dysregulation of autophagy commonly seen in neurodegeneration can contribute to neuron loss. From here, we discuss potential treatment strategies relevant to such cell-death pathways.

| S-EPMC5563708 | biostudies-other

Ferroptosis is an autophagic cell death process.

Project description:Ferroptosis is an iron-dependent form of regulated necrosis. It is implicated in various human diseases, including ischemic organ damage and cancer. Here, we report the crucial role of autophagy, particularly autophagic degradation of cellular iron storage proteins (a process known as ferritinophagy), in ferroptosis. Using RNAi screening coupled with subsequent genetic analysis, we identified multiple autophagy-related genes as positive regulators of ferroptosis. Ferroptosis induction led to autophagy activation and consequent degradation of ferritin and ferritinophagy cargo receptor NCOA4. Consistently, inhibition of ferritinophagy by blockage of autophagy or knockdown of NCOA4 abrogated the accumulation of ferroptosis-associated cellular labile iron and reactive oxygen species, as well as eventual ferroptotic cell death. Therefore, ferroptosis is an autophagic cell death process, and NCOA4-mediated ferritinophagy supports ferroptosis by controlling cellular iron homeostasis.

| S-EPMC5034113 | biostudies-other