Implications For Cell Survival Research Articles

RETRACTION: Nuclear Clusterin Accumulation during Heat Shock Response: Implications for Cell Survival and Thermo-tolerance Induction in Immortalized and Prostate Cancer Cells.

A. E. Caccamo, S. Desenzani, L. Belloni, A. F. Borghetti, S. Bettuzzi, "Nuclear Clusterin Accumulation during Heat Shock Response: Implications for Cell Survival and Thermo-tolerance Induction in Immortalized and Prostate Cancer Cells," Journal of Cellular Physiology 207, no. 1 (2006): 208-219, https://doi.org/10.1002/jcp.20561. The above article, published online on 5 December 2005 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal Editor-in-Chief, Alexander Hutchison; and Wiley Periodicals LLC. The retraction has been agreed following allegations raised by third parties. Several lanes within the Western Blot images displayed in Figures 1 A, 2 A, 2B, and 7 were found to display highly similar patterns despite depicting protein extracts from samples of different origin/treatment. As the raw data could not be retrieved due to the significant time elapsed since publication, the concerns could not be addressed. In light of the significant number of concerns, the editors have lost trust in the overall accuracy of the data presented. The corresponding author S. Bettuzzi disagrees with the decision of retraction. Confirmation of retraction could not be obtained by the remaining co-authors.

NO-iron compounds release NO after exposure to UVA radiation: implications for cell survival in the in vitro skin models

NO-iron compounds release NO after exposure to UVA radiation: implications for cell survival in the in vitro skin models

A Comparative Assessment of Replication Stress Markers in the Context of Telomerase.

Simple SummaryGenetic alterations such as oncogenic- or aneuploidy-inducing mutations can induce replication stress as a tumor protection mechansim. Previous data indicated that telomerase may ameliorate the cellular responses that induce replication stress. However, the mechanisms how this may occur are still unclear. In order to address this question, the accurate evaluation of replication stress in the presence and absence of telomerase is crucial. Therefore, we used telomerase negative normal human fibroblasts, as well as their telomerase positive counterparts to compare the suitability of three protein markers (pRPA2, γ-H2AX and 53BP1), which were previously reported to accumulate in response to harmful conditions leading to replication stress in cells. In summary, we find that pRPA2 is the most consistent and reliable marker for the detection of replication stress. Further, we demonstrated that the inhibition of the DNA-damage activated ATM and ATR kinases by specific small compounds impaired the accumulation of pRPA2 foci in the absence of telomerase. These data suggest that telomerase rescues the cells from replication stress upon supression of DNA damage induction by modulating the ATM and ATR signaling pathways, and may therefore support tumor formation of genetically unstable cells.Aberrant replication stress (RS) is a source of genome instability and has serious implications for cell survival and tumourigenesis. Therefore, the detection of RS and the identification of the underlying molecular mechanisms are crucial for the understanding of tumourigenesis. Currently, three protein markers—p33-phosphorylated replication protein A2 (pRPA2), γ-phosphorylated H2AX (γ-H2AX), and Tumor Protein P53 Binding Protein 1 (53BP1)—are frequently used to detect RS. However, to our knowledge, there is no report that compares their suitability for the detection of different sources of RS. Therefore, in this study, we evaluate the suitability of pRPA2, γ-H2AX, and 53BP1 for the detection of RS caused by different sources of RS. In addition, we examine their suitability as markers of the telomerase-mediated alleviation of RS. For these purposes, we use here telomerase-negative human fibroblasts (BJ) and their telomerase-immortalized counterparts (BJ-hTERT). Replication stress was induced by the ectopic expression of the oncogenic RAS mutant RASG12V (OI-RS), by the knockdown of ploidy-control genes ORP3 or MAD2 (AI-RS), and by treatment with hydrogen peroxide (ROS-induced RS). The level of RS was determined by immunofluorescence staining for pRPA2, γ-H2AX, and 53BP1. Evaluation of the staining results revealed that pRPA2- and γ-H2AX provide a significant and reliable assessment of OI-RS and AI-RS compared to 53BP1. On the other hand, 53BP1 and pRPA2 proved to be superior to γ-H2AX for the evaluation of ROS-induced RS. Moreover, the data showed that among the tested markers, pRPA2 is best suited to evaluate the telomerase-mediated suppression of all three types of RS. In summary, the data indicate that the choice of marker is important for the evaluation of RS activated through different conditions.

34 - High Affinity NGF TrkA Receptors are Expressed in Gastric Endothelial Cells Mitochondria & Membranes and Translocate to Nucleus Upon NGF Stimulation in a Manner Independent of PI3K. Implications for Cell Survival and Angiogenesis

34 - High Affinity NGF TrkA Receptors are Expressed in Gastric Endothelial Cells Mitochondria & Membranes and Translocate to Nucleus Upon NGF Stimulation in a Manner Independent of PI3K. Implications for Cell Survival and Angiogenesis

SIRT1 interacts with and protects glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from nuclear translocation: Implications for cell survival after irradiation

Upon apoptotic stimulation, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a cytosolic enzyme normally active in glycolysis, translocates into the nucleus and activates an apoptotic cascade therein. In the present work, we show that SIRT1 prevents nuclear translocation of GAPDH via interaction with GAPDH. SIRT1 depletion triggered nuclear translocation of cytosolic GAPDH even in the absence of apoptotic stress. Such translocation was not, however, observed when SIRT1 enzymatic activity was inhibited, indicating that SIRT1 protein per se, rather than the deacetylase activity of the protein, is required to inhibit GAPDH translocation. Upon irradiation, SIRT1 prevented irradiation-induced nuclear translocation of GAPDH, accompanied by interaction of SIRT1 and GAPDH. Thus, SIRT1 functions to retain GAPDH in the cytosol, protecting the enzyme from nuclear translocation via interaction with these two proteins. This serves as a mechanism whereby SIRT1 regulates cell survival upon induction of apoptotic stress by means that include irradiation.

Oxygen diffusion through collagen scaffolds at defined densities: implications for cell survival in tissue models

For the success of any biomaterial for tissue engineering, its mechanical properties and ability to support nutrient diffusion will be critical. Collagen scaffolds are ideal candidates, due to their ability to immerse cells in a biomimetic nanofibrous matrix. We have established O(2) diffusion coefficients through native, dense collagen scaffolds at two tissue-like densities, with and without photo-chemical crosslinking, by adapting an optical fibre-based system for real-time core O(2) monitoring deep within collagen constructs. Using a Fick's law model, we then derived O(2) diffusion coefficients; 4.5 × 10(-6) cm(2) /s for 11% density collagen scaffolds; 1.7 × 10(-6) cm(2) /s for 34% collagen scaffolds; 3.4 × 10(-6) cm(2) /s for photochemically crosslinked collagen scaffolds at 11%. Both O(2) diffusion coefficients of the 11% collagen fall within the range of native intestinal submucosa. The high diffusion coefficients of these collagen scaffolds, as well as their material properties, render them viable tissue-engineering matrices for tissue replacement.

Flightless I Regulates Hemidesmosome Formation and Integrin-Mediated Cellular Adhesion and Migration during Wound Repair

Flightless I (Flii), a highly conserved member of the gelsolin family of actin-remodelling proteins associates with actin structures and is involved in cellular motility and adhesion. Our previous studies have shown that Flii is an important negative regulator of wound repair. Here, we show that Flii affects hemidesmosome formation and integrin-mediated keratinocyte adhesion and migration. Impaired hemidesmosome formation and sparse arrangements of keratin cytoskeleton tonofilaments and actin cytoskeleton anchoring fibrils were observed in Flii(Tg/+) and Flii(Tg/Tg) mice with their skin being significantly more fragile than Flii(+/-) and WT mice. Flii(+/-) primary keratinocytes showed increased adhesion on laminin and collagen I than WT and Flii(Tg/Tg) primary keratinocytes. Decreased expression of CD151 and laminin-binding integrins alpha3, beta1, alpha6 and beta4 were observed in Flii overexpressing wounds, which could contribute to the impaired wound re-epithelialization observed in these mice. Flii interacts with proteins directly linked to the cytoplasmic domain of integrin receptors suggesting that it may be a mechanical link between ligand-bound integrin receptors and the actin cytoskeleton driving adhesion-signaling pathways. Therefore Flii may regulate wound repair through its effect on hemidesmosome formation and integrin-mediated cellular adhesion and migration.

ZEB1 Links p63 and p73 in a Novel Neuronal Survival Pathway Rapidly Induced in Response to Cortical Ischemia

BackgroundAcute hypoxic/ischemic insults to the forebrain, often resulting in significant cellular loss of the cortical parenchyma, are a major cause of debilitating injury in the industrialized world. A clearer understanding of the pro-death/pro-survival signaling pathways and their downstream targets is critical to the development of therapeutic interventions to mitigate permanent neurological damage.Methodology/Principal FindingsWe demonstrate here that the transcriptional repressor ZEB1, thought to be involved in regulating the timing and spatial boundaries of basic-Helix-Loop-Helix transactivator-mediated neurogenic determination/differentiation programs, functions to link a pro-survival transcriptional cascade rapidly induced in cortical neurons in response to experimentally induced ischemia. Employing histological, tissue culture, and molecular biological read-outs, we show that this novel pro-survival response, initiated through the rapid induction of p63, is mediated ultimately by the transcriptional repression of a pro-apoptotic isoform of p73 by ZEB1. We show further that this phylogenetically conserved pathway is induced as well in the human cortex subjected to episodes of clinically relevant stroke.Conclusions/SignificanceThe data presented here provide the first evidence that ZEB1 induction is part of a protective response by neurons to ischemia. The stroke-induced increase in ZEB1 mRNA and protein levels in cortical neurons is both developmentally and phylogenetically conserved and may therefore be part of a fundamental cellular response to this insult. Beyond the context of stroke, the finding that ZEB1 is regulated by a member of the p53 family has implications for cell survival in other tissue and cellular environments subjected to ischemia, such as the myocardium and, in particular, tumor masses.

Mitochondrial Targeting of Adenomatous Polyposis Coli Protein Is Stimulated by Truncating Cancer Mutations: REGULATION OF Bcl-2 AND IMPLICATIONS FOR CELL SURVIVAL

The adenomatous polyposis coli (APC) protein tumor suppressor is mutated in the majority of colon cancers. Most APC gene mutations cause deletion of the C terminus and disrupt APC regulation of beta-catenin turnover, microtubule dynamics, and chromosome segregation. Truncated APC mutant peptides may also gain unique properties, not exhibited by wild-type APC, which contribute to tumor cell survival and proliferation. Here we report a differential subcellular localization pattern for wild-type and mutant APC. A pool of APC truncation mutants was detected at mitochondria by cellular fractionation and confocal microscopy. In contrast, wild-type APC located poorly at mitochondria. Similar results were observed for endogenous and stably induced forms of APC, with the shortest N-terminal mutant peptides (N750, N853, N1309, N1337) displaying the strongest mitochondrial staining. The knock down of mutant APC(N1337) in SW480 tumor cells caused an increase in apoptosis and mitochondrial membrane permeability, and this correlated with reduced Bcl-2 protein levels in mitochondrial fractions. Interestingly, the silencing of APC did not alter expression of beta-catenin or the apoptotic regulatory factors Bax, Bcl-xL, or survivin. APC formed a complex with Bcl-2 in mitochondrial fractions, and this may contribute to the APC-dependent regulation of Bcl-2. We propose that a subset of cancer mutations induce APC mitochondrial localization and that APC regulation of Bcl-2 at mitochondria may contribute to tumor cell survival.

B-MYB is hypophosphorylated and resistant to degradation in neuroblastoma: Implications for cell survival

B-MYB is an oncoprotein highly expressed and frequently amplified in human neoplasia. B-MYB is more expressed in neuroblastoma patients with adverse prognostic indicators, corroborating the hypothesis that it plays an important role in this pediatric malignancy. While attempting targeting strategies for therapeutic purposes, we found that the B-MYB protein was difficult to downregulate in neuroblastoma cells using siRNA approaches. This lead us to discover that the B-MYB protein half-life is increased in neuroblastoma compared to other normal or transformed human cell lines. The B-MYB protein is quickly destroyed and apoptosis is induced in Ewing sarcoma cells exposed to UV irradiation. In contrast, neuroblastoma cells are resistant to UV-induced apoptosis and B-MYB protein levels do not change in UV-treated cells. In further experiments, we show that the B-MYB protein extracted from neuroblastoma cells is hypophosphorylated. It was previously shown that B-MYB phosphorylation activates its transcriptional activity but also promotes its destruction. Overexpression of a non-phosphorylatable B-MYB mutant protects cells from UV-induced apoptosis, suggesting that its reduced phosphorylation, rather than causing its inactivation, facilitates B-MYB pro-survival activity. Thus, expression of stable, hypophosphorylated B-MYB in neuroblastoma may promote cell survival and induce aggressive tumour growth.

Nuclear clusterin accumulation during heat shock response: implications for cell survival and thermo-tolerance induction in immortalized and prostate cancer cells.

Clusterin (CLU), whose role is still debated, is differentially regulated in several patho-physiological processes and invariably induced during apoptosis. In heat shock response, CLU is considered a stress-inducible, pro-survival/cyto-protective factor via an HSE element present in his promoter. In both human prostate PNT1A and PC-3 epithelial cells we found that apoptotic stimuli induced nuclear localization of CLU (nCLU), and that overexpression of nCLU is pro-apoptotic. We show here that CLU time-course accumulation kinetic is different from that of HSP70 in these cells, thus other factor(s) might mediate HSF-1 activation and CLU expression. Sub-lethal heat shock inhibited the secretion of CLU (sCLU), leading to increased cytoplasm accumulation of CLU (cCLU) in association to cell survival. At difference, lethal heat stress caused massive accumulation of pro-apoptotic nCLU in cells dying by caspase-3-dependent apoptosis. Double heat stress (sub-lethal heat shock followed by recovery and lethal stress) induced HSP70 and thermo-tolerance in PNT1A cells, but not in PC-3 cells. In PNT1A cells, CLU secretion was inhibited and cCLU was accumulated, suggesting that cCLU might be pro-survival, while in PC-3 cells accumulation of nCLU was concomitant to caspase-3 induction and PARP activation instead. Thus, CLU expression/sub-cellular localization is strictly related to cell fate. In particular, nCLU and physiological levels of HSP70 affected cell survival in an antagonistic fashion. Prevalence of heat-induced nCLU, not allowing PC-3 cells to cope with heat shock, could be the rational explaining why malignant cells are more sensitive to heat when delivered by minimally invasive procedures for ablation of localized prostate cancer.

Mechanisms of Neuroprotection by Polyphenols

Several lines of evidence suggest a role for oxidative cascades of events leading to neurodegeneration associated with Parkinsons, Alzheimer, Huntington diseases, and amyotrophic lateral sclerosis. In agreement with the notion of oxidative/nitrosative involvement in these chronic diseases, in vivo models of disease as well as biochemical and epidemiological evidence suggest a neuroprotective role for natural antioxidant polyphenols in neurodegenerative diseases. However, the molecular mechanisms for neuroprotection do not merely rely on a direct radical scavenging/antioxidant activity. Rather, polyphenols may function at several cellular levels, including direct interaction and modulation of enzymatic activities and the regulation of signaling pathways with implications for cell survival and death. Nitric oxide is a paradigmatic example. In view of the wide collection of activities of nitric oxide in the brain, ranging from synaptic plasticity to excitotoxicity, the regulation of its rate and pattern of production and decay in tissues by polyphenols is of obvious physiological relevance. Thus, the elucidation of polyphenol activities at the molecular level may lay the foundations for new pharmacological approaches in relation to neurodegeneration. In this review, the molecular mechanisms underlying the potential health promoting effects of natural polyphenols in connection with neurodegenerative diseases are discussed. Additionally, we provide evidence for a modulatory effect of hydroxycinnamic phenol caffeic acid on glutamate NMDA receptor/nitric oxide pathway in hippocampal slices. Keywords: flavanols, reactive nitrogen species (RNS), age-related neurological disorder, antioxidant, gene expression, topoisomerase

Attenuated 5-HT1A receptor signaling in brains of suicide victims: involvement of adenylyl cyclase, phosphatidylinositol 3-kinase, Akt and mitogen-activated protein kinase.

Positron emission tomography studies in major depression show reduced serotonin (5-HT)1A receptor antagonist-binding potentials in many brain regions including occipital cortex. The functional meaning of this observation in terms of signal transduction is unknown. We used postmortem brain samples from depressed suicide victims to examine the downstream effectors of 5-HT1A receptor activation. The diagnosis was established by means of psychological autopsy using Diagnostic and Statistical Manual of Mental Disorders (DSM) III-R criteria. Measurements of [35S]GTPgammaS binding to Galphai/o in the occipital cortex of suicide victims and matched controls revealed a blunted response in suicide subjects and a decrease in the coupling of 5-HT1A receptor to adenylyl cyclase. No significant group differences were detected in the expression levels of Galphai/o, Galphaq/11 or Galphas proteins, or in the activity of cAMP-dependent protein kinase A. Studies of a parallel transduction pathway downstream from 5-HT1A receptor activation demonstrated a decrease in the activity of phosphatidylinositol 3-kinase and its downstream effector Akt, as well as an increase in PTEN (phosphatase and tensin homolog deleted on chromosome 10), the phosphatase that hydrolyzes phosphatidylinositol 3,4,5-triphosphate. Finally, the activation of extracellular signal-regulated kinases 1 and 2 was attenuated in suicide victims. These data suggest that the alterations in agonist-stimulated 5-HT1A receptor activation in depressed suicide victims are also manifest downstream from the associated G protein, affecting the activity of second messengers in two 5-HT1A receptor transduction pathways that may have implications for cell survival.

Costimulation of resting B lymphocytes alters the IL-4-activated IRS2 signaling pathway in a STAT6 independent manner: implications for cell survival and proliferation.

IL-4 is an important B cell survival and growth factor. IL-4 induced the tyrosine phosphorylation of IRS2 in resting B lymphocytes and in LPS- or CD40L-activated blasts. Phosphorylated IRS2 coprecipitated with the p85 subunit of PI 3' kinase in both resting and activated cells. By contrast, association of phosphorylated IRS2 with GRB2 was not detected in resting B cells after IL-4 treatment although both proteins were expressed. However, IL-4 induced association of IRS2 with GRB2 in B cell blasts. The pattern of IL-4-induced recruitment of p85 and GRB2 to IRS2 observed in B cells derived from STAT6 null mice was identical to that observed for normal mice. While IL-4 alone does not induce activation of MEK, a MEK1 inhibitor suppressed the IL-4-induced proliferative response of LPS-activated B cell blasts. These results demonstrate that costimulation of splenic B cells alters IL-4-induced signal transduction independent of STAT6 leading to proliferation. Furthermore, proliferation induced by IL-4 in LPS-activated blasts is dependent upon the MAP kinase pathway.

The effect of an hypoxic cell sensitizer on tumour growth delay and cell survival. Implications for cell survival in situ and in vitro.

A comparison has been made of the effects of the 2-nitroimidazole Ro-07-0582 on tumour growth delay after irradiation and tumour cell survival in vitro after irradiation in vivo. This compound has previously been shown to be a specific sensitizer of hypoxic cells. A dose of 1 mg/g body weight gave an enhancement ratio of 2-2 for both growth delay and cell survival in a system where high pressure oxygen has been shown to have no effect. However, while the hypoxic fraction in the tumour was estimated to be less then 10% from the growth delay curves, the survival curves gave a value in excess of 50%. This discrepancy probably reflects differences in the response of cells left in situ or removed and assayed in vitro.