scholarly journals The translocator protein (TSPO) is prodromal to mitophagy loss in neurotoxicity

2021 ◽  
Author(s):  
Michele Frison ◽  
Danilo Faccenda ◽  
Rosella Abeti ◽  
Manuel Rigon ◽  
Daniela Strobbe ◽  
...  
Keyword(s):  
Cell Death ◽  
Transcription Factor ◽  
Translocator Protein ◽  
Redox Stress ◽  
Cellular Redox ◽  
Extracellular Signal ◽  
Transcription Factor Eb ◽  
Stress Susceptibility

AbstractDysfunctional mitochondria characterise Parkinson’s Disease (PD). Uncovering etiological molecules, which harm the homeostasis of mitochondria in response to pathological cues, is therefore pivotal to inform early diagnosis and therapy in the condition, especially in its idiopathic forms. This study proposes the 18 kDa Translocator Protein (TSPO) to be one of those. Both in vitro and in vivo data show that neurotoxins, which phenotypically mimic PD, increase TSPO to enhance cellular redox-stress, susceptibility to dopamine-induced cell death, and repression of ubiquitin-dependent mitophagy. TSPO amplifies the extracellular signal-regulated protein kinase 1 and 2 (ERK1/2) signalling, forming positive feedback, which represses the transcription factor EB (TFEB) and the controlled production of lysosomes. Finally, genetic variances in the transcriptome confirm that TSPO is required to alter the autophagy–lysosomal pathway during neurotoxicity.

Doxorubicin impairs cardiomyocyte viability by suppressing transcription factor EB expression and disrupting autophagy

2016 ◽  
Vol 473 (21) ◽  
pp. 3769-3789 ◽  
Author(s):  
Jordan J. Bartlett ◽  
Purvi C. Trivedi ◽  
Pollen Yeung ◽  
Petra C. Kienesberger ◽  
Thomas Pulinilkunnil
Keyword(s):  
Cell Death ◽  
Transcription Factor ◽  
Cathepsin B ◽  
Ex Vivo ◽  
Calcium Flux ◽  
Autophagic Flux ◽  
Mitochondrial Energy Metabolism ◽  
Transcription Factor Eb

Doxorubicin (DOX) is an effective anti-cancer agent. However, DOX treatment increases patient susceptibility to dilated cardiomyopathy. DOX predisposes cardiomyocytes to insult by suppressing mitochondrial energy metabolism, altering calcium flux, and disrupting proteolysis and proteostasis. Prior studies have assessed the role of macroautophagy in DOX cardiotoxicity; however, limited studies have examined whether DOX mediates cardiac injury through dysfunctions in inter- and/or intra-lysosomal signaling events. Lysosomal signaling and function is governed by transcription factor EB (TFEB). In the present study, we hypothesized that DOX caused myocyte injury by impairing lysosomal function and signaling through negative regulation of TFEB. Indeed, we found that DOX repressed cellular TFEB expression, which was associated with impaired cathepsin proteolytic activity across in vivo, ex vivo, and in vitro models of DOX cardiotoxicity. Furthermore, we observed that loss of TFEB was associated with reduction in macroautophagy protein expression, inhibition of autophagic flux, impairments in lysosomal cathepsin B activity, and activation of cell death. Restoration and/or activation of TFEB in DOX-treated cardiomyocytes prevented DOX-induced suppression of cathepsin B activity, reduced DOX-mediated reactive oxygen species (ROS) overproduction, attenuated activation of caspase-3, and improved cellular viability. Collectively, loss of TFEB inhibits lysosomal autophagy, rendering cardiomyocytes susceptible to DOX-induced proteotoxicity and injury. Our data reveal a novel mechanism wherein DOX primes cardiomyocytes for cell death by depleting cellular TFEB.

scholarly journals RIP3 impedes transcription factor EB to suppress autophagic degradation in septic acute kidney injury

2021 ◽  
Vol 12 (6) ◽  
Author(s):  
Ruizhao Li ◽  
Xingchen Zhao ◽  
Shu Zhang ◽  
Wei Dong ◽  
Li Zhang ◽  
...  
Keyword(s):  
Acute Kidney Injury ◽  
Transcription Factor ◽  
Nuclear Translocation ◽  
Kidney Injury ◽  
Septic Acute Kidney Injury ◽  
Transcription Factor Eb ◽  
Autophagic Degradation ◽  
Lps Treatment

AbstractAutophagy is an important renal-protective mechanism in septic acute kidney injury (AKI). Receptor interacting protein kinase 3 (RIP3) has been implicated in the renal tubular injury and renal dysfunction during septic AKI. Here we investigated the role and mechanism of RIP3 on autophagy in septic AKI. We showed an activation of RIP3, accompanied by an accumulation of the autophagosome marker LC3II and the autophagic substrate p62, in the kidneys of lipopolysaccharide (LPS)-induced septic AKI mice and LPS-treated cultured renal proximal tubular epithelial cells (PTECs). The lysosome inhibitor did not further increase the levels of LCII or p62 in LPS-treated PTECs. Moreover, inhibition of RIP3 attenuated the aberrant accumulation of LC3II and p62 under LPS treatment in vivo and in vitro. By utilizing mCherry-GFP-LC3 autophagy reporter mice in vivo and PTECs overexpression mRFP-GFP-LC3 in vitro, we observed that inhibition of RIP3 restored the formation of autolysosomes and eliminated the accumulated autophagosomes under LPS treatment. These results indicated that RIP3 impaired autophagic degradation, contributing to the accumulation of autophagosomes. Mechanistically, the nuclear translocation of transcription factor EB (TFEB), a master regulator of the lysosome and autophagy pathway, was inhibited in LPS-induced mice and LPS-treated PTECs. Inhibition of RIP3 restored the nuclear translocation of TFEB in vivo and in vitro. Co-immunoprecipitation further showed an interaction of RIP3 and TFEB in LPS-treated PTECs. Also, the expression of LAMP1 and cathepsin B, two potential target genes of TFEB involved in lysosome function, were decreased under LPS treatment in vivo and in vitro, and this decrease was rescued by inhibiting RIP3. Finally, overexpression of TFEB restored the autophagic degradation in LPS-treated PTECs. Together, the present study has identified a pivotal role of RIP3 in suppressing autophagic degradation through impeding the TFEB-lysosome pathway in septic AKI, providing potential therapeutic targets for the prevention and treatment of septic AKI.

scholarly journals Expression and subcellular localization of BNIP3 in hypoxic hepatocytes and liver stress

2009 ◽  
Vol 296 (3) ◽  
pp. G499-G509 ◽  
Author(s):  
Mallikarjuna R. Metukuri ◽  
Donna Beer-Stolz ◽  
Rajaie A. Namas ◽  
Rajeev Dhupar ◽  
Andres Torres ◽  
...  
Keyword(s):  
Cell Death ◽  
Western Blot ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Ischemia Reperfusion ◽  
Redox Stress ◽  
No Donor ◽  
Interacting Protein

We have previously demonstrated that the Bcl-2/adenovirus EIB 19-kDa interacting protein 3 (BNIP3), a cell death-related member of the Bcl-2 family, is upregulated in vitro and in vivo in both experimental and clinical settings of redox stress and that nitric oxide (NO) downregulates its expression. In this study we sought to examine the expression and localization of BNIP3 in murine hepatocytes and in a murine model of hemorrhagic shock (HS) and ischemia-reperfusion (I/R). Freshly isolated mouse hepatocytes were exposed to 1% hypoxia for 6 h followed by reoxygenation for 18 h, and protein was isolated for Western blot analysis. Hepatocytes grown on coverslips were fixed for localization studies. Similarly, livers from surgically cannulated C57Bl/6 mice and from mice cannulated and subjected to 1–4 h of HS were processed for protein isolation and Western blot analysis. In hepatocytes, BNIP3 was expressed constitutively but was upregulated under hypoxic conditions, and this upregulation was countered by treatment with a NO donor. Surprisingly, BNIP3 was localized in the nucleus of normoxic hepatocytes, in the cytoplasm following hypoxia, and again in the nucleus following reoxygenation. Upregulation of BNIP3 partially required p38 MAPK activation. BNIP3 contributed to hypoxic injury in hepatocytes, since this injury was diminished by knockdown of BNIP3 mRNA. Hepatic BNIP3 was also upregulated in two different models of liver stress in vivo, suggesting that a multitude of inflammatory stresses can lead to the modulation of BNIP3. In turn, the upregulation of BNIP3 appears to be one mechanism of hepatocyte cell death and liver damage in these settings.

scholarly journals A Novel Transcription Factor, ERD15 (Early Responsive to Dehydration 15), Connects Endoplasmic Reticulum Stress with an Osmotic Stress-induced Cell Death Signal

2011 ◽  
Vol 286 (22) ◽  
pp. 20020-20030 ◽  
Author(s):  
Murilo S. Alves ◽  
Pedro A. B. Reis ◽  
Silvana P. Dadalto ◽  
Jerusa A. Q. A. Faria ◽  
Elizabeth P. B. Fontes ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Transcription Factor ◽  
Osmotic Stress ◽  
Er Stress ◽  
Unfolded Protein ◽  
Eukaryotic Organisms ◽  
Protein Response

As in all other eukaryotic organisms, endoplasmic reticulum (ER) stress triggers the evolutionarily conserved unfolded protein response in soybean, but it also communicates with other adaptive signaling responses, such as osmotic stress-induced and ER stress-induced programmed cell death. These two signaling pathways converge at the level of gene transcription to activate an integrated cascade that is mediated by N-rich proteins (NRPs). Here, we describe a novel transcription factor, GmERD15 (Glycine max Early Responsive to Dehydration 15), which is induced by ER stress and osmotic stress to activate the expression of NRP genes. GmERD15 was isolated because of its capacity to stably associate with the NRP-B promoter in yeast. It specifically binds to a 187-bp fragment of the NRP-B promoter in vitro and activates the transcription of a reporter gene in yeast. Furthermore, GmERD15 was found in both the cytoplasm and the nucleus, and a ChIP assay revealed that it binds to the NRP-B promoter in vivo. Expression of GmERD15 in soybean protoplasts activated the NRP-B promoter and induced expression of the NRP-B gene. Collectively, these results support the interpretation that GmERD15 functions as an upstream component of stress-induced NRP-B-mediated signaling to connect stress in the ER to an osmotic stress-induced cell death signal.

Potent Antineoplastic Activity of Two Inhibitors of Lymphoid Enhancer Binding Factor-1 (LEF-1) in Chronic Lymphocytic Leukemia (B-CLL).

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 885-885
Author(s):  
Rajesh Kumar Gandhirajan ◽  
Iris Gehrke ◽  
Alexandra Filipovich ◽  
Julian Paesler ◽  
Regina Razavi ◽  
...  
Keyword(s):  
Cell Death ◽  
Transcription Factor ◽  
B Cells ◽  
Small Molecules ◽  
Target Genes ◽  
Down Regulation ◽  
Binding Factor ◽  
Subcutaneous Xenograft

Abstract Abstract 885 Recent studies indicate factors governing aberrant activation of WNT signaling in chronic lymphoctic leukemia (CLL) cells. Thus, there is an increased secretion of WNT ligands indicating an autocrine loop leading to the extended survival of CLL cells. Lymphoid enhancer binding factor-1 (LEF-1) is a potent transcription factor regulating the expression of several WNT induced target genes. A comprehensive gene expression profiling from two independent studies revealed that LEF-1 mRNA was ∼3,000 fold overexpressed in B-CLL when compared to its healthy counterpart. Hence LEF-1 is a transcription factor expressed exclusively in CLL cells. The objective of this present study is to demonstrate the therapeutic benefit of inhibiting LEF-1 expression in B-CLL cells using novel small molecule inhibitors CGP049090 and PKF115-584 in vivo and in vitro. JVM-3 cells and primary CLL cells were investigated by siRNA mediated knock down of LEF-1 and viability was assayed after 16h of incubation by flow cytometry. In vitro cytotoxicity and IC50 of the two compounds was enumerated using ATP based cell viability assay. Apoptotic response was investigated in time course experiments. Specificity of the small molecules was demonstrated by co-immunoprecipitation experiments for the LEF-1/βcatenin interaction in primary CLL cells. In vivo efficacy of the small molecules inhibitors were studied using a JVM-3 subcutaneous xenograft model in nu/nu mice. The results indicate there is a high protein expression and nuclear localization of LEF-1 and β-catenin indicating active LEF-1 mediated transcription in CLL cells, whereas LEF-1 remained undetectable in healthy B cells. Preliminary experiments of LEF-1 inhibition using siRNAs resulted in increased apoptosis indicating LEF-1 to be an important player in the survival of B-CLL cells. This observation was extended using CGP049090 and PKF-115584 as they induce both dose and time dependent cytotoxicity in B-CLL, whereas healthy B cells are not significantly affected. The IC50 for CGP049090 and PKF-115584 in CLL cells were 0.7 μM and 0.9 μM, respectively. Healthy B cells were not significantly affected, as ascertained by the fact that IC50 values could not be reached due to lacking total cell death. CGP049090 and PKF-115584 induced apoptotic cell death in primary CLL cells and cell lines by cleavage of caspases 8, 9, 3 and 7 and subsequent cleavage of poly (adenosine diphospate-ribose) polymerase (PARP). Both the inhibitors also altered the expression of several anti apoptotic proteins like XIAP, mcl-1 and bcl-2. Co-immunoprecipitation experiments revealed that both the inhibitors effectively break the β-catenin/LEF-1 interaction, resulting in down regulation of expression of LEF-1 target genes such as c-myc, cyclin D1 and LEF-1. Furthermore, the inhibitors were tested in an in vivo JVM-3 subcutaneous xenograft nude mouse model resulted in >70% inhibition of tumor growth and an increase in the median survival of the treated group without leading to systemic toxicity. Immunohistochemistry analysis of the tumor sections revealed LEF-1 down regulation paralleled by inhibition of proliferation by down regulation of Proliferating Cell Nuclear Antigen (PCNA) and increase in apoptosis (induction of cleaved PARP). In summary, we show that LEF-1 is a potential therapeutic target in the treatment of CLL. Both CGP049090 and PKF115-584 show potent inhibitory effects on the survival of CLL cells in vitro and in vivo without affecting healthy B-cells, suggesting them as potential anti-cancer agents in CLL and other neoplastic malignancies with aberrant LEF-1/TCF transcriptional activity. Further investigations are warranted to determine the feasibility of these small molecules for therapeutic approaches in humans. Disclosures: Schlösser: Novartis: Employment. Schmitt:Novartis: Employment. Hallek:BayerScheringAG: Honoraria, Research Funding.

scholarly journals Multiple Mechanisms Converging on Transcription Factor EB Activation by the Natural Phenol Pterostilbene

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Martina La Spina ◽  
Michele Azzolini ◽  
Andrea Salmaso ◽  
Sofia Parrasia ◽  
Eva Galletta ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Therapeutic Potential ◽  
Body Weight Gain ◽  
Mitochondrial Respiratory Chain ◽  
Reduced Body ◽  
Diet Induced Obesity ◽  
Activation Of Transcription ◽  
Transcription Factor Eb

Pterostilbene (Pt) is a potentially beneficial plant phenol. In contrast to many other natural compounds (including the more celebrated resveratrol), Pt concentrations producing significant effects in vitro can also be reached with relative ease in vivo. Here we focus on some of the mechanisms underlying its activity, those involved in the activation of transcription factor EB (TFEB). A set of processes leading to this outcome starts with the generation of ROS, attributed to the interaction of Pt with complex I of the mitochondrial respiratory chain, and spreads to involve Ca2+ mobilization from the ER/mitochondria pool, activation of CREB and AMPK, and inhibition of mTORC1. TFEB migration to the nucleus results in the upregulation of autophagy and lysosomal and mitochondrial biogenesis. Cells exposed to several μM levels of Pt experience a mitochondrial crisis, an indication for using low doses in therapeutic or nutraceutical applications. Pt afforded significant functional improvements in a zebrafish embryo model of ColVI-related myopathy, a pathology which also involves defective autophagy. Furthermore, long-term supplementation with Pt reduced body weight gain and increased transcription levels of Ppargc1a and Tfeb in a mouse model of diet-induced obesity. These in vivo findings strengthen the in vitro observations and highlight the therapeutic potential of this natural compound.

scholarly journals Caspase-dependent Regulation of Histone Deacetylase 4 Nuclear-Cytoplasmic Shuttling Promotes Apoptosis

2004 ◽  
Vol 15 (6) ◽  
pp. 2804-2818 ◽  
Author(s):  
Gabriela Paroni ◽  
Michela Mizzau ◽  
Clare Henderson ◽  
Giannino Del Sal ◽  
Claudio Schneider ◽  
...  
Keyword(s):  
Cell Death ◽  
Transcription Factor ◽  
Caspase 3 ◽  
Dependent Manner ◽  
Cytochrome C Release ◽  
Amino Terminal ◽  
Terminal Fragment ◽  
Amino Terminal Fragment

Histone deacetylases (HDACs) are important regulators of gene expression as part of transcriptional corepressor complexes. Here, we demonstrate that caspases can repress the activity of the myocyte enhancer factor (MEF)2C transcription factor by regulating HDAC4 processing. Cleavage of HDAC4 occurs at Asp 289 and disjoins the carboxy-terminal fragment, localized into the cytoplasm, from the amino-terminal fragment, which accumulates into the nucleus. In the nucleus, the caspase-generated fragment of HDAC4 is able to trigger cytochrome c release from mitochondria and cell death in a caspase-9–dependent manner. The caspase-cleaved amino-terminal fragment of HDAC4 acts as a strong repressor of the transcription factor MEF2C, independently from the HDAC domain. Removal of amino acids 166–289 from the caspase-cleaved fragment of HDAC4 abrogates its ability to repress MEF2 transcription and to induce cell death. Caspase-2 and caspase-3 cleave HDAC4 in vitro and caspase-3 is critical for HDAC4 cleavage in vivo during UV-induced apoptosis. After UV irradiation, GFP-HDAC4 translocates into the nucleus coincidentally/immediately before the retraction response, but clearly before nuclear fragmentation. Together, our data indicate that caspases could specifically modulate gene repression and apoptosis through the proteolyic processing of HDAC4.

L-Tetrahydropalmatine Inhibits the Progression of Glioblastoma Tumor by Suppressing the Extracellular-Signal-Regulated Kinase/Nuclear Factor-Kappa B Signaling Pathway

2020 ◽  
Vol 19 (2) ◽  
pp. 164-171
Author(s):  
Feng Xue ◽  
Tingting Chen
Keyword(s):  
Glioblastoma Multiforme ◽  
Nuclear Factor Kappa B ◽  
Matrix Metalloproteinase 2 ◽  
Nuclear Factor ◽  
Nuclear Factor Kappa ◽  
Extracellular Signal ◽  
Apoptosis Protein ◽  
Endothelial Growth Factor

Glioblastoma multiforme is the most common malignancy of central nervous system. Herein we have evaluated the effect of L-tetrahydropalmatine, an isoquinoline alkaloid, on the tumor growth both in vivo and in vitro using C6 glioblastoma multiforme cells and BALB/c mice injected subcutaneously with C6/luc2 cells. The results of these studies show that L-tetrahydropalmatine exhibited cytotoxic effect on C6 glioblastoma multiforme cells, suppressed nuclear factor-kappa B activity, suppressed the levels of tumor-linked proteins such as matrix metalloproteinase-2/9, Cyclin-D1, vascular endothelial growth factor, and X-linked inhibitor of apoptosis protein via ERK/nuclear factor-kappa B cascade. Further, L-tetrahydropalmatine inhibited the cell migration and invasion properties of C6 cells, and also suppressed the tumor weight and volume in mice. Immunohistochemical staining of tumor tissues suggested that L-tetrahydropalmatine inhibited the extracellular-signal-regulated kinase/nuclear factor-kappa B cascade and suppressed the levels of Cyclin-D1; matrix metalloproteinase-2/9; X-linked inhibitor of apoptosis protein; and vascular endothelial growth factor, and also the progression and growth of glioblastoma multiforme in mice. In summary, L-tetrahydropalmatine inhibits the ERK/nuclear factor-kappa B cascade, decreases the tumor volume, and inhibits the proteins responsible for tumor growth both in vivo and in vitro.

Targeting Tau Hyperphosphorylation via Kinase Inhibition: Strategy to Address Alzheimer's Disease

2020 ◽  
Vol 20 (12) ◽  
pp. 1059-1073 ◽  
Author(s):  
Ahmad Abu Turab Naqvi ◽  
Gulam Mustafa Hasan ◽  
Md. Imtaiyaz Hassan
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Tau Protein ◽  
Glycogen Synthase ◽  
Paired Helical Filaments ◽  
Tau Hyperphosphorylation ◽  
Microtubule Stabilization ◽  
Extracellular Signal

Microtubule-associated protein tau is involved in the tubulin binding leading to microtubule stabilization in neuronal cells which is essential for stabilization of neuron cytoskeleton. The regulation of tau activity is accommodated by several kinases which phosphorylate tau protein on specific sites. In pathological conditions, abnormal activity of tau kinases such as glycogen synthase kinase-3 β (GSK3β), cyclin-dependent kinase 5 (CDK5), c-Jun N-terminal kinases (JNKs), extracellular signal-regulated kinase 1 and 2 (ERK1/2) and microtubule affinity regulating kinase (MARK) lead to tau hyperphosphorylation. Hyperphosphorylation of tau protein leads to aggregation of tau into paired helical filaments like structures which are major constituents of neurofibrillary tangles, a hallmark of Alzheimer’s disease. In this review, we discuss various tau protein kinases and their association with tau hyperphosphorylation. We also discuss various strategies and the advancements made in the area of Alzheimer's disease drug development by designing effective and specific inhibitors for such kinases using traditional in vitro/in vivo methods and state of the art in silico techniques.

Subnuclear compartmentalization of sequence-specific transcription factors and regulation of eukaryotic gene expression

2005 ◽  
Vol 83 (4) ◽  
pp. 535-547 ◽  
Author(s):  
Gareth N Corry ◽  
D Alan Underhill
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Transcriptional Activation ◽  
Current Knowledge ◽  
Nuclear Architecture ◽  
Subnuclear Localization ◽  
Modular Structures

To date, the majority of the research regarding eukaryotic transcription factors has focused on characterizing their function primarily through in vitro methods. These studies have revealed that transcription factors are essentially modular structures, containing separate regions that participate in such activities as DNA binding, protein–protein interaction, and transcriptional activation or repression. To fully comprehend the behavior of a given transcription factor, however, these domains must be analyzed in the context of the entire protein, and in certain cases the context of a multiprotein complex. Furthermore, it must be appreciated that transcription factors function in the nucleus, where they must contend with a variety of factors, including the nuclear architecture, chromatin domains, chromosome territories, and cell-cycle-associated processes. Recent examinations of transcription factors in the nucleus have clarified the behavior of these proteins in vivo and have increased our understanding of how gene expression is regulated in eukaryotes. Here, we review the current knowledge regarding sequence-specific transcription factor compartmentalization within the nucleus and discuss its impact on the regulation of such processes as activation or repression of gene expression and interaction with coregulatory factors.Key words: transcription, subnuclear localization, chromatin, gene expression, nuclear architecture.

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