scholarly journals Cyclophilin A is a mitochondrial factor that forms complexes with p23. Correlative evidence for an antiapoptotic action

2020 ◽  
pp. jcs.253401
Author(s):  
Cristina Daneri-Becerra ◽  
Brenda Valeiras ◽  
Luciana I. Gallo ◽  
Mariana Lagadari ◽  
Mario D. Galigniana
Keyword(s):  
Signal Transduction ◽  
Heat Shock ◽  
Intracellular Trafficking ◽  
Functional Unit ◽  
Cyclophilin A ◽  
Ternary Complexes ◽  
Cellular Processes ◽  
Immunosuppressive Action ◽  
Per Se ◽  
High Level

Cyclophilin A (CyPA) is an abundant and ubiquitously expressed protein belonging to the immunophilin family that has intrinsic peptidyl-prolyl-(cis/trans)-isomerase enzymatic activity. CyPA mediates immunosuppressive action of the cyclic undecapeptide cyclosporine A and is also involved in multiple cellular processes such as protein folding, intracellular trafficking, signal transduction, and transcriptional regulation. CyPA is abundantly expressed in cancer cells, and due to its chaperone nature, its expression is induced upon the onset of stress. In this study, it is demonstrated that a significant pool of this immunophilin is primarily an intramitochondrial factor that migrates to the nucleus when cells are stimulated with stressors. CyPA shows antiapoptotic action per se and the capability of forming ternary complexes with cytochrome c and the small acidic cochaperone p23, the latter interaction being independent of the usual association of p23 with the heat-shock protein of 90-kDa, Hsp90. These CyPA•p23 complexes enhance the antiapoptotic response of the cell, suggesting that both proteins form a functional unit whose high level of expression plays a significant role in cell survival.

scholarly journals Cyclophilin A is a mitochondrial factor that forms antiapoptotic complexes with p23

2020 ◽  
Author(s):  
Cristina Daneri-Becerra ◽  
Brenda Valeiras ◽  
Mariana Lagadari ◽  
Mario D. Galigniana
Keyword(s):  
Signal Transduction ◽  
Heat Shock ◽  
Molecular Chaperone ◽  
Intracellular Trafficking ◽  
Functional Unit ◽  
Cyclophilin A ◽  
Cell Types ◽  
Cellular Processes ◽  
Murine Liver ◽  
High Level

AbstractCyclophilin A (CyPA) is an abundant and ubiquitously expressed protein belonging to the immunophilin family that has intrinsic peptidyl-prolyl-(cis/trans)-isomerase enzymatic activity. In addition to mediating the immunosuppressive effects of the drug cyclosporine A, CyPA is involved in multiple cellular processes such as protein folding, intracellular trafficking, signal transduction, and transcriptional regulation. Because CyPA is also a molecular chaperone, its expression is induced by several stressor agents and is a highly abundant protein in cancer cells. In this study, it is demonstrated that in several cell types and at least in murine liver, a significant pool of this immunophilin is primarily an intramitochondrial factor that migrates to the nucleus upon the onset of stress. It is also shown that CyPA has antiapoptotic action. Importantly, the capability of CyPA to form complexes with the small acidic cochaperone p23 is proven, this interaction being independent of the usual association of p23 with the heat-shock protein of 90-kDa, Hsp90. Furthermore, it is demonstrated that the CyPA•p23 complex enhances the antiapoptotic response of the cell, suggesting that both proteins form a functional unit whose high level of expression plays a significant role in cell survival.

scholarly journals The emerging role of phosphoinositide clustering in intracellular trafficking and signal transduction

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 422 ◽  
Author(s):  
Laura Picas ◽  
Frederique Gaits-Iacovoni ◽  
Bruno Goud
Keyword(s):  
Signal Transduction ◽  
Intracellular Trafficking ◽  
Recent Observation ◽  
Metabolizing Enzymes ◽  
Master Regulators ◽  
Cellular Processes ◽  
Cellular Compartments ◽  
Cytoskeleton Dynamics ◽  
Protein Modules

Phosphoinositides are master regulators of multiple cellular processes: from vesicular trafficking to signaling, cytoskeleton dynamics, and cell growth. They are synthesized by the spatiotemporal regulated activity of phosphoinositide-metabolizing enzymes. The recent observation that some protein modules are able to cluster phosphoinositides suggests that alternative or complementary mechanisms might operate to stabilize the different phosphoinositide pools within cellular compartments. Herein, we discuss the different known and potential molecular players that are prone to engage phosphoinositide clustering and elaborate on how such a mechanism might take part in the regulation of intracellular trafficking and signal transduction.

North America

2018 ◽  
Author(s):  
Gregory Shushan
Keyword(s):  
Native American ◽  
North America ◽  
Reciprocal Relationship ◽  
Native American Religions ◽  
Widespread Acceptance ◽  
Revitalization Movements ◽  
Per Se ◽  
High Level ◽  
Near Death Experiences ◽  
Afterlife Beliefs

Dozens of Native American near-death experiences (NDEs) from the late sixteenth to early twentieth centuries are presented, ranging from across the continent. Many were accompanied by indigenous claims that they were the source for local afterlife beliefs. There were also many afterlife-related myths, and shamanic practices with NDE-like afterlife themes. In addition, numerous religious/cultural revitalization movements were claimed to have been grounded in the NDEs of their founders, and were conceptually related to the phenomenon. Near-death experiences could thus be an empowering force on a socio-cultural-political level in response to the threat of European dominance. There was a widespread acceptance and valorization of NDEs and related phenomena, and a high level of interest in the afterlife per se. Native American religions often showed a clear reciprocal relationship between shamanism, afterlife beliefs, and NDEs.

scholarly journals Considerations when investigating lncRNA function in vivo

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Andrew R Bassett ◽  
Asifa Akhtar ◽  
Denise P Barlow ◽  
Adrian P Bird ◽  
Neil Brockdorff ◽  
...  
Keyword(s):  
Normal Cell ◽  
Regulatory Elements ◽  
Genomic Locus ◽  
Cellular Processes ◽  
Cell Processes ◽  
Non Coding Rnas ◽  
Per Se ◽  
Dna Regulatory Elements

Although a small number of the vast array of animal long non-coding RNAs (lncRNAs) have known effects on cellular processes examined in vitro, the extent of their contributions to normal cell processes throughout development, differentiation and disease for the most part remains less clear. Phenotypes arising from deletion of an entire genomic locus cannot be unequivocally attributed either to the loss of the lncRNA per se or to the associated loss of other overlapping DNA regulatory elements. The distinction between cis- or trans-effects is also often problematic. We discuss the advantages and challenges associated with the current techniques for studying the in vivo function of lncRNAs in the light of different models of lncRNA molecular mechanism, and reflect on the design of experiments to mutate lncRNA loci. These considerations should assist in the further investigation of these transcriptional products of the genome.

High level soluble expression and ATPase characterization of human heat shock protein GRP78

2017 ◽  
Vol 82 (2) ◽  
pp. 186-191
Author(s):  
Shuang Wu ◽  
Hongpeng Zhang ◽  
Miao Luo ◽  
Ke Chen ◽  
Wei Yang ◽  
...  
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Soluble Expression ◽  
High Level ◽  
Human Heat Shock Protein

scholarly journals A control engineering approach to understanding the TGF-β paradox in cancer

2011 ◽  
Vol 9 (71) ◽  
pp. 1389-1397 ◽  
Author(s):  
Seung-Wook Chung ◽  
Carlton R. Cooper ◽  
Mary C. Farach-Carson ◽  
Babatunde A. Ogunnaike
Keyword(s):  
Cancer Cells ◽  
Mechanistic Model ◽  
Tumour Suppressor ◽  
Cancer Tissue ◽  
Control Engineering ◽  
Cellular Processes ◽  
Proliferation And Apoptosis ◽  
High Level ◽  
Quantitative Explanation

TGF-β, a key cytokine that regulates diverse cellular processes, including proliferation and apoptosis, appears to function paradoxically as a tumour suppressor in normal cells, and as a tumour promoter in cancer cells, but the mechanisms underlying such contradictory roles remain unknown. In particular, given that this cytokine is primarily a tumour suppressor, the conundrum of the unusually high level of TGF-β observed in the primary cancer tissue and blood samples of cancer patients with the worst prognosis, remains unresolved. To provide a quantitative explanation of these paradoxical observations, we present, from a control theory perspective, a mechanistic model of TGF-β-driven regulation of cell homeostasis. Analysis of the overall system model yields quantitative insight into how cell population is regulated, enabling us to propose a plausible explanation for the paradox: with the tumour suppressor role of TGF-β unchanged from normal to cancer cells, we demonstrate that the observed increased level of TGF-β is an effect of cancer cell phenotypic progression (specifically, acquired TGF-β resistance), not the cause . We are thus able to explain precisely why the clinically observed correlation between elevated TGF-β levels and poor prognosis is in fact consistent with TGF-β's original (and unchanged) role as a tumour suppressor.

scholarly journals Calreticulin, a Peptide-binding Chaperone of the Endoplasmic Reticulum, Elicits Tumor- and Peptide-specific Immunity

1999 ◽  
Vol 189 (5) ◽  
pp. 797-802 ◽  
Author(s):  
Sreyashi Basu ◽  
Pramod K. Srivastava
Keyword(s):  
Endoplasmic Reticulum ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Antigen Processing ◽  
Peptide Binding ◽  
Cd8 T Cell ◽  
T Cell Response ◽  
Specific Immunity ◽  
Per Se

Calreticulin (CRT), a peptide-binding heat shock protein (HSP) of the endoplasmic reticulum (ER), has been shown previously to associate with peptides transported into the ER by transporter associated with antigen processing (Spee, P., and J. Neefjes. 1997. Eur. J. Immunol. 27: 2441–2449). Our studies show that CRT preparations purified from tumors elicit specific immunity to the tumor used as the source of CRT but not to an antigenically distinct tumor. The immunogenicity is attributed to the peptides associated with the CRT molecule and not to the CRT molecule per se. It is further shown that CRT molecules can be complexed in vitro to unglycosylated peptides and used to elicit peptide-specific CD8+ T cell response in spite of exogenous administration. These characteristics of CRT closely resemble those of HSPs gp96, hsp90, and hsp70, although CRT has no apparent structural homologies to them.

Adenovirus E1A requires synthesis of a cellular protein to establish a stable transcription complex in injected Xenopus laevis oocytes

1987 ◽  
Vol 7 (9) ◽  
pp. 3049-3056
Author(s):  
J D Richter ◽  
H C Hurst ◽  
N C Jones
Keyword(s):  
Protein Synthesis ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Heat Shock Protein 70 ◽  
Mammalian Cells ◽  
Cellular Protein ◽  
Xenopus Laevis Oocytes ◽  
Protein Synthesis Inhibitors ◽  
Adenovirus E1a ◽  
High Level

The Escherichia coli-expressed adenovirus E1A 13S mRNA product injected into Xenopus oocytes was active, as assessed by its ability to stimulate the transcription of an injected gene which is normally responsive to E1A in mammalian cells. In the presence of the protein synthesis inhibitors pactamycin or cycloheximide, E1A was correctly posttranslationally modified (phosphorylated) and transported to the nucleus; but it failed to stimulate the transcription of an injected gene containing the human heat shock protein 70 promoter. The basal (unstimulated) level of transcription of the gene was unaffected by these inhibitors. If oocytes were cultured in the presence of cycloheximide after E1A stimulated transcription, however, the high level of transcription was maintained for several hours without new protein synthesis. Results of competition studies with the same promoter (the heat shock protein 70 promoter) linked to two marked genes demonstrated that once the induction of transcription by E1A took place, the stimulated levels of transcription were maintained, even when they were challenged with excess competitor DNA. Results of these studies suggest that E1A requires the synthesis of a cellular protein to form a stable transcription complex.

Stoichiometry of G protein subunits affects the Saccharomyces cerevisiae mating pheromone signal transduction pathway

1990 ◽  
Vol 10 (2) ◽  
pp. 510-517
Author(s):  
G M Cole ◽  
D E Stone ◽  
S I Reed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Signal Transduction ◽  
G Protein ◽  
Signal Transduction Pathway ◽  
Mating Pheromone ◽  
Gal1 Promoter ◽  
Gamma Subunits ◽  
Adaptation Response ◽  
High Level

The Saccharomyces cerevisiae GPA1, STE4, and STE18 genes encode products homologous to mammalian G-protein alpha, beta, and gamma subunits, respectively. All three genes function in the transduction of the signal generated by mating pheromone in haploid cells. To characterize more completely the role of these genes in mating, we have conditionally overexpressed GPA1, STE4, and STE18, using the galactose-inducible GAL1 promoter. Overexpression of STE4 alone, or STE4 together with STE18, generated a response in haploid cells suggestive of pheromone signal transduction: arrest in G1 of the cell cycle, formation of cellular projections, and induction of the pheromone-inducible transcript FUS1 25- to 70-fold. High-level STE18 expression alone had none of these effects, nor did overexpression of STE4 in a MATa/alpha diploid. However, STE18 was essential for the response, since overexpression of STE4 was unable to activate a response in a ste18 null strain. GPA1 hyperexpression suppressed the phenotype of STE4 overexpression. In addition, cells that overexpressed GPA1 were more resistant to pheromone and recovered more quickly from pheromone than did wild-type cells, which suggests that GPA1 may function in an adaptation response to pheromone.

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