scholarly journals Pharmacological Inhibition of the VCP/Proteasome Axis Rescues Photoreceptor Degeneration in RHOP23H Rat Retinal Explants

Biomolecules ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1528
Author(s):  
Merve Sen ◽  
Oksana Kutsyr ◽  
Bowen Cao ◽  
Sylvia Bolz ◽  
Blanca Arango-Gonzalez ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Autosomal Dominant ◽  
Misfolded Proteins ◽  
Protein Recognition ◽  
Photoreceptor Degeneration ◽  
Common Cause ◽  
Pharmacological Modulation ◽  
Retinal Explants ◽  
Prevalent Mutation

Rhodopsin (RHO) misfolding mutations are a common cause of the blinding disease autosomal dominant retinitis pigmentosa (adRP). The most prevalent mutation, RHOP23H, results in its misfolding and retention in the endoplasmic reticulum (ER). Under homeostatic conditions, misfolded proteins are selectively identified, retained at the ER, and cleared via ER-associated degradation (ERAD). Overload of these degradation processes for a prolonged period leads to imbalanced proteostasis and may eventually result in cell death. ERAD of misfolded proteins, such as RHOP23H, includes the subsequent steps of protein recognition, targeting for ERAD, retrotranslocation, and proteasomal degradation. In the present study, we investigated and compared pharmacological modulation of ERAD at these four different major steps. We show that inhibition of the VCP/proteasome activity favors cell survival and suppresses P23H-mediated retinal degeneration in RHOP23H rat retinal explants. We suggest targeting this activity as a therapeutic approach for patients with currently untreatable adRP.

scholarly journals Pharmacological inhibition of the VCP/proteasome axis rescues photoreceptor degeneration in RHOP23H rat retinal explants

2021 ◽  
Author(s):  
Merve Sen ◽  
Oksana Kutsyr ◽  
Bowen Cao ◽  
Sylvia Bolz ◽  
Blanca Arango-Gonzalez ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Autosomal Dominant ◽  
Misfolded Proteins ◽  
Protein Recognition ◽  
Photoreceptor Degeneration ◽  
Common Cause ◽  
Pharmacological Modulation ◽  
Retinal Explants ◽  
Prevalent Mutation

Rhodopsin (RHO) misfolding mutations are a common cause of the blinding disease autosomal dominant retinitis pigmentosa (adRP). The most prevalent mutation, RHOP23H, results in its misfolding and retention in the Endoplasmic Reticulum (ER). Under homeostatic conditions, misfolded proteins are selectively identified, retained at the ER, and cleared via ER-associated degradation (ERAD) and/or autophagy. Overload of these degradation processes for a prolonged period leads to imbalanced proteostasis and may eventually result in cell death. ERAD of misfolded proteins like RHOP23H includes the subsequent steps of protein recognition, targeting for ERAD, retrotranslocation, and proteasomal degradation. In the present study, we investigated and compared pharmacological modulation of ERAD at these four different major steps. We show that inhibition of the VCP/proteasome activity favors cell survival and suppresses P23H-mediated retinal degeneration in RHOP23H rat retinal explants. We suggest targeting this activity as a therapeutic approach for patients with currently untreatable adRP.

scholarly journals Interplay between Endoplasmic Reticulum (ER) Stress and Autophagy Induces Mutant p53H273 Degradation

Biomolecules ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 392 ◽  
Author(s):  
Alessia Garufi ◽  
Giulia Federici ◽  
Maria Saveria Gilardini Montani ◽  
Alessandra Crispini ◽  
Mara Cirone ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Er Stress ◽  
Zinc Supplementation ◽  
Zinc Ion ◽  
Misfolded Proteins ◽  
Missense Mutations ◽  
Chemical Chaperone ◽  
Cancer Cell Death ◽  
The Unfolded Protein Response

The unfolded protein response (UPR) is an adaptive response to intrinsic and external stressors, and it is mainly activated by the accumulation of misfolded proteins at the endoplasmic reticulum (ER) lumen producing ER stress. The UPR signaling network is interconnected with autophagy, the proteolytic machinery specifically devoted to clearing misfolded proteins in order to survive bioenergetic stress and/or induce cell death. Oncosuppressor TP53 may undergo inactivation following missense mutations within the DNA-binding domain (DBD), and mutant p53 (mutp53) proteins may acquire a misfolded conformation, often due to the loss of the DBD-bound zinc ion, leading to accumulation of hyperstable mutp53 proteins that correlates with more aggressive tumors, resistance to therapies, and poorer outcomes. We previously showed that zinc supplementation induces mutp53 protein degradation by autophagy. Here, we show that mutp53 (i.e., Arg273) degradation following zinc supplementation is correlated with activation of ER stress and of the IRE1α/XBPI arm of the UPR. ER stress inhibition with chemical chaperone 4-phenyl butyrate (PBA) impaired mutp53 downregulation, which is similar to IRE1α/XBPI specific inhibition, reducing cancer cell death. Knockdown of mutp53 failed to induce UPR/autophagy activation indicating that the effect of zinc on mutp53 folding was likely the key event occurring in ER stress activation. Recently discovered small molecules targeting components of the UPR show promise as a novel anticancer therapeutic intervention. However, our findings showing UPR activation during mutp53 degradation indicate that caution is necessary in the design of therapies that inhibit UPR components.

CUX1 controls endoplasmic reticulum stress and autophagy related cell death

2016 ◽  
Vol 54 (12) ◽  
pp. 1343-1404
Author(s):  
G Metzger ◽  
P Di Fazio ◽  
DK Bartsch ◽  
T Gress ◽  
TT Wissniowski
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Endoplasmic Reticulum Stress ◽  
Related Cell

Inhibition of Autophagy Potentiated Hippocampal Cell Death Induced by Endoplasmic Reticulum Stress and its Activation by Trehalose Failed to be Neuroprotective

2019 ◽  
Vol 16 (1) ◽  
pp. 3-11
Author(s):  
Luisa Halbe ◽  
Abdelhaq Rami
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Er Stress ◽  
Cell Damage ◽  
Protective Mechanism ◽  
Unfolded Proteins ◽  
Neuronal Viability ◽  
Hippocampal Cell ◽  
Trigger Cell Death ◽  
Autophagy Inhibition

Introduction: Endoplasmic reticulum (ER) stress induced the mobilization of two protein breakdown routes, the proteasomal- and autophagy-associated degradation. During ERassociated degradation, unfolded ER proteins are translocated to the cytosol where they are cleaved by the proteasome. When the accumulation of misfolded or unfolded proteins excels the ER capacity, autophagy can be activated in order to undertake the degradative machinery and to attenuate the ER stress. Autophagy is a mechanism by which macromolecules and defective organelles are included in autophagosomes and delivered to lysosomes for degradation and recycling of bioenergetics substrate. Materials and Methods: Autophagy upon ER stress serves initially as a protective mechanism, however when the stress is more pronounced the autophagic response will trigger cell death. Because autophagy could function as a double edged sword in cell viability, we examined the effects autophagy modulation on ER stress-induced cell death in HT22 murine hippocampal neuronal cells. We investigated the effects of both autophagy-inhibition by 3-methyladenine (3-MA) and autophagy-activation by trehalose on ER-stress induced damage in hippocampal HT22 neurons. We evaluated the expression of ER stress- and autophagy-sensors as well as the neuronal viability. Results and Conclusion: Based on our findings, we conclude that under ER-stress conditions, inhibition of autophagy exacerbates cell damage and induction of autophagy by trehalose failed to be neuroprotective.

scholarly journals Polyhexamethylene Guanidine Phosphate Induces Apoptosis through Endoplasmic Reticulum Stress in Lung Epithelial Cells

2021 ◽  
Vol 22 (3) ◽  
pp. 1215
Author(s):  
Mi Ho Jeong ◽  
Mi Seon Jeon ◽  
Ga Eun Kim ◽  
Ha Ryong Kim
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Epithelial Cell ◽  
Er Stress ◽  
Lung Fibrosis ◽  
A549 Cells ◽  
Polyhexamethylene Guanidine ◽  
Lung Epithelial ◽  
Epithelial Cell Death ◽  
Guanidine Phosphate

Airway epithelial cell death contributes to the pathogenesis of lung fibrosis. Polyhexamethylene guanidine phosphate (PHMG-p), commonly used as a disinfectant, has been shown to be strongly associated with lung fibrosis in epidemiological and toxicological studies. However, the molecular mechanism underlying PHMG-p-induced epithelial cell death is currently unclear. We synthesized a PHMG-p–fluorescein isothiocyanate (FITC) conjugate and assessed its uptake into lung epithelial A549 cells. To examine intracellular localization, the cells were treated with PHMG-p–FITC; then, the cytoplasmic organelles were counterstained and observed with confocal microscopy. Additionally, the organelle-specific cell death pathway was investigated in cells treated with PHMG-p. PHMG-p–FITC co-localized with the endoplasmic reticulum (ER), and PHMG-p induced ER stress in A549 cells and mice. The ER stress inhibitor tauroursodeoxycholic acid (TUDCA) was used as a pre-treatment to verify the role of ER stress in PHMG-p-induced cytotoxicity. The cells treated with PHMG-p showed apoptosis, which was inhibited by TUDCA. Our results indicate that PHMG-p is rapidly located in the ER and causes ER-stress-mediated apoptosis, which is an initial step in PHMG-p-induced lung fibrosis.

scholarly journals Ca2+ overload- and ROS-associated mitochondrial dysfunction contributes to δ-tocotrienol-mediated paraptosis in melanoma cells

APOPTOSIS ◽  
2021 ◽  
Author(s):  
Michela Raimondi ◽  
Fabrizio Fontana ◽  
Monica Marzagalli ◽  
Matteo Audano ◽  
Giangiacomo Beretta ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Mitochondrial Dysfunction ◽  
Atp Synthesis ◽  
Melanoma Cells ◽  
Human Melanoma ◽  
Ros Generation ◽  
Therapy Outcomes ◽  
Human Melanoma Cells ◽  
Oxphos Complex

Abstract Melanoma is an aggressive tumor with still poor therapy outcomes. δ-tocotrienol (δ-TT) is a vitamin E derivative displaying potent anti-cancer properties. Previously, we demonstrated that δ-TT triggers apoptosis in human melanoma cells. Here, we investigated whether it might also activate paraptosis, a non-canonical programmed cell death. In accordance with the main paraptotic features, δ-TT was shown to promote cytoplasmic vacuolization, associated with endoplasmic reticulum/mitochondrial dilation and protein synthesis, as well as MAPK activation in A375 and BLM cell lines. Moreover, treated cells exhibited a significant reduced expression of OXPHOS complex I and a marked decrease in oxygen consumption and mitochondrial membrane potential, culminating in decreased ATP synthesis and AMPK phosphorylation. This mitochondrial dysfunction resulted in ROS overproduction, found to be responsible for paraptosis induction. Additionally, δ-TT caused Ca2+ homeostasis disruption, with endoplasmic reticulum-derived ions accumulating in mitochondria and activating the paraptotic signaling. Interestingly, by using both IP3R and VDAC inhibitors, a close cause-effect relationship between mitochondrial Ca2+ overload and ROS generation was evidenced. Collectively, these results provide novel insights into δ-TT anti-melanoma activity, highlighting its ability to induce mitochondrial dysfunction-mediated paraptosis. Graphic Abstract δ-tocotrienol induces paraptotic cell death in human melanoma cells, causing endoplasmic reticulum dilation and mitochondrial swelling. These alterations induce an impairment of mitochondrial function, ROS production and calcium overload.

scholarly journals The Rice TAL Effector–Dependent Resistance Protein XA10 Triggers Cell Death and Calcium Depletion in the Endoplasmic Reticulum

2014 ◽  
Vol 26 (1) ◽  
pp. 497-515 ◽  
Author(s):  
Dongsheng Tian ◽  
Junxia Wang ◽  
Xuan Zeng ◽  
Keyu Gu ◽  
Chengxiang Qiu ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Calcium Depletion ◽  
Tal Effector ◽  
Resistance Protein
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