scholarly journals Cantharidin alters GPI-anchored protein sorting by targeting Cdc1 mediated remodeling in Endoplasmic Reticulum

2018 ◽  
Author(s):  
Pushpendra Kumar Sahu ◽  
Raghuvir Singh Tomar
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Genetic Interaction ◽  
Protein Sorting ◽  
Model Organism ◽  
Cell Wall Integrity ◽  
Yeast Cells ◽  
Growth Media ◽  
Gpi Anchor ◽  
Associated Functions

ABSTRACTCantharidin (CTD) is a potent anticancer small molecule produced by several species of blister beetle. It has been a traditional medicine for the treatment of warts and tumors for many decades. CTD suppresses the tumor growth by inducing apoptosis, cell cycle arrest, and DNA damage. It is a known inhibitor of PP2A and PP1. In this study, we identified new molecular targets of CTD usingSaccharomyces cerevisiaeas a model organism which expresses a Cantharidin Resistance Gene (CRG1).CRG1encodes a SAM-dependent methyltransferase that inactivates CTD by methylation. CTD alters lipid homeostasis, cell wall integrity, endocytosis, adhesion, and invasion in yeast cells. We found that CTD specifically affects the phosphatidylethanolamine (PE) associated functions which can be rescued by supplementation of ethanolamine (ETA) in the growth media. CTD also perturbed ER homeostasis and cell wall integrity by altering the GPI-anchored protein sorting. The CTD dependent genetic interaction profile ofCRG1revealed that Cdc1 activity in GPI-anchor remodeling is the key target of CTD, which we found to be independent of PP2A and PP1. Furthermore, our experiments with human cells suggest that CTD functions through a conserved mechanism in higher eukaryotes as well. Altogether, we conclude that CTD induces cytotoxicity by targeting Cdc1 activity in GPI-anchor remodeling in the endoplasmic reticulum (ER).

scholarly journals Hyperactive TORC1 sensitizes yeast cells to endoplasmic reticulum stress by compromising cell wall integrity

2019 ◽  
Author(s):  
Khadija Ahmed ◽  
David E. Carter ◽  
Patrick Lajoie
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Endoplasmic Reticulum Stress ◽  
Er Stress ◽  
Fungal Infections ◽  
Pathogenic Fungi ◽  
Stress Sensitivity ◽  
Antifungal Drugs ◽  
Cell Wall Integrity ◽  
Yeast Cells

ABSTRACTThe disruption of protein folding homeostasis in the endoplasmic reticulum (ER) results in an accumulation of toxic misfolded proteins and activates a network of signaling events collectively known as the unfolded protein response (UPR). While UPR activation upon ER stress is well characterized, how other signaling pathways integrate into the ER proteostasis network is unclear. Here, we sought to investigate how the target of rapamycin complex 1 (TORC1) signaling cascade acts in parallel with the UPR to regulate ER stress sensitivity. Using S. cerevisiae, we found that TORC1 signaling is attenuated during ER stress and constitutive activation of TORC1 increases sensitivity to ER stressors such as tunicamycin and inositol deprivation. This phenotype is independent of the UPR. Transcriptome analysis revealed that TORC1 hyperactivation results in cell wall remodelling. Conversely, hyperactive TORC1 sensitizes cells to cell wall stressors, including the antifungal caspofungin. Elucidating the crosstalk between the UPR, cell wall integrity, and TORC1 signaling may uncover new paradigms through which the response to protein misfolding is regulated, and thus have crucial implications for the development of novel therapeutics against pathogenic fungal infections.IMPORTANCEThe prevalence of pathogenic fungal infections, coupled with the emergence of new fungal pathogens, has brought these diseases to the forefront of global health problems. While antifungal treatments have advanced over the last decade, patient outcomes have not substantially improved. These shortcomings are largely attributed to the evolutionary similarity between fungi and humans, which limits the scope of drug development. As such, there is a pressing need to understand the unique cellular mechanisms that govern fungal viability. Given that Saccharomyces cerevisiae is evolutionarily related to a number of pathogenic fungi, and in particular to the Candida species, most genes from S. cerevisiae are highly conserved in pathogenic fungal strains. Here we show that hyperactivation of TORC1 signaling sensitizes S. cerevisiae cells to both endoplasmic reticulum stress and cell wall stressors by compromising cell wall integrity. Therefore, targeting TORC1 signaling and endoplasmic reticulum stress pathways may be useful in developing novel targets for antifungal drugs.

scholarly journals Endoplasmic Reticulum α-Glycosidases of Candida albicans Are Required for N Glycosylation, Cell Wall Integrity, and Normal Host-Fungus Interaction

2007 ◽  
Vol 6 (12) ◽  
pp. 2184-2193 ◽  
Author(s):  
Héctor M. Mora-Montes ◽  
Steven Bates ◽  
Mihai G. Netea ◽  
Diana F. Díaz-Jiménez ◽  
Everardo López-Romero ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Candida Albicans ◽  
Systemic Infection ◽  
Cell Wall Integrity ◽  
Yeast Cells ◽  
Chain Elongation ◽  
Cell Wall Integrity Pathway ◽  
Oligosaccharide Processing ◽  
Host Fungus

ABSTRACT The cell surface of Candida albicans is enriched in highly glycosylated mannoproteins that are involved in the interaction with the host tissues. N glycosylation is a posttranslational modification that is initiated in the endoplasmic reticulum (ER), where the Glc3Man9GlcNAc2 N-glycan is processed by α-glucosidases I and II and α1,2-mannosidase to generate Man8GlcNAc2. This N-oligosaccharide is then elaborated in the Golgi to form N-glycans with highly branched outer chains rich in mannose. In Saccharomyces cerevisiae, CWH41, ROT2, and MNS1 encode for α-glucosidase I, α-glucosidase II catalytic subunit, and α1,2-mannosidase, respectively. We disrupted the C. albicans CWH41, ROT2, and MNS1 homologs to determine the importance of N-oligosaccharide processing on the N-glycan outer-chain elongation and the host-fungus interaction. Yeast cells of Cacwh41Δ, Carot2Δ, and Camns1Δ null mutants tended to aggregate, displayed reduced growth rates, had a lower content of cell wall phosphomannan and other changes in cell wall composition, underglycosylated β-N-acetylhexosaminidase, and had a constitutively activated PKC-Mkc1 cell wall integrity pathway. They were also attenuated in virulence in a murine model of systemic infection and stimulated an altered pro- and anti-inflammatory cytokine profile from human monocytes. Therefore, N-oligosaccharide processing by ER glycosidases is required for cell wall integrity and for host-fungus interactions.

The presence of an ER exit signal determines the protein sorting upon ER exit in yeast

2008 ◽  
Vol 414 (2) ◽  
pp. 237-245 ◽  
Author(s):  
Reika Watanabe ◽  
Guillaume A. Castillon ◽  
Anja Meury ◽  
Howard Riezman
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Sorting ◽  
Surface Protein ◽  
The Other ◽  
Gpi Anchor ◽  
Rich Region ◽  
Characteristic Features ◽  
Detergent Resistant Membrane

In yeast, there are at least two vesicle populations upon ER (endoplasmic reticulum) exit, one containing Gap1p (general aminoacid permease) and a glycosylated α-factor, gpαF (glycosylated proα-factor), and the other containing GPI (glycosylphosphatidylinositol)-anchored proteins, Gas1p (glycophospholipid-anchored surface protein) and Yps1p. We attempted to identify sorting determinants for this protein sorting event in the ER. We found that mutant Gas1 proteins that lack a GPI anchor and/or S/T region (serine- and threonine-rich region), two common characteristic features conserved among yeast GPI-anchored proteins, were still sorted away from Gap1p-containing vesicles. Furthermore, a mutant glycosylated α-factor, gpαGPI, which contains both the GPI anchor and S/T region from Gas1p, still entered Gap1p-containing vesicles, demonstrating that these conserved characteristics do not prevent proteins from entering Gap1p-containing vesicles. gpαF showed severely reduced budding efficiency in the absence of its ER exit receptor Erv29p, and this residual budding product no longer entered Gap1p-containing vesicles. These results suggest that the interaction of gpαF with Erv29p is essential for sorting into Gap1p-containing vesicles. We compared the detergent solubility of Gas1p and the gpαGPI in the ER with that in ER-derived vesicles. Both GPI-anchored proteins similarly partitioned into the DRM (detergent-resistant membrane) in the ER. Based on the fact that they entered different ER-derived vesicles, we conclude that DRM partitioning of GPI-anchored proteins is not the dominant determinant of protein sorting upon ER exit. Interestingly, upon incorporation into the ER-derived vesicles, gpαGPI was no longer detergent-insoluble, in contrast with the persistent detergent insolubility of Gas1p in the ER-derived vesicles. We present different explanations for the different behaviours of GPI-anchored proteins in distinct ER-derived vesicle populations.

scholarly journals Deletion of Atg22 gene contributes to reduce programmed cell death induced by acetic acid stress in Saccharomyces cerevisiae

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Jingjin Hu ◽  
Yachen Dong ◽  
Wei Wang ◽  
Wei Zhang ◽  
Hanghang Lou ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Cell Death ◽  
Cell Wall ◽  
Acetic Acid ◽  
Programmed Cell Death ◽  
Cell Wall Integrity ◽  
Yeast Cells ◽  
Death Process ◽  
Lignocellulosic Biofuel

Abstract Background Programmed cell death (PCD) induced by acetic acid, the main by-product released during cellulosic hydrolysis, cast a cloud over lignocellulosic biofuel fermented by Saccharomyces cerevisiae and became a burning problem. Atg22p, an ignored integral membrane protein located in vacuole belongs to autophagy-related genes family; prior study recently reported that it is required for autophagic degradation and efflux of amino acids from vacuole to cytoplasm. It may alleviate the intracellular starvation of nutrition caused by Ac and increase cell tolerance. Therefore, we investigate the role of atg22 in cell death process induced by Ac in which attempt is made to discover new perspectives for better understanding of the mechanisms behind tolerance and more robust industrial strain construction. Results In this study, we compared cell growth, physiological changes in the absence and presence of Atg22p under Ac exposure conditions. It is observed that disruption and overexpression of Atg22p delays and enhances acetic acid-induced PCD, respectively. The deletion of Atg22p in S. cerevisiae maintains cell wall integrity, and protects cytomembrane integrity, fluidity and permeability upon Ac stress by changing cytomembrane phospholipids, sterols and fatty acids. More interestingly, atg22 deletion increases intracellular amino acids to aid yeast cells for tackling amino acid starvation and intracellular acidification. Further, atg22 deletion upregulates series of stress response genes expression such as heat shock protein family, cell wall integrity and autophagy. Conclusions The findings show that Atg22p possessed the new function related to cell resistance to Ac. This may help us have a deeper understanding of PCD induced by Ac and provide a new strategy to improve Ac resistance in designing industrial yeast strains for bioethanol production during lignocellulosic biofuel fermentation.

L'influence de la carence en pyridoxine sur la morphologie et l'ultrastructure cellulaire de Ceratocystis ulmi

1983 ◽  
Vol 61 (8) ◽  
pp. 2079-2084 ◽  
Author(s):  
Y. Dalpé
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Comparative Study ◽  
Synthetic Medium ◽  
Filamentous Growth ◽  
Yeast Cells ◽  
Growth Morphology ◽  
The Comparative Study

Deficiency in pyridoxine of a synthetic medium induces yeastlike growth of Ceratocystis ulmi. The addition of pyridoxine allows the organism, incubated 1 to 12 days in the absence of the vitamin, to recover in 24 h its filamentous growth morphology. The comparative study of the ultrastructure of mycelial and yeast cells reveals for the latter a thickening of the cell wall, a quantitative cytoplasmic impoverishment in endoplasmic reticulum and ribosomes, and an accumulation of lipidic and osmiophilic bodies.

scholarly journals Crosstalk between calcineurin and the cell wall integrity pathways prevents chitin overexpression in Candida albicans

2021 ◽  
Author(s):  
Alessandra da Silva Dantas ◽  
Filomena Nogueira ◽  
Keunsook K. Lee ◽  
Louise A. Walker ◽  
Matt Edmondson ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Antifungal Drugs ◽  
Cell Wall Integrity ◽  
Yeast Cells ◽  
Outer Cell ◽  
Chitin Synthesis ◽  
Simultaneous Activation ◽  
Glucan Synthesis ◽  
Calcineurin Pathway

Echinocandins such as caspofungin are front line antifungal drugs that compromise β-1,3 glucan synthesis in the cell wall. Recent reports have shown that fungal cells can resist killing by caspofungin by up-regulation of chitin synthesis, thereby sustaining cell wall integrity. When echinocandins are removed, the chitin content of cells quickly returns to basal levels, suggesting that there is a fitness cost associated with having elevated levels of chitin in the cell wall. We show here that simultaneous activation of the calcineurin and CWI pathways generates a sub-population of Candida albicans yeast cells that have supra-normal chitin levels interspersed throughout the inner and outer cell wall, and that these cells are non-viable, perhaps due to loss of wall elasticity required for cell expansion and growth. Mutations in the Ca2+-calcineurin pathway prevented the formation of these non-viable super high chitin cells by negatively regulating chitin synthesis driven by the CWI pathway. The Ca2+-calcineurin pathway may therefore act as an attenuator that prevents the overproduction of chitin by coordinating both chitin upregulation and negative regulation of the CWI signaling pathway.

scholarly journals Candida albicans Sfp1 Is Involved in the Cell Wall and Endoplasmic Reticulum Stress Responses Induced by Human Antimicrobial Peptide LL-37

2021 ◽  
Vol 22 (19) ◽  
pp. 10633
Author(s):  
Chun-Min Hsu ◽  
Yi-Ling Liao ◽  
Che-Kang Chang ◽  
Chung-Yu Lan
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Candida Albicans ◽  
Stress Responses ◽  
Molecular Mechanisms ◽  
Wall Stress ◽  
Cell Wall Integrity ◽  
Gene Encoding ◽  
Host Interactions ◽  
Life Threatening

Candida albicans is a commensal fungus of humans but can cause infections, particularly in immunocompromised individuals, ranging from superficial to life-threatening systemic infections. The cell wall is the outermost layer of C. albicans that interacts with the host environment. Moreover, antimicrobial peptides (AMPs) are important components in innate immunity and play crucial roles in host defense. Our previous studies showed that the human AMP LL-37 binds to the cell wall of C. albicans, alters the cell wall integrity (CWI) and affects cell adhesion of this pathogen. In this study, we aimed to further investigate the molecular mechanisms underlying the C. albicans response to LL-37. We found that LL-37 causes cell wall stress, activates unfolded protein response (UPR) signaling related to the endoplasmic reticulum (ER), induces ER-derived reactive oxygen species and affects protein secretion. Interestingly, the deletion of the SFP1 gene encoding a transcription factor reduced C. albicans susceptibility to LL-37, which is cell wall-associated. Moreover, in the presence of LL-37, deletion of SFP1 attenuated the UPR pathway, upregulated oxidative stress responsive (OSR) genes and affected bovine serum albumin (BSA) degradation by secreted proteases. Therefore, these findings suggested that Sfp1 positively regulates cell wall integrity and ER homeostasis upon treatment with LL-37 and shed light on pathogen-host interactions.

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