scholarly journals HacA-Independent Induction of Chaperone-Encoding Gene bipA in Aspergillus niger Strains Overproducing Membrane Proteins

2006 ◽  
Vol 72 (1) ◽  
pp. 953-955 ◽  
Author(s):  
Anoushka Davé ◽  
David J. Jeenes ◽  
Donald A. Mackenzie ◽  
David B. Archer
Keyword(s):  
Aspergillus Niger ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Unfolded Protein Response ◽  
Mrna Levels ◽  
Unfolded Protein ◽  
Protein Overproduction ◽  
Encoding Gene ◽  
Protein Response

ABSTRACT Transcription of two unfolded protein response genes, hacA and bipA, was examined in Aspergillus niger strains overproducing membrane proteins. Despite elevated bipA mRNA levels, no 5′-truncated hacA transcript was detected, raising the possibility of a hacA-independent induction of bipA mRNA under the stress of membrane protein overproduction in A. niger.

scholarly journals Improvement of Foreign-Protein Production in Aspergillus niger var. awamori by Constitutive Induction of the Unfolded-Protein Response

2003 ◽  
Vol 69 (12) ◽  
pp. 6979-6986 ◽  
Author(s):  
Mari Valkonen ◽  
Michael Ward ◽  
Huaming Wang ◽  
Merja Penttilä ◽  
Markku Saloheimo
Keyword(s):  
Aspergillus Niger ◽  
Unfolded Protein Response ◽  
Protein Production ◽  
Production Systems ◽  
Foreign Protein ◽  
Mrna Levels ◽  
Unfolded Protein ◽  
Novel Strategy ◽  
The Unfolded Protein Response ◽  
Protein Response

ABSTRACT Unfolded-protein response (UPR) denotes the upregulation of endoplasmic reticulum (ER)-resident chaperone and foldase genes and numerous other genes involved in secretory functions during the accumulation of unfolded proteins into the ER. Overexpression of individual foldases and chaperones has been used in attempts to improve protein production in different production systems. We describe here a novel strategy to improve foreign-protein production. We show that the constitutive induction of the UPR pathway in Aspergillus niger var. awamori can be achieved by expressing the activated form of the transcription factor hacA. This induction enhances the production of Trametes versicolor laccase by up to sevenfold and of bovine preprochymosin by up to 2.8-fold in this biotechnically important fungus. The regulatory range of UPR was studied by analyzing the mRNA levels of novel A. niger var. awamori genes involved in different secretory functions. This revealed both similarities and differences to corresponding studies in Saccharomyces cerevisiae.

scholarly journals The Unfolded Protein Response Regulates Multiple Aspects of Secretory and Membrane Protein Biogenesis and Endoplasmic Reticulum Quality Control

2000 ◽  
Vol 150 (1) ◽  
pp. 77-88 ◽  
Author(s):  
Davis T.W. Ng ◽  
Eric D. Spear ◽  
Peter Walter
Keyword(s):  
Membrane Protein ◽  
Unfolded Protein Response ◽  
Intracellular Signaling ◽  
Target Genes ◽  
Yeast Saccharomyces Cerevisiae ◽  
Regulatory Pathways ◽  
Unfolded Protein ◽  
Protein Biogenesis ◽  
The Unfolded Protein Response ◽  
Protein Response

The unfolded protein response (UPR) is an intracellular signaling pathway that relays signals from the lumen of the ER to activate target genes in the nucleus. We devised a genetic screen in the yeast Saccharomyces cerevisiae to isolate mutants that are dependent on activation of the pathway for viability. Using this strategy, we isolated mutants affecting various aspects of ER function, including protein translocation, folding, glycosylation, glycosylphosphatidylinositol modification, and ER-associated protein degradation (ERAD). Extending results gleaned from the genetic studies, we demonstrate that the UPR regulates trafficking of proteins at the translocon to balance the needs of biosynthesis and ERAD. The approach also revealed connections of the UPR to other regulatory pathways. In particular, we identified SON1/RPN4, a recently described transcriptional regulator for genes encoding subunits of the proteasome. Our genetic strategy, therefore, offers a powerful means to provide insight into the physiology of the UPR and to identify novel genes with roles in many aspects of secretory and membrane protein biogenesis.

Abstract 105: Maternal Diet Leads to Nephron Count Differences After Postnatal Day 14 and Time-dependent Differences in Apoptosis and Unfolded Protein Response in Dahl Salt-sensitive Rats

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Erwin T Cabacungan ◽  
Aron M Geurts ◽  
David L Mattson ◽  
Liang Mingyu
Keyword(s):  
Protein Expression ◽  
Unfolded Protein Response ◽  
Time Dependent ◽  
Mrna Levels ◽  
Related Protein ◽  
Apoptotic Pathway ◽  
Time Points ◽  
Unfolded Protein ◽  
Caspase 12 ◽  
Protein Response

We have shown that maternal exposure to Casein-based AIN-76A diet [SS/JrHsdMcwi (SS/Mcw) rats] compared to grain-based 5L2F diet [SS/JrHsdMcwiCrl (SS/Crl) rats] during the gestational-lactational period exacerbates the development of salt-induced hypertension and renal injury in adult SS rats. We hypothesized that SS/Mcw rats will have significantly fewer glomeruli than SS/Crl rats, and determined its potential mechanisms. At different time points during development [embryonic day 20 (E 20), day of life (DOL) 14, 21, 56]: glomerular counts were determined by maceration method and by glomerular density (total glomerular number/renal cortex area); apoptosis was measured by TUNEL assay; RT-PCR, Western Blot and immunostaining were used to examine the expression level of genes involved in the apoptotic pathway and unfolded protein response (UPR). We found lower glomerular counts in SS/Mcw compared to SS/Crl rats at DOL 21 [26048±1423 per kidney vs. 34766±1821 (p<0.001] and DOL 56 [15717±2052 vs. 27999±3362 (p <0.001)], and lower glomerular densities [DOL 21, 10.8±1.0/mm2 vs. 13.2±1.6 (p<0.001); DOL 56, 2.4±0.1 vs. 3.6±0.2 (p < 0.001)]. Glomerular density was not different between SS/Mcw and SS/Crl at DOL 14 when nephrogenesis is complete. We found higher glomerular apoptosis in SS/Mcw compared to SS/Crl rats at DOL 14 [9.5±1.4 per 100 glomeruli vs. 5.1±1.8 (p<0.01)] and DOL 21 [5.2±0.7 vs. 3.6±0.5 (p <0.01)]. mRNA levels of several genes involved in intrinsic apoptotic pathway and UPR were significantly upregulated in SS/Mcw rats compared to SS/Crl rats at different time points. Significantly lower UPR-related protein expression in SS/Mcw compared to SS/Crl rats was detected for JNK and GRP78 (DOL 14 and 56) and CHOP (DOL 56). Significantly higher UPR-related protein expression in SS/Mcw compared to SS/Crl rats were detected for GRP78 (E 20), JNK (DOL 21) and Caspase 12 (DOL 14, 21 and 56). Caspase 12 was located in the glomeruli in DOL 21 and 56 kidneys. Our results show marked decrease of glomerular counts with age in SS/Mcw compared to SS/Crl after DOL 14. The time-dependent differences in the expression of apoptosis and UPR-related genes leading to glomerular apoptosis may be a potential mechanism for the nephron count differences between SS/Mcw and SS/Crl.

XBP-1 Levels Predict Sensitivity of Myelomas to Proteasome Inhibitor Bortezomib.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1473-1473
Author(s):  
Silvia C. Ling ◽  
Edwin Lau ◽  
Lye L. Ho ◽  
Joy Ho ◽  
Douglas E. Joshua ◽  
...  
Keyword(s):  
Unfolded Protein Response ◽  
Cell Lines ◽  
Cancer Cell ◽  
Cancer Cell Lines ◽  
Myeloma Cell ◽  
26S Proteasome ◽  
Mrna Levels ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

Abstract Background: Proteasome inhibitors (PI) are remarkably effective in relapsed and refractory myeloma but the origin of this peculiar sensitivity remains unclear. Myeloma is dependent on the unfolded protein response (UPR) and its regulator, transcription factor XBP-1. PI perturbs the unfolded protein response (UPR) by inhibition of the 26S proteasome-the main pathway for protein degradation. We hypothesize that the dependence on the UPR and XBP-1 mediates sensitivity to PI and the level of XBP-1 correlates with sensitivity to PI. The aim of this study is to correlate Bortezomib sensitivity with XBP-1 in vitro and in myeloma patients; to check the effect of manipulating XBP-1 on Bortezomib sensitivity and develop Bortezomib-resistant myeloma cell lines to ascertain the effects on XBP-1 and the UPR. Methods and Results: Sensitivity to Bortezomib was measured by growth inhibition assay. XBP-1 mRNA levels and its isoforms were measured by a two-step quantitative QPCR assay, in 6 myeloma cell lines and 17 other cancer cell lines. There is a strong inverse correlation in myeloma cell lines between total or unspliced XBP-1 with Bortezomib sensitivity (r = −0.9) but not in other cancer cell lines. 23 marrow biopsies from 11 Bortezomib-treated myeloma patients were analysed for XBP-1 expression. Myeloma cells (CD38 hi, CD14 lo, kappa or lambda light chain +ve) were purified by flow cytometry. XBP-1 levels in myeloma cell lines were manipulated by shRNA-mediated knockdown and overexpression by retroviral transduction and had little effect on Bortezomib sensitivity. Bortezomib-resistant myeloma lines were developed. The mechanism of resistance was elucidated (XBP-1, ATF6, P-EIF2a, P58 INK and immunogloblin production). Marked downregulation of XBP-1 was demonstrated. Conclusion: XBP-1 is a surrogate marker of Bortezomib sensitivity and its clinical utility is being tested now. Sensitivity to PI is related to the dependence on the UPR, reflected in the level of XBP-1. Bortezomib resistance is mediated by downregulation of the UPR.

scholarly journals Congenital Tufting Enteropathy-Associated Mutant of Epithelial Cell Adhesion Molecule Activates the Unfolded Protein Response in a Murine Model of the Disease

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 946 ◽  
Author(s):  
Barun Das ◽  
Kevin Okamoto ◽  
John Rabalais ◽  
Ronald R. Marchelletta ◽  
Kim E. Barrett ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Epithelial Cell ◽  
Unfolded Protein Response ◽  
Adhesion Molecule ◽  
Cell Adhesion Molecule ◽  
Translation Initiation Factor ◽  
Mrna Levels ◽  
Epithelial Cell Adhesion Molecule ◽  
Unfolded Protein ◽  
Protein Response

Congenital tufting enteropathy (CTE) is a rare chronic diarrheal disease of infancy caused by mutations in epithelial cell adhesion molecule (EpCAM). Previously, a murine CTE model showed mis-localization of EpCAM away from the basolateral cell surface in the intestine. Here we demonstrate that mutant EpCAM accumulated in the endoplasmic reticulum (ER) where it co-localized with ER chaperone, GRP78/BiP, revealing potential involvement of ER stress-induced unfolded protein response (UPR) pathway in CTE. To investigate the significance of ER-localized mutant EpCAM in CTE, activation of the three UPR signaling branches initiated by the ER transmembrane protein components IRE1, PERK, and ATF6 was tested. A significant reduction in BLOS1 and SCARA3 mRNA levels in EpCAM mutant intestinal cells demonstrated that regulated IRE1-dependent decay (RIDD) was activated. However, IRE1 dependent XBP1 mRNA splicing was not induced. Furthermore, an increase in nuclear-localized ATF6 in mutant intestinal tissues revealed activation of the ATF6-signaling arm. Finally, an increase in both the phosphorylated form of the translation initiation factor, eIF2α, and ATF4 expression in the mutant intestine provided support for activation of the PERK-mediated pathway. Our results are consistent with a significant role for UPR in gastrointestinal homeostasis and provide a working model for CTE pathophysiology.

HIV protease inhibitors activate the unfolded protein response and disrupt lipid metabolism in primary hepatocytes

2006 ◽  
Vol 291 (6) ◽  
pp. G1071-G1080 ◽  
Author(s):  
Huiping Zhou ◽  
Emily C. Gurley ◽  
Sirikalaya Jarujaron ◽  
Hong Ding ◽  
Youwen Fang ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Unfolded Protein Response ◽  
Protease Inhibitors ◽  
Hiv Protease ◽  
Hiv Protease Inhibitors ◽  
Mrna Levels ◽  
Primary Hepatocytes ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

Treatment of human immunodeficiency virus (HIV)-infected patients with HIV protease inhibitors (PIs) has been associated with serious lipid disturbances. However, the incidence and degree of impaired lipid metabolism observed in the clinic vary considerably between individual HIV PIs. Our previous studies demonstrated that HIV PIs differ in their ability to increase the levels of transcriptionally active sterol regulatory element-binding proteins (SREBPs), activate the unfolded protein response (UPR), induce apoptosis, and promote foam cell formation in macrophages. In the present study, we examined the effects of three HIV PIs, including amprenavir, atazanavir, and ritonavir, on the UPR activation and the expression of key genes involved in lipid metabolism in primary rodent hepatocytes. Both atazanavir and ritonavir activated the UPR, induced apoptosis, and increased nuclear SREBP levels, but amprenavir had no significant effect at the same concentrations. In rat primary hepatocytes, cholesterol 7α-hydroxylase (CYP7A1) mRNA levels were significantly decreased by atazanavir (38%) and ritonavir (56%) but increased by amprenavir (90%); 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase mRNA levels were increased by amprenavir (23%) but not by ritonavir and atazanavir; low-density lipoprotein receptor mRNA was increased by atazanavir (20%) but not by amprenavir and ritonavir. Similar results were obtained in mouse primary hepatocytes. Atazanavir and ritonavir also decreased CYP7A1 protein levels and bile acid biosynthesis, while amprenavir had no significant effect. The current results may help provide a better understanding of the cellular mechanisms of HIV PI-induced dyslipidemia and also provide useful information to help predict clinical adverse effects in the development of new HIV PIs.

scholarly journals The unfolded protein response of the endoplasmic reticulum supports mitochondrial biogenesis by buffering non-imported proteins

2021 ◽  
Author(s):  
Katharina Knoeringer ◽  
Carina Groh ◽  
Lena Kraemer ◽  
Kevin C Stein ◽  
Katja G Hansen ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Unfolded Protein Response ◽  
Mitochondrial Membrane ◽  
Cellular Protein ◽  
Mitochondrial Proteins ◽  
Protein Homeostasis ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

Almost all mitochondrial proteins are synthesized in the cytosol and subsequently targeted to mitochondria. The accumulation of non-imported precursor proteins occurring upon mitochondrial dysfunction can challenge cellular protein homeostasis. Here we show that blocking protein translocation into mitochondria results in the accumulation of mitochondrial membrane proteins at the endoplasmic reticulum, thereby triggering the unfolded protein response (UPR-ER). Moreover, we find that mitochondrial membrane proteins are also routed to the ER under physiological conditions. The levels of ER-resident mitochondrial precursors is enhanced by import defects as well as metabolic stimuli that increase the expression of mitochondrial proteins. Under such conditions, the UPR-ER is crucial to maintain protein homeostasis and cellular fitness. We propose the ER serves as a physiological buffer zone for those mitochondrial precursors that cannot be immediately imported into mitochondria while engaging the UPRER to adjust the ER proteostasis capacity to the extent of precursor accumulation.

scholarly journals Noncanonical mitochondrial unfolded protein response impairs placental oxidative phosphorylation in early-onset preeclampsia

2019 ◽  
Vol 116 (36) ◽  
pp. 18109-18118 ◽  
Author(s):  
Hong Wa Yung ◽  
Francesca Colleoni ◽  
Emilie Dommett ◽  
Tereza Cindrova-Davies ◽  
John Kingdom ◽  
...  
Keyword(s):  
Oxidative Phosphorylation ◽  
Unfolded Protein Response ◽  
Early Onset ◽  
Nuclear Translocation ◽  
Mitochondrial Fission ◽  
Later Life ◽  
Mrna Levels ◽  
Unfolded Protein ◽  
Early Onset Preeclampsia ◽  
Protein Response

Preeclampsia (PE) is a dangerous complication of pregnancy, especially when it presents at <34 wk of gestation (PE < 34 wk). It is a major cause of maternal and fetal morbidity and mortality and also increases the risk of cardiometabolic diseases in later life for both mother and offspring. Placental oxidative stress induced by defective placentation sits at the epicenter of the pathophysiology. The placenta is susceptible to activation of the unfolded protein response (UPR), and we hypothesized this may affect mitochondrial function. We first examined mitochondrial respiration before investigating evidence of mitochondrial UPR (UPRmt) in placentas of PE < 34 wk patients. Reduced placental oxidative phosphorylation (OXPHOS) capacity measured in situ was observed despite no change in protein or mRNA levels of electron transport chain complexes. These results were fully recapitulated by subjecting trophoblast cells to repetitive hypoxia–reoxygenation and were associated with activation of a noncanonical UPRmt pathway; the quality-control protease CLPP, central to UPRmt signal transduction, was reduced, while the cochaperone, TID1, was increased. Transcriptional factor ATF5, which regulates expression of key UPRmt genes including HSP60 and GRP75, showed no nuclear translocation. Induction of the UPRmt with methacycline reduced OXPHOS capacity, while silencing CLPP was sufficient to reduce OXPHOS capacity, membrane potential, and promoted mitochondrial fission. CLPP was negatively regulated by the PERK-eIF2α arm of the endoplasmic reticulum UPR pathway, independent of ATF4. Similar changes in the UPRmt pathway were observed in placentas from PE < 34 wk patients. Our results identify UPRmt as a therapeutic target for restoration of placental function in early-onset preeclampsia.

scholarly journals EPO and TMBIM3/GRINA Promote the Activation of the Adaptive Arm and Counteract the Terminal Arm of the Unfolded Protein Response after Murine Transient Cerebral Ischemia

2019 ◽  
Vol 20 (21) ◽  
pp. 5421 ◽  
Author(s):  
Pardes Habib ◽  
Ann-Sophie Stamm ◽  
Joerg B. Schulz ◽  
Arno Reich ◽  
Alexander Slowik ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Cerebral Ischemia ◽  
Unfolded Protein Response ◽  
Calcium Release ◽  
Mrna Levels ◽  
Mixed Cell ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response ◽  
The Impact

Ischemic stroke is known to cause the accumulation of misfolded proteins and loss of calcium homeostasis leading to impairment of endoplasmic reticulum (ER) function. The unfolded protein response (UPR) is an ER-located and cytoprotective pathway that aims to resolve ER stress. Transmembrane BAX inhibitor-1 motif-containing (TMBIM) protein family member TMBIM3/GRINA is highly expressed in the brain and mostly located at the ER membrane suppressing ER calcium release by inositol-1,4,5-trisphosphate receptors. GRINA confers neuroprotection and is regulated by erythropoietin (EPO) after murine cerebral ischemia. However, the role of GRINA and the impact of EPO treatment on the post-ischemic UPR have not been elucidated yet. We subjected GRINA-deficient (Grina−/−) and wildtype mice to transient (30 min) middle cerebral artery occlusion (tMCAo) followed by 6 h or 72 h of reperfusion. We administered EPO or saline 0, 24 and 48 h after tMCAo/sham surgery. Oxygen–glucose deprivation (OGD) and pharmacological stimulation of the UPR using Tunicamycin and Thapsigargin were carried out in primary murine cortical mixed cell cultures. Treatment with the PERK-inhibitor GSK-2606414, IRE1a-RNase-inhibitor STF-083010 and EPO was performed 1 h prior to either 1 h, 2 h or 3 h of OGD. We found earlier and larger infarct demarcations in Grina−/− mice compared to wildtype mice, which was accompanied by a worse neurological outcome and an abolishment of EPO-mediated neuroprotection after ischemic stroke. In addition, GRINA-deficiency increased apoptosis and the activation of the corresponding PERK arm of the UPR after stroke. EPO enhanced the post-ischemic activation of pro-survival IRE1a and counteracted the pro-apoptotic PERK branch of the UPR. Both EPO and the PERK-inhibitor GSK-2606414 reduced cell death and regulated Grina mRNA levels after OGD. In conclusion, GRINA plays a crucial role in post-ischemic UPR and the use of both GSK-2606414 and EPO might lead to neuroprotection.

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