The role of MAPK in the biphasic dose-response phenomenon induced by cadmium and mercury in HEK293 cells

2009 ◽  
Vol 23 (4) ◽  
pp. 660-666 ◽  
Author(s):  
Changfu Hao ◽  
Weidong Hao ◽  
Xuetao Wei ◽  
Lina Xing ◽  
Jianjun Jiang ◽  
...  
Keyword(s):  
Dose Response ◽  
Hek293 Cells ◽  
Biphasic Dose Response

Inhibition of TSH/IGF-1 receptor crosstalk by Teprotumumab as a treatment modality of Thyroid Eye Disease

2021 ◽  
Author(s):  
Christine C Krieger ◽  
Xiangliang Sui ◽  
George J Kahaly ◽  
Susanne Neumann ◽  
Marvin C Gershengorn
Keyword(s):  
Dose Response ◽  
Treatment Modality ◽  
Thyroid Eye Disease ◽  
Tsh Receptor ◽  
Eye Disease ◽  
Receptor Crosstalk ◽  
Orbital Fibroblast ◽  
Orbital Fibroblasts ◽  
Biphasic Dose Response

Abstract Context We previously presented evidence that TSH receptor (TSHR)-stimulating autoantibodies (TSAbs) bind to and activate TSHRs but do not bind to IGF1 receptors (IGF1Rs). Nevertheless, we showed that IGF1Rs were involved in thyroid eye disease (TED) pathogenesis because TSAbs activated crosstalk between TSHR and IGF1R. Teprotumumab, originally generated to inhibit IGF1 binding to IGF1R, was recently approved for the treatment of TED (Tepezza®). Objective To investigate the role of TSHR/IGF1R crosstalk in teprotumumab treatment of TED. Design We used orbital fibroblasts from patients with TED (TEDOFs) and measured stimulated hyaluronan (HA) secretion as a measure of orbital fibroblast activation by TED immunoglobulins (TED-Igs) and monoclonal TSAb M22. We previously showed that M22, which does not bind to IGF1R, stimulated HA in a biphasic dose-response with the higher-potency phase dependent on TSHR/IGF1R crosstalk and the lower-potency phase independent of IGF1R. Stimulation by TED-Igs and M22 was measured in the absence or presence of Teprotumumab Biosimilar (Tepro) or K1-70, an antibody that inhibits TSHR. Results We show: 1) Tepro dose-dependently inhibits stimulation by TED-Igs; 2) Tepro does not bind to TSHRs; 3) Tepro inhibits IGF1R-dependent M22-induced HA production, which is mediated by TSHR/IGF1R crosstalk, but not IGF1R-independent M22 stimulation; and 4) β-arrestin 1 knockdown, which blocks TSHR/IGF1R crosstalk, prevents Tepro inhibition of HA production by M22 and by a pool of TED-Igs. Conclusion We conclude that Tepro inhibits HA production by TEDOFs by inhibiting TSHR/IGF1R crosstalk and suggest that inhibition of TSHR/IGF1R crosstalk is the mechanism of its action in treating TED.

scholarly journals Dietary fiber intake from fresh and preserved food and risk of nasopharyngeal carcinoma: observational evidence from a Chinese population

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Zhi-Ming MAI ◽  
Roger Kai-Cheong NGAN ◽  
Dora Lai-Wan KWONG ◽  
Wai-Tong NG ◽  
Kam-Tong Yuen ◽  
...  
Keyword(s):  
Nasopharyngeal Carcinoma ◽  
Dietary Fiber ◽  
Dose Response ◽  
Sun Exposure ◽  
Fiber Intake ◽  
Total Dietary Fiber ◽  
Dietary Fiber Intake ◽  
Fresh Vegetables ◽  
Incident Cases

Abstract Background The role of dietary fiber intake on risk of nasopharyngeal carcinoma (NPC) remains unclear. We examined the associations of dietary fiber intake on the risk of NPC adjusting for a comprehensive list of potential confounders. Methods Using data from a multicenter case-control study, we included 815 histologically confirmed NPC incident cases and 1502 controls in Hong Kong, China recruited in 2014–2017. Odds ratios (ORs) of NPC (cases vs controls) for dietary fiber intake from different sources at different life periods (age 13–18, age 19–30, and 10 years before recruitment) were evaluated using unconditional logistic regression, adjusting for sex, age, socioeconomic status, smoking and drinking status, occupational hazards, family history of cancer, salted fish, and total energy intake in Model 1, Epstein-Barr virus viral capsid antigen serological status in Model 2, and duration of sun exposure and circulating 25-hydroxyvitamin D in Model 3. Results Higher intake of total dietary fiber 10 years before recruitment was significantly associated with decreased NPC risk, with demonstrable dose-response relationship (P-values for trend = 0.001, 0.020 and 0.024 in Models 1–3, respectively). The adjusted ORs (95% CI) in the highest versus the lowest quartile were 0.51 (0.38–0.69) in Model 1, 0.48 (0.33–0.69) in Model 2, and 0.48 (0.33–0.70) in Model 3. However, the association was less clear after adjustment of other potential confounders (e.g. EBV) in the two younger periods (age of 13–18 and 19–30 years). Risks of NPC were significantly lower for dietary fiber intake from fresh vegetables and fruits and soybean products over all three periods, with dose-response relationships observed in all Models (P-values for trend for age 13–18, age 19–30 and 10 years before recruitment were, respectively, 0.002, 0.009 and 0.001 for Model1; 0.020, 0.031 and 0.003 for Model 2; and 0.022, 0.037 and 0.004 for Model 3). No clear association of NPC risk with dietary fiber intake from preserved vegetables, fruits and condiments was observed. Conclusion Our study has shown the protective role of dietary fiber from fresh food items in NPC risk, but no association for total dietary fiber intake was observed, probably because total intake also included intake of preserved food. Further studies with detailed dietary information and in prospective settings are needed to confirm this finding, and to explore the possible underlying biological mechanisms.

scholarly journals The role of Ca2+ in the protoveratrine-induced release of γ-aminobutyrate from rat brain slices

1980 ◽  
Vol 190 (2) ◽  
pp. 333-339 ◽  
Author(s):  
M C W Minchin
Keyword(s):  
Cerebral Cortex ◽  
Rat Brain ◽  
Dose Response ◽  
Transmitter Release ◽  
Response Curve ◽  
Brain Slices ◽  
Veratrum Alkaloids ◽  
Similar Dose ◽  
22Na Uptake

1. Protoveratrine A increased the release of gamma-amino[3H]butyrate from small slices of rat cerebral cortex. This effect increased with increasing protoveratrine concentration, reaching a maximum at 100 microM. 2. Removal of Ca2+ from the superfusing medium did not change the increase in release due to 10 microM-protoveratrine; however, the Ca2+ antagonists, compound D-600, La3+, Mn2+, Mg2+ and also high Ca2+ concentration inhibited the effect of the alkaloid, as did procaine. 3. Protoveratrine A increased the uptake of 22Na+ into the slices with a similar dose-response curve to that found for gamma-aminobutyrate release. For the most part, the substances that inhibited protoveratrine-stimulated gamma-aminobutyrate release also inhibited 22Na+ uptake, although the correlation was not perfect. 4. Although extracellular Ca2+ is not required for protoveratrine-induced gamma-aminobutyrate release, an increase in Na+ influx that is susceptible to inhibition by some Ca2+ antagonists does appear to be associated with this phenomenon. However, the possibility remains that changes in the free intracellular Ca2+ concentration may be important for transmitter release induced by depolarizing veratrum alkaloids.

Role of oxygen in the production of human decompression sickness

1987 ◽  
Vol 63 (6) ◽  
pp. 2380-2387 ◽  
Author(s):  
P. K. Weathersby ◽  
B. L. Hart ◽  
E. T. Flynn ◽  
W. F. Walker
Keyword(s):  
Dose Response ◽  
Response Curve ◽  
Decompression Sickness ◽  
Animal Experiments ◽  
Inert Gases ◽  
Relative Risks ◽  
Data Variability ◽  
Increase Risk ◽  
High O2

In the calculation of decompression schedules, it is commonly assumed that only the inert gas needs to be considered; all inspired O2 is ignored. Animal experiments have shown that high O2 can increase risk of serious decompression sickness (DCS). A trial was performed to assess the relative risks of O2 and N2 in human no-decompression dives. Controlled dives (477) of 30- to 240-min duration were performed with subjects breathing mixtures with low (0.21–0.38 ATA) or high (1.0–1.5 ATA) Po2. Depths were chosen by a sequential dose-response format. Only 11 cases of DCS and 18 cases of marginal symptoms were recorded despite exceeding the presently accepted no-decompression limits by greater than 20%. Analysis by maximum likelihood showed a shallow dose-response curve for increasing depth. O2 was estimated to have zero influence on DCS risk, although data variability still allows a slight chance that O2 could be 40% as effective as N2 in producing a risk of DCS. Consideration of only inert gases is thus justified in calculating human decompression tables.

scholarly journals Heme oxygenase-2 (HO-2) binds and buffers labile heme, which is largely oxidized, in human embryonic kidney cells

2021 ◽  
Author(s):  
David A Hanna ◽  
Courtney M Moore ◽  
Liu Liu ◽  
Xiaojing Yuan ◽  
Angela S Fleischhacker ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Physiological Function ◽  
Hek293 Cells ◽  
Kidney Cells ◽  
Human Embryonic Kidney ◽  
Human Embryonic Kidney Cells ◽  
Heme Oxygenases ◽  
Heme Trafficking ◽  
Ferrous Heme

Heme oxygenases (HO) detoxify heme by oxidatively degrading it into carbon monoxide, iron, and biliverdin, which is reduced to bilirubin and excreted. Humans express two isoforms: inducible HO-1, which is up-regulated in response to various stressors, including excess heme, and constitutive HO-2. While much is known about the regulation and physiological function of HO-1, comparatively little is known about the role of HO-2 in regulating heme homeostasis. The biochemical necessity for expressing constitutive HO-2 is largely dependent on whether heme is sufficiently abundant and accessible as a substrate under conditions in which HO-1 is not induced. By measuring labile heme, total heme, and bilirubin in human embryonic kidney HEK293 cells with silenced or over-expressed HO-2, and various HO-2 mutant alleles, we found that endogenous heme is too limiting to support HO-2 catalyzed heme degradation. Rather, we discovered that a novel role for HO-2 is to bind and buffer labile heme. Taken together, in the absence of excess heme, we propose that HO-2 regulates heme homeostasis by acting as a heme buffering factor in control of heme bioavailability. When heme is in excess, HO-1 is induced and both HO-2 and HO-1 can provide protection from heme toxicity by enzymatically degrading it. Our results explain why catalytically inactive mutants of HO-2 are cytoprotective against oxidative stress. Moreover, the change in bioavailable heme due to HO-2 overexpression, which selectively binds ferric over ferrous heme, is consistent with the labile heme pool being oxidized, thereby providing new insights into heme trafficking and signaling.

scholarly journals Activation and activity of glycosylated KLKs 3, 4 and 11

2018 ◽  
Vol 399 (9) ◽  
pp. 1009-1022 ◽  
Author(s):  
Shihui Guo ◽  
Peter Briza ◽  
Viktor Magdolen ◽  
Hans Brandstetter ◽  
Peter Goettig
Keyword(s):  
Physiological Function ◽  
Periodic Acid ◽  
Hek293 Cells ◽  
Secretory Expression ◽  
Detailed Characterization ◽  
Periodic Acid Schiff ◽  
Clinical Biomarkers ◽  
Schiff Reaction

Abstract Human kallikrein-related peptidases 3, 4, 11, and KLK2, the activator of KLK3/PSA, belong to the prostatic group of the KLKs, whose major physiological function is semen liquefaction during the fertilization process. Notably, these KLKs are upregulated in prostate cancer and are used as clinical biomarkers or have been proposed as therapeutic targets. However, this potential awaits a detailed characterization of these proteases. In order to study glycosylated prostatic KLKs resembling the natural proteases, we used Leishmania (LEXSY) and HEK293 cells for secretory expression. Both systems allowed the subsequent purification of soluble pro-KLK zymogens with correct propeptides and of the mature forms. Periodic acid-Schiff reaction, enzymatic deglycosylation assays, and mass spectrometry confirmed the glycosylation of these KLKs. Activation of glycosylated pro-KLKs 4 and 11 turned out to be most efficient by glycosylated KLK2 and KLK4, respectively. By comparing the glycosylated prostatic KLKs with their non-glycosylated counterparts from Escherichia coli, it was observed that the N-glycans stabilize the KLK proteases and change their activation profiles and their enzymatic activity to some extent. The functional role of glycosylation in prostate-specific KLKs could pave the way to a deeper understanding of their biology and to medical applications.

Abstract MP20: Optogenetic Control Of Pip2 To Assess Mechanisms Regulating The Epithelial Sodium Channel

Hypertension ◽  
2021 ◽  
Vol 78 (Suppl_1) ◽  
Author(s):  
Crystal R Archer ◽  
Amanpreet Kaur ◽  
Tarek Mohamed ◽  
James D Stockand
Keyword(s):  
Binding Sites ◽  
Hek293 Cells ◽  
Proper Function ◽  
Small Decrease ◽  
Kidney Tubules ◽  
Wild Type ◽  
N Terminus ◽  
Patch Clamp Electrophysiology ◽  
G Protein Coupled

The epithelial Na + channel (ENaC) plays a key role in Na + transport in epithelial linings to include the lung, colon and kidney. In the distal kidney tubules, ENaC regulates Na + reabsorption and blood volume. Thus, dysfunctions in signaling pathways regulating ENaC activity are linked to hypertension or hypotension. Phosphatidylinositol 4,5-bisphosphate (PIP 2 ) is a target of the G protein coupled receptor P2Y2 pathway, and is necessary for the proper function of ENaC. This nonvoltage-gated trimeric channel is comprised of α, β, and γ subunits. We recently described two intracellular PIP 2 binding sites on the N termini of β-, and γ-ENaC, with moderate μM affinity. Here, we report the functional effects on ENaC containing a combination of mutations to those PIP 2 binding sites, by controlled depletion of PIP 2 . We used a CIBN/CRY2-5-ptase optogenetic dimerization system to deplete PIP 2 levels in HEK293 cells transiently expressing wild type (wt) ENaC or the mutant ENaC constructs. A fluorescent Na + indicator, was used to monitor ENaC activity by tracking the relative intracellular Na + levels. Upon optogenetic-controlled depletion of PIP 2 , Na + levels decreased in cells expressing wt ENaC. Mutations to the PIP 2 sites of ENaC were expected to have no change in Na + levels upon PIP 2 depletion due to the disruption of PIP 2 binding. As a control, mutations to non-PIP 2 binding sites were included, and were expected to have decreased Na + levels similar to wt ENaC. Interestingly, mutation of each independent PIP 2 site resulted in only a small decrease of intracellular Na + , compared to wt ENaC. However, mutations throughout the entire N-terminus of β-ENaC, including the PIP 2 binding site, resulted in a significant increase of Na + upon PIP 2 depletion. We performed patch clamp electrophysiology and found that the ENaC recordings corresponded to the Na + fluctuations. These data suggest that the residues surrounding the PIP 2 binding sites play a significant role in the affinity of PIP 2 for ENaC. The role of these other domains in PIP 2 binding is still under investigation.

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