scholarly journals Tau: A Signaling Hub Protein

Author(s):  
Rebecca L. Mueller ◽  
Benjamin Combs ◽  
Mohammed M. Alhadidy ◽  
Scott T. Brady ◽  
Gerardo A. Morfini ◽  
...  

Over four decades ago,in vitroexperiments showed that tau protein interacts with and stabilizes microtubules in a phosphorylation-dependent manner. This observation fueled the widespread hypotheses that these properties extend to living neurons and that reduced stability of microtubules represents a major disease-driving event induced by pathological forms of tau in Alzheimer’s disease and other tauopathies. Accordingly, most research efforts to date have addressed this protein as a substrate, focusing on evaluating how specific mutations, phosphorylation, and other post-translational modifications impact its microtubule-binding and stabilizing properties. In contrast, fewer efforts were made to illuminate potential mechanisms linking physiological and disease-related forms of tau to the normal and pathological regulation of kinases and phosphatases. Here, we discuss published work indicating that, through interactions with various kinases and phosphatases, tau may normally act as a scaffolding protein to regulate phosphorylation-based signaling pathways. Expanding on this concept, we also review experimental evidence linking disease-related tau species to the misregulation of these pathways. Collectively, the available evidence supports the participation of tau in multiple cellular processes sustaining neuronal and glial function through various mechanisms involving the scaffolding and regulation of selected kinases and phosphatases at discrete subcellular compartments. The notion that the repertoire of tau functions includes a role as a signaling hub should widen our interpretation of experimental results and increase our understanding of tau biology in normal and disease conditions.

Marine Drugs ◽  
2018 ◽  
Vol 16 (7) ◽  
pp. 239 ◽  
Author(s):  
Lei Wang ◽  
WonWoo Lee ◽  
Jae Oh ◽  
Yong Cui ◽  
BoMi Ryu ◽  
...  

Our previous study evaluated the antioxidant activities of sulfated polysaccharides from Celluclast-assisted extract of Hizikia fusiforme (HFPS) in vitro in Vero cells and in vivo in zebrafish. The results showed that HFPS possesses strong antioxidant activity and suggested the potential photo-protective activities of HFPS. Hence, in the present study, we investigated the protective effects of HFPS against ultraviolet (UV) B-induced skin damage in vitro in human dermal fibroblasts (HDF cells). The results indicate that HFPS significantly reduced intracellular reactive oxygen species (ROS) level and improved the viability of UVB-irradiated HDF cells in a dose-dependent manner. Furthermore, HFPS significantly inhibited intracellular collagenase and elastase activities, remarkably protected collagen synthesis, and reduced matrix metalloproteinases (MMPs) expression by regulating nuclear factor kappa B (NF-κB), activator protein 1 (AP-1), and mitogen-activated protein kinases (MAPKs) signaling pathways in UVB-irradiated HDF cells. These results suggest that HFPS possesses strong UV protective effect, and can be a potential ingredient in the pharmaceutical and cosmetic industries.


2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Flurina Boehi ◽  
Patrick Manetsch ◽  
Michael O. Hottiger

AbstractSignaling cascades provide integrative and interactive frameworks that allow the cell to respond to signals from its environment and/or from within the cell itself. The dynamic regulation of mammalian cell signaling pathways is often modulated by cascades of protein post-translational modifications (PTMs). ADP-ribosylation is a PTM that is catalyzed by ADP-ribosyltransferases and manifests as mono- (MARylation) or poly- (PARylation) ADP-ribosylation depending on the addition of one or multiple ADP-ribose units to protein substrates. ADP-ribosylation has recently emerged as an important cell regulator that impacts a plethora of cellular processes, including many intracellular signaling events. Here, we provide an overview of the interplay between the intracellular diphtheria toxin-like ADP-ribosyltransferase (ARTD) family members and five selected signaling pathways (including NF-κB, JAK/STAT, Wnt-β-catenin, MAPK, PI3K/AKT), which are frequently described to control or to be controlled by ADP-ribosyltransferases and how these interactions impact the cellular responses.


2009 ◽  
Vol 21 (1) ◽  
pp. 189
Author(s):  
V. H. Dang ◽  
E.-B. Jeung

Calbindin-D9k (CaBP-9k), a cytosolic protein, is one of the members of the family of vitamin D-dependent calcium-binding proteins with high affinity for calcium. The previous in vitro studies indicated that this gene is controlled by 17β-estradiol (E2), a physiological estrogen, via both genomic (through its classical nuclear receptors) and non-genomic (through different cypoplasmic signals) mechanisms. In order to provide a better understanding in molecular events by which E2 exerts its actions in the regulation of CaBP-9k, we employed GH3 cells as an in vitro model to examine the possible non-genomic effects of E2 on the induction of CaBP-9k. GH3 cells were treated dose-dependently (10–5, 10–6, 10–7, 10–8, and 10–9 m) with E2-BSA, a membrane-impermeable E2 conjugated with BSA, for 24 h. To examine the time dependency, the cells were also exposed to a high concentration (10–6 m) of E2-BSA and harvested at various time points (5 min, 15 min, 30 min, 1 h, 3 h, 6 h, 12 h, 24 h, and 48 h). Furthermore, in order to determine the potential involvement of non-genomic signaling pathways in E2-BSA-induced expression of CaBP-9k, several inhibitors also were employed, including ICI 182 780 for membrane estrogen receptor (ER) pathway, pertussis toxin (PTX) for G protein signaling, U0126 for ERK pathway, and wortmannin for Akt pathway. The non-genomic effects of E2-BSA on the induction of CaBP-9k mRNA and protein were determined by semi-quantitative RT-PCR and Western blotting, respectively. In a dose-dependent manner, administration with E2-BSA (10–6 m) induced the highest response of CaBP-9k at transcriptional (mRNA) level, whereas protein level of CaBP-9k peaked at E2-BSA concentration (10–7 m) at 24 h. In a time course, E2-BSA (10–6 m) exposure caused a significant increase in both CaBP-9k mRNA and protein expressions as early as 15 min and peaked at 24 h. Co-treatment with ICI 182 780 and PTX completely inhibited E2-BSA-induced CaBP-9k mRNA and protein expressions. Interestingly, although co-treatments with U0126 and/or wortmannin alone failed to attenuate the effects of E2-BSA, a combination of 2 inhibitors completely reversed E2-BSA-induced CaBP-9k expressions at both transcriptional (mRNA) and translational (protein) levels, suggesting their involvement in the regulation of CaBP-9k in GH3 cells. Taken together, these results demonstrate that various signaling pathways may be involved in E2-induced regulation of CaBP-9k in which membrane ER and G protein signaling pathways play a central role in non-genomic responses. Further in vitro experiments are required to elucidate additional details of the interaction of ERK and Akt pathways in the regulation of CaBP-9k in these cells, offering a new insight into the mode of E2 action in the pituitary gland of human and wildlife.


Author(s):  
Hongfang Wang ◽  
Jinlian Fu ◽  
Aiguo Wang

Obesity has become a global health problem. Research suggests that leptin, a hormone that responds to fat deposition, may be involved in mammalian reproduction; however, its precise role in embryo implantation is poorly understood. Here, primary porcine endometrium epithelium cells (PEECs) were cultured in vitro and used to evaluate the regulatory role of different leptin levels on β3-integrin, MMP9, HB-EGF, and IL-1β, which are, respectively, involved in four critical steps of embryo implantation. Results showed that only 0.01 nM leptin significantly improved β3-integrin mRNA expression (p < 0.05). MMP9 and HB-EGF mRNA expressions were upregulated by 0.10–10.00 nM leptin (p < 0.05). The IL-1β expression level was only increased by 10.00 nM leptin (p < 0.05). β3-integrin, MMP9, HB-EGF, and IL-1β mRNA and protein have a similar fluctuant response to increased leptin. Leptin’s influence on β3-integrin, MMP9, HB-EGF, and IL-1β disappeared when the JAK2, PI(3)K, or MAPK signaling pathways were blocked, respectively. In conclusion, leptin affected porcine implantation by regulating the expression of β3-integrin, MMP9, HB-EGF, and IL-1β in a dose-dependent manner. The signaling pathways of JAK2, PI(3)K, and MAPK may participate in this regulatory process. These findings will contribute to further understanding the mechanisms of reproductive disorders in obesity.


2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ming Gao ◽  
Guijie Guo ◽  
Jinzhou Huang ◽  
Jake A. Kloeber ◽  
Fei Zhao ◽  
...  

Abstract Human C-terminal binding protein (CtBP)–interacting protein (CtIP) is a central regulator to initiate DNA end resection and homologous recombination (HR). Several studies have shown that post-translational modifications control the activity or expression of CtIP. However, it remains unclear whether and how cells restrain CtIP activity in unstressed cells and activate CtIP when needed. Here, we identify that USP52 directly interacts with and deubiquitinates CtIP, thereby promoting DNA end resection and HR. Mechanistically, USP52 removes the ubiquitination of CtIP to facilitate the phosphorylation and activation of CtIP at Thr-847. In addition, USP52 is phosphorylated by ATM at Ser-1003 after DNA damage, which enhances the catalytic activity of USP52. Furthermore, depletion of USP52 sensitizes cells to PARP inhibition in a CtIP-dependent manner in vitro and in vivo. Collectively, our findings reveal the key role of USP52 and the regulatory complexity of CtIP deubiquitination in DNA repair.


2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Xinyi Lu ◽  
Xingli Wu ◽  
Lin Jing ◽  
Lingjia Tao ◽  
Yingxuan Zhang ◽  
...  

Objective. To analyze the active compounds, potential targets, and diseases of JianPi Fu Recipe (JPFR) based on network pharmacology and bioinformatics and verify the potential biological function and mechanism of JPFR in vitro and in vivo. Methods. Network pharmacology databases including TCMSP, TCM-PTD, TCMID, and DrugBank were used to screen the active compounds and potential drug targets of JPFR. Cytoscape 3.7 software was applied to construct the interaction network between active compounds and potential targets. The DAVID online database analysis was performed to investigate the potential effective diseases and involved signaling pathways according to the results of the GO function and KEGG pathways enrichment analysis. To ensure standardization and maintain interbatch reliability of JPFR, High Performance Liquid Chromatography (HPLC) was used to establish a “chemical fingerprint.” For biological function validation, the effect of JPFR on the proliferation and migration of CRC cells in vitro was investigated by CCK-8 and transwell and wound healing assay, and the effect of JPFR on the growth and metastasis of CRC cells in vivo was detected by building a lung metastasis model in nude mice and in vivo imaging. For the potential mechanism validation, the expressions of MALAT1, PTBP-2, and β-catenin in CRC cells and transplanted CRC tumors were detected by real-time PCR, western blot, and immunohistochemical staining analysis. Results. According to the rules of oral bioavailability (OB) > 30% and drug-likeness (DL) > 0.18, 244 effective compounds in JPFR were screened out, as well as the corresponding 132 potential drug targets. By the analysis of DAVID database, all these key targets were associated closely with the cancer diseases such as prostate cancer, colorectal cancer, bladder cancer, small cell lung cancer, pancreatic cancer, and hepatocellular carcinoma. In addition, multiple signaling pathways were closely related to JPFR, including p53, Wnt, PI3K-Akt, IL-17, HIF-1, p38-MAPK, NF-κB, PD-L1 expression and PD-1 checkpoint pathway, VEGF, JAK-STAT, and Hippo. The systematical analysis showed that various active compounds of JPFR were closely connected with Wnt/β-catenin, EGFR, HIF-1, TGFβ/Smads, and IL6-STAT3 signaling pathway, including kaempferol, isorhamnetin, calycosin, quercetin, medicarpin, phaseol, spinasterol, hederagenin, beta-sitosterol, wighteone, luteolin, and isotrifoliol. For in vitro experiments, the migration and growth of human CRC cells were inhibited by the JPFR extract in a dose-dependent way, and the expression of MALAT1, PTBP-2, β-catenin, MMP7, c-Myc, and Cyclin D1 in CRC cells were downregulated by the JPFR extract in a dose-dependent way. For in vivo metastasis experiments, the numbers of lung metastasis were found to be decreased by the JPFR extract in a dose-dependent manner, and the expressions of metastasis-associated genes including MALAT1, PTBP-2, β-catenin, and MMP7 in the lung metastases were downregulated dose dependently by the JPFR extract. For the orthotopic transplanted tumor experiments, the JPFR extract could inhibit the growth of orthotopic transplanted tumors and downregulate the expression of c-Myc and Cyclin D1 in a dose-dependent manner. Moreover, the JPFR extract could prolong the survival time of tumor-bearing mice in a dose-dependent manner. Conclusions. Through effective network pharmacology analysis, we found that JPFR contains many effective compounds which may directly target cancer-associated signaling pathways. The in vitro and in vivo experiments further confirmed that JPFR could inhibit the growth and metastasis of CRC cells by regulating β-catenin signaling-associated genes or proteins.


Drug Research ◽  
2017 ◽  
Vol 68 (03) ◽  
pp. 153-158 ◽  
Author(s):  
Rahmaniah Rahmaniah ◽  
Yuyuntia Yuyuntia ◽  
Vivian Soetikno ◽  
Wawaimuli Arozal ◽  
Radiana Antarianto ◽  
...  

Abstract Background Alpha mangostin has been reported to have activity for the treatment of liver fibrosis in the rats. However, the mechanisms of action are poorly understood. This study was aimed to investigate the effect of alpha mangostin on hepatic stellate cells (HSC) activation and proliferation through TGF-β/Smad and Akt signaling pathways. Methods Immortalized HSC, LX2 cells, were incubated with TGF-β with or without alpha mangostin (5 or 10 μM). Sorafenib 10 µM was used as positive control. LX2 viability was counted using trypan blue exclusion method. The effect of alpha mangostin on TGF-β concentrations, and the expressions of proliferation and fibrogenic markers were evaluated. Results Alpha mangostin treatment resulted in a reduced proliferation of HSC, decreased Ki-67 and p-Akt expressions. These findings were followed with decreased concentrations of TGF-β in the medium of cells treated with alpha mangostin, decreased expressions of COL1A1, TIMP1, PAI1, α-SMA, and p-Smad3 as fibrogenic markers. These effects were shown to be dose-dependent. Conclusions Alpha mangostin inhibits hepatic stellate cells proliferation and activation through TGF-β/Smad and Akt signaling pathways in dose dependent manner.


2014 ◽  
Vol 462 (1) ◽  
pp. 77-88 ◽  
Author(s):  
Kristen E. Funk ◽  
Stefani N. Thomas ◽  
Kelsey N. Schafer ◽  
Grace L. Cooper ◽  
Zhongping Liao ◽  
...  

Diverse post-translational modifications regulate tau protein function and misfolding. In the present study we identified lysine methylation as a tau post-translational modification in normal human brain, and found it depressed tau aggregation propensity when modelled in vitro.


Author(s):  
Vladan Bajić ◽  
Bo Su ◽  
Hyoung-Gon Lee ◽  
Wataru Kudo ◽  
Sandra Siedlak ◽  
...  

AbstractPost-mitotic neurons are typically terminally differentiated and in a quiescent status. However, in Alzheimer disease (AD), many neurons display ectopic re-expression of cell cycle-related proteins. Cyclin-dependent kinase 11 (CDK11) mRNA produces a 110-kDa protein (CDK11p110) throughout the cell cycle, a 58-kDa protein (CDK11p58) that is specifically translated from an internal ribosome entry site and expressed only in the G2/M phase of the cell cycle, and a 46-kDa protein (CDK11p46) that is considered to be apoptosis specific. CDK11 is required for sister chromatid cohesion and the completion of mitosis. In this study, we found that the expression patterns of CDK11 vary such that cytoplasmic CDK11 is increased in AD cellular processes, compared to a pronounced nuclear expression pattern in most controls. We also investigated the effect of amyloid precursor protein (APP) on CDK11 expression in vitro by using M17 cells overexpressing wild-type APP and APP Swedish mutant phenotype and found increased CDK11 expression compared to empty vector. In addition, amyloid-β25–35 resulted in increased CDK11 in M17 cells. These data suggest that CDK11 may play a vital role in cell cycle re-entry in AD neurons in an APP-dependent manner, thus presenting an intriguing novel function of the APP signaling pathway in AD.


2019 ◽  
Vol 10 (11) ◽  
Author(s):  
Junya Ning ◽  
Zhaomin Lin ◽  
Xuan Zhao ◽  
Baoxiang Zhao ◽  
Junying Miao

Abstract The level of hypochlorous acid (HOCl) in cancer cells is higher than that in non-cancer cells. HOCl is an essential signal for the regulation of cell fate and works mainly through the protein post-translational modifications in cancer cells. However, the mechanism of HOCl regulating autophagy has not been clarified. Here we reported that a HOCl probe named ZBM-H targeted endoplasmic reticulum and induced an intact autophagy flux in lung cancer cells. Furthermore, ZBM-H promoted the binding of GRP78 to AMPK and increased the phosphorylation of AMPK in a dose- and time-dependent manner. GRP78 knockdown inhibited ZBM-H-induced AMPK phosphorylation and ZBM-H-stimulated autophagy. In addition, mass spectrometry combined with point mutation experiments revealed that ZBM-H increased GRP78 activity by inhibiting HOCl-induced lysine 353 oxidation of GRP78. Following ZBM-H treatment in vitro and in vivo, cell growth was significantly inhibited while apoptosis was induced. Nevertheless, exogenous HOCl partially reversed ZBM-H-inhibited cell growth and ZBM-H-induced GRP78 activation. In brief, we found that an endoplasmic reticulum-targeted HOCl probe named ZBM-H, acting through attenuating HOCl-induced GRP78 oxidation, inhibited tumor cell survival by promoting autophagy and apoptosis. Overall, these data demonstrated a novel mechanism of hypochlorous acid regulating autophagy by promoting the oxidation modification of GRP78.


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