Hasil untuk "physics.atm-clus"

S. Abdi, A. Alghamdi, Nouf Nasser Abduallah AlGhunaim et al.

BACKGROUND In the wake of the warning by WHO that the prevalence of dementia may have a rise of 125% in the Middle East by 2050, identification of the genetic risk factors in Arab populations is urgent. OBJECTIVE To investigate the association of Single Nucleotide Polymorphisms (SNPs) in apolipoprotein E (ApoE), clusterin (CLU), tumor necrotic factor- α (TNF-α) and interleukin-6 (IL-6) genes, with risk of Alzheimer's disease (AD) in Saudi Arabian participants. METHOD A total of 42 Saudi AD patients and 23 age-matched control participants were genotyped for eight SNPs: rs429358, rs7412 (ApoE); rs11136000, rs1532278(CLU); rs1800629, rs1799724(TNF-α) and rs1800796, rs1800795(IL-6), by RT-PCR using the TaqMan assay. Serum concentrations of amyloid beta peptide 1-40(Aβ1-40), amyloid beta peptide 1-42(Aβ1-42), CLU and some other biochemical markers were measured. RESULTS A significant increase (p=0.004) in the serum CLU level was detected in the AD group (340.4 ± 74.6) compared with control group (265.0 ± 80.9). For rs1532278 (CLU), genotype GA was significantly higher in AD patients (57.1%) than in the control participants (26.1%), [p=0.036, OR = 3.67, 95% CI (1.10-12.32)]. For rs429358 (ApoE), patients showed a significantly increased frequency of the TC genotype than controls [p = 0.008, OR = 17.5, 95% CI (2.10-145.78)]. AD patients with CC genotype for ApoE rs429358 had significantly lower levels of Aβ1-40 (p=0.04) in AD patients than controls. Carriers of genotype GG for rs1800629(TNF-α) showed significantly higher levels of serum IL-6 (p = 0.04) in AD patients. CONCLUSION Genetic variants in ApoE and CLU may influence susceptibility to AD among Saudi Arabian participants.

R. Sawyer, S. Demel, M. Comeau et al.

Apolipoprotein E alleles have been associated with both Alzheimer’s disease (AD) and intracerebral hemorrhage (ICH). In addition, ICH is associated with a markedly high risk of subsequent dementia compared to other subtypes of stroke. We sought to evaluate if other genetic markers for AD were also associated with ICH. We examined whether published AD risk single nucleotide polymorphisms (SNPs) and haplotypes were associated with ICH utilizing genome-wide association study data from 2 independent studies (genetic and environmental risk factors for hemorrhagic stroke [GERFHS] study and genetics of cerebral hemorrhage with anticoagulation [GOCHA]). Analyses included evaluation by location of ICH. GERFHS and GOCHA cohorts contained 745 ICH cases and 536 controls for analysis. The strongest association was on 1q32 near Complement receptor type 1 (CR1), where rs6701713 was associated with all ICH (P = .0074, odds ratio [OR] = 2.07) and lobar ICH (P = .0073, OR = 2.80). The 51 most significant 2-SNP haplotypes associated with lobar ICH were identified within the Clusterin (CLU) gene. We identified that variation within CR1 and CLU, previously identified risk factors for AD, and are associated with an increased risk for ICH driven primarily by lobar ICH. Previous work implicated CR1 and CLU in cerebral amyloid clearance, the innate immune system, and cellular stress response.

Biswajit Padhy, Kapuganti Ramani Shyam, Bushra Hayat et al.

Polymorphisms in the PTK2B-CLU locus have been associated with various neurodegenerative disorders including pseudoexfoliation glaucoma, Alzheimer's and Parkinson's. Many of these genomic variants are within enhancer elements and modulate genes associated with the disease pathogenesis. However, mechanisms by which they control the gene expression is unknown. Previously, we have shown that clusterin enhancer element surrounding rs2279590 intronic variant, a risk factor in the pathogenesis of pseudoexfoliation glaucoma modulates gene expression of clusterin (CLU), protein tyrosine kinase 2 beta (PTK2B) and epoxide hydrolase 2 (EPHX2). Here, we explored the mechanism by which rs2279590 enhancer regulates their gene expression through chromosome conformation capture assays. 3C assays revealed a strong enhancer-promoter chromatin interaction between rs2279590 enhancer and promoters of genes CLU, PTK2B and EPHX2 in the HEK293 wild type cells. Moreover, genomic knockout of rs2279590 element significantly decreases the chromatin-chromatin cross-linking frequency suggesting gene regulation at transcriptional level through formation of chromatin loop. In addition, molecular assays showed a significantly decreased expression of EPHX2 but not PTK2B at both mRNA and protein level in the lens capsule of pseudoexfoliation affected patients in comparison to control subjects implying a role of EPHX2 in the pathogenesis of pseudoexfoliation.

Shaobo Huang, Xu Li, Weiqi Gu et al.

Simple Summary We show that CLU, especially cytoplasmic precursor CLU, is downregulated in lung cancer and correlates with poor survival. The silencing of CLU promotes lung cancer cell migration and invasion, while the overexpression of CLU potently inhibits these phenomena. Interestingly, secretory CLU proteins are slightly decreased in lung cancer tissue and fail to exert similar anti-metastatic effects like cytoplasmic precursor CLU, demonstrating that cytoplasmic precursor CLU is the primary functional isoform of CLU, which exerts the anti-metastatic effects of lung cancer. Mechanistically, cytoplasmic precursor CLU binds ROCK1 to decrease phosphorylation of ERK1/2 by inhibiting the kinase activity of ROCK1, leading to an anti-metastatic effect in lung cancer cells. These findings reveal a novel insight into the function and regulation of cytoplasmic CLU in lung cancer, which might be a potential target for the diagnosis and treatment of metastatic lung cancer. Abstract Clusterin (CLU) is a heterodimeric glycoprotein that has been detected in diverse human tissues and implicated in many cellular processes. Accumulating evidence indicates that the expression of secreted CLU correlates with the progression of cancers. However, the molecular mechanisms underlying its tumor-suppressive roles are incompletely uncovered. In this study, we demonstrate that precursor CLU is widely downregulated in lung cancer tissue, in which secretory CLU proteins are slightly decreased. Impressively, overexpressing CLU potently inhibits the migration, invasion and metastasis of lung cancer cells, whereas silencing CLU promotes this behavior; however, it appears that secretory CLU fails to exert similar anti-metastatic effects. Interestingly, the cytoplasmic precursor CLU binds ROCK1 to abrogate the interaction between ROCK1 and ERK and impair ERK activity, leading to the suppression of lung cancer invasiveness. Meanwhile, the expression of CLU was remarkably diminished in lung cancer bone metastasis loci when compared with subcutaneous tumors in the mouse model and hardly detected in the bone metastasis loci of lung cancer patients when compared with the primary. These findings reveal a novel insight into the function and regulation of cytoplasmic CLU in lung cancer, which might be a potential target for the diagnosis and treatment of metastatic lung cancer.

Liang He, Yury Loika, A. Kulminski

Elucidating regulatory effects of Alzheimer’s disease (AD)-associated genetic variants is critical for unraveling their causal pathways and understanding the pathology. However, their cell-type-specific regulatory mechanisms in the brain remain largely unclear. Here, we conducted an analysis of allele-specific expression quantitative trait loci (aseQTLs) for 33 AD-associated variants in four brain regions and seven cell types using ~3000 bulk RNA-seq samples and >0.25 million single nuclei. We first develop a flexible hierarchical Poisson mixed model (HPMM) and demonstrate its superior statistical power to a beta-binomial model achieved by unifying samples in both allelic and genotype-level expression data. Using the HPMM, we identified 24 (~73%) aseQTLs in at least one brain region, including three new eQTLs associated with CA12 , CHRNE , and CASS4 . Notably, the APOE ε4 variant reduces APOE expression across all regions, even in AD-unaffected controls. Our results reveal region-dependent and exon-specific effects of multiple aseQTLs, such as rs2093760 with CR1 , rs7982 with CLU , and rs3865444 with CD33 . In an attempt to pinpoint the cell types responsible for the observed tissue-level aseQTLs using the snRNA-seq data, we detected many aseQTLs in microglia or monocytes associated with immune-related genes, including HLA-DQB1 , HLA-DQA2 , CD33 , FCER1G , MS4A6A , SPI1 , and BIN1 , highlighting the regulatory role of AD-associated variants in the immune response. These findings provide further insights into potential causal pathways and cell types mediating the effects of the AD-associated variants.

Tachatra Ungsudechachai, S. Honsawek, Jiraphun Jittikoon et al.

Objectives This study aimed to determine possible associations between transcriptional and translational levels of clusterin (CLU) in the systemic and local joint environments with the severity of knee osteoarthritis (OA) and to investigate CLU mRNA expression in knee OA fibroblast-like synoviocytes (FLSs) stimulated with tumor necrosis factor-α. Design Circulating and synovial fluid CLU levels in 259 knee OA patients were quantified using an enzyme-linked immunosorbent assay. Relative CLU mRNA expression in 50 knee OA synovial tissues and 4 knee OA FLSs was determined using real-time polymerase chain reaction. Results Plasma CLU levels of knee OA patients were significantly higher than paired synovial fluid samples. Compared with early-stage knee OA patients, those with advanced-stage OA had considerably increased plasma and synovial fluid CLU levels. There were significant positive associations of plasma and synovial fluid CLU levels with radiographic severity of knee OA. Plasma CLU levels were directly correlated with its synovial fluid levels and high-sensitivity C-reactive protein levels in the patients. Receiver-operating characteristic curve analysis unveiled the potential utility of plasma CLU as a novel biomarker for knee OA severity (AUC = 0.80), with a sensitivity of 71.4% and a specificity of 73.3%. Marked upregulation of CLU mRNA expression was observed in both the inflamed synovial tissues and FLSs of knee OA. Conclusion Increased CLU mRNA and protein levels in the systemic and local joint environments of knee OA might reflect knee OA severity, especially systemic and synovial inflammation.

C. Lenzi, Ileana Ramazzina, Isabella Russo et al.

Parkinson’s Disease (PD) is a progressive neurodegenerative disease characterized by the presence of proteinaceous aggregates of αSynuclein (αSyn) in the dopaminergic neurons. Chaperones are key components of the proteostasis network that are able to counteract αSyn’s aggregation, as well as its toxic effects. Clusterin (CLU), a molecular chaperone, was consistently found to interfere with Aβ aggregation in Alzheimer’s Disease (AD). However, its role in PD pathogenesis has yet to be extensively investigated. In this study, we assessed the involvement of CLU in the αSyn aggregation process by using SH-SY5Y cells stably overexpressing αSyn (SH-Syn). First, we showed that αSyn overexpression caused a strong increase in CLU expression without affecting levels of Hsp27, Hsp70, and Hsp90, which are the chaperones widely recognized to counteract αSyn burden. Then, we demonstrated that αSyn aggregation, induced by proteasome inhibition, determines a strong increase of CLU in insoluble aggregates. Remarkably, we revealed that CLU down-regulation results in an increase of αSyn aggregates in SH-Syn without significantly affecting cell viability and the Unfolded Protein Response (UPR). Furthermore, we demonstrated the direct molecular interaction between CLU and αSyn via a co-immunoprecipitation (co-IP) assay. All together, these findings provide incontrovertible evidence that CLU is an important player in the response orchestrated by the cell to cope with αSyn burden.

Zhipeng Chen, Zhenzhen Fan, Xiaowei Dou et al.

Purpose: Clinical success of precision medicine is severely limited by de novo or acquired drug resistance. It remains a clinically unmet need to treat these patients. Tumor suppressor genes (TSGs) play a critical role in tumorigenesis and impact the therapeutic effect of various treatments. Experimental Design: Using clinical data, in vitro cell line data and in vivo mouse model data, we revealed the tumor suppressive role of Clusterin in lung cancer. We also delineated the signaling cascade elicited by loss of function of CLU in NSCLC cells and tested precision medicine for CLU deficient lung cancers. Results: CLU is a potent and clinically relevant TSG in lung cancer. Mechanistically, CLU inhibits TGFBR1 to recruit TRAF6/TAB2/TAK1 complex and thus inhibits activation of TAK1- NF-κB signaling axis. Lung cancer cells with loss of function of CLU show exquisite sensitivity to TAK1 inhibitors. Importantly, we show that a significant portion of Kras mutation positive NSCLC patients are concurrently deficient of CLU and that TAK1 kinase inhibitor synergizes with existing drugs to treat this portion of lung cancers patients. Conclusions: Combinational treatment with TAK1 inhibitor and MEK1/2 inhibitor effectively shrank Kras mutation positive and CLU deficient NSCLC tumors. Moreover, we put forward a concept that loss of function of a TSG rewires signaling network and thereby creates an Achilles' heel in tumor cells which could be exploited in precision medicine.

Chiara Tarquini, S. Pucci, M. Scioli et al.

Osteoarthritis (OA) is the most common joint disease characterized by destruction of articular cartilage. OA-induced cartilage degeneration causes inflammation, oxidative stress and the hypertrophic shift of quiescent chondrocytes. Clusterin (CLU) is a ubiquitous glycoprotein implicated in many cellular processes and its upregulation has been recently reported in OA cartilage. However, the specific role of CLU in OA cartilage injury has not been investigated yet. We analyzed CLU expression in human articular cartilage in vivo and in cartilage-derived chondrocytes in vitro. CLU knockdown in OA chondrocytes was also performed and its effect on proliferation, hypertrophic phenotype, apoptosis, inflammation and oxidative stress was investigated. CLU expression was upregulated in human OA cartilage and in cultured OA cartilage-derived chondrocytes compared with control group. CLU knockdown reduced cell proliferation and increased hypertrophic phenotype as well as apoptotic death. CLU-silenced OA chondrocytes showed higher MMP13 and COL10A1 as well as greater TNF-α, Nox4 and ROS levels. Our results indicate a possible cytoprotective role of CLU in OA chondrocytes promoting cell survival by its anti-apoptotic, anti-inflammatory and antioxidant properties and counteracting the hypertrophic phenotypic shift. Further studies are needed to deepen the role of CLU in order to identify a new potential therapeutic target for OA.

N. Schwarz, Srinu Tumpara, S. Wrenger et al.

Elevated levels of plasma alpha1-antitrypsin (AAT) correlate with a poor prognosis of various cancers. Herein, we investigated effects of exogenous AAT on non-small lung cancer cell lines with high (H1975) and very low (H661) baseline expression of SERPINA1 gene encoding AAT protein. Comparison of cells grown for 3 weeks in a regular medium versus medium supplemented with 2 mg/ml of AAT revealed that in the presence of AAT cells acquire better proliferative properties, resistance to staurosporine (STS)-induced apoptosis, and show higher expression of CLU , a pro-tumorigenic gene coding clusterin protein. Similarly, the co-administration of STS with AAT or addition of AAT to the cells pre-treated with STS abrogated effects of STS in both cell lines. Following experiments with H1975 cells have shown that AAT blocks critical steps in STS-induced cell death: inhibition of AKT/MAPK pathways, and activation of caspase 3 and autophagy. AAT does not inhibit apoptosis-triggered by chloroquine (inhibitor of autophagy) or streptonigrin (inducer of p53 pathway). The anti-apoptotic effects of AAT were unaffected by lipopolysaccharide (LPS). However, AAT induced TLR4 levels and enhanced LPS effects on the production of IL-6, a tumor-promoting cytokine. Our data provide further evidence that AAT plays a significant role in the tumorigenesis.

Meixia Zhao, Haiyang Zhang, Yu Zhong et al.

This study evaluated the status of coral communities at the fringing reefs in the northern South China Sea, and their potential role in maintaining nearby coastline stability of northeastern Hainan Island (Puqian Bay, Hainan Bay). Thirty-nine coral species were recorded with mean coral cover of 5.3%, and are dominated by massive Galaxea, Platygyra and Porites. The coral communities were clustered into two groups (Clu-HNB and Clu-PQB) corresponding to different stable coastal conditions. Coral communities at the Hainan Bay with higher diversity and greater cover corresponded to relatively stable coastline, whereas those at the southern Puqian Bay (with the lowest coral diversity and spatial coverage) corresponded to severe coastline erosion. This work provides some direct evidence that declined coral reefs would weaken their functions to maintain a stable coastline, resulting in severe coastal erosion. It is also useful to help coastal managers and local people pay more attention to the importance of coral reefs in coastal protection and encourage them to change their ways to get sustainable use of coral reef resources. It may be beneficial to inspire or initiate coastal engineering to manage coasts with natural coral reef solution.

Yuhan Dong, Rui Wen, Zhide Li et al.

Diabetes is a kind of metabolic disease characterized by increased chronic blood glucose (BG) and may introduce a series of severe complications in a long run. To facilitate health management for diabetic patients, continuous monitoring and prediction of BG concentration are particularly important. Among the popular data driven solutions to BG prediction, machine learning methods, e.g. SVR, RNN and etc., utilize BG data of multiple patients to train the prediction model. However, all the training data sharing the same parameters may not be able to capture the characteristics of BG fluctuation effectively. Motivated by the fact that different subgroups of diabetic patients possess different BG fluctuation patterns, we propose a new BG prediction approach referred to as Clu-RNN based on recurrent neural networks (RNN) by incorporating a pre-process of clustering into the classical RNN. Numerical results suggest that the proposed Clu-RNN approach utilizes more than one cluster for both type I and type II diabetes and has gained improvements compared with support vector regression (SVR) and other RNN methods in terms of BG prediction accuracy.

Ravi S. Pandey, Leah C. Graham, A. Uyar et al.

New genetic and genomic resources have identified multiple genetic risk factors for late-onset Alzheimer’s disease (LOAD) and characterized this common dementia at the molecular level. Experimental studies in model organisms can validate these associations and elucidate the links between specific genetic factors and transcriptomic signatures. Animal models based on LOAD-associated genes can potentially connect common genetic variation with LOAD transcriptomes, thereby providing novel insights into basic biological mechanisms underlying the disease. We performed RNA-Seq on whole brain samples from a panel of six-month-old female mice, each carrying one of the following mutations: homozygous deletions of Apoe and Clu; hemizygous deletions of Bin1 and Cd2ap; and a transgenic APOEε4. Similar data from a transgenic APP/PS1 model was included for comparison to early-onset variant effects. Weighted gene co-expression network analysis (WGCNA) was used to identify modules of correlated genes and each module was tested for differential expression by strain. We then compared mouse modules with human postmortem brain modules from the Accelerating Medicine’s Partnership for AD (AMP-AD) to determine the LOAD-related processes affected by each genetic risk factor. Mouse modules were significantly enriched in multiple AD-related processes, including immune response, inflammation, lipid processing, endocytosis, and synaptic cell function. WGCNA modules were significantly associated with Apoe−/−, APOEε4, Clu−/−, and APP/PS1 mouse models. Apoe−/−, GFAP-driven APOEε4, and APP/PS1 driven modules overlapped with AMP-AD inflammation and microglial modules; Clu−/− driven modules overlapped with synaptic modules; and APP/PS1 modules separately overlapped with lipid-processing and metabolism modules. This study of genetic mouse models provides a basis to dissect the role of AD risk genes in relevant AD pathologies. We determined that different genetic perturbations affect different molecular mechanisms comprising AD, and mapped specific effects to each risk gene. Our approach provides a platform for further exploration into the causes and progression of AD by assessing animal models at different ages and/or with different combinations of LOAD risk variants.

P. Artemaki, A. Sklirou, C. Kontos et al.

OBJECTIVES Clusterin (CLU) is a multifunctional intra-/extra-cellular molecular chaperone with indications of serving as a promising prognostic biomarker for colorectal cancer (CRC). Several studies have examined the potential prognostic value of the CLU protein in CRC; however, our research follows an alternative approach, focusing on the CLU mRNA expression. DESIGN AND METHODS Total RNA from 172 cancerous tissue specimens and 39 paired non-cancerous ones was isolated and 2 μg of this were subjected to reverse transcription with an oligo-dT primer. The single stranded DNA, which was synthesized, was amplified with an in-house developed highly sensitive and precise qPCR method, using specific pair of primers for the CLU molecule. Finally, an extensive biostatical analysis took place for the assessment of the results. RESULTS Patients with tumors expressing high CLU mRNA levels had a higher probability for poor outcome (relapse and death), comparing to those with CLU mRNA-negative tumors. This association between CLU mRNA expression status and both disease-free survival (DFS) and overall survival (OS) is evident in Cox regression analysis and is also depicted in the Kaplan-Meier survival curves. Consistently, the aforementioned associations and the CLU mRNA expression levels are significantly enhanced as CRC tumors progress from TNM stage I to IV, further supporting the functional implication of CLU in tumorigenesis. CONCLUSIONS High CLU mRNA levels in CRC tumors can act as a new adverse prognostic biomarker of DFS and OS for CRC, independent of clinicopathological and biological features of the patient.

Yujing Zhang, Yiyuan Zhang, Yuanyuan Xiao et al.

Our group found that long-term low-dose exposure to hexavalent chromium [Cr(VI)] in L-02 hepatocytes resulted in premature senescence, which accompanied by the increased expression of Clusterin (CLU), but the functional role of CLU in premature senescence has never been explored. In the present study, the CLU overexpressed or silenced L-02 hepatocytes were established by lentiviral vector transfection. Cell viability assay, cell cycle analysis, western blotting, plate clone formation assay, and confocal microcopy were performed. The results indicated that Cr(VI)-induced premature senescence was associated with phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway inhibition, and high expression of CLU in the senescent cells exerted its functional role of promoting cell proliferation. CLU could complex with eukaryotic translation initiation factor 3 subunit I (EIF3I) and prevent its degradation, leading to the increase of AKT activity in Cr(VI)-exposed senescent hepatocytes. Blockage of the PI3K/AKT pathway with its inhibitor LY294002 eliminated the inhibitory effect of CLU on Cr(VI)-induced premature senescence. We concluded that high expression of CLU suppressed Cr(VI)-induced premature senescence through activation of PI3K/AKT pathway, which will provide the experimental basis for the study of Cr(VI)-induced liver cancer, especially for the elucidation of the mechanism of liver cancer cells escaping from senescence.

Biswajit Padhy, Bushra Hayat, G. Nanda et al.

Genetic variants at PTK2B-CLU locus pose as high-risk factors for many age-related disorders. However, the role of these variants in disease progression is less characterized. In this study, we aimed to investigate the functional significance of a clusterin intronic SNP, rs2279590, that has been associated with pseudoexfoliation, Alzheimer's disease (AD) and diabetes. We have previously shown that the alleles at rs2279590 differentially regulate clusterin (CLU) gene expression in lens capsule tissues. This polymorphism resides in an active regulatory region marked by H3K27Ac and DNase I hypersensitive site and is an eQTL for CLU expression. Here, we report the presence of an enhancer element in surrounding region of rs2279590. Deletion of a 115 bp intronic region flanking the rs2279590 variant through CRISPR-Cas9 genome editing in HEK293 cells demonstrated a decreased clusterin gene expression. Electrophoretic mobility shift and chromatin immunoprecipitation assays show that rs2279590 with allele 'A' constitutes a transcription factor binding site for heat shock factor-1 (HSF1) but not with allele 'G'. By binding to allele 'A', HSF1 abrogates the enhancer effect of the locus as validated by reporter assays. Interestingly, rs2279590 locus has a widespread enhancer effect on two nearby genes, protein tyrosine kinase 2 beta (PTK2B) and epoxide hydrolase-2 (EPHX2); both of which have been previously associated with AD as risk factors. To summarize, our study unveils a mechanistic role of the common variant rs2279590 that can affect a variety of aging disorders by regulating the expression of a specific set of genes.

Xinjing Wang, Jing Xie, Xiongxiong Lu et al.

Stephanie A. Schultz, Elizabeth A. Boots, B. Darst et al.

G. Hong, Hyouk-Soo Kwon, Keun-ai Moon et al.

A. Saratsis, M. Kambhampati, Kendall Snyder et al.