scholarly journals Spontaneous self-assembly of pathogenic huntingtin exon 1 protein into amyloid structures

2014 ◽  
Vol 56 ◽  
pp. 167-180 ◽  
Author(s):  
Philipp Trepte ◽  
Nadine Strempel ◽  
Erich E. Wanker
Keyword(s):  
Self Assembly ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Cytoplasmic Inclusion ◽  
Spinocerebellar Ataxia Type ◽  
Neuronal Processes ◽  
Exon 1 ◽  
Novel Therapeutic Strategies

PolyQ (polyglutamine) diseases such as HD (Huntington's disease) or SCA1 (spinocerebellar ataxia type 1) are neurodegenerative disorders caused by abnormally elongated polyQ tracts in human proteins. PolyQ expansions promote misfolding and aggregation of disease-causing proteins, leading to the appearance of nuclear and cytoplasmic inclusion bodies in patient neurons. Several lines of experimental evidence indicate that this process is critical for disease pathogenesis. However, the molecular mechanisms underlying spontaneous polyQ-containing aggregate formation and the perturbation of neuronal processes are still largely unclear. The present chapter reviews the current literature regarding misfolding and aggregation of polyQ-containing disease proteins. We specifically focus on studies that have investigated the amyloidogenesis of polyQ-containing HTTex1 (huntingtin exon 1) fragments. These protein fragments are disease-relevant and play a critical role in HD pathogenesis. We outline potential mechanisms behind mutant HTTex1 aggregation and toxicity, as well as proteins and small molecules that can modify HTTex1 amyloidogenesis in vitro and in vivo. The potential implications of such studies for the development of novel therapeutic strategies are discussed.

scholarly journals Dissecting the Structure-Function Relationship of a Fungicidal Peptide Derived from the Constant Region of Human Immunoglobulins

2016 ◽  
Vol 60 (4) ◽  
pp. 2435-2442 ◽  
Author(s):  
Tecla Ciociola ◽  
Thelma A. Pertinhez ◽  
Laura Giovati ◽  
Martina Sperindè ◽  
Walter Magliani ◽  
...  
Keyword(s):  
Self Assembly ◽  
Galleria Mellonella ◽  
Critical Role ◽  
Yeast Cells ◽  
Therapeutic Effects ◽  
Constant Region ◽  
Content Type ◽  
Complementarity Determining Regions

ABSTRACTSynthetic peptides encompassing sequences related to the complementarity-determining regions of antibodies or derived from their constant region (Fc peptides) were proven to exert differential antimicrobial, antiviral, antitumor, and/or immunomodulatory activitiesin vitroand/orin vivo, regardless of the specificity and isotype of the parental antibody. Alanine substitution derivatives of these peptides exhibited unaltered, increased, or decreased candidacidal activitiesin vitro. The bioactive IgG-derived Fc N10K peptide (NQVSLTCLVK) spontaneously self-assembles, a feature previously recognized as relevant for the therapeutic activity of another antibody-derived peptide. We evaluated the contribution of each residue to the peptide self-assembling capability by circular-dichroism spectroscopy. The interaction of the N10K peptide and its derivatives withCandida albicanscells was studied by confocal, transmission, and scanning electron microscopy. The apoptosis and autophagy induction profiles in yeast cells treated with the peptides were evaluated by flow cytometry, and the therapeutic efficacy against candidal infection was studied in aGalleria mellonellamodel. Overall, the results indicate a critical role for some residues in the self-assembly process and a correlation of that capability with the candidacidal activities of the peptidesin vitroand their therapeutic effectsin vivo.

scholarly journals Hydroxychloroquine Synergizes With The PI3K Inhibitor BKM120 to Exhibit Antitumor Efficacy Independent of Autophagy

2021 ◽  
Author(s):  
Xin Peng ◽  
Shaolu Zhang ◽  
Wenhui Jiao ◽  
Zhenxing Zhong ◽  
Yuqi Yang ◽  
...  
Keyword(s):  
Tumor Cells ◽  
Cell Biology ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Single Agent ◽  
Antitumor Efficacy ◽  
Antitumor Effects ◽  
Autophagy Inhibitor

Abstract Background: The critical role of phosphoinositide 3-kinase (PI3K) activation in tumor cell biology has prompted massive efforts to develop PI3K inhibitors (PI3Kis) for cancer therapy. However, recent results from clinical trials have shown only a modest therapeutic efficacy of single-agent PI3Kis in solid tumors. Targeting autophagy has controversial context-dependent effects in cancer treatment. As a FDA-approved lysosomotropic agent, hydroxychloroquine (HCQ) has been well tested as an autophagy inhibitor in preclinical models. Here, we elucidated the novel mechanism of HCQ alone or in combination with PI3Ki BKM120 in the treatment of cancer.Methods: The antitumor effects of HCQ and BKM120 on three different types of tumor cells were assessed by in vitro PrestoBlue assay, colony formation assay and in vivo zebrafish and nude mouse xenograft models. The involved molecular mechanisms were investigated by MDC staining, LC3 puncta formation assay, immunofluorescent assay, flow cytometric analysis of apoptosis and ROS, qRT-PCR, Western blot, comet assay, homologous recombination (HR) assay and immunohistochemical staining. Results: HCQ significantly sensitized cancer cells to BKM120 in vitro and in vivo. Interestingly, the sensitization mediated by HCQ could not be phenocopied by treatment with other autophagy inhibitors (Spautin-1, 3-MA and bafilomycin A1) or knockdown of the essential autophagy genes Atg5/Atg7, suggesting that the sensitizing effect might be mediated independent of autophagy status. Mechanistically, HCQ induced ROS production and activated the transcription factor NRF2. In contrast, BKM120 prevented the elimination of ROS by inactivation of NRF2, leading to accumulation of DNA damage. In addition, HCQ activated ATM to enhance HR repair, a high-fidelity repair for DNA double-strand breaks (DSBs) in cells, while BKM120 inhibited HR repair by blocking the phosphorylation of ATM and the expression of BRCA1/2 and Rad51. Conclusions: Our study revealed that HCQ and BKM120 synergistically increased DSBs in tumor cells and therefore augmented apoptosis, resulting in enhanced antitumor efficacy. Our findings provide a new insight into how HCQ exhibits antitumor efficacy and synergizes with PI3Ki BKM120, and warn that one should consider the “off target” effects of HCQ when used as autophagy inhibitor in the clinical treatment of cancer.

scholarly journals Cotranslational folding allows misfolding-prone proteins to circumvent deep kinetic traps

2020 ◽  
Vol 117 (3) ◽  
pp. 1485-1495 ◽  
Author(s):  
Amir Bitran ◽  
William M. Jacobs ◽  
Xiadi Zhai ◽  
Eugene Shakhnovich
Keyword(s):  
Self Assembly ◽  
Molecular Mechanisms ◽  
Folding Kinetics ◽  
Rare Codons ◽  
Cotranslational Folding ◽  
Nascent Chain ◽  
Kinetic Traps ◽  
Optimal Window

Many large proteins suffer from slow or inefficient folding in vitro. It has long been known that this problem can be alleviated in vivo if proteins start folding cotranslationally. However, the molecular mechanisms underlying this improvement have not been well established. To address this question, we use an all-atom simulation-based algorithm to compute the folding properties of various large protein domains as a function of nascent chain length. We find that for certain proteins, there exists a narrow window of lengths that confers both thermodynamic stability and fast folding kinetics. Beyond these lengths, folding is drastically slowed by nonnative interactions involving C-terminal residues. Thus, cotranslational folding is predicted to be beneficial because it allows proteins to take advantage of this optimal window of lengths and thus avoid kinetic traps. Interestingly, many of these proteins’ sequences contain conserved rare codons that may slow down synthesis at this optimal window, suggesting that synthesis rates may be evolutionarily tuned to optimize folding. Using kinetic modeling, we show that under certain conditions, such a slowdown indeed improves cotranslational folding efficiency by giving these nascent chains more time to fold. In contrast, other proteins are predicted not to benefit from cotranslational folding due to a lack of significant nonnative interactions, and indeed these proteins’ sequences lack conserved C-terminal rare codons. Together, these results shed light on the factors that promote proper protein folding in the cell and how biomolecular self-assembly may be optimized evolutionarily.

The new tumor-suppressor gene inhibitor of growth family member 4 (ING4) regulates the production of proangiogenic molecules by myeloma cells and suppresses hypoxia-inducible factor-1 α (HIF-1α) activity: involvement in myeloma-induced angiogenesis

Blood ◽  
2007 ◽  
Vol 110 (13) ◽  
pp. 4464-4475 ◽  
Author(s):  
Simona Colla ◽  
Sara Tagliaferri ◽  
Francesca Morandi ◽  
Paolo Lunghi ◽  
Gaetano Donofrio ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Family Member ◽  
Tumor Suppressor Gene ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Hypoxia Inducible Factor ◽  
Direct Interaction ◽  
Suppressor Gene

Angiogenesis has a critical role in the pathophysiology of multiple myeloma (MM); however, the molecular mechanisms underlying this process are not completely elucidated. The new tumor-suppressor gene inhibitor of growth family member 4 (ING4) has been recently implicated in solid tumors as a repressor of angiogenesis. In this study, we found that ING4 expression in MM cells was correlated with the expression of the proangiogenic molecules interleukin-8 (IL-8) and osteopontin (OPN). Moreover, we demonstrate that ING4 suppression in MM cells up-regulated IL-8 and OPN, increasing the hypoxia inducible factor-1α (HIF-1α) activity and its target gene NIP-3 expression in hypoxic condition. In turn, we show that the inhibition of HIF-1α by siRNA suppressed IL-8 and OPN production by MM cells under hypoxia. A direct interaction between ING4 and the HIF prolyl hydroxylase 2 (HPH-2) was also demonstrated. Finally, we show that ING4 suppression in MM cells significantly increased vessel formation in vitro, blunted by blocking IL-8 or OPN. These in vitro observations were confirmed in vivo by finding that MM patients with high IL-8 production and microvascular density (MVD) have significantly lower ING4 levels compared with those with low IL-8 and MVD. Our data indicate that ING4 exerts an inhibitory effect on the production of proangiogenic molecules and consequently on MM-induced angiogenesis.

scholarly journals C-terminal truncated HBx initiates hepatocarcinogenesis by downregulating TXNIP and reprogramming glucose metabolism

Oncogene ◽  
2020 ◽  
Author(s):  
Yu Zhang ◽  
Qian Yan ◽  
Lanqi Gong ◽  
Hang Xu ◽  
Beilei Liu ◽  
...  
Keyword(s):  
Glucose Metabolism ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Genetic Alterations ◽  
Metabolic Reprogramming ◽  
Mice Model ◽  
Activated T Cells ◽  
Chronic Hepatitis B Virus

AbstractChronic hepatitis B virus (HBV) infection is strongly associated with the initiation and development of hepatocellular carcinoma (HCC). However, the genetic alterations and pathogenesis mechanisms remain significantly unexplored, especially for HBV-induced metabolic reprogramming. Analysis of integration breakpoints in HBV-positive HCC samples revealed the preferential clustering pattern within the 3′-end of X gene in the HBV genome, leading to the production of C-terminal truncated X protein (Ct-HBx). In this study, we not only characterized the oncogenic role of two Ct-HBx (HBx-120 and HBx-134) via in vitro and in vivo functional assays but also deciphered their underlying molecular mechanisms. Gene expression profiling by transcriptome sequencing identified potential targets of Ct-HBx and novel malignant hallmarks such as glycolysis, cell cycle, and m-TORC1 signaling in Ct-HBx-expressing cells. TXNIP, a well-established regulator of glucose metabolism, was shown to be downregulated by Ct-HBx and play a pivotal role in Ct-HBx-mediated HCC progression. Suppression of TXNIP is frequently observed in HCC patients with Ct-HBx expression and significantly (P = 0.015) correlated to a poorer prognosis. Re-introduction of TXNIP attenuated the metabolic reprogramming induced by the Ct-HBx and inhibited the tumor growth in the mice model. Further study suggested that Ct-HBx could downregulate TXNIP via a transcriptional repressor nuclear factor of activated T cells 2 (NFACT2). Collectively, our findings indicate that TXNIP plays a critical role in Ct-HBx-mediated hepatocarcinogenesis, serving as a novel therapeutic strategy in HCC treatment.

scholarly journals Downregulation of Exosomal miR-26a-5p Promotes Lymphangiogenesis and Lymphatic Metastasis in Endometrial Cancer

2021 ◽  
Author(s):  
Jing Wang ◽  
Xiaodi Gong ◽  
Linlin Yang ◽  
Lijuan Li ◽  
Xiaoyan Gao ◽  
...  
Keyword(s):  
Endometrial Cancer ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Cell Communication ◽  
Lymphatic Endothelial Cell ◽  
Tube Formation ◽  
Downstream Target ◽  
Ec Cells

Abstract Background: Endometrial cancer (EC) patients with lymph node (LN) metastasis have poor prognosis. However, the potential biomarkers that predict LN metastasis and the molecular mechanism of tumor-induced peritumoral lymphangiogenesis have not been well explored. Cancer-secreted exosomal miRNAs are emerging mediators of cell-cell communication in the tumor environment.Methods: Exosomes were isolated with a differential centrifugation method and confirmed by Transmission electron microscopy, NanoSight analysis, and Western blot. MicroRNA (miRNA) sequencing of exosomes derived from EC patients and healthy donors were performed. FISH and qRT-PCR were used to detect the indicated miRNA expression. Exosomal miRNA transferred to cells were confirmed by immunofluorescence and confocal microscope. siRNA and plasmid transfections as well as viral infection were performed to manipulate gene expression. A series of in vitro and in vivo phenotype experiments (tube formation, migration, and popliteal LN metastasis model) were performed to investigate the role of indicated miRNA in EC. RNA sequencing was used to select the underlying transcription factor, and luciferase activity assay and chromatin immunoprecipitation were performed to elucidate the molecular mechanisms. Results: Our data showed that serum exosomal miR-26a-5p was significantly reduced in EC patients, and its level was positively associated with LN metastasis. Loss of miR-26a-5p promoted the migratory and invasive abilities of EC cells, and miR-26a-5p could be transferred from EC cells-secreted exosomes into human lymphatic endothelial cell (HLEC). Mechanistically, miR-26a-5p could regulate LEF1/c-myc/VEGFA axis via binding to its direct downstream target lymphoid enhancer binding factor 1 (LEF1), consequently promoting HLEC tube formation and migration in vitro, facilitating lymphangiogenesis and LN metastasis in vivo. Re-expression and knockdown of LEF1 could respectively promote and rescue the effects induced by exosomal miR-26a-5p. Moreover, we demonstrated that transcriptional factor EB (TFEB) directly induced miR-26a-5p expression.Conclusions: Our results show that exosomal miR-26a-5p/LEF1/c-myc/VEGFA axis is dysregulated and plays a critical role in LN metastasis and exosomal miR-26a-5p may be used as a blood-based biomarker for EC patients with LN metastasis.

A Comprehensive Review on Preclinical Diabetic Models

2020 ◽  
Vol 16 (2) ◽  
pp. 104-116
Author(s):  
Anshul Shakya ◽  
Sushil Kumar Chaudary ◽  
Debapriya Garabadu ◽  
Hans Raj Bhat ◽  
Bibhuti Bhusan Kakoti ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Animal Models ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Therapeutic Agents ◽  
Ongoing Research ◽  
Chronic Hyperglycemia ◽  
Limited Effectiveness

Background: Preclinical experimental models historically play a critical role in the exploration and characterization of disease pathophysiology. Further, these in-vivo and in-vitro preclinical experiments help in target identification, evaluation of novel therapeutic agents and validation of treatments. Introduction: Diabetes mellitus (DM) is a multifaceted metabolic disorder of multidimensional aetiologies with the cardinal feature of chronic hyperglycemia. To avoid or minimize late complications of diabetes and related costs, primary prevention and early treatment are therefore necessary. Due to its chronic manifestations, new treatment strategies need to be developed, because of the limited effectiveness of the current therapies. Methods: The study included electronic databases such as Pubmed, Web of Science and Scopus. The datasets were searched for entries of studies up to June, 2018. Results: A large number of in-vivo and in-vitro models have been presented for evaluating the mechanism of anti-hyperglycaemic effect of drugs in hormone-, chemically-, pathogen-induced animal models of diabetes mellitus. The advantages and limitations of each model have also been addressed in this review. Conclusion: This review encompasses the wide pathophysiological and molecular mechanisms associated with diabetes, particularly focusing on the challenges associated with the evaluation and predictive validation of these models as ideal animal models for preclinical assessments and discovering new drugs and therapeutic agents for translational application in humans. This review may further contribute to discover a novel drug to treat diabetes more efficaciously with minimum or no side effects. Furthermore, it also highlights ongoing research and considers the future perspectives in the field of diabetes.

scholarly journals CHIP Represses Myocardin-Induced Smooth Muscle Cell Differentiation via Ubiquitin-Mediated Proteasomal Degradation

2009 ◽  
Vol 29 (9) ◽  
pp. 2398-2408 ◽  
Author(s):  
Ping Xie ◽  
Yongna Fan ◽  
Hua Zhang ◽  
Yuan Zhang ◽  
Mingpeng She ◽  
...  
Keyword(s):  
Gene Expression ◽  
Smooth Muscle ◽  
Molecular Mechanisms ◽  
Serum Response Factor ◽  
Ex Vivo ◽  
Critical Role ◽  
Physiological Control ◽  
Interacting Protein

ABSTRACT Myocardin, a coactivator of serum response factor (SRF), plays a critical role in the differentiation of vascular smooth muscle cells (SMCs). However, the molecular mechanisms regulating myocardin stability and activity are not well defined. Here we show that the E3 ligase C terminus of Hsc70-interacting protein (CHIP) represses myocardin-dependent SMC gene expression and transcriptional activity. CHIP interacts with and promotes myocardin ubiquitin-mediated degradation by the proteasome in vivo and in vitro. Furthermore, myocardin ubiquitination by CHIP requires its phosphorylation. Importantly, CHIP overexpression reduces the level of myocardin-dependent SMC contractile gene expression and diminishes arterial contractility ex vivo. These findings for the first time, to our knowledge, demonstrate that CHIP-promoted proteolysis of myocardin plays a key role in the physiological control of SMC phenotype and vessel tone, which may have an important implication for pathophysiological conditions such as atherosclerosis, hypertension, and Alzheimer's disease.

scholarly journals Dynamics of a Protein Interaction Network Associated to the Aggregation of polyQ-Expanded Ataxin-1

Genes ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1129
Author(s):  
Aimilia-Christina Vagiona ◽  
Miguel A. Andrade-Navarro ◽  
Fotis Psomopoulos ◽  
Spyros Petrakis
Keyword(s):  
Animal Models ◽  
Protein Aggregation ◽  
Disease Progression ◽  
Protein Interaction ◽  
Molecular Mechanisms ◽  
Spinocerebellar Ataxia Type ◽  
In Vivo Model ◽  
Ppi Networks

Background: Several experimental models of polyglutamine (polyQ) diseases have been previously developed that are useful for studying disease progression in the primarily affected central nervous system. However, there is a missing link between cellular and animal models that would indicate the molecular defects occurring in neurons and are responsible for the disease phenotype in vivo. Methods: Here, we used a computational approach to identify dysregulated pathways shared by an in vitro and an in vivo model of ATXN1(Q82) protein aggregation, the mutant protein that causes the neurodegenerative polyQ disease spinocerebellar ataxia type-1 (SCA1). Results: A set of common dysregulated pathways were identified, which were utilized to construct cerebellum-specific protein-protein interaction (PPI) networks at various time-points of protein aggregation. Analysis of a SCA1 network indicated important nodes which regulate its function and might represent potential pharmacological targets. Furthermore, a set of drugs interacting with these nodes and predicted to enter the blood–brain barrier (BBB) was identified. Conclusions: Our study points to molecular mechanisms of SCA1 linked from both cellular and animal models and suggests drugs that could be tested to determine whether they affect the aggregation of pathogenic ATXN1 and SCA1 disease progression.

scholarly journals Curcumin Suppresses Metastasis via Sp-1, FAK Inhibition, and E-Cadherin Upregulation in Colorectal Cancer

2013 ◽  
Vol 2013 ◽  
pp. 1-17 ◽  
Author(s):  
Chun-Chieh Chen ◽  
Munisamy Sureshbabul ◽  
Huei-Wen Chen ◽  
Yu-Shuang Lin ◽  
Jen-Yi Lee ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Public Health Problem ◽  
Stress Factors ◽  
Dependent Manner ◽  
Extracellular Matrix Components ◽  
E Cadherin

Colorectal cancer (CRC) is a serious public health problem that results due to changes of diet and various environmental stress factors in the world. Curcumin is a traditional medicine used for treatment of a wide variety of tumors. However, antimetastasis mechanism of curcumin on CRC has not yet been completely investigated. Here, we explored the underlying molecular mechanisms of curcumin on metastasis of CRC cellsin vitroandin vivo. Curcumin significantly inhibits cell migration, invasion, and colony formationin vitroand reduces tumor growth and liver metastasisin vivo. We found that curcumin suppresses Sp-1 transcriptional activity and Sp-1 regulated genes including ADEM10, calmodulin, EPHB2, HDAC4, and SEPP1 in CRC cells. Curcumin inhibits focal adhesion kinase (FAK) phosphorylation and enhances the expressions of several extracellular matrix components which play a critical role in invasion and metastasis. Curcumin reduces CD24 expression in a dose-dependent manner in CRC cells. Moreover, E-cadherin expression is upregulated by curcumin and serves as an inhibitor of EMT. These results suggest that curcumin executes its antimetastasis function through downregulation of Sp-1, FAK, and CD24 and by promoting E-cadherin expression in CRC cells.

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