Methods for Monitoring ER-Phagy.

The endoplasmic reticulum (ER) serves as a central hub for protein synthesis, folding, and lipid biosynthesis in eukaryotic cells. Maintaining ER homeostasis is essential for optimal cellular function, and one mechanism that has garnered attention is endoplasmic reticulum-specific autophagy, or ER-phagy. ER-phagy selectively removes specific ER portions, playing a pivotal role in cellular health and adaptation to environmental stressors. ER-phagy can be induced by diverse cellular conditions such as amino acid starvation, disruption of ER quality control mechanisms, and accumulation of misfolded ER protein, highlighting cellular adaptability and the significance of ER-phagy in stress responses. Clinically relevant mutations in ER-phagy receptors are implicated in various diseases, underlining the fundamental importance of ER-phagy in ER homeostasis. Here, we provide comprehensive protocols and general considerations while investigating ER-phagy using three fundamental techniques-Western blotting, immunofluorescence, and flow cytometry-commonly used in ER-phagy detection and quantitation.

Sequential Double Immunoblotting with Peptide Antibodies.

Immunoblotting, also termed western blotting, is a powerful method for detection and characterization of proteins separated by various electrophoretic techniques. The combination of sodium dodecyl sulfate-poly acrylamide gel electrophoresis (SDS-PAGE), having high separating power, immunoblotting to synthetic membranes, and detection with highly specific peptide antibodies, is especially useful for studying individual proteins in relation to cellular processes, disease mechanisms, etc. Here, we describe a protocol for the sequential detection of various forms of an individual protein using peptide antibodies, exemplified by the characterization of antibody specificity for different forms of the protein calreticulin by double SDS-PAGE immunoblotting.

Detection of Plasmodium knowlesi in whole blood samples with sandwich enzyme-linked immunosorbent assay (ELISA) using rhoptry-associated protein 1 specific polyclonal antibodies.

BACKGROUND OBJECTIVES: Plasmodium knowlesi, a simian malaria species, is now known to infect humans. Due to disadvantages in the current diagnosis methods, many efforts have been placed into developing new methods to diagnose the disease. This study assessed the ability of the PkRAP-1 sandwich enzyme-linked immunosorbent (ELISA) to detect P knowlesi antigens in whole blood specimens. METHODS: Western blot assay was conducted to evaluate the ability of raised mouse and rabbit anti-PkRAP-1 polyclonal antibodies to bind to the native proteins in P. knowlesi lysate. The polyclonal antibodies were then used in sandwich ELISA to detect P. knowlesi. In the sandwich ELISA, mouse and rabbit polyclonal antibodies were used as the capture and detection antibodies, respectively. The limit of detection (LOD) of the assay was determined using P. knowlesi A1H1 culture and purified recombinant PkRAP-1. RESULTS: Western blot results showed positive reactions towards the proteins in P. knowlesi lysate. The LOD of the assay from three technical replicates was 0.068% parasitaemia. The assay performance in detecting P. knowlesi was 83% sensitivity and 70% specificity with positive and negative predictive values of 74% and 80%, respectively. The anti-PkRAP-1 polyclonal antibodies did not cross-react with P. falciparum and healthy samples, but P. vivax by detecting all 12 samples. INTERPRETATION CONCLUSION: PkRAP-1 has the potential as a biomarker for the development of a new diagnostic tool for P. knowlesi detection. Further studies need to be conducted to establish the full potential of the usage of anti-PkRAP-1 antibodies for P. knowlesi detection.

Rapid tests should be used with caution for HIV-1 primary infection screening.

Rapid tests allow outpatient, low cost, reliable, screening for chronic HIV infection. However, data regarding their sensitivity on primary infection remain scarce. The objective of this study was to assess sensitivity of nine HIV rapid tests for primary HIV-1 infection screening. Seventy-five serum samples from patients during HIV-1 primary infection were included. Primary infection was diagnosed by a positive 4th generation ELISA and HIV-1 RNA positivity confirmed by Western blot patterns associated with HIV-1 primary infection. Early seroconversion was defined as the absence of antibodies on HIV-1 Western blot associated with HIV-1 RNA and p24-antigen positivity. An identical sensitivity (95% CI) of 76.7% (65.2-84.2%) was observed for HIV 1/2 STAT-PAK® Assay (STAT-PAK), INSTI™ HIV-1/HIV-2 antibody Test (INSTI), SURE CHECK® HIV 1/2 (SURE CHECK) and MULTISURE HIV rapid test (MULTISURE) with visual reading. Sensitivity was 74.7% (63.8-83.1%) for MULTISURE (automatic reading), 77.0% (66.3-85.1%) for FIRST RESPONSE® Test VIH 1-2.O CARTE (FIRST RESPONSE), 83.8% (73.8-90.5%) for VIKIA HIV1/2® (VIKIA), 88.0% (78.7-93.6%) for Genie™ Fast HIV 1/2 (Genie Fast), 88.6% (79.0-94.1%) for Hexagon HIV (Hexagon), and 92.8% (83.6-96.3%) for Exacto® TEST HIV Pro (Exacto). However, rapid tests performed poorly for the early seroconversion subgroup (n = 14), with sensitivities ranging from 7% (1.3-31.5%) for STAT-PAK, INSTI, SURE CHECK, MULTISURE (automatic reading), to 29% (12-55%) for FIRST RESPONSE, 31% (13-58%) for VIKIA, 43% (21-67%) for Hexagon and 57.1% (32.6-78.6%) for Exacto and Genie Fast. Overall, despite significant discrepancies in sensitivity, HIV rapid tests should be used with caution in the context of a suspected primary infection.

Protocol to test for the formation of ternary protein complexes in vivo or in vitro using a two-step immunoprecipitation approach.

Co-immunoprecipitation (coIP) is an experimental technique to study protein-protein interactions (PPIs). However, single-step coIP can only be used to identify the interaction between two proteins and does not solve the interaction testing of ternary complexes. Here, we present a protocol to test for the formation of ternary protein complexes in vivo or in vitro using a two-step coIP approach. We describe steps for cell culture and transfection, elution of target proteins, and two-step coIP including western blot analyses. For complete details on the use and execution of this protocol, please refer to Li et al.1.

Protocol for identifying OXCT1-mediated LACTB succinylation sites in vitro.

OXCT1 acts as a succinyltransferase to promote serine beta-lactamase-like protein (LACTB) K284 succinylation. Here, we present a protocol for detecting OXCT1-mediated LACTB succinylation levels and sites. We describe steps for using western blotting (WB) and mass spectrometry to determine OXCT1-mediated LACTB succinylation levels and sites in vitro. This protocol can be applied to detect and identify succinylation levels and sites on other proteins. For complete details on the use and execution of this protocol, please refer to Ma et al.1.

Biochemical Detection of Capsid in the Nucleus During HIV-1 Infection.

Recent evidence has shown that uncoating and reverse transcription precede nuclear import. These recent breakthroughs have been made possible through the development of innovative biochemical and imaging techniques. This method outlines the biochemical assay used for detecting the presence of the HIV-1 core in the nuclear compartment. In this procedure, human cells are infected with HIV-1NL4-3, with or without the inclusion of PF74, a small molecule that inhibits core entry into the nuclear compartment. Subsequently, cells are separated into cytosolic and nuclear fractions. To assess whether the capsid protein has reached the nuclear compartment, cytosolic and nuclear fractions are subjected to Western blot analysis, utilizing antibodies specific to the HIV-1 capsid protein p24. To validate the true origin of these fractions, Western blot analysis employing antibodies against cytosolic and nuclear markers are also performed. In summary, this assay provides a reliable and efficient means to detect the presence of the HIV-1 capsid protein in the nucleus during infection under various conditions.

Chemical cross-linking to study protein self-assembly in cellulo.

Many proteins self-assemble into dimers and higher-order oligomers. Therefore, the goal of this protocol is to characterize the conformational states of an endogenous protein of interest. Here, we present a protocol for assessing protein self-assembly in cell lysates using chemical cross-linking. We describe steps for chemical cross-linking with recombinant proteins as well as steps for cell culture and cell lysate preparation, chemical cross-linking, SDS-PAGE, and western blotting for the detection of endogenous proteins. For complete details on the use and execution of this protocol, please refer to Balaji et al.1.

Validation of a novel western blot assay to monitor patterns and levels of alpha dystroglycan in skeletal muscle of patients with limb girdle muscular dystrophies.

The cell membrane protein, dystroglycan, plays a crucial role in connecting the cytoskeleton of a variety of mammalian cells to the extracellular matrix. The α-subunit of dystroglycan (αDG) is characterized by a high level of glycosylation, including a unique O-mannosyl matriglycan. This specific glycosylation is essential for binding of αDG to extracellular matrix ligands effectively. A subset of muscular dystrophies, called dystroglycanopathies, are associated with aberrant, dysfunctional glycosylation of αDG. This defect prevents myocytes from attaching to the basal membrane, leading to contraction-induced injury. Here, we describe a novel Western blot (WB) assay for determining levels of αDG glycosylation in skeletal muscle tissue. The assay described involves extracting proteins from fine needle tibialis anterior (TA) biopsies and separation using SDS-PAGE followed by WB. Glycosylated and core αDG are then detected in a multiplexed format using fluorescent antibodies. A practical application of this assay is demonstrated with samples from normal donors and patients diagnosed with LGMD2I/R9. Quantitative analysis of the WB, which employed the use of a normal TA derived calibration curve, revealed significantly reduced levels of αDG in patient biopsies relative to unaffected TA. Importantly, the assay was able to distinguish between the L276I homozygous patients and a more severe form of clinical disease observed with other FKRP variants. Data demonstrating the accuracy and reliability of the assay are also presented, which further supports the potential utility of this novel assay to monitor changes in ⍺DG of TA muscle biopsies in the evaluation of potential therapeutics.

A Multiplexed Approach to Assess Small Cell Lung Cancer Subtype Heterogeneity in Primary and Patient-Derived Tumor Samples.

Unlocking the heterogeneity of cancers is crucial for developing therapeutic approaches that effectively eradicate disease. As our understanding of markers specific to cancer subclones or subtypes expands, there is a growing demand for advanced technologies that enable the simultaneous investigation of multiple targets within an individual tumor sample. Indeed, multiplex approaches offer distinct benefits, particularly when tumor specimens are small and scarce. Here we describe the utility of two fluorescence-based multiplex approaches; fluorescent Western blots, and multiplex immunohistochemistry (Opal™) staining to interrogate heterogeneity, using small cell lung cancer as an example. Critically, the coupling of Opal™ staining with advanced image quantitation, permits the dissection of cancer cell phenotypes at a single cell level. These approaches can be applied to patient biopsies and/or patient-derived xenograft (PDX) models and serve as powerful methodologies for assessing tumor cell heterogeneity in response to therapy or between metastatic lesions across diverse tissue sites.

Assessing Protein Expression in Patient-Derived Xenografts Using Western Blotting.

The use of patient-derived xenografts (PDXs) in cancer research is increasing due to their ability to closely mimic the features of patient tumors. The ability to quickly and robustly measure protein expression levels in these tissues is a key methodology required in a broad range of experimental designs. Western blotting (WB) is a cost effective and simple tool that is highly specific and sensitive for detecting and quantifying individual proteins, posttranslational modifications and aberrant signaling pathways. Here, we described a method to assess protein expression in PDX tissues using WB to detect proteins involved in cell growth signaling pathways.

Photosensitive Hydrogel with Temperature-Controlled Reversible Nano-Apertures for Single-Cell Protein Analysis.

Single cell western blot (scWB) is one of the most important methods for cellular heterogeneity profiling. However, current scWB based on conventional photoactive polyacrylamide hydrogel material suffers from the tradeoff between in-gel probing and separation resolution. Here, a highly sensitive temperature-controlled single-cell western blotting (tc-scWB) method is introduced, which is based on a thermo/photo-dualistic-sensitive polyacrylamide hydrogel, namely acrylic acid-functionalized graphene oxide (AFGO) assisted, N-isopropylacrylamide modified polyacrylamide (ANP) hydrogel. The ANP hydrogel is contracted at high-temperature to constrain protein band diffusion during microchip electrophoretic separation, while the gel aperture is expanded under low-temperature for better antibody penetration into the hydrogel. The tc-scWB method enables the separation and profiling of small-molecule-weight proteins with highly crosslinked gel (12% T) in SDS-PAGE. The tc-scWB is demonstrated on three metabolic and ER stress-specific proteins (CHOP, MDH2 and FH) in four pancreatic cell subtypes, revealing the expression of key enzymes in the Krebs cycle is upregulated with enhanced ER stress. It is found that ER stress can regulate crucial enzyme (MDH2 and FH) activities of metabolic cascade in cancer cells, boosting aerobic respiration to attenuate the Warburg effect and promote cell apoptosis. The tc-scWB is a general toolbox for the analysis of low-abundance small-molecular functional proteins at the single-cell level.

An optimized Western blot assay provides a comprehensive assessment of the physiological endoproteolytic processing of the prion protein.

The prion protein (PrPC) is subjected to several conserved endoproteolytic events producing bioactive fragments that are of increasing interest for their physiological functions and their implication in the pathogenesis of prion diseases and other neurodegenerative diseases. However, systematic and comprehensive investigations on the full spectrum of PrPC proteoforms have been hampered by the lack of methods able to identify all PrPC-derived proteoforms. Building on previous knowledge of PrPC endoproteolytic processing, we thus developed an optimized Western blot assay able to obtain the maximum information about PrPC constitutive processing and the relative abundance of PrPC proteoforms in a complex biological sample. This approach led to the concurrent identification of the whole spectrum of known endoproteolytic-derived PrPC proteoforms in brain homogenates, including C-terminal, N-terminal and, most importantly, shed PrPC-derived fragments. Endoproteolytic processing of PrPC was remarkably similar in the brain of widely used wild type and transgenic rodent models, with α-cleavage-derived C1 representing the most abundant proteoform and ADAM10-mediated shedding being an unexpectedly prominent proteolytic event. Interestingly, the relative amount of shed PrPC was higher in WT mice than in most other models. Our results indicate that constitutive endoproteolytic processing of PrPC is not affected by PrPC overexpression or host factors other than PrPC but can be impacted by PrPC primary structure. Finally, this method represents a crucial step in gaining insight into pathophysiological roles, biomarker suitability, and therapeutic potential of shed PrPC and for a comprehensive appraisal of PrPC proteoforms in therapies, drug screening, or in the progression of neurodegenerative diseases.

Suitability of GRK Antibodies for Individual Detection and Quantification of GRK Isoforms in Western Blots.

G protein-coupled receptors (GPCRs) are regulated by GPCR kinases (GRKs) which phosphorylate intracellular domains of the active receptor. This results in the recruitment of arrestins, leading to desensitization and internalization of the GPCR. Aside from acting on GPCRs, GRKs regulate a variety of membrane, cytosolic, and nuclear proteins not only via phosphorylation but also by acting as scaffolding partners. GRKs' versatility is also reflected by their diverse roles in pathological conditions such as cancer, malaria, Parkinson's-, cardiovascular-, and metabolic disease. Reliable tools to study GRKs are the key to specify their role in complex cellular signaling networks. Thus, we examined the specificity of eight commercially available antibodies targeting the four ubiquitously expressed GRKs (GRK2, GRK3, GRK5, and GRK6) in Western blot analysis. We identified one antibody that did not recognize its antigen, as well as antibodies that showed unspecific signals or cross-reactivity. Hence, we strongly recommend testing any antibody with exogenously expressed proteins to clearly confirm identity of the obtained Western blot results. Utilizing the most-suitable antibodies, we established the Western blot-based, cost-effective simple tag-guided analysis of relative protein abundance (STARPA). This method allows comparison of protein levels obtained by immunoblotting with different antibodies. Furthermore, we applied STARPA to determine GRK protein levels in nine commonly used cell lines, revealing differential isoform expression.

Confirmation value of Western blotting in detecting anti-treponema pallidum specific antibodies with suspicious results.

BACKGROUND: Due to the inconsistent results of anti-treponema pallidum (TP) specific antibodies by enzyme-linked immunosorbent assay (ELISA) and Treponema pallidum granule agglutination assay (TPPA) in clinical work, there will be a certain proportion of false-positives and false-negatives depending on TPPA as confirmation results. This study aimed to evaluate the necessity of Western blotting (WB) in samples with inconsistent results in detecting anti-TP antibodies by ELISA and TPPA. METHODS: Specific anti-TP test results in our clinical laboratory were retrospectively analyzed. The specimens with a positive or a negative result, but with colored ELISA plates, were retested by TPPA. WB was used to confirm the suspicious results between ELISA and TPPA. The Chi-square test was used to analyze whether the difference was statistically significant. RESULTS: A total of 106,757 anti-TP specimens were screened by ELISA from August 2018 to December 2019; 3972 were retested by TPPA, and 3809 were positive by TPPA. ELISA and TPPA showed different results in 163 specimens. Among them, 29 specimens were negative and 134 were positive by ELISA; 76 were negative, 23 were positive, and 64 were "reserve" by TPPA; 93 were negative, 31 were positive, and 39 were suspicious by the WB confirmation test. Compared with WB, the difference in the results of ELISA and TPPA was statistically significant. CONCLUSIONS: TPPA is an effective retest method for anti-TP antibody detection. If the results of anti-TP antibodies by ELISA and TPPA are inconsistent, it is necessary to use WB for confirmation. Trial registration This retrospective analysis is in accordance with the ethical guidelines of China and approved by the second hospital of Jiaxing (jxey-2018048).

Chitinase 3-like 1 secreted from cancer-associated fibroblasts promotes tumor angiogenesis via interleukin-8 secretion in colorectal cancer.

The cancer­stromal interaction has been demonstrated to promote tumor progression, and cancer-associated fibroblasts (CAFs), which are the main components of stromal cells, have attracted attention as novel treatment targets. Chitinase 3-like 1 (CHI3L1) is a chitinase-like protein, which affects cell proliferation and angiogenesis. However, the mechanisms through which cells secrete CHI3L1 and through which CHI3L1 mediates tumor progression in the cancer microenvironment are still unclear. Accordingly, the present study assessed the secretion of CHI3L1 in the microenvironment of colorectal cancer and evaluated how CHI3L1 affects tumor angiogenesis. CAFs and normal fibroblasts (NFs) established from colorectal cancer tissue, and human colon cancer cell lines were evaluated using immunostaining, cytokine antibody array, RNA interference, reverse transcription-quantitative PCR (RT-qPCR), ELISA, western blotting and angiogenesis assays. The expression and secretion of CHI3L1 in CAFs were stronger than those in NFs and colorectal cancer cell lines. In addition, interleukin-13 receptor α2 (IL-13Rα2), a receptor for CHI3L1, was not expressed in colorectal cancer cell lines, but was expressed in fibroblasts, particularly CAFs. Furthermore, the expression and secretion of IL-8 in CAFs was stronger than that in NFs and cancer cell lines, and recombinant CHI3L1 addition increased IL-8 expression in CAFs, whereas knockdown of CHI3L1 suppressed IL-8 expression. Furthermore, IL-13Rα2 knockdown suppressed the enhancement of IL-8 expression induced by CHI3L1 treatment in CAFs. For vascular endothelial growth factor-A (VEGFA), similar results to IL-8 were observed in an ELISA for comparison of secretion between CAFs and NFs and for changes in secretion after CHI3L1 treatment in CAFs; however, no significant differences were observed for changes in expression after CHI3L1 treatment or IL-13Rα2 knockdown in CAFs assessed using RT-qPCR assays. Angiogenesis assays revealed that tube formation in vascular endothelial cells was suppressed by conditioned medium from CAFs with the addition of human CHI3L1 neutralizing antibodies compared with control IgG, and also suppressed by conditioned medium from CAFs transfected with CHI3L1, IL-8 or VEGFA small interfering RNA compared with negative control small interfering RNA. Overall, the present findings indicated that CHI3L1 secreted from CAFs acted on CAFs to increase the secretion of IL-8, thereby affecting tumor angiogenesis in colorectal cancer.

Clonagem, expressão recombinante e validação por microarray de proteínas alimentares potencialmente alergênicas / Cloning, recombinant expression and validation by microarray of potentially allergenic food proteins

A maioria das respostas alérgicas a alimentos é mediada por IgE, que pode ser detectada para fins de diagnóstico da alergia alimentar. No entanto, para isso é necessário que alérgenos purificados estejam disponíveis para a elaboração dos diferentes formatos de ensaio, inclusive por microarray, que se constitui em uma ferramenta bastante útil para análise simultânea, e também para a identificação de reatividade cruzada. A esse respeito, é imprescindível ampliar a plataforma de alérgenos que possam ser empregados para a confecção de microarrays. Atualmente, alguns alimentos que constituem objeto de interesse na clínica em função do número de casos de alergia, e sobre os quais as informações a respeito dos alérgenos são escassas, são: abacaxi, mamão, mandioca e manga. Assim, o objetivo desse trabalho foi clonar, expressar e purificar proteínas potencialmente alergênicas de alimentos de importância regional. Após confirmadas por ensaios imunológicos, essas proteínas foram utilizadas na construção e validação de um microarray através de ensaios com os soros de pacientes alérgicos aos alimentos selecionados. Para atingir esse objetivo, foram selecionadas proteínas potencialmente alergênicas coincidentes, apontadas tanto pela similaridade com espécies taxonomicamente mais próximas, quanto pela técnica 2D Western Blotting acoplada à espectrometria de massas. Dezenove proteínas, sendo 4 de abacaxi, 5 de mamão, 6 de mandioca e 4 de manga, foram expressas em Pichia pastoris, purificadas e impressas em um microarray. Após incubar essas proteínas com os soros dos pacientes alérgicos aos alimentos estudados, 18 proteínas mostraram-se potencialmente alergênicas. Além disso, foi observada reatividade cruzada entre proteínas dos alimentos estudados e também em relação ao látex e outros frutos

The majority of allergic reactions to foods is IgE-mediated, which can be detected for the diagnosis of food allergy. However, purified allergens are necessary to produce different kinds of allergy tests, including microarray, which is a useful tool for simultaneous analysis, as well as for the identification of cross-reactivity. In this respect, it is essential to expand the platform of allergens to include them on microarrays. Nowadays, some foods that are object of interest in the clinical area in Brazil and it is necessary a further evaluation about their potential allergens, since there is a limited information about them, are: pineapple, papaya, cassava and mango. Therefore, the aim of this study was cloning, expressing and purifying potentially allergenic proteins of important Brazilian foods. After confirmed by immunological tests, these proteins were used in microarray production and validation by assays with sera from allergic patients to the selected foods. Achieving this goal, matching potentially allergenic proteins were selected, which were identified by comparison among taxonomically closer species (in silico) and 2D Western Blotting coupled with Mass Spectrometry. Nineteen proteins: 4 from pineapple, 5 from papaya, 6 from cassava and 4 from mango were expressed in Pichia pastoris, purified and printed on a microarray. After incubating those proteins with sera from allergic patients to the selected foods, 18 proteins were detected as potentially allergenic. In addition, cross-reactivity was observed among the proteins from the studied foods, and also regarding to the latex and other fruits

Establishment and comparison of two methods to produce a rat model of mammary gland hyperplasia with hyperprolactinemia

Abstract This study aimed to establish and compare models of mammary gland hyperplasia (MGH) with hyperprolactinemia (HPRL) using two different methods. The models provide information on the relationship between mammary gland hyperplasia and associated hormones. Model A was constructed using intramuscular injections of estradiol benzoate injection (EBI), followed by progesterone (P), and then metoclopramide dihydrochloride (MDI). Model B was designed by administering MDI, follow by EBI, and then P intramuscularly. Model B showed higher MGH progression compared with model A. Notably, increase in estradiol (E2) was negatively correlated with prolactin (PRL) secretion. However, PRL levels in model B were significantly higher compared with the levels in model A. Estrogen (ER), prolactin receptor (PRLR), and progesterone receptor (PR) mRNA and protein expression levels in model B rats were positively correlated with changes in the corresponding hormone levels. However, E2, P, and PRL levels in model A showed no direct relationship with levels of the mRNAs of related hormones and protein expression levels. Our results suggest that model B is an appropriate model of MGH with HPRL that can be used to perform further studies about the interactions of the E2, P, and PRL hormones in this disorder.

Ligustrazine suppresses platelet aggregation through inhibiting the activities of calcium sensors

Abstract Ligustrazine is widely used for the treatment of cardiovascular diseases in traditional Chinese medication. It has been reported that Ligustrazine decreases the concentration of intracellular calcium ions (Ca2+); however, the underlying mechanism remains unknown. In the present study, the effect of Ligustrazine on adenosine diphosphate (ADP)-induced platelet aggregation was evaluated using a turbidimetric approach. The changes in concentration of intracellular Ca2+ stimulated by ADP was measured using fluo-4, a fluorescent Ca2+ indicator dye. The mRNA expression of stromal interaction molecule l (STIM1) and Orai1, calcium sensor, was determined using real-time PCR. In addition, the protein expression of STIM1, Orai1, and serum/glucocorticoid-regulated protein kinase 1 (SGK1) was determined using Western blot analysis. The data demonstrated that Ligustrazine significantly suppressed platelet aggregation in a dose-dependent manner and reduced the concentration of intracellular Ca2+ triggered by ADP. Our data showed that Ligustrazine treatment inhibited the expression of STIM1 and Orai1 induced by ADP at both mRNA and protein levels, and suppressed the protein expression of SGK1. Taken together, our data indicated that Ligustrazine suppressed platelet aggregation by partly inhibiting the activities of calcium sensors, thereby suggesting that Ligustrazine may be a promising candidate for the treatment of platelet aggregation.