scholarly journals The accumulation of exosome-associated microRNA-1246 and microRNA-150-3p in human red blood cell suspensions

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Yujie Kong ◽  
Xue Tian ◽  
Rui He ◽  
Chenyue Li ◽  
Haixia Xu ◽  
...  
Keyword(s):  
Blood Cell ◽  
Signaling Pathways ◽  
Red Blood Cell ◽  
Expression Profiles ◽  
Storage Period ◽  
Gene Chip ◽  
Ras Signaling ◽  
Qrt Pcr ◽  
Exosomal Mirnas ◽  
Exosomal Mirna

Abstract Background Transfusion-related immunomodulation (TRIM) can be caused by exosomes, in which case, microRNAs (miRNAs) are one critical factor impacting exosome behavior. This study aims to investigate and analyze the expression profiles of exosomal miRNA in red blood cell (RBC) suspensions during storage and to identify potential TRIM-related miRNAs as well as their potential functions. Methods A total of 25 packs of RBC suspensions were randomly collected. Exosome were extracted by ultracentrifugation and then identified and characterized by nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM) and western blot (WB). Exosomal miRNA profiles were acquired using gene chips in five packs on week 1 and week 5. The expression data were compared from the two time points identifying accumulated miRNAs with statistical significance and their predicted targeting genes were analyzed. Based on the gene chip results, quantitative reverse transcription-polymerase chain reactions (qRT-PCR) were performed to verify miRNA accumulation in the rest 20 packs sampling on week 1, 3 and 5. Results Gene chip analysis revealed that most exosomal miRNAs were enriched as the storage period progressed. Compared to samples from week 1, week 5 samples exhibited a total of 539 differential miRNA expressions, among which, 159 were statistically significant (P < 0.05) and 148 (93.08%) were accumulated. In the bioinformatics functional analysis, significant immunoregulatory annotations related to the thyroid hormone, mitogen-activated protein kinase (MAPK), focal adhesion and RAS signaling pathways were identified. The top 17 differential expression miRNAs were validated by qRT-PCR. The results confirmed that all the 17 miRNAs were accumulated with increasing storage time. In particular, miRNA-1246 and miRNA-150-3p were the most enriched strands by more than 150-folds in the 5-week storage period. Conclusions As storage progressed, numerous exosomal miRNAs accumulated in the RBC suspensions, which are informatically connected to multiple immuno-signaling pathways. MiRNA-1246 and miRNA-150-3p may be essential mediators impacting the immunoregulation functions of exosomes in RBC suspensions, considering their significant accumulating scales. Further research should therefore focus on the relationship between these miRNAs and TRIM.

scholarly journals Expression Profile of Exosome-associated MicroRNA Derived from Human Red Blood Cell Suspensions During Storage: Predicting microRNA-1246 and microRNA-150-3p Exert Essential Roles in Transfusion-related Immunomodulation

2021 ◽  
Author(s):  
Yujie Kong ◽  
Xue Tian ◽  
Rui He ◽  
Chenyue Li ◽  
Haixia Xu ◽  
...  
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Storage Time ◽  
Target Genes ◽  
Mitogen Activated Protein Kinase ◽  
Ras Signaling ◽  
Qrt Pcr ◽  
Exosomal Mirnas ◽  
Storage Times ◽  
Functional Components

Abstract Background: Transfusion-related immunomodulation (TRIM) can be caused by exosomes and microRNA (miRNA) is one of the critical functional components in exosomes. This study intends to investigate the differences in the expression of exosomal miRNAs in red blood cell (RBC) suspensions at different storage times, also the potential functions related to TRIM of the abundant miRNAs. Methods: Twenty-five bags of RBC suspensions were selected randomly, and exosomes were separated by ultracentrifugation at different storage times. Isolated exosomes were identified by Nanoparticle Tracking Analysis (NTA), Transmission Electron Microscopy (TEM), and Western Blot (WB). Exosomal miRNA profiles were analyzed using genechip in 5 RBC suspension samples, and the miRNA expressions between different storage times were compared. For the statistically upregulated microRNAs, the bioinformation of their predicted target genes was analyzed. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to identify the miRNAs upregulated more than 10 folds at 5weeks storage time in 20 RBC suspension samples.Results: The detection of the gene chip showed most exosomal miRNAs were up-regulated as storage time increases. Compared to RBC suspensions stored for 1 week, that kept for 5 weeks had 539 differential miRNA expressions, among which 159 were significantly different (P<0.05) and 148 (93.08%) were up-regulated. For the bioinformatic analysis, significant immunoregulatory annotations related to thyroid hormone, mitogen-activated protein kinase (MAPK), focal adhesion, and ras signaling pathway were found. The top 17 miRNAs were validated by qRT-PCR, and the results showed miRNA-1246 and miRNA-150-3p were the most significantly enriched miRNAs (more than 150 folds during 5weeks storage).Conclusions: As storage time increased, various exosomal miRNAs in RBC suspensions accumulated and involved multiple immuno-signaling pathways. The predominantly accumulated miRNA-1246 and miRNA-150-3p were confirmed to participate in pro-inflammation responses and immune-regulation, which might exert essential roles in TRIM.

scholarly journals MicroRNA Profiling of Exosomes Derived from Red Blood Cell Units: Implications in Transfusion-Related Immunomodulation

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Haobo Huang ◽  
Jinfeng Zhu ◽  
Liping Fan ◽  
Qiuyan Lin ◽  
Danhui Fu ◽  
...  
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Storage Time ◽  
Bioinformatic Analysis ◽  
Mirna Microarray ◽  
Qrt Pcr ◽  
Transmission Electron ◽  
Mean Size ◽  
The Mean ◽  
Polymerase Chain

Purpose. To elucidate the microRNAs existent in exosomes derived from stored red blood cell (RBC) unit and their potential function. Materials and Methods. Exosomes were isolated from the supernatant derived from stored RBC units by sequential centrifugation. Isolated exosomes were characterized by TEM (transmission electron microscopy), western blotting, and DLS (dynamic light scattering). MicroRNA (miRNA) microarray was performed to detect the expression of miRNAs in 3 exosome samples. Results revealed miRNAs that were simultaneously expressed in the 3 exosome samples and were previously reported to exist in mature RBCs. Functions and potential pathways of some detected miRNAs were illustrated by bioinformatic analysis. Validation of the top 3 abundant miRNAs was carried out by qRT-PCR (quantitative reverse transcription‐polymerase chain reaction). Results. TEM and DLS revealed the mean size of the exosomes (RBC-derived) as 64.08 nm. These exosomes exhibited higher abundance of short RNA than the long RNA. 78 miRNAs were simultaneously detected in 3 exosome samples and mature RBCs. Several biological processes might be impacted by these miRNAs, through their target gene(s) enriched in a particular signalling pathway. The top 3 (abundant) miRNAs detected were as follows: miR-125b-5p, miR-4454, and miR-451a. qRT-PCR revealed higher abundance of miR-451a than others. Only miR-4454 and miR-451a abundance tended to increase with increasing storage time. Conclusion. Exosomes derived from stored RBC units possessed multiple miRNAs and, hence, could serve various functions. The function of exosomes (RBC-derived) might be implemented partly by the predominantly enriched miR-451a.

scholarly journals Plasmodium falciparum erythrocyte-binding antigen 175 triggers a biophysical change in the red blood cell that facilitates invasion

2017 ◽  
Vol 114 (16) ◽  
pp. 4225-4230 ◽  
Author(s):  
Marion Koch ◽  
Katherine E. Wright ◽  
Oliver Otto ◽  
Maik Herbig ◽  
Nichole D. Salinas ◽  
...  
Keyword(s):  
Cell Surface ◽  
Blood Cell ◽  
Signaling Pathways ◽  
Red Blood Cell ◽  
Malaria Parasite ◽  
Red Cell ◽  
Biophysical Properties ◽  
Parasite Invasion ◽  
Bending Modulus ◽  
Erythrocyte Binding

Invasion of the red blood cell (RBC) by the Plasmodium parasite defines the start of malaria disease pathogenesis. To date, experimental investigations into invasion have focused predominantly on the role of parasite adhesins or signaling pathways and the identity of binding receptors on the red cell surface. A potential role for signaling pathways within the erythrocyte, which might alter red cell biophysical properties to facilitate invasion, has largely been ignored. The parasite erythrocyte-binding antigen 175 (EBA175), a protein required for entry in most parasite strains, plays a key role by binding to glycophorin A (GPA) on the red cell surface, although the function of this binding interaction is unknown. Here, using real-time deformability cytometry and flicker spectroscopy to define biophysical properties of the erythrocyte, we show that EBA175 binding to GPA leads to an increase in the cytoskeletal tension of the red cell and a reduction in the bending modulus of the cell’s membrane. We isolate the changes in the cytoskeleton and membrane and show that reduction in the bending modulus is directly correlated with parasite invasion efficiency. These data strongly imply that the malaria parasite primes the erythrocyte surface through its binding antigens, altering the biophysical nature of the target cell and thus reducing a critical energy barrier to invasion. This finding would constitute a major change in our concept of malaria parasite invasion, suggesting it is, in fact, a balance between parasite and host cell physical forces working together to facilitate entry.

scholarly journals Promising Roles of Exosomal microRNAs in Systemic Lupus Erythematosus

2021 ◽  
Vol 12 ◽  
Author(s):  
Wenqian Wang ◽  
Chenran Yue ◽  
Sheng Gao ◽  
Shuting Li ◽  
Jianan Zhou ◽  
...  
Keyword(s):  
Systemic Lupus Erythematosus ◽  
Signaling Pathways ◽  
Lupus Erythematosus ◽  
Biological Fluids ◽  
Immunomodulatory Effects ◽  
Systemic Lupus ◽  
Non Invasive ◽  
Donor Cells ◽  
Exosomal Mirnas ◽  
Exosomal Mirna

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by the loss of immune tolerance. Lupus nephritis (LN) is still a major cause of the morbidity and mortality of SLE. In clinical practice, diagnosis, and therapy of SLE is complicated and challenging due to lack of ideal biomarkers. Exosomes could be detected from numerous kinds of biological fluids and their specific contents are considered as hallmarks of autoimmune diseases. The exosomal miRNA profiles of SLE/LN patients significantly differ from those of the healthy controls making them as attractive biomarkers for renal injury. Exosomes are considered as optimal delivery vehicles owing to their higher stable, minimal toxicity, lower immunogenicity features and specific target effects. Endogenous miRNAs can be functionally transferred by exosomes from donor cells to recipient cells, displaying their immunomodulatory effects. In addition, it has been confirmed that exosomal miRNAs could directly interact with Toll-like receptors (TLRs) signaling pathways to regulate NF-κB activation and the secretion of inflammatory cytokines. The present Review mainly focuses on the immunomodulatory effects of exosomal-miRNAs, the complex interplay between exosomes, miRNAs and TLR signaling pathways, and how the exosomal-miRNAs can become non-invasive diagnostic molecules and potential therapeutic strategies for the management of SLE.

scholarly journals Aquaporin 3 Promotes Human Extravillous Trophoblast Migration and Invasion

2020 ◽  
Author(s):  
Ying-qi Nong ◽  
Shi-fen Li ◽  
Wen-juan Liu ◽  
Xi-qian Zhang ◽  
Lin Fan ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Expression Profiles ◽  
Bioinformatic Analysis ◽  
Gene Chip ◽  
Cell Counting ◽  
Extravillous Trophoblast ◽  
Migration And Invasion ◽  
Aquaporin 3 ◽  
Protein Levels ◽  
Proliferation And Apoptosis

Abstract Problem: Does aquaporin 3 (AQP3) affect the migration and invasion of human extravillous trophoblast (HTR8/Svneo) cells?Method of Study: A lentivirus infection system was used to construct stable cell lines with either AQP3 knockdown or overexpression. RT-PCR and western blotting were used to verify the efficiencies of AQP3 knockdown or overexpression in HTR8/Svneo cells at mRNA and protein levels, respectively. Cell Counting Kit-8 and flow cytometry assays were used to detect the influence of AQP3 knockdown or overexpression on proliferation and apoptosis of HTR8/Svneo cells. In addition, wound healing and Transwell invasion assays were used to detect the effects of AQP3 knockdown or overexpression on migration and invasion capabilities of HTR8/Svneo cells. An Agilent gene chip was used to screen for significant differentially expressed genes after AQP3 knockdown. Finally, mechanisms by which AQP3 influences the migration and invasion of HTR8/Svneo cells were explored using bioinformatic analysis.Results: Compared with controls, migration and invasion capabilities of HTR8/Svneo cells were significantly reduced after AQP3 knockdown, and significantly increased after AQP3 overexpression. Subsequent bioinformatic analysis of gene chip expression profiles indicated downregulation of genes related to adhesion such as PDGF-B, as well as signaling pathways (such as PIK3/AKT, NF-κB, and TNF) after AQP3 knockdown. Conclusions: AQP3 could significantly promote migration and invasion capabilities of human extravillous trophoblasts, it may mediate embryo invasion and adhesion to endometrium by regulating PDGF-B、PIK3/AKT signaling pathways, although this requires further verification.

scholarly journals Phosphorylation-Dependent Assembly of a 14-3-3 Mediated Signaling Complex During Red Blood Cell Invasion by Plasmodium falciparum Merozoites

2020 ◽  
Author(s):  
Kunal R. More ◽  
Inderjeet Kaur ◽  
Quentin Giai Gianetto ◽  
Brandon M. Invergo ◽  
Thibault Chaze ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Protein Kinase ◽  
Blood Cell ◽  
Signaling Pathways ◽  
Red Blood Cell ◽  
Protein Complex ◽  
Merozoite Invasion ◽  
Signaling Complex ◽  
Novel Approach ◽  
Low K

AbstractRed blood cell (RBC) invasion by Plasmodium merozoites requires multiple steps that are regulated by signaling pathways. Exposure of P. falciparum merozoites to the physiological signal of low K+, as found in blood plasma, leads to a rise in cytosolic Ca2+, which mediates microneme secretion, motility, and invasion. We have used global phosphoproteomic analysis of merozoites to identify signaling pathways that are activated during invasion. Using quantitative phosphoproteomics we found 394 protein phosphorylation site changes in merozoites subjected to different ionic environments (high K+/ low K+) out of which 143 were Ca2+-dependent. These included a number of signaling proteins such as catalytic and regulatory subunits of protein kinase A (PfPKAc and PfPKAr) and calcium-dependent protein kinase 1 (PfCDPK1). Proteins of the 14-3-3 family interact with phosphorylated target proteins to assemble signaling complexes. Here, using co-immunoprecipitation and gel filtration chromatography, we demonstrate that Pf14-3-3I binds phosphorylated PfPKAr and PfCDPK1 to mediate the assembly of a multi-protein complex in P. falciparum merozoites. A phospho-peptide, P1, based on the Ca2+ dependent phosphosites of PKAr, binds Pf14-3-3I and disrupts assembly of the Pf14-3-3I-mediated multi-protein complex. Disruption of the multi-protein complex with P1 inhibits microneme secretion and RBC invasion. This study thus identifies a novel signaling complex that plays a key role in merozoite invasion of RBCs. Disruption of this signaling complex could serve as a novel approach to inhibit blood stage growth of malaria parasites.ImportanceInvasion of red blood cells (RBCs) by Plasmodium falciparum merozoites is a complex process that is regulated by intricate signaling pathways. Here, we have used phosphoproteomic profiling to identify the key proteins involved in signaling events during invasion. We found changes in the phosphorylation of various merozoite proteins including multiple kinases previously implicated in the process of invasion. We also found that a phosphorylation dependent multi-protein complex including signaling kinases assembles during the process of invasion. Disruption of this multi-protein complex impairs merozoite invasion of RBCs providing a novel approach for the development of inhibitors to block the growth of blood stage malaria parasites.

scholarly journals Liquid Biopsy for Colorectal Adenoma: Is the Exosomal miRNA Derived from Organoid a Potential Diagnostic Biomarker?

2020 ◽  
Author(s):  
Tomoyuki Handa ◽  
Masatake Kuroha ◽  
Hiroshi Nagai ◽  
Yusuke Shimoyama ◽  
Takeo Naito ◽  
...  
Keyword(s):  
Microarray Analysis ◽  
Colorectal Adenoma ◽  
Liquid Biopsy ◽  
Expression Profiles ◽  
Human Colon ◽  
Normal Colon ◽  
Organoid Culture ◽  
Large Size ◽  
Exosomal Mirnas ◽  
Exosomal Mirna

Abstract Background: MicroRNAs (miRNAs) have attracted considerable attention as tumor biomarkers. Nevertheless, few reports have described studies of colorectal adenoma (CRA) for liquid biopsy. Recently, organoid culture system development has supported the long-term expansion of investigations of human colon epithelium. This study examined the profile of exosomal miRNAs extracted from CRA organoid and potentiation of candidate miRNAs for clinical application of liquid biopsy in CRA patients. Method: We established organoids from normal colon tissues and CRA from endoscopically resected specimens. Exosomes were prepared from the conditioned medium of the organoids. miRNAs were prepared from the exosomes and their source organoids. The microRNA expression profiles were compared using microarray analysis. To investigate exosomal miRNAs extracted from organoid culture as a candidate for liquid biopsy, we prospectively compared changes in the expression of serum and exosomal miRNA before and after endoscopic resection in 26 patients with CRA.Result: We established three organoid lines from normal colon epithelium and CRA. Microarray analysis revealed that seven exosomal miRNAs expression in CRA organoids were increased compared with normal colon organoids: miR-4323, miR-4284, miR-1268a, miR-1290, miR-6766-3p, miR-21-5p, and miR-1246. The expressions of four exosomal miRNAs (miR-4323, miR-4284, miR-1290, and miR-1246) and two serum miRNAs (miR-1290 and miR-1246) were significantly lower in post-treatment sera. Combinations of four exosomal miRNA expressions can differentiate both CRA and large-size (>12.6 cm2) CRA with respective areas under the curve (AUCs) of 0.698 (95% CI = 0.536–0.823) and 0.834 (95% CI = 0.660–0.929). Combinations of two-serum miRNA expression can differentiate both CRA and large-size CRA with respective AUCs of 0.691 (95% CI = 0.528–0.817) and 0.834 (95% CI = 0.628–0.938). Conclusion: This report is the first to show that exosomal miRNAs derived from CRA organoid culture have potential for use as diagnostic biomarkers for CRA.

scholarly journals Exosomal miR-125b Exerts Anti-Metastatic Properties and Predicts Early Metastasis of Hepatocellular Carcinoma

2021 ◽  
Vol 11 ◽  
Author(s):  
Hye Seon Kim ◽  
Jin Seoub Kim ◽  
Na Ri Park ◽  
Heechul Nam ◽  
Pil Soo Sung ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Protein Expression ◽  
Migration And Invasion ◽  
Large Set ◽  
Mesenchymal Transition ◽  
Qrt Pcr ◽  
Exosomal Mirnas ◽  
Exosomal Mirna ◽  
Tgf Β1

Background &amp; AimsCancer metastasis is responsible for the majority of cancer-related deaths. Exosomal miRNAs have emerged as promising biomarkers for cancer, serving as signaling molecules that can regulate tumor growth and metastasis. This study examined circulating exosomal miRNAs that could predict hepatocellular carcinoma (HCC) metastasis.MethodsExosomal miRNA was measured by quantitative real-time PCR (qRT-PCR) in a large set of patients (n = 284). To investigate the role of exosomal miRNA in HCC, we performed a series of in vitro tests, such as exosome labeling, qRT-PCR, reverse transcription PCR, wound healing assay, transwell assay, and Western blot assay.ResultsExosomal miR-125b was drastically downregulated in HCC patients with metastasis than in those without metastasis. In vitro, we observed the uptake of miR-125b by exosome in recipient cells. Exosome-mediated miR-125b significantly inhibited migration and invasion abilities and downregulated the mRNA expressions of MMP-2, MMP-9, and MMP-14 in recipient cells via intercellular communication. Further investigation revealed that miR-125b suppressed SMAD2 protein expression in recipient cells by binding to its 3′ untranslated regions. Exosome-mediated miR-125b transfer also disrupted TGF-β1–induced epithelial–mesenchymal transition and TGF-β1/SMAD signaling pathway in recipient cells by leading to a decrease of SMAD2 protein expression. Moreover, exosomal miR-125b was downregulated after metastasis compared with that at baseline in patients with serial measurements before and after metastasis.ConclusionsThe results imply that exosome-mediated miR-125b exerts anti-metastatic properties in HCC. These findings highlight that circulating exosomal miR-125b might represent a reliable biomarker with diagnostic and therapeutic implications for extrahepatic metastasis from HCC.

scholarly journals Phosphorylation-Dependent Assembly of a 14-3-3 Mediated Signaling Complex during Red Blood Cell Invasion by Plasmodium falciparum Merozoites

mBio ◽  
2020 ◽  
Vol 11 (4) ◽  
Author(s):  
Kunal R. More ◽  
Inderjeet Kaur ◽  
Quentin Giai Gianetto ◽  
Brandon M. Invergo ◽  
Thibault Chaze ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Protein Kinase ◽  
Blood Cell ◽  
Signaling Pathways ◽  
Red Blood Cell ◽  
Multiprotein Complex ◽  
Content Type ◽  
Signaling Complex ◽  
Novel Approach ◽  
Low K

ABSTRACT Red blood cell (RBC) invasion by Plasmodium merozoites requires multiple steps that are regulated by signaling pathways. Exposure of P. falciparum merozoites to the physiological signal of low K+, as found in blood plasma, leads to a rise in cytosolic Ca2+, which mediates microneme secretion, motility, and invasion. We have used global phosphoproteomic analysis of merozoites to identify signaling pathways that are activated during invasion. Using quantitative phosphoproteomics, we found 394 protein phosphorylation site changes in merozoites subjected to different ionic environments (high K+/low K+), 143 of which were Ca2+ dependent. These included a number of signaling proteins such as catalytic and regulatory subunits of protein kinase A (PfPKAc and PfPKAr) and calcium-dependent protein kinase 1 (PfCDPK1). Proteins of the 14-3-3 family interact with phosphorylated target proteins to assemble signaling complexes. Here, using coimmunoprecipitation and gel filtration chromatography, we demonstrate that Pf14-3-3I binds phosphorylated PfPKAr and PfCDPK1 to mediate the assembly of a multiprotein complex in P. falciparum merozoites. A phospho-peptide, P1, based on the Ca2+-dependent phosphosites of PKAr, binds Pf14-3-3I and disrupts assembly of the Pf14-3-3I-mediated multiprotein complex. Disruption of the multiprotein complex with P1 inhibits microneme secretion and RBC invasion. This study thus identifies a novel signaling complex that plays a key role in merozoite invasion of RBCs. Disruption of this signaling complex could serve as a novel approach to inhibit blood-stage growth of malaria parasites. IMPORTANCE Invasion of red blood cells (RBCs) by Plasmodium falciparum merozoites is a complex process that is regulated by intricate signaling pathways. Here, we used phosphoproteomic profiling to identify the key proteins involved in signaling events during invasion. We found changes in the phosphorylation of various merozoite proteins, including multiple kinases previously implicated in the process of invasion. We also found that a phosphorylation-dependent multiprotein complex including signaling kinases assembles during the process of invasion. Disruption of this multiprotein complex impairs merozoite invasion of RBCs, providing a novel approach for the development of inhibitors to block the growth of blood-stage malaria parasites.

scholarly journals Regulation of red blood cell filterability by Ca2+ influx and cAMP-mediated signaling pathways

1997 ◽  
Vol 273 (6) ◽  
pp. C1828-C1834 ◽  
Author(s):  
Tadahiro Oonishi ◽  
Kanako Sakashita ◽  
Nobuhiro Uyesaka
Keyword(s):  
Blood Cell ◽  
Red Blood Cells ◽  
Signaling Pathways ◽  
Mechanical Stress ◽  
Red Blood Cell ◽  
Blood Cells ◽  
Camp Level ◽  
Membrane Properties ◽  
Cell Deformability ◽  
Red Blood Cell Deformability

To investigate the mechanism of the regulation of human red blood cell deformability, we examined the deformability under mechanical stress. Washed human red blood cells were rapidly injected through a fine needle, and their filterability was measured using a nickel mesh filter. The decrease in filterability showed a V-shaped curve depending on the extracellular Ca2+ concentration; the maximum decrease was achieved at ∼50 μM. The decreased filterability was accompanied by no change in cell morphology and cell volume, indicating that the decrease in filterability can be ascribed to alterations of the membrane properties. Ca2+entry blockers (nifedipine and felodipine) inhibited the impairment of filterability under mechanical stress. Prostaglandins E1 and E2, epinephrine, and pentoxifylline, which are thought to modulate the intracellular adenosine 3′,5′-cyclic monophosphate (cAMP) level of red blood cells, improved or worsened the impaired filterability according to their expected actions on the cAMP level of the cells. These results strongly suggest that the membrane properties regulating red blood cell deformability are affected by the signal transduction system, including Ca2+-dependent and cAMP-mediated signaling pathways.

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