Effect Of Annexin A5 Research Articles

Effects of Annexin A5 on Endothelial Inflammation Induced by Lipopolysaccharide-Activated Platelets and Extracellular Vesicles

Sepsis is a leading cause of death worldwide with no targeted therapeutics available to treat the underlying septic response. Sepsis results from a dysregulated immune and inflammatory response. During sepsis or lipopolysaccharide (LPS) stimulation, platelets are activated, and release procoagulant/proinflammatory membrane-derived extracellular vesicles (EVs). Our previous studies show recombinant human annexin A5 (Anx5), a phosphatidylserine-binding protein, inhibits inflammation and improves survival in endotoxic mice, a model of sepsis.

Therapeutic Potential of Annexins in Sepsis and COVID-19.

Sepsis is a continuing problem in modern healthcare, with a relatively high prevalence, and a significant mortality rate worldwide. Currently, no specific anti-sepsis treatment exists despite decades of research on developing potential therapies. Annexins are molecules that show efficacy in preclinical models of sepsis but have not been investigated as a potential therapy in patients with sepsis. Human annexins play important roles in cell membrane dynamics, as well as mediation of systemic effects. Most notably, annexins are highly involved in anti-inflammatory processes, adaptive immunity, modulation of coagulation and fibrinolysis, as well as protective shielding of cells from phagocytosis. These discoveries led to the development of analogous peptides which mimic their physiological function, and investigation into the potential of using the annexins and their analogous peptides as therapeutic agents in conditions where inflammation and coagulation play a large role in the pathophysiology. In numerous studies, treatment with recombinant human annexins and annexin analogue peptides have consistently found positive outcomes in animal models of sepsis, myocardial infarction, and ischemia reperfusion injury. Annexins A1 and A5 improve organ function and reduce mortality in animal sepsis models, inhibit inflammatory processes, reduce inflammatory mediator release, and protect against ischemic injury. The mechanisms of action and demonstrated efficacy of annexins in animal models support development of annexins and their analogues for the treatment of sepsis. The effects of annexin A5 on inflammation and platelet activation may be particularly beneficial in disease caused by SARS-CoV-2 infection. Safety and efficacy of recombinant human annexin A5 are currently being studied in clinical trials in sepsis and severe COVID-19 patients.

High Annexin A5 expression promotes tumor progression and poor prognosis in renal cell carcinoma.

AnnexinA5 has been found to act as an oncogenic protein in a variety of cancers. However, its specific biological role and mechanism in renal cell cancer(RCC) remains unknown. Quantitative Real-time PCR and western blotting were used to evaluate the mRNA and protein expression level of AnnexinA5 in human RCC cell lines and tissues. Immunohistochemistry was adopted to measure the AnnexinA5 expression in 123cases of RCC tissues. Survival analysis was performed to explore the association between AnnexinA5 expression and the prognosis of RCC. The effect of AnnexinA5 on RCC growth and metastasis was studied invitro and invivo. AnnexinA5 was frequently highly expressed in both human RCC cells and tissues. High AnnexinA5 expression was associated with higher clinical stage and histological grade. In addition, AnnexinA5 might be used as a predictive factor for the prognosis of RCC. Further research suggested that upregulated AnnexinA5 in RCC cells could significantly promote tumor cell proliferation, migration and invasion invitro. Subcutaneous xenograft tumor model displayed that knockdown of AnnexinA5 could impede tumorigenesis invivo. Moreover, mechanism study exhibited that AnnexinA5 could activate PI3K/Akt/mTOR signaling pathway, promote epithelial-mesenchymal transition(EMT) and the expression of MMP2 and MMP9. AnnexinA5 may be a potential prognostic biomarker in RCC and promotes proliferation, migration and invasion of RCC cells via activating PI3K/Akt/mTOR signaling pathway and regulating EMT process and MMP expression.

AB072. Annexin A5 regulates Leydig cell testosterone production via ERK1/2 pathway

ObjectiveThis study was to investigate the effect of annexin A5 on testosterone secretion from primary rat Leydig cells and the underlying mechanisms.MethodsIsolated rat Leydig cells were treated with annexin A5. Testosterone production was detected by chemiluminescence assay. The protein and mRNA of steroidogenic acute regulatory (StAR), P450scc, 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-hydroxysteroid dehydrogenase (17β-HSD) and 17α-hydroxylase were examined by western blotting and RT-PCR, respectively.ResultsAnnexin A5 significantly stimulated testosterone secretion from rat Leydig cells in dose- and time-dependent manners and increased mRNA and protein expression of StAR, P450scc, 3β-HSD and 17β-HSD but not 17α-hydroxylase. Annexin A5 knockdown by siRNA significantly decreased the level of testosterone and protein expression of P450scc, 3β-HSD and 17β-HSD. The significant activation of ERK1/2 signaling was observed at 5, 10, and 30 min after annexin A5 treatment. After the pretreatment of Leydig cells with ERK inhibitor PD98059 (50 μmol/L) for 20 min, the effects of annexin A5 on promoting testosterone secretion and increasing the expression of P450scc, 3β-HSD and 17β- HSD were completely abrogated (P<0.05).ConclusionsThus, ERK1/2 signaling is involved in the roles of annexin A5 in mediating testosterone production and the expression of P450scc, 3β-HSD and 17β-HSD in Leydig cells.

Upregulation of annexin A5 affects the biological behaviors of lung squamous carcinoma cells in vitro

Annexin A5 is a Ca2+-dependent phospholipid-binding protein and protein kinase C inhibitory protein. It has a potential role in cellular signal transduction, inflammation, growth and differentiation. In this study, we evaluated the expression of this protein in lung tumor tissues and subsequently established a NCI-H520 cell line that stably expresses the wild-type ANXA5 gene to determine the effects of annexin A5 upregulation on the cell morphology, proliferation and metastasis potential in vitro. The effects of annexin A5 on NCI-H520 cells were tested by crystal violet staining, CCK-8 assay, scratch wound assay, and Transwell assay. The expressions of Akt, PCNA, vimentin, and E-cadherin were examined by Western blot assay. In this study, we demonstrated that annexin A5 is expressed at lower levels in tumor tissues compared with normal tissues. Additionally, the upregulation of this protein may inhibit the proliferation, migration, and invasion abilities of NCI-H520 cells in vitro. The transfected cells were arrested in the G1/S phase of the cell cycle, and the expression levels of Akt, PCNA and Vimentin were downregulated, while E-cadherin was upregulated.

Inhibition of Hep-2 cell apoptosis after annexin A5 knockdown

To study the effect of annexin A5 on the apoptosis of laryngeal cancer cells. Special siRNAs were used to knock annexinA5 down in Hep-2 cell, and RT-PCR and Western blot were applied to identify the efficacy of RNA interference. The flow cytometry assay was performed to detect the Hep-2 cell apoptosis. RT-PCR analysis showed that the relative mRNA expression of annexin A5 in siRNA group, negative control group, Lipofectamine 2000 group and blank control group were 0.70 ± 0.03, 1.18 ± 0.05, 1.17 ± 0.06 and 1.23 ± 0.07. The relative mRNA expression of annexin A5 in siRNA group was significantly decreased than contrast groups(t = -14.77, t = -13.23, t = -12.99, P < 0.05).In Western blot assay, the trend of protein expression level was consistent with the mRNA expression levels of annexin A5. The relative levels of proteins in siRNA group, negative control group, Lipofectamine 2000 group and blank control group were shown 1.21 ± 0.03, 3.88 ± 0.06, 3.87 ± 0.02 and 3.95 ± 0.08. The relative protein expression of annexin A5 in siRNA group was significantly decreased than contrast groups(t = -70.34, t = -150.62, t = -56.32, P < 0.05). At the same time in flow cytometry the apoptotic rate of siRNA group, negative control group, Lipofectamine 2000 group and blank control group were 4.43% ± 0.12%, 13.67% ± 0.22%, 13.66% ± 0.12% and 13.35% ± 0.13%, the difference between the siRNA group and contrast groups was statistically significant(t = -62.50, t = -14.16, t = -11.47, P < 0.05).So after RNA interference, expression of annexin A5 decreased, and the results in the apoptosis inhibition of Hep-2 cell. Annexin A5 promotes apoptosis of Hep-2 cells, and it may be a potential therapeutic target for the laryngeal cancer.

Immobilizing Single Lipid and Channel Molecules in Artificial Lipid Bilayers with Annexin A5

The effects of annexin A5 on the lateral diffusion of single-molecule lipids and single-molecule proteins were studied in an artificial lipid bilayer membrane. Annexin A5 is a member of the annexin superfamily, which binds preferentially to anionic phospholipids in a Ca2+-dependent manner. In this report, we were able to directly monitor single BODIPY 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (DHPE) and ryanodine receptor type 2 (RyR2) labeled with Cy5 molecules in lipid bilayers containing phosphatidylserine (PS) by using fluorescence microscopy. The diffusion coefficients were calculated at various annexin A5 concentrations. The diffusion coefficients of BODIPY-DHPE and Cy5-RyR2 in the absence of annexin A5 were 4.81 x 10(-8) cm(2)/s and 2.13 x 10(-8) cm(2)/s, respectively. In the presence of 1 microM annexin A5, the diffusion coefficients of BODIPY-DHPE and Cy5-RyR2 were 2.2 x 10(-10) cm(2)/s and 9.5 x 10(-11) cm(2)/s, respectively. Overall, 1 microM of annexin A5 was sufficient to induce a 200-fold decrease in the lateral diffusion coefficient. Additionally, we performed electrophysiological examinations and determined that annexin A5 has little effect on the function of RyR2. This means that annexin A5 can be used to immobilize RyR2 in a lipid bilayer when imaging and analyzing RyR2.