OBJECTIVES: Pyroptosis plays a critical role in tubulointerstitial lesions of diabetic kidney disease (DKD). Annexin A2 (ANXA2) is involved in cell proliferation, apoptosis, and adhesion and may be closely related to DKD, but its specific mechanism remains unclear. This study aims to investigate the role and molecular mechanism of ANXA2 in high glucose-induced pyroptosis of renal tubular epithelial cells, providing new targets for DKD prevention and treatment. METHODS: Human renal tubular epithelial HK-2 cells were divided into a normal glucose group (5.5 mmol/L), a high glucose group (30.0 mmol/L), and a osmotic control group (24.5 mmol/L mannitol+5.5 mmol/L glucose). ANXA2 expression was modulated by overexpression of plasmids and small interfering RNA (siRNA). Cell proliferation was measured by 5-ethynyl-2'-deoxyuridine (EdU) assay, apoptosis by flow cytometry, and ANXA2, p50, and p65 subcellular localization by immunofluorescence. Western blotting was employed to detect α-smooth muscle actin (α-SMA), fibronectin (FN), and collagen type IV (Col-IV). Real-time fluorescence quantitative PCR (RT-qPCR) and Western blotting were used to analyze nuclear factor-κB (NF-κB) subunits p50/p65 and the pyroptosis pathway factors NLR family Pyrin domain containing 3 (NLRP3), caspase-1, inferleukin (IL)-1β, and IL-18. Protein interactions between ANXA2 and p50/p65 were examined by co-immunoprecipitation, while chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assays were used to examine NF-κB binding to the ANXA2 promoter. RESULTS: High glucose upregulated ANXA2 expression and promoted its nuclear translocation (P<0.01). High glucose reduced cell proliferation, increased apoptosis, and elevated α-SMA, FN, and Col-IV expression (all P<0.05); ANXA2 overexpression aggravated these effects (all P<0.05), while ANXA2 knockdown reversed them (all P<0.05). High glucose activated NF-κB and increased NLRP3, caspase-1, L-1β, and IL-18 mRNA and protein expression (all P<0.05); ANXA2 overexpression further enhanced this, whereas knockdown suppressed NF-κB activation and downstream factors (all P<0.05). Co-immunoprecipitation confirmed ANXA2 directly binds the NF-κB subunit p65. ChIP assays revealed p65 binds specifically to ANXA2 promoter regions (ChIP-2, ChIP-4, and ChIP-6), and luciferase activity in corresponding mutant constructs (M2, M4, and M6) was significantly increased versus controls (all P<0.05), confirming positive transcriptional regulation of ANXA2 by p65. CONCLUSIONS ANXA2 and NF-κB form a positive feedback loop that sustains NLRP3 inflammasome activation, promotes pyroptosis pathway activation, and aggravates high glucose-induced renal tubular epithelial cell injury. Targeting ANXA2 or blocking its interaction with p65 may be a novel strategy to slow DKD progression.
Humans ; Pyroptosis/drug effects* ; Annexin A2/physiology* ; Epithelial Cells/cytology* ; Kidney Tubules/cytology* ; Glucose/pharmacology* ; Diabetic Nephropathies/metabolism* ; NF-kappa B/metabolism* ; Cell Line ; Cell Proliferation ; Transcription Factor RelA/metabolism* ; Feedback, Physiological

OBJECTIVETo investigate the effect of annexin A2 (AnxA2) on epithelial growth factor receptor (EGFR)/nuclear factor-κB (NF-κB) signal transduction and mucin expression in human airway epithelial H292 cells treated with Mycoplasma pneumoniae (MP).

METHODSH292 cells were divided into control group, MP group, NC-siRNA+MP group, and AnxA2 siRNA+MP group. The cells in the MP group were incubated with 5 μg/mL MP antigen for 2 hours. The cells in the NC-siRNA+MP and AnxA2 siRNA+MP groups were transfected with NC-siRNA and AnxA2 siRNA for 24 hours, followed by MP antigen stimulation for 2 hours. The MTT method was used to measure cell viability; quantitative real-time PCR was used to measure the mRNA expression of AnxA2; Western blot was used to measure the protein expression of AnxA2, phosphorylated EGFR (p-EGFR), and phosphorylated p65 NF-κB (p-p65 NF-κB); ELISA was used to measure the secretion of mucin 5AC (MUC5AC) and mucin 5B (MUC5B).

RESULTSThe MP and NC-siRNA+MP groups had lower cell viability than the control group (P<0.05). The AnxA2 siRNA+MP group had higher cell viability than the MP and NC-siRNA+MP groups and lower cell viability than the control group (P<0.05). The MP and NC-siRNA+MP groups had significantly higher mRNA and protein expression of AnxA2 than the AnxA2 siRNA+MP group (P<0.05). Compared with the control group, the MP and NC-siRNA+MP groups had significant increases in the protein expression of p-EGFR, p-p65 NF-κB, MUC5AC, and MUC5B (P<0.05); the AnxA2 siRNA+MP group had lower protein expression than the MP and NC-siRNA+MP groups, but higher protein expression than the control group (P<0.05).

CONCLUSIONSAnxA2 is involved in the airway lesion induced by MP antigen via mediating EGFR/NF-κB signaling activation and mucin expression in human airway epithelial cells.

Annexin A2 ; physiology ; Bronchi ; physiology ; Cells, Cultured ; Epithelial Cells ; microbiology ; Humans ; Mucins ; analysis ; Mycoplasma pneumoniae ; pathogenicity ; NF-kappa B ; physiology ; Receptor, Epidermal Growth Factor ; physiology ; Signal Transduction ; physiology

BACKGROUNDChoroidal neovascularization (CNV) is a common cause of visual loss in the elderly patients with age-related macular degeneration and represents the growth of subretinal new vessels in the macular region. This study aimed to investigate the relationship between annexin A2 (ANXA2) and vascular endothelial growth factor (VEGF) in CNV.

METHODSIn a rat model of argon laser coagulation-induced CNV, the mRNA expressions of the annexins and VEGF protein expression in the retina were detected using fluorescent real-time polymerase chain reaction (PCR) and immunohistochemistry, respectively. The interactions between ANXA2 and VEGF in both a retinal pigment epithelial cell line RPE-J and the rat model of CNV were examined by means of RNA interference, real-time PCR, Western blotting, enzyme-linked immunosorbent assay (ELISA) and histopathological examinations.

RESULTSFundus fluorescein angiography (FFA) showed that argon laser coagulation of the retina induced stable CNV models in the rats. Two to three weeks after the coagulation, ANXA2 and VEGF expressions in the coagulated area in the retina and choroid increased to the peak level, while the other annexin members (ANXA4, ANXA5, ANXA7 and ANXA11) showed no obvious changes. In RPE-J cells and the CNV model, RNA interference of ANXA2 gene significantly lowered the VEGF protein and mRNA expressions, and application of an adenoviral vector containing ANXA2 gene markedly increased VEGF expressions in the rat model of CNV, but produced no significant effects on the expressions of the kinase insert domain-containing receptor (KDR) or the fms-like tyrosine kinase (Flt-1). The expression of KDR inhibited the increment in ANXA2 expression, but VEGF and Flt-1 did not directly affect ANXA2 expression.

CONCLUSIONBesides the role as a plasminogen and the receptor of tissue plasminogen activator, ANXA2, which is under regulation of KDR via a negative feedback mechanism, also participates in neovascularization by regulating VEGF expression through a positive feedback mechanism.

Animals ; Annexin A2 ; analysis ; genetics ; physiology ; Cells, Cultured ; Choroidal Neovascularization ; etiology ; metabolism ; Disease Models, Animal ; Immunohistochemistry ; Laser Coagulation ; Lasers, Gas ; RNA, Messenger ; analysis ; Rats ; Rats, Inbred BN ; Vascular Endothelial Growth Factor A ; analysis ; genetics ; physiology

AIMTo determine the cellular distribution of secretory phospholipase A(2) (sPLA(2)) in dependence on the acrosomal state and under the action of elastase released under inflammatory processes from leukocytes.

METHODSAcrosome reaction of spermatozoa was triggered by calcimycin. Human leukocyte elastase was used to simulate inflammatory conditions. To visualize the distribution of sPLA(2) and to determine the acrosomal state, immunofluorescence techniques and lectin binding combined with confocal laser scanning fluorescence microscopy and flow cytometry were used.

RESULTSAlthough sPLA(2) was detected at the acrosome and tail regions in intact spermatozoa, it disappeared from the head region after triggering the acrosome reaction. This release of sPLA(2) was associated with enhanced binding of annexin V-fluoroscein isothiocyanate (FITC) to spermatozoa surfaces, intercalation of ethidium-homodimer I, and binding of FITC-labelled concanavalin A at the acrosomal region. Spermatozoa from healthy subjects treated with elastase were characterized by release of sPLA(2), disturbance of acrosome structure, and loss of vitality.

CONCLUSIONThe ability of spermatozoa to release secretory phospholipase A(2) is related to the acrosomal state. Premature destabilization of the acrosome and loss of sPLA(2) can occur during silent inflammations in the male genital tract. The distribution pattern of sPLA(2) in intact spermatozoa might be an additional parameter for evaluating sperm quality.

Acrosome ; drug effects ; physiology ; Acrosome Reaction ; drug effects ; Annexin A5 ; metabolism ; Anti-Bacterial Agents ; pharmacology ; Calcimycin ; pharmacology ; Ethidium ; Flow Cytometry ; Fluorescent Dyes ; Humans ; In Vitro Techniques ; Male ; Microscopy, Confocal ; Pancreatic Elastase ; metabolism ; Phosphatidylserines ; metabolism ; Phospholipases A2, Secretory ; metabolism ; Semen ; cytology ; drug effects ; Spermatozoa ; drug effects ; enzymology

Animals ; Annexin A2 ; chemistry ; genetics ; metabolism ; physiology ; DNA Replication ; Endocytosis ; Exocytosis ; Humans ; Neoplasm Invasiveness ; Neoplasm Metastasis ; Neoplasms ; metabolism ; pathology ; Prognosis ; Tissue Plasminogen Activator ; metabolism ; physiology

The study was designed to investigate annexin II resulting in molecular pathological mechanism of the primary fibrinolysis and establish annexin II vector model for further research on disturbance of coagulation. A target gene was amplified from human umbilical vein endothelial cells (HUVEC) by RT-PCR. Annexin II gene fragment was purified and ligated with molecular biological recombinant technology. The recombinant of plasmid annexin II was transfected into HL-60 cells and its distribution in the cell and structure characteristics of annexin II protein were evaluated by multi-photon excitation laser scanning microscope. By means of flow cytometry (FCM) and Werstern blot technique, the protein expression was qualitatively and quantitatively analyzed. Transfected cells were treated in vitro with annexin II antisense oligonucleotide (AS) targeting to the start site of annexin II cDNA. The results showed that the recombinant pZeoSV2(+)/ANN II was constructed successfully and expressed in HL-60 cells. The protein expression was distributed on the surface of cell by fluorescence assay. After transfection for 48 hours, the cells occurred higher level of expression. The level of the plasmin was significantly enhanced in the present of annexin II. The FCM and Western blot analysis showed the annexin II expression was similar both in transiently and stably transfected in HL-60 cells. Annexin II antisense oligonucletide and McAb significantly inhibited the activity of plasminogen. It was concluded that annexin II plays an important role in the fibrinotysis. Annexin II vector was defined as a expression tool for further studying fibrinolysis and coagulopathy in malignant disease.
Annexin A2 ; genetics ; physiology ; Endothelium, Vascular ; chemistry ; cytology ; Fibrinolysis ; Genetic Vectors ; HL-60 Cells ; Humans ; Oligonucleotides, Antisense ; pharmacology ; Polymerase Chain Reaction ; Recombinant Proteins ; biosynthesis

In order to study the role of annexin II, a recombinant expression vector, pZeoSV2(+) ANN II, containing the annexin II cDNA, was developed. The 1.1-kb-length annexin II cDNA was inserted into a expression vector, PZeoSV(+) and transfected into HL-60 cells which had low baseline expression of Ann- II. pZeoSV(+) ANN II was analyzed by restriction mapping and the Ann- II sequence identified. The ability of the transfected cells, non-transfected and mock-transfected cells to stimulate t-PA-depend plasminogen activation was compared. The results showed that HL-60 with pZeoSV(+) ANN II transfection could significantly increase the plasminogen activation (8.9 +/- 1.2 U) in vitro with the difference being significant as compared with non-transfected (1.5 +/- 0.4 U) and mock-transfected cells (4.2 +/- 0.9 U), respectively. Antiannexin II oligonucleotides significantly inhibited the binding ability of t-PA and plasminogen to annexin II, and obviously reduced the plasminogen activation in vitro. The above findings showed human umbilical vein endothelial cells (HUVECs) treated with sense or missense oligonucleotides indicated no significant change in binding of t-PA and PLG. Treatment of HUVECs with antiannexin II oligonucleotides could significantly reduce the plasminogen activation by 2.4 +/- 0.3 U as compared with sense oligonucleotide group in binding of t-PA and PLG. These results, therefore, suggest that Ann- II can bind plasminogen and participate in the stimulation of t-PA-dependent activation of plasminogen, and that interference with Ann-II mRNA by antisense oligonucleotide may be a new strategy for the therapy of bleeding in patients with hyperfibrinolysis.
Annexin A2 ; genetics ; metabolism ; physiology ; DNA, Complementary ; genetics ; Endothelium, Vascular ; cytology ; HL-60 Cells ; pathology ; Humans ; Oligonucleotides, Antisense ; genetics ; metabolism ; Plasminogen ; metabolism ; RNA, Messenger ; genetics ; metabolism ; physiology ; Receptors, Cell Surface ; metabolism ; Recombinant Proteins ; genetics ; metabolism ; Tissue Plasminogen Activator ; metabolism ; Transfection ; Umbilical Veins ; cytology