Annexin II mediates the neutrophil elastase-stimulated exocytosis of mucin 5ac

Annexin A2 Expression in Aerogenous Metastasis of Pulmonary Invasive Mucinous Adenocarcinoma: A Case Report including Immunohistochemical Analysis

Aerogenous metastasis (AM) is a form of lung cancer that spreads in a unique fashion, but its mechanisms are still unclear. Annexin A2 (ANX A2), a membrane-binding protein, promotes cancer invasion and is involved in cell adhesion and polarity. The relationship between ANX A2 and cancers with poor stromal invasion capacity has not been studied. We immunohistochemically analyzed ANX A2 expression in AM observed in a patient with pulmonary invasive mucinous adenocarcinoma. In the primary site, ANX A2 immunopositivity on the cell-cell borders weakened as tumor cells projected and separated into alveolar spaces. In AM, tumor cell aggregates with ANX A2 immunopositivity near the surface and within the cytoplasm attached to alveolar epithelial cells, then engulfed them and formed a protrusion. As tumor cell aggregates adhered to the alveolar wall and formed a single layer, cytoplasmic ANX A2-positive products accumulated in the lateral sides of the tumor cells and exhibited distinct membranous positivity. These results indicated that ANX A2 near the tumor cell surface was related to alveolar wall attachment. Furthermore, the translocation of cytoplasmic ANX A2 to cell-cell borders changed cell morphology, adhesion, and polarity restoration.

Resolvin D1 Increases Mucin Secretion in Cultured Rat Conjunctival Goblet Cells via Multiple Signaling Pathways

Purpose

Goblet cells in the conjunctiva secrete mucin into the tear film protecting the ocular surface. The proresolution mediator resolvin D1 (RvD1) regulates mucin secretion to maintain homeostasis during physiological conditions and in addition, actively terminates inflammation. We determined the signaling mechanisms used by RvD1 in cultured rat conjunctival goblet cells to increase intracellular [Ca²⁺] ([Ca²⁺]_i) and induce glycoconjugate secretion.

Methods

Increase in [Ca²⁺]_i were measured using fura 2/AM and glycoconjugate secretion determined using an enzyme-linked lectin assay with the lectin Ulex Europaeus Agglutinin 1. Signaling pathways activated by RvD1 were studied after goblet cells were pretreated with signaling pathway inhibitors before stimulation with RvD1. The results were compared with results when goblet cells were stimulated with RvD1 alone and percent inhibition calculated.

Results

The increase in [Ca²⁺]_i stimulated by RvD1 was blocked by inhibitors to phospholipases (PL-) -D, -C, -A₂, protein kinase C (PKC), extracellular signal-regulated kinases (ERK)1/2 and Ca²⁺/calmodulin-dependent kinase (Ca²⁺/CamK). Glycoconjugate secretion was significantly inhibited by PLD, -C, -A₂, ERK1/2 and Ca²⁺/CamK, but not PKC.

Conclusions

We conclude that RvD1 increases glycoconjugate secretion from goblet cells via multiple signaling pathways including PLC, PLD, and PLA₂, as well as their signaling components ERK1/2 and Ca²⁺/CamK to preserve the mucous layer and maintain homeostasis by protecting the eye from desiccating stress, allergens, and pathogens.

Neutrophil elastase stimulates MUC5AC expression in human biliary epithelial cells: a possible pathway of PKC/Nox/ROS

INTRODUCTION

Bacterial infection and bile flow retardation form a vicious cycle which promotes stone formation and recurrence, and it seems that mucin overexpression plays an important role in this process. However, the mechanism of increased mucus secretion in the biliary tract by bacterial infection and its treatment remain unclear.

MATERIAL AND METHODS

Human biliary epithelial cells were induced by neutrophil elastase (NE), and H₂O₂ production in the cell supernatants was detected by a specific kit, and then cells were pretreated with a H₂O₂ inhibitor, and expression of MUC5AC was detected by real-time polymerase chain reaction (PCR), Western blot, and immunohistochemistry. Moreover, selective PKC and Nox inhibitors, apocynin and bisindolylmaleimide I, were used to pretreat cells and detect H₂O₂, MUC5AC mRNA and protein expression. Then, we pretreated cells with selective inhibitors or NE, and detected transforming growth factor α (TGF-α) using an ELISA kit.

RESULTS

H₂O₂ production increased in an NE dose-dependent manner (p < 0.001), and NE upregulated MUC5AC expression at both mRNA and protein levels, while DMTU, could reduce this high expression (p < 0.01 at mRNA level, p < 0.001 at grey analysis for western blot and p < 0.01 at mean density for immunohistochemical staining at protein level). Moreover, apocynin and bisindolylmaleimide I could reduce the H₂O₂ production stimulated by NE (p < 0.05), and reduce MUC5AC high expression (p < 0.01 at mRNA level, p < 0.001 at both grey analysis for western blot and mean density for immunohistochemical staining at protein level). In addition, NE induced TGF-α production, and any of the three selective inhibitors could reduce it (p < 0.05).

CONCLUSIONS

NE-induced reactive oxygen species participated in the upregulation of MUC5AC production. Moreover, protein kinase C and NADPH oxidase (Nox) regulate MUC5AC production in NE-challenged human biliary epithelial cells.

Annexin A2 autoantibodies in thrombosis and autoimmune diseases

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by arterial, venous or small-vessel thrombotic events, and recurrent miscarriages or fetal loss. APS diagnosis is based on the repeated detection of anti-phospholipid (PL) antibodies (Ab), typically associated with anti-β2 glycoprotein I (β2GPI)-Ab. Recent studies suggest that anti-β2GPI Ab activity involves a protein complex including β2GPI and annexin A2 (ANXA2). Anti-ANXA2 Ab recognizes this complex, and these Ab can effectively promote thrombosis by inhibiting plasmin generation, and by activating endothelial cells. Therefore, anti-ANXA2 Ab represent a new biomarker, which can be detected in up to 25% of APS patients. Moreover, anti-ANXA2 Ab have been detected, in thrombotic associated diseases including pre-eclampsia, in other autoimmune diseases, and in cancer.