Identification and functional characterization of annexin A2 in half-smooth tongue sole (Cynoglossus semilaevis)

Annexin A2 (AnxA2), belonging to the annexin family, plays a crucial role in immune responses. In this study, the cDNA of the AnxA2 gene was identified in half-smooth tongue sole, Cynoglossus semilaevis. The transcript of AnxA2 gene in C. semilaevis (CsAnxA2) showed broad tissue distribution, with the highest expression level observed in the gut. CsAnxA2 expression was significantly up-regulated in the intestine, spleen, and kidney tissues following exposure to Shewanella algae. Immunohistochemical staining revealed that CsAnxA2 was predominantly expressed in epithelial cells and significantly elevated after S. algae challenge. Subcellular localization showed that CsAnxA2 was primarily localized in the cytoplasmic compartment. Moreover, proinflammatory cytokines (IL-6, IL-8 and IL-1β) exhibited significant upregulation after CsAnxA2 was overexpressed in vivo. One hundred and fifty-eight CsAnxA2-interacting proteins were captured in the intestinal tissue, showing the top two normalized abundance observed for actin beta (ACTB) and protein S100-A10 (p11). Fifty-four high abundance CsAnxA2-interacting proteins (HIPs) were primary enriched in ten pathways, with the top three significantly enriched pathways being Salmonella infection, glycolysis/gluconeogenesis, and peroxisome proliferator-activated receptor (PPAR) signaling pathway. These results provide valuable information for further investigation into the functional mechanism of AnxA2 in C. semilaevis.

The extracellular matrix differentially directs myoblast motility and differentiation in distinct forms of muscular dystrophy: Dystrophic matrices alter myoblast motility

Extracellular matrix (ECM) pathologic remodeling underlies many disorders, including muscular dystrophy. Tissue decellularization removes cellular components while leaving behind ECM components. We generated "on-slide" decellularized tissue slices from genetically distinct dystrophic mouse models. The ECM of dystrophin- and sarcoglycan-deficient muscles had marked thrombospondin 4 deposition, while dysferlin-deficient muscle had excess decorin. Annexins A2 and A6 were present on all dystrophic decellularized ECMs, but annexin matrix deposition was excessive in dysferlin-deficient muscular dystrophy. Muscle-directed viral expression of annexin A6 resulted in annexin A6 in the ECM. C2C12 myoblasts seeded onto decellularized matrices displayed differential myoblast mobility and fusion. Dystrophin-deficient decellularized matrices inhibited myoblast mobility, while dysferlin-deficient decellularized matrices enhanced myoblast movement and differentiation. Myoblasts treated with recombinant annexin A6 increased mobility and fusion like that seen on dysferlin-deficient decellularized matrix and demonstrated upregulation of ECM and muscle cell differentiation genes. These findings demonstrate specific fibrotic signatures elicit effects on myoblast activity.

Annexin A2 combined with TTK accelerates esophageal cancer progression via the Akt/mTOR signaling pathway

Annexin A2 (ANXA2) is a widely reported oncogene. However, the mechanism of ANXA2 in esophageal cancer is not fully understood. In this study, we provided evidence that ANXA2 promotes the progression of esophageal squamous cell carcinoma (ESCC) through the downstream target threonine tyrosine kinase (TTK). These results are consistent with the up-regulation of ANXA2 and TTK in ESCC. In vitro experiments by knockdown and overexpression of ANXA2 revealed that ANXA2 promotes the progression of ESCC by enhancing cancer cell proliferation, migration, and invasion. Subsequently, animal models also confirmed the role of ANXA2 in promoting the proliferation and metastasis of ESCC. Mechanistically, the ANXA2/TTK complex activates the Akt/mTOR signaling pathway and accelerates epithelial-mesenchymal transition (EMT), thereby promoting the invasion and metastasis of ESCC. Furthermore, we identified that TTK overexpression can reverse the inhibition of ESCC invasion after ANXA2 knockdown. Overall, these data indicate that the combination of ANXA2 and TTK regulates the activation of the Akt/mTOR pathway and accelerates the progression of ESCC. Therefore, the ANXA2/TTK/Akt/mTOR axis is a potential therapeutic target for ESCC.

Modulation of prostaglandin transport activity of SLCO2A1 by annexin A2 and S100A10

Solute carrier organic anion transporter family member 2A1 (SLCO2A1) is a prostaglandin (PG) transporter and serves as the osmosensitive ATP-permeable maxi-anion channel (Maxi-Cl). Since a heterotetrameric complex of annexin A2 (ANXA2) and S100A10 is obligatory for the channel activity, the present study aimed to determine if they regulate SLCO2A1-mediated PG transport. This study examined PGE2 uptake and ATP release in Anxa2 and/or S100a10 knockout (KO) murine breast C127 cells. Deletion of Slco2a1 decreased PGE2-d4 uptake by wild-type (WT) cells in an isotonic medium (290 mosmol/kgH2O). Decreased osmolarity (135 mosmol/kgH2O) stimulated ATP release but did not affect PGE2 uptake kinetics, showing Km (1,280 nM) and Vmax (10.38 pmol/15 s/mg protein) similar to those in isotonic medium (1,227 nM and 10.65 pmol/15 s/mg protein), respectively, in WT cells. Deletion of Anxa2 associated with loss of S100a10 diminished SLCO2A1-mediated ATP release and uncompetitively inhibited PGE2 uptake with lowered Km (376 nM) and Vmax (2.59 pmol/15 s/mg protein). Moreover, the immunoprecipitation assay confirmed the physical interaction of ANXA2 with SLCO2A1 in WT cells. Enforcement of ANXA2 expression to Anxa2 KO cells partially restored PGE2 uptake and increased Km (744.3 nM) and Vmax (9.07 pmol/15 s/mg protein), whereas the uptake clearance (Vmax/Km) did not change much regardless of ANXA2 expression. These results suggest that an ANXA2/S100A10 complex modulates PG transport activity but osmolality has little effect on it; therefore, the bound form of SLCO2A1, which functions as a PG transporter and Maxi-Cl, may exist regardless of changes in the cell volume.NEW & NOTEWORTHY A previous study indicated that the ANXA2/S100A10 complex represents the regulatory component of SLCO2A1-mediated Maxi-Cl channel activity. The present study showed that apparent PGE2 uptake by C127 cells was osmoinsensitive and uncompetitively inhibited by loss of ANXA2 expression, demonstrating that ANXA2 is a regulatory factor of SLCO2A1-mediated PG transport activity.

Nuclear autoantigenic sperm protein facilitates glioblastoma progression and radioresistance by regulating the ANXA2/STAT3 axis

AIMS

Although radiotherapy is a core treatment modality for various human cancers, including glioblastoma multiforme (GBM), its clinical effects are often limited by radioresistance. The specific molecular mechanisms underlying radioresistance are largely unknown, and the reduction of radioresistance is an unresolved challenge in GBM research.

METHODS

We analyzed and verified the expression of nuclear autoantigenic sperm protein (NASP) in gliomas and its relationship with patient prognosis. We also explored the function of NASP in GBM cell lines. We performed further mechanistic experiments to investigate the mechanisms by which NASP facilitates GBM progression and radioresistance. An intracranial mouse model was used to verify the effectiveness of combination therapy.

RESULTS

NASP was highly expressed in gliomas, and its expression was negatively correlated with the prognosis of glioma. Functionally, NASP facilitated GBM cell proliferation, migration, invasion, and radioresistance. Mechanistically, NASP interacted directly with annexin A2 (ANXA2) and promoted its nuclear localization, which may have been mediated by phospho-annexin A2 (Tyr23). The NASP/ANXA2 axis was involved in DNA damage repair after radiotherapy, which explains the radioresistance of GBM cells that highly express NASP. NASP overexpression significantly activated the signal transducer and activator of transcription 3 (STAT3) signaling pathway. The combination of WP1066 (a STAT3 pathway inhibitor) and radiotherapy significantly inhibited GBM growth in vitro and in vivo.

CONCLUSION

Our findings indicate that NASP may serve as a potential biomarker of GBM radioresistance and has important implications for improving clinical radiotherapy.

ANXA2 (annexin A2) is crucial to ATG7-mediated autophagy, leading to tumor aggressiveness in triple-negative breast cancer cells

Triple-negative breast cancer (TNBC) is associated with a poor prognosis and metastatic growth. TNBC cells frequently undergo macroautophagy/autophagy, contributing to tumor progression and chemotherapeutic resistance. ANXA2 (annexin A2), a potential therapeutic target for TNBC, has been reported to stimulate autophagy. In this study, we investigated the role of ANXA2 in autophagic processes in TNBC cells. TNBC patients exhibited high levels of ANXA2, which correlated with poor outcomes. ANXA2 increased LC3B-II levels following bafilomycin A1 treatment and enhanced autophagic flux in TNBC cells. Notably, ANXA2 upregulated the phosphorylation of HSF1 (heat shock transcription factor 1), resulting in the transcriptional activation of ATG7 (autophagy related 7). The mechanistic target of rapamycin kinase complex 2 (MTORC2) played an important role in ANXA2-mediated ATG7 transcription by HSF1. MTORC2 did not affect the mRNA level of ANXA2, but it was involved in the protein stability of ANXA2. HSPA (heat shock protein family A (Hsp70)) was a potential interacting protein with ANXA2, which may protect ANXA2 from lysosomal proteolysis. ANXA2 knockdown significantly increased sensitivity to doxorubicin, the first-line chemotherapeutic regimen for TNBC treatment, suggesting that the inhibition of autophagy by ANXA2 knockdown may overcome doxorubicin resistance. In a TNBC xenograft mouse model, we demonstrated that ANXA2 knockdown combined with doxorubicin administration significantly inhibited tumor growth compared to doxorubicin treatment alone, offering a promising avenue to enhance the effectiveness of chemotherapy. In summary, our study elucidated the molecular mechanism by which ANXA2 modulates autophagy, suggesting a potential therapeutic approach for TNBC treatment.Abbreviation: ATG: autophagy related; ChIP: chromatin-immunoprecipitation; HBSS: Hanks' balanced salt solution; HSF1: heat shock transcription factor 1; MTOR: mechanistic target of rapamycin kinase; TNBC: triple-negative breast cancer; TFEB: transcription factor EB; TFE3: transcription factor binding to IGHM enhancer 3.

LncNFYB promotes the proliferation of rheumatoid arthritis fibroblast-like synoviocytes via LncNFYB/ANXA2/ERK1/2 axis

Long noncoding RNAs (lncRNAs) are specifically expressed in different diseases and regulate disease progression. To explore the functions of rheumatoid arthritis (RA)-specific lncRNA, we determined the lncRNA expression profile of fibroblast-like synoviocytes (FLS) obtained from patients with RA and osteoarthritis (OA) using a LncRNA microarray and identified up-regulated LncNFYB in RA as a potential therapeutic target. Using gain- and loss-of-function studies, LncNFYB was proven to promote FLS proliferation and cell cycle progress but not affect their invasion, migration, and apoptotic abilities. Further investigation discovered that LncRNA could combine with annexin A2 (ANXA2) and enhance the level of phospho-ANXA2 (Tyr24) in the plasma membrane area, which induced the activation of ERK1/2 to promote proliferation. These findings provide new insights into the biological functions of LncNFYB on modification of FLS, which may be exploited for the therapy of RA.

Hsa_circ_0013561 promotes epithelial-mesenchymal transition and tumor progression by regulating ANXA2 via miR-23b-3p in ovarian cancer

Our preliminary experiment discovered that hsa_circ_0013561 was aberrantly expressed in OC. However, the underlying mechanism is unclear. The expression of hsa_circ_0013561 in OC cells and tissues was detected by RT-qPCR and fluorescence in situ hybridization. The effects of hsa_circ_0013561 on the proliferation and metastasis of OC were explored by functional experiments such as cell counting kit-8, transwell, and tumor xenograft models. To mechanistically understand the regulatory role of hsa_circ_0013561, bioinformatics analysis, Western blot, luciferase reporter assay, and a series of rescue experiments were applied. We found that the hsa_circ_0013561 expression was elevated in OC cells and tissues, and was correlated with metastasis formation. Downregulation of hsa_circ_0013561 suppressed the proliferation and migration of OC cells both in vitro and in vivo. Regarding the interactions of hsa_circ_0013561, the luciferase reporter assay verified that miR-23b-3p and Annexin A2 (ANXA2) were its downstream targets. MiR-23b-3p inhibition or ANXA2 overexpression reversed OC cell proliferation, migration, and epithelial-mesenchymal transition (EMT) post-hsa_circ_0013561 silencing. Moreover, ANXA2 overexpression also reversed OC cell migration, proliferation, and EMT after miR-23b-3p upregulation. Our data suggest that hsa_circ_0013561 increases the expression of ANXA2 by regulating miR-23b-3p competitively, resulting in EMT and metastasis of OC. Thus, hsa_circ_0013561 may serve as a novel oncogenic biomarker for OC progression.

Machine learning identifies ferroptosis-related gene ANXA2 as potential diagnostic biomarkers for NAFLD

Introduction

Non-alcoholic fatty liver disease (NAFLD), a major cause of chronic liver disease, still lacks effective therapeutic targets today. Ferroptosis, a type of cell death characterized by lipid peroxidation, has been linked to NAFLD in certain preclinical trials, yet the exact molecular mechanism remains unclear. Thus, we analyzed the relationship between ferroptosis genes and NAFLD using high-throughput data.

Method

We utilized a total of 282 samples from five datasets, including two mouse ones, one human one, one single nucleus dataset and one single cell dataset from Gene Expression Omnibus (GEO), as the data basis of our study. To filter robust treatment targets, we employed four machine learning methods (LASSO, SVM, RF and Boruta). In addition, we used an unsupervised consensus clustering algorithm to establish a typing scheme for NAFLD based on the expression of ferroptosis related genes (FRGs). Our study is also the first to investigate the dynamics of FRGs throughout the disease process by time series analysis. Finally, we validated the relationship between core gene and ferroptosis by in vitro experiments on HepG2 cells.

Results

We discovered ANXA2 as a central focus in NAFLD and indicated its potential to boost ferroptosis in HepG2 cells. Additionally, based on the results obtained from time series analysis, ANXA2 was observed to significantly define the disease course of NAFLD. Our results demonstrate that implementing a ferroptosis-based staging method may hold promise for the diagnosis and treatment of NAFLD.

Conclusion

Our findings suggest that ANXA2 may be a useful biomarker for the diagnosis and characterization of NAFLD.

Inhibition of ANXA2 activity attenuates epileptic susceptibility and GluA1 phosphorylation

INTRODUCTION

Annexin A2 (ANXA2) participates in the pathology of a variety of diseases. Nevertheless, the impact of ANXA2 on epilepsy remains to be clarified.

AIMS

Hence, the study aimed at investigating the underlying role of ANXA2 in epilepsy through behavioral, electrophysiological, and pathological analyses.

RESULTS

It was found that ANXA2 was markedly upregulated in the cortical tissues of temporal lobe epilepsy patients (TLE), kainic acid (KA)-induced epilepsy mice, and in a seizure-like model in vitro. ANXA2 silencing in mice suppressed first seizure latency, number of seizures, and seizure duration in behavioral analysis. In addition, abnormal brain discharges were less frequent and shorter in the hippocampal local field potential (LFP) record. Furthermore, the results showed that the frequency of miniature excitatory postsynaptic currents was decreased in ANXA2 knockdown mice, indicating that the excitatory synaptic transmission is reduced. Co-immunoprecipitation (COIP) experiments demonstrated that ANXA2 interacted with the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) subunit GluA1. Moreover, ANXA2 knockdown decreased GluA1 expression on the cell surface and its phosphorylation onserine 831 and serine 845, related to the decreased phosphorylation levels mediated by protein kinases A and C (PKA and PKC).

CONCLUSIONS

This study covers a previously unknown and key function of ANXA2 in epilepsy. These findings indicate that ANXA2 can regulate excitatory synaptic activity mediated by AMPAR subunit GluA1 to improve seizure activity, which can provide novel insights for the treatment and prevention of epilepsy.

Accumulation of annexin A2 and S100A10 prevents apoptosis of apically delaminated, transformed epithelial cells

In various epithelial tissues, the epithelial monolayer acts as a barrier. To fulfill its function, the structural integrity of the epithelium is tightly controlled. When normal epithelial cells detach from the basal substratum and delaminate into the apical lumen, the apically extruded cells undergo apoptosis, which is termed anoikis. In contrast, transformed cells often become resistant to anoikis and able to survive and grow in the apical luminal space, leading to the formation of multilayered structures, which can be observed at the early stage of carcinogenesis. However, the underlying molecular mechanisms still remain elusive. In this study, we first demonstrate that S100A10 and ANXA2 (Annexin A2) accumulate in apically extruded, transformed cells in both various cell culture systems and murine epithelial tissues in vivo. ANXA2 acts upstream of S100A10 accumulation. Knockdown of ANXA2 promotes apoptosis of apically extruded RasV12-transformed cells and suppresses the formation of multilayered epithelia. In addition, the intracellular reactive oxygen species (ROS) are elevated in apically extruded RasV12 cells. Treatment with ROS scavenger Trolox reduces the occurrence of apoptosis of apically extruded ANXA2-knockdown RasV12 cells and restores the formation of multilayered epithelia. Furthermore, ROS-mediated p38MAPK activation is observed in apically delaminated RasV12 cells, and ANXA2 knockdown further enhances the p38MAPK activity. Moreover, the p38MAPK inhibitor promotes the formation of multilayered epithelia of ANXA2-knockdown RasV12 cells. These results indicate that accumulated ANXA2 diminishes the ROS-mediated p38MAPK activation in apically extruded transformed cells, thereby blocking the induction of apoptosis. Hence, ANXA2 can be a potential therapeutic target to prevent multilayered, precancerous lesions.

Plasminogen Receptors Promote Lipoprotein(a) Uptake by Enhancing Surface Binding and Facilitating Macropinocytosis

BACKGROUND

High levels of Lp(a) (lipoprotein(a)) are associated with multiple forms of cardiovascular disease. Lp(a) consists of an apoB100-containing particle attached to the plasminogen homologue apo(a). The pathways for Lp(a) clearance are not well understood. We previously discovered that the plasminogen receptor PlgRKT (plasminogen receptor with a C-terminal lysine) promoted Lp(a) uptake in liver cells. Here, we aimed to further define the role of PlgRKT and to investigate the role of 2 other plasminogen receptors, annexin A2 and S100A10 (S100 calcium-binding protein A10) in the endocytosis of Lp(a).

METHODS

Human hepatocellular carcinoma (HepG2) cells and haploid human fibroblast-like (HAP1) cells were used for overexpression and knockout of plasminogen receptors. The uptake of Lp(a), LDL (low-density lipoprotein), apo(a), and endocytic cargos was visualized and quantified by confocal microscopy and Western blotting.

RESULTS

The uptake of both Lp(a) and apo(a), but not LDL, was significantly increased in HepG2 and HAP1 cells overexpressing PlgRKT, annexin A2, or S100A10. Conversely, Lp(a) and apo(a), but not LDL, uptake was significantly reduced in HAP1 cells in which PlgRKT and S100A10 were knocked out. Surface binding studies in HepG2 cells showed that overexpression of PlgRKT, but not annexin A2 or S100A10, increased Lp(a) and apo(a) plasma membrane binding. Annexin A2 and S100A10, on the other hand, appeared to regulate macropinocytosis with both proteins significantly increasing the uptake of the macropinocytosis marker dextran when overexpressed in HepG2 and HAP1 cells and knockout of S100A10 significantly reducing dextran uptake. Bringing these observations together, we tested the effect of a PI3K (phosphoinositide-3-kinase) inhibitor, known to inhibit macropinocytosis, on Lp(a) uptake. Results showed a concentration-dependent reduction confirming that Lp(a) uptake was indeed mediated by macropinocytosis.

CONCLUSIONS

These findings uncover a novel pathway for Lp(a) endocytosis involving multiple plasminogen receptors that enhance surface binding and stimulate macropinocytosis of Lp(a). Although the findings were produced in cell culture models that have limitations, they could have clinical relevance since drugs that inhibit macropinocytosis are in clinical use, that is, the PI3K inhibitors for cancer therapy and some antidepressant compounds.

ANNEXIN A2 FACILITATES NEOVASCULARIZATION TO PROTECT AGAINST MYOCARDIAL INFARCTION INJURY VIA INTERACTING WITH MACROPHAGE YAP AND ENDOTHELIAL INTEGRIN Β3

ABSTRACT

Cardiac macrophages with different polarization phenotypes regulate ventricular remodeling and neovascularization after myocardial infarction (MI). Annexin A2 (ANXA2) promotes macrophage polarization to the repair phenotype and regulates neovascularization. However, whether ANXA2 plays any role in post-MI remodeling and its underlying mechanism remains obscure. In this study, we observed that expression levels of ANXA2 were dynamically altered in mouse hearts upon MI and peaked on the second day post-MI. Using adeno-associated virus vector-mediated overexpression or silencing of ANXA2 in the heart, we also found that elevation of ANXA2 in the infarcted myocardium significantly improved cardiac function, reduced cardiac fibrosis, and promoted peri-infarct angiogenesis, compared with controls. By contrast, reduction of cardiac ANXA2 exhibited opposite effects. Furthermore, using in vitro coculture system, we found that ANXA2-engineered macrophages promoted cardiac microvascular endothelial cell (CMEC) proliferation, migration, and neovascularization. Mechanistically, we identified that ANXA2 interacted with yes-associated protein (YAP) in macrophages and skewed them toward pro-angiogenic phenotype by inhibiting YAP activity. In addition, ANXA2 directly interacted with integrin β3 in CMECs and enhanced their growth, migration, and tubule formation. Our results indicate that increased expression of ANXA2 could confer protection against MI-induced injury by promoting neovascularization in the infarcted area, partly through the inhibition of YAP in macrophages and activation of integrin β3 in endothelial cells. Our study provides new therapeutic strategies for the treatment of MI injury.

Annexin A2 Stabilizes Oncogenic JAG1 Intracellular Domain by Inhibiting Proteasomal Degradation in Glioblastoma Cells

Glioblastoma (GBM) is the most lethal brain cancer, causing inevitable deaths of patients owing to frequent relapses of cancer stem cells (CSCs). The significance of the NOTCH signaling pathway in CSCs has been well recognized; however, there is no NOTCH-selective treatment applicable to patients with GBM. We recently reported that Jagged1 (JAG1), a NOTCH ligand, drives a NOTCH receptor-independent signaling pathway via JAG1 intracellular domain (JICD1) as a crucial signal that renders CSC properties. Therefore, mechanisms regulating the JICD1 signaling pathway should be elucidated to further develop a selective therapeutic regimen. Here, we identified annexin A2 (ANXA2) as an essential modulator to stabilize intrinsically disordered JICD1. The binding of ANXA2 to JICD1 prevents the proteasomal degradation of JICD1 by heat shock protein-70/90 and carboxy-terminus of Hsc70 interacting protein E3 ligase. Furthermore, JICD1-driven propagation and tumor aggressiveness were inhibited by ANXA2 knockdown. Taken together, our findings show that ANXA2 maintains the function of the NOTCH receptor-independent JICD1 signaling pathway by stabilizing JICD1, and the targeted suppression of JICD1-driven CSC properties can be achieved by blocking its interaction with ANXA2.

Upregulation of HDAC9 in hippocampal neurons mediates depression-like behaviours by inhibiting ANXA2 degradation

Major depressive disorder (MDD) is a pervasive and devastating mental disease. Broad spectrum histone deacetylase (HDAC) inhibitors are considered to have potential for the treatment of depressive phenotype in mice. However, due to its non-specific inhibition, it has extensive side effects and can not be used in clinical treatment of MDD. Therefore, finding specific HDAC subtypes that play a major role in the etiology of MDD is the key to develop corresponding specific inhibitors as antidepressants in the future. Copy number variation in HDAC9 gene is thought to be associated with the etiology of some psychiatric disorders. Herein, we found that HDAC9 was highly expressed in the hippocampus of chronic restraint stress (CRS) mouse model of depression. Upregulation of HDAC9 expression in hippocampal neurons of mice induced depression-like phenotypes, including anhedonia, helplessness, decreased dendritic spine density, and neuronal hypoexcitability. Moreover, knockdown or knockout of HDAC9 in hippocampal neurons alleviated depression-like phenotypes caused by chronic restraint stress (CRS) in WT mice. Importantly, using immunoprecipitation-mass spectrometry (IP-MS), we further found that Annexin A2 (ANXA2) was coupled to and deacetylated by HDAC9. This coupling resulted in the inhibition of ubiquitinated ANXA2 degradation and then mediates depression-like behavior. Overall, we discovered a previously unrecognized role for HDAC9 in hippocampal neurons in the pathogenesis of depression, indicating that inhibition of HDAC9 might be a promising clinical strategy for the treatment of depressive disorders.

FBXW10-S6K1 promotes ANXA2 polyubiquitination and KRAS activation to drive hepatocellular carcinoma development in males

The incidence rate of human hepatocellular carcinoma (HCC) is approximately three times higher in males than in females. A better understanding of the mechanisms underlying HCC development in males could lead to more effective therapies for HCC. Our previous study found that FBXW10 played a critical role in promoting HCC development in male mice and patients, but the mechanism remains unknown. Here, we found that FBXW10 promoted K63-linked ANXA2 polyubiquitination and activation in HCC tissues from males, and this process was required for S6K1-mediated phosphorylation. Activated ANXA2 further translocated from the cytoplasm to the cell membrane to bind KRAS and then activated the MEK/ERK pathway, leading to HCC proliferation and lung metastasis. Interfering with ANXA2 significantly blocked FBXW10-driven HCC growth and lung metastasis in vitro and in vivo. Notably, membrane ANXA2 was upregulated and positively correlated with FBXW10 expression in male HCC patients. These findings offer new insights into the regulation and function of FBXW10 signaling in HCC tumorigenesis and metastasis and suggest that the FBXW10-S6K1-ANXA2-KRAS-ERK axis may serve as a potential biomarker and therapeutic target in male HCC patients with high FBXW10 expression.

Cell Entry of Avian Reovirus Modulated by Cell-Surface Annexin A2 and Adhesion G Protein-Coupled Receptor Latrophilin-2 Triggers Src and p38 MAPK Signaling Enhancing Caveolin-1- and Dynamin 2-Dependent Endocytosis

The specifics of cell receptor-modulated avian reovirus (ARV) entry remain unknown. By using a viral overlay protein-binding assay (VOPBA) and an in-gel digestion coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS), we determined that cell-surface annexin A2 (AnxA2) and adhesion G protein-coupled receptor Latrophilin-2 (ADGRL2) modulate ARV entry. Direct interaction between the ARV σC protein and AnxA2 and ADGRL2 in Vero and DF-1 cells was demonstrated in situ by proximity ligation assays. By using short hairpin RNAs (shRNAs) to silence the endogenous AnxA2 and ADGRL2 genes, ARV entry could be efficiently blocked. A significant decrease in virus yields and the intracellular specific signal for σC protein was observed in Vero cells preincubated with the specific AnxA2 and ADGRL2 monoclonal antibodies, indicating that AnxA2 and ADGRL2 are involved in modulating ARV entry. Furthermore, we found that cells pretreated with the AnxA2/S100A10 heterotetramer (A2t) inhibitor A2ti-1 suppressed ARV-mediated activation of Src and p38 mitogen-activated protein kinase (MAPK), demonstrating that Src and p38 MAPK serve as downstream molecules of cell-surface AnxA2 signaling. Our results reveal that suppression of cell-surface AnxA2 with the A2ti-1 inhibitor increased Csk-Cbp interaction, suggesting that ARV entry suppresses Cbp-mediated relocation of Csk to the membrane, thereby activating Src. Furthermore, reciprocal coimmunoprecipitation assays revealed that σC can interact with signaling molecules, lipid raft, and vimentin. The current study provides novel insights into cell-surface AnxA2- and ADGRL2-modulated cell entry of ARV which triggers Src and p38 MAPK signaling to enhance caveolin-1-, dynamin 2-, and lipid raft-dependent endocytosis. IMPORTANCE By analyzing results from VOPBA and LC-MS/MS, we have determined that cell-surface AnxA2 and ADGRL2 modulate ARV entry. After ARV binding to receptors, Src and p38 MAPK signaling were triggered and, in turn, increased the phosphorylation of caveolin-1 (Tyr14) and upregulated dynamin 2 expression to facilitate caveolin-1-mediated and dynamin 2-dependent endocytosis. In this work, we demonstrated that ARV triggers Src activation by impeding Cbp-mediated relocation of Csk to the membrane in the early stages of the life cycle. This work provides better insight into cell-surface AnxA2 and ADGRL2, which upregulate Src and p38MAPK signaling pathways to enhance ARV entry and productive infection.

Selenomethionine promotes ANXA2 phosphorylation for proliferation and protein synthesis of myoblasts and skeletal muscle growth

Selenomethionine (Se-Met) has many beneficial effects on higher animals and human, and can regulate cellular physiology through distinct signaling pathways. However, the role and molecular mechanism of Se-Met in skeletal muscle growth remains unclear. In this study, we observed the effects of Se-Met on C2C12 myoblasts and skeletal muscle growth of mice, and explored the corresponding molecular mechanism. Se-Met affected proliferation and protein synthesis of C2C12 myoblasts in a hormesis type of relationship, and had an optimal stimulatory effect at 50 µM concentration. Se-Met also affected mTOR, ANXA2, and PKCα phosphorylation in the same manner. ANXA2 knockdown blocked the stimulation of Se-Met on cell proliferation and protein synthesis and inhibition of Se-Met on autophagy of C2C12 myoblasts. Western blotting analysis showed that PI3K inhibition blocked the stimulation of Se-Met on mTOR phosphorylation. ANXA2 knockdown further blocked the stimulation of Se-Met on PI3K and mTOR phosphorylation. Point mutation experiment showed that ANXA2 mediated the stimulation of Se-Met on the PI3K-mTOR signaling through phosphorylation at Ser26. PKCα interacted with ANXA2, and PKCα knockdown blocked the stimulation of Se-Met on ANXA2 phosphorylation at Ser26. Se-Met addition (7.5mg/kg diet, 4 weeks) increased mouse carcass weight, promoted gastrocnemius skeletal muscle growth and ANXA2 and mTOR phosphorylation in this tissue. Collectively, our findings reveal that Se-Met can promote proliferation and protein synthesis of myoblasts and skeletal muscle growth through ANXA2 phosphorylation.

Silencing circ_0000644 inhibits papillary thyroid cancer cell malignancy by combining with miR-671-5p to release the inhibition on ANXA2

BACKGROUND

Papillary thyroid cancer (PTC) is life-threatening due to its malignant progression. Considerable evidence demonstrates that circular RNA (circRNA) regulates PTC development. This study aims to explore the mechanism of circ_0000644 modulating PTC malignant progression.

METHODS

The RNA levels of circ_0000644, microRNA-671-5p (miR-671-5p) and annexin A2 (ANXA2) were detected by quantitative real-time polymerase chain reaction. Western blot was performed to check protein expression. Cell proliferation and cell apoptosis were investigated by 5-ethynyl-29-deoxyuridine and flow cytometry. Angiogenic capacity, migration and invasion were analyzed by tube formation assay and transwell assay. The interaction between miR-671-5p and circ_0000644 or ANXA2 was identified by dual-luciferase reporter assay. Xenograft mouse model assay was performed to analyze the effect of circ_0000644 on tumor formation in vivo.

RESULTS

Circ_0000644 and ANXA2 expression was significantly upregulated, while miR-671-5p was downregulated in PTC tissues and cells when compared with control groups. Circ_0000644 knockdown inhibited PTC cell proliferation, tube formation, migration, and invasion, but induced apoptosis in vitro. Moreover, circ_0000644 knockdown led to delayed tumorigenesis in vivo. In addition, circ_0000644 acted as a miR-671-5p sponge and mediated PTC cell tumor properties through miR-671-5p. ANXA2 was identified as a target gene of miR-671-5p, and its overexpression relieved miR-671-5p-induced effects in PTC cells. Furthermore, circ_0000644 depletion inhibited ANXA2 production by combining with miR-671-5p.

CONCLUSION

Circ_0000644 depletion repressed PTC cell tumor properties through the miR-671-5p/ANXA2 axis.

Annexin A2 modulates phospholipid membrane composition upstream of Arp2 to control angiogenic sprout initiation

The intersection of protein and lipid biology is of growing importance for understanding how cells address structural challenges during adhesion and migration. While protein complexes engaged with the cytoskeleton play a vital role, support from the phospholipid membrane is crucial for directing localization and assembly of key protein complexes. During angiogenesis, dramatic cellular remodeling is necessary for endothelial cells to shift from a stable monolayer to invasive structures. However, the molecular dynamics between lipids and proteins during endothelial invasion are not defined. Here, we utilized cell culture, immunofluorescence, and lipidomic analyses to identify a novel role for the membrane binding protein Annexin A2 (ANXA2) in modulating the composition of specific membrane lipids necessary for cortical F-actin organization and adherens junction stabilization. In the absence of ANXA2, there is disorganized cortical F-actin, reduced junctional Arp2, excess sprout initiation, and ultimately failed sprout maturation. Furthermore, we observed reduced filipin III labeling of membrane cholesterol in cells with reduced ANXA2, suggesting there is an alteration in phospholipid membrane dynamics. Lipidomic analyses revealed that 42 lipid species were altered with loss of ANXA2, including an accumulation of phosphatidylcholine (16:0_16:0). We found that supplementation of phosphatidylcholine (16:0_16:0) in wild-type endothelial cells mimicked the ANXA2 knock-down phenotype, indicating that ANXA2 regulated the phospholipid membrane upstream of Arp2 recruitment and organization of cortical F-actin. Altogether, these data indicate a novel role for ANXA2 in coordinating events at endothelial junctions needed to initiate sprouting and show that proper lipid modulation is a critical component of these events.

The cooperative folding of annexin A2 relies on a transient nonnative intermediate

Annexins (Anxs) are a family of highly homologous proteins that bind and aggregate lipid vesicles in the presence of calcium. All members of the family contain a variable N-terminus determining specific functions, followed by a conserved core region responsible for the general calcium-dependent lipid-binding property. The core structure consists of four homologous domains (DI-DIV), each consisting of a right-handed super-helix of five α-helices. We present data from a combination of site-directed mutagenesis, NMR, and circular dichroism showing that the G25-D34 region of the N-terminus as well as the contacts between residues D38A, R63A, and Q67A of AnxA2-DI are crucial for the autonomous folding and stability of DI of AnxA2. However, we also show that the folding of the full-length protein is very robust in that mutations and truncations that disrupted the folding of AnxA2-DI did not abolish the folding of full-length AnxA2, only lowering its thermal stability. This robustness of the folding of full-length AnxA2 is likely to be mediated by the existence of at least one transient nonnative intermediate as suggested by our kinetic data using stopped-flow fluorescence experiments. We also show that hydrophobic amino acids in AnxA2-DI involved in interfacial contacts with AnxA2-DIV are important for the cooperative folding and stability of the full-length protein. Mutating all of the V57E-V98R-G101Y residues in AnxA2-DI did not affect the folding of the domain, only its stability, but prevented the cooperative folding of the full-length protein. Our collective results favor a highly cooperative and robust folding process mediated by alternative intermediate steps. Since AnxA2 is a multifunctional protein involved in several steps of the progression of cell transformation, these data on structure and folding pathways are therefore crucial to designing anticancer drugs targeting AnxA2.

Annexin A2/TLR2/MYD88 pathway induces arginase 1 expression in tumor-associated neutrophils

Myeloid lineage cells suppress T cell viability through arginine depletion via arginase 1 (ARG1). Despite numerous studies exploring the mechanisms by which ARG1 perturbs lymphocyte function, the cellular populations responsible for its generation and release remain poorly understood. Here, we showed that neutrophil lineage cells and not monocytes or macrophages expressed ARG1 in human non-small cell lung cancer (NSCLC). Importantly, we showed that approximately 40% of tumor-associated neutrophils (TANs) actively transcribed ARG1 mRNA. To determine the mechanism by which ARG1 mRNA is induced in TANs, we utilized FPLC followed by MS/MS to screen tumor-derived factors capable of inducing ARG1 mRNA expression in neutrophils. These studies identified ANXA2 as the major driver of ARG1 mRNA expression in TANs. Mechanistically, ANXA2 signaled through the TLR2/MYD88 axis in neutrophils to induce ARG1 mRNA expression. The current study describes what we believe to be a novel mechanism by which ARG1 mRNA expression is regulated in neutrophils in cancer and highlights the central role that neutrophil lineage cells play in the suppression of tumor-infiltrating lymphocytes.

Annexin A2 Improves the Osteogenic Differentiation of Mesenchymal Stem Cells Exposed to High-Glucose Conditions through Lessening the Senescence

Osteoporosis is frequently found in chronic diabetic patients, and it results in an increased risk of bone fractures occurring. The underlying mechanism of osteoporosis in diabetic patients is still largely unknown. Annexin A2 (ANXA2), a family of calcium-binding proteins, has been reported to be involved in many biological process including bone remodeling. This study aimed to investigate the role of ANXA2 in mesenchymal stem cells (MSCs) during in vitro osteoinduction under high-glucose concentrations. Osteogenic gene expression, calcium deposition, and cellular senescence were determined. The high-glucose conditions reduced the osteogenic differentiation potential of the MSCs along with the lower expression of ANXA2. Moreover, the high-glucose conditions increased the cellular senescence of the MSCs as determined by senescence-associated β-galactosidase staining and the expression of p16, p21, and p53 genes. The addition of recombinant ANXA2 could recover the glucose-induced deterioration of the osteogenic differentiation of the MSCs and ameliorate the glucose-induced cellular senescence of the MSCs. A Western blot analysis revealed an increase in p53 and phosphorylated p53 (Ser 15), which was decreased by recombinant ANXA2 in MSC osteoblastic differentiation under high-glucose conditions. Our study suggested that the alteration of ANXA2 in high-glucose conditions may be one of the plausible factors in the deterioration of bones in diabetic patients by triggering cellular senescence.

Annexin A2 regulates Mycoplasma bovis adhesion and invasion to embryo bovine lung cells affecting molecular expression essential to inflammatory response

Mycoplasma bovis (M. bovis) is an important pathogen of the bovine respiratory disease complex, invading lower respiratory tracts and causing severe pneumonia. However, its molecular mechanism largely remains unknown. Host annexin A2 (ANXA2) is a calcium-dependent phospholipid-binding protein. The current study sought to determine whether ANXA2 could mediate M. bovis adhesion and invasion thereby affecting its induction of inflammatory response. ANXA2 expression was upregulated in M. bovis-infected bovine lung epithelial cells (EBL), and blocking ANXA2 with an anti-ANXA2 antibody reduced M. bovis adhesion to EBL. Compared with uninfected cells, more ANXA2 was translocated from the cytoplasm to the cell surface after M. bovis infection. Furthermore, RNA interference knockdown of ANXA2 expression in EBL cells resulted in a significant decrease in M. bovis invasion and F-actin polymerization. Next, the transcriptomic study of M. bovis-infected EBL cells with and without ANXA2 knockdown were performed. The data exhibited that ANXA2 knockdown EBL cells had 2487 differentially expressed genes (DEGs), with 1175 upregulated and 1312 downregulated compared to control. According to GO and KEGG analyses, 50 genes potentially linked to inflammatory responses, 23 involved in extracellular matrix (ECM) receptor interaction, and 48 associated with PI3K-AKT signal pathways were upregulated, while 38 mRNA binding genes, 16 mRNA 3′-UTR binding genes, and 34 RNA transport genes were downregulated. Furthermore, 19 genes with various change-folds were selected for qPCR verification, and the results agreed with the RNA-seq findings. Above all, the transcription of two chemokines (IL-8 and CXCL5) and a key bovine β-defensin TAP in IL-17 signaling pathway were significantly increased in ANXA2 knockdown cells. Moreover, ANXA2 knockdown or knockout could increase NF-κB and MAPK phosphorylation activity in response to M. bovis infection. Additionally, ANXA2 knockdown also significantly decreased the CD44 transcripts via exon V3 and V7 skipping after M. bovis infection. We concluded that M. bovis borrowed host ANXA2 to mediate its adhesion and invasion thereby negatively regulating molecular expression essential to IL-17 signal pathway. Furthermore, CD44 V3 and V7 isoforms might contribute to this ANXA2 meditated processes in M. bovis infected EBL cells. These findings revealed a new understanding of pathogenesis for M. bovis infection.

The prognostic value of S100A calcium binding protein family members in predicting severe forms of COVID-19

Background

Excessive inflammation has been implicated in the immunopathogenesis of coronavirus disease 2019 (COVID-19). In the current study, the involvement of S100 calcium binding protein S100A4, S100A9, and S100A10 in the inflammatory settings of COVID-19 patients were evaluated.

Methods

Peripheral blood samples were obtained from 65 COVID-19 subjects and 50 healthy controls. From the blood samples, RNA was extracted and cDNA was synthesized, and then the mRNA expression levels of S100A4, S100A9, and S100A10 were measured by Real-time PCR.

Results

The mRNA expression of S100A4 (fold change [FC] = 1.45, P = 0.0011), S100A9 (FC = 1.47, P = 0.0013), and S100A10 (FC = 1.35, P = 0.0053) was significantly upregulated in COVID-19 patients than controls. The mRNA expression of S100A4 (FC = 1.43, P = 0.0071), (FC = 1.66, P = 0.0001), and S100A10 (FC = 1.63, P = 0.0003) was significantly upregulated in the severe COVID-19 subjects than mild-to-moderate subjects. There was a significant positive correlation between mRNA expression of S100A4 (ρ = 0.49, P = 0.030), S100A9 (ρ = 0.55, P = 0.009), and S100A10 (ρ = 0.39, P = 0.040) and d-dimer in the COVID-19 patients. The AUC for S100A4, S100A9, and S100A10 mRNAs were 0.79 (95% CI 0.66–0.92, P = 0.004), 0.80 (95% CI 0.67–0.93, P = 0.002), and 0.71 (95% CI 0.56–0.85, P = 0.010), respectively.

Conclusions

S100A4, S100A9, and S100A10 play a role in the inflammatory conditions in COVID-19 patients and have potential in prognosis of severe form of COVID-19. Targeting these modules, hopefully, might confer a therapeutic tool in preventing sever symptoms in the COVID-19 patients.

Annexin A2 acts as an adherent molecule under the regulation of steroids during embryo implantation

We previously showed that annexin A2 (Axna2) was transiently expressed at the embryo-uterine luminal epithelium interface during the window of implantation and was involved in mouse embryo implantation. At the same time, Axna2 was reported to be upregulated in human receptive endometrium, which was critical for embryo attachment as an intracellular molecule. Here, we identified Axna2 as a membrane-bound molecule on human endometrial epithelial cells and trophoblast cells, and the outer surface membrane-bound Axna2 was involved in human embryo attachment. In addition, physiological levels of estrogen and progesterone increased the expression of overall Axna2 as well as that in the extracellular surface membrane protein fraction in human endometrial cells. Furthermore, p11 (or S100A10, a member of the S100 EF-hand family protein, molecular weight 11 kDa) was involved in the translocation of Axna2 to the outer surface membrane of endometrial epithelial cells without affecting its overall expression. Finally, the surface relocation of Axna2 was also dependent on cell-cell contact and calcium binding. A better understanding of the function and regulation of Axna2 in human endometrium may help us to identify a potential therapeutic target for subfertile and infertile patients.

Regulation of S100A10 Gene Expression

S100A10, a member of the S100 family of Ca²⁺-binding proteins, is a widely distributed protein involved in many cellular and extracellular processes. The best recognized role of S100A10 is the regulation, via interaction with annexin A2, of plasminogen conversion to plasmin. Plasmin, together with other proteases, induces degradation of the extracellular matrix (ECM), which is an important step in tumor progression. Additionally, S100A10 interacts with 5-hydroxytryptamine 1B (5-HT1B) receptor, which influences neurotransmitter binding and, through that, depressive symptoms. Taking this into account, it is evident that S100A10 expression in the cell should be under strict control. In this work, we summarize available literature data concerning the physiological stimuli and transcription factors that influence S100A10 expression. We also present our original results showing for the first time regulation of S100A10 expression by grainyhead-like 2 transcription factor (GRHL2). By applying in silico analysis, we have found two highly conserved GRHL2 binding sites in the 1st intron of the gene encoding S100A10 protein. Using chromatin immunoprecipitation (ChIP) and luciferase assays, we have shown that GRHL2 directly binds to these sites and that this DNA region can affect transcription of S100A10.

Mesoglycan exerts its fibrinolytic effect through the activation of annexin A2

Mesoglycan is a drug based on a mixture of glycosaminoglycans mainly used for the treatment of blood vessel diseases acting as antithrombotic and profibrinolytic drugs. Besides the numerous clinical studies, there is no information about its function on the fibrinolytic cascade. Here, we have elucidated the mechanism of action by which mesoglycan induces the activation of plasmin from endothelial cells. Surprisingly, by a proteomic analysis, we found that, following mesoglycan treatment, these cells show a notable amount of annexin A2 (ANXA2) at the plasma membrane. This protein has been widely associated with fibrinolysis and appears able to move to the membrane when phosphorylated. In our model, this translocation has proven to enhance cell migration, invasion, and angiogenesis. Furthermore, the interaction of mesoglycan with syndecan 4 (SDC4), a coreceptor belonging to the class of heparan sulfate proteoglycans, represents the upstream event of the ANXA2 behavior. Indeed, the activation of SDC4 triggers the motility of endothelial cells culminating in angiogenesis. Interestingly, mesoglycan can induce the release of plasmin in endothelial cell supernatants only in the presence of ANXA2. This evaluation suggests that mesoglycan triggers the formation of a chain mechanism starting from the activation of SDC4, and the related cascade of events, including src complex and PKCα activation, promoting the phosphorylation of ANXA2 and its translocation to plasma membrane. This indicates a connection among mesoglycan, SDC4-(PKCα-src), and ANXA2 which, in turn, links the tissue plasminogen activator bringing it closer to plasminogen. This latter is so cleaved to release the plasmin and degrade fibrin sleeves.

Annexin A2 in Fibrinolysis, Inflammation and Fibrosis

As a cell surface tissue plasminogen activator (tPA)-plasminogen receptor, the annexin A2 (A2) complex facilitates plasmin generation on the endothelial cell surface, and is an established regulator of hemostasis. Whereas A2 is overexpressed in hemorrhagic disease such as acute promyelocytic leukemia, its underexpression or impairment may result in thrombosis, as in antiphospholipid syndrome, venous thromboembolism, or atherosclerosis. Within immune response cells, A2 orchestrates membrane repair, vesicle fusion, and cytoskeletal organization, thus playing a critical role in inflammatory response and tissue injury. Dysregulation of A2 is evident in multiple human disorders, and may contribute to the pathogenesis of various inflammatory disorders. The fibrinolytic system, moreover, is central to wound healing through its ability to remodel the provisional matrix and promote angiogenesis. A2 dysfunction may also promote tissue fibrogenesis and end-organ fibrosis.

Characterization of Extracellular Vesicle Cargo in Sjögren's Syndrome through a SWATH-MS Proteomics Approach

Primary Sjögren’s syndrome (pSS) is a complex heterogeneous disease characterized by a wide spectrum of glandular and extra-glandular manifestations. In this pilot study, a SWATH-MS approach was used to monitor extracellular vesicles-enriched saliva (EVs) sub-proteome in pSS patients, to compare it with whole saliva (WS) proteome, and assess differential expressed proteins between pSS and healthy control EVs samples. Comparison between EVs and WS led to the characterization of compartment-specific proteins with a moderate degree of overlap. A total of 290 proteins were identified and quantified in EVs from healthy and pSS patients. Among those, 121 proteins were found to be differentially expressed in pSS, 82% were found to be upregulated, and 18% downregulated in pSS samples. The most representative functional pathways associated to the protein networks were related to immune-innate response, including several members of S100 protein family, annexin A2, resistin, serpin peptidase inhibitors, azurocidin, and CD14 monocyte differentiation antigen. Our results highlight the usefulness of EVs for the discovery of novel salivary-omic biomarkers and open novel perspectives in pSS for the identification of proteins of clinical relevance that could be used not only for the disease diagnosis but also to improve patients’ stratification and treatment-monitoring. Data are available via ProteomeXchange with identifier PXD025649.

LINC01133 promotes hepatocellular carcinoma progression by sponging miR-199a-5p and activating annexin A2

BACKGROUND

Long noncoding RNAs (lncRNAs) are functionally associated with cancer development and progression. Although gene copy number variation (CNV) is common in hepatocellular carcinoma (HCC), it is not known how CNV in lncRNAs affects HCC progression and recurrence. We aimed to identify a CNV-related lncRNA involved in HCC progression and recurrence and illustrate its underlying mechanisms and prognostic value.

METHODS

We analyzed the whole genome sequencing (WGS) data of matched cancerous and noncancerous liver samples from 49 patients with HCC to identify lncRNAs with CNV. The results were validated in another cohort of 238 paired HCC and nontumor samples by TaqMan copy number assay. We preformed Kaplan-Meier analysis and log-rank test to identify lncRNA CNV with prognostic value. We conducted loss- and gain-of-function studies to explore the biological functions of LINC01133 in vitro and in vivo. The competing endogenous RNAs (ceRNAs) mechanism was clarified by microRNA sequencing (miR-seq), quantitative real-time PCR (qRT-PCR), western blot, and dual-luciferase reporter assays. We confirmed the binding mechanism between lncRNA and protein by RNA pull-down, RNA immunoprecipitation, qRT-PCR, and western blot analyses.

RESULTS

Genomic copy numbers of LINC01133 were increased in HCC, which were positively related with the elevated expression of LINC01133. Increased copy number of LINC01133 predicted the poor prognosis in HCC patients. LINC01133 overexpression in HCC cells promoted proliferation and aggressive phenotypes in vitro, and facilitated tumor growth and lung metastasis in vivo, whereas LINC01133 knockdown had the opposite effects. LINC01133 sponged miR-199a-5p, resulting in enhanced expression of SNAI1, which induced epithelial-to-mesenchymal transition (EMT) in HCC cells. In addition, LINC01133 interacted with Annexin A2 (ANXA2) to activate the ANXA2/STAT3 signaling pathway.

CONCLUSIONS

LINC01133 promotes HCC progression by sponging miR-199a-5p and interacting with ANXA2. LINC01133 CNV gain is predictive of poor prognosis in patients with HCC.

Reduced expression of annexin A2 is associated with impaired cell surface fibrinolysis and venous thromboembolism

Reduced plasma fibrinolysis has been identified as a potential risk factor for venous thromboembolism (VTE), but the role of cell surface fibrinolysis in VTE is unknown. The annexin A2/S100A10 complex serves as a coreceptor for plasminogen and tissue plasminogen activator (tPA), augmenting plasmin generation by 60-fold on the endothelial cell surface. Several studies in both mice and humans support the concept that A2 regulates fibrin homeostasis and intravascular thrombosis in vivo. Here, we examined A2 protein expression and function in 115 adult subjects with VTE and 87 healthy controls. Using peripheral blood mononuclear cells as a surrogate for endothelial cells, we found a 41% mean decrease in cell surface tPA-dependent fibrinolytic activity in subjects who had a positive personal and family history of VTE but tested negative for known inherited thrombophilias (ITs). A2 protein was reduced on average by 70% and messenger RNA levels by 30%, but neither decrease correlated with anticoagulant therapy. Neither cell A2 protein nor cell surface plasmin generation correlated with plasma-based clot lysis times, suggesting that the plasma and cell surface fibrinolytic systems operate independently of one another. These data suggest that reduced expression of annexin A2 protein is associated with cell surface hypofibrinolysis and may represent a novel risk factor for IT.

Proteomic screening identifies the direct targets of chrysin anti-lipid depot in adipocytes

ETHNOPHARMACOLOGICAL RELEVANCE

Overweight/obesity was mentioned by many countries as an obstacle to good health and long life, which increases risk of diseases and disorders. Previous studies suggested that the chronic low-grade inflammation present in the body was considered as the essential pathogenesis for obesity. Chrysin is extracted from traditional Chinese medicine Oroxylum indicum (Linn.) Kurz and plays a superior anti-obesity role. Chrysin could reduce the lipid depot by inhibiting the obesity-related inflammation in adipose tissue. However, the target protein for chrysin to exert its anti-obesity role are not verified.

AIM OF STUDY

The present study aimed to screen and validate the target protein for chrysin to reduce the lipid depot in palmitic acid-induced 3T3-L1 adipocytes.

MATERIALS AND METHODS

Obesity model was established employing 0.5 mmol/L palmitic acid-induced 3T3-L1 adipocytes through "Cocktails" method. Two-dimensional gel electrophoresis (2-DE) combined with liquid chromatography-mass spectrometry (LC-MS) was applied to analyze the differentially expressed proteins for chrysin intervention by lipid formation in adipocytes. Gene silencing was utilized to decrease gene expression of the candidate proteins, then production of triglyceride in 3T3-L1 was detected by triglycerides assay to determine the target proteins. Ultraviolet (UV) absorption together with fluorescence spectra validated the direct target proteins of chrysin. They also computed the correlation constants of combination between chrysin and the target proteins. Molecular docking was further employed to identify the main binding amino acids between chrysin and the target protein.

RESULTS

2-DE combined with LC-MS screened four candidate proteins which were related to metabolism and inflammation. The production of triglycerides in 3T3-L1 was reduced after decreasing gene expression of Annexin A2 (ANXA2), 60 kDa heat shock protein (HSP-60) and succinyl-CoA:3-ketoacid coenzyme A transferase 1 (SCOT-S), respectively. UV spectrum showed that the absorbance spectra of ANXA2 from 260 to 300 nm shifted upwards along with the increase in chrysin concentration, meanwhile the absorbance spectra of HSP-60 from 200 to 220 nm and from 265 to 280 nm shifted slightly upwards along with the increase in chrysin concentrations. The results indicated the conjugated structures between chrysin and ANXA2 or HSP-60. Fluorescence quenching further suggested a spontaneous interaction between chrysin and ANXA2 or HSP-60. Finally, molecular docking identified the main binding amino acids between ANXA2 and chrysin were Ser22, Tyr24, Pro267, Val298, Asp299, and Lys302.

CONCLUSIONS

Chrysin can reduce the amount of triglycerides by directly downregulating the inflammation-related target proteins ANXA2 and HSP-60, exerting an anti-obesity role.

Early Enriched Environment Prevents Epigenetic p11 Gene Changes Induced by Adulthood Stress in Mice

Positive experiences in early life may improve the capacity to cope with adulthood stress through epigenetic modification. We investigated whether an enriched environment (EE) in the postnatal period affected epigenetic changes in the p11 gene induced by chronic unpredictable stress (CUS) in adult C57BL/6J mice. EE was introduced for 5 weeks during postnatal days 21–55. After EE, the mice were subjected to CUS for 4 weeks. EE prevented depression-like behavior induced by adult CUS. EE prevented a decrease in p11 mRNA and histone H3 acetylation induced by CUS, with changes in the expression of histone deacetylase 5. Moreover, EE prevented changes in trimethylation of histone H3 lysine 4 (H3K4) and H3K27 induced by CUS. Furthermore, EE had positive effects on behavior and epigenetic alterations in adult mice without CUS. These results suggest that one of the underlying mechanisms of early-life EE may involve epigenetic modification of the hippocampal p11 gene promoter.

Altered Serum Annexin A2 Might Be a New Potential Diagnostic Biomarker in Human Colorectal Cancer

OBJECTIVE

Annexin A2 is a calcium dependent phospholipid binding protein that is a biomarker in cancers. However, the value of serum Annexin A2 in the diagnosis of colorectal cancer (CRC) is not clear. This study aimed to investigate clinical utility of serum Annexin A2 as a potential biomarker for CRC.

METHODS

Annexin A2 was analyzed in 20 cases of CRC tissues and 20 controls of normal adjacent paired tissues. Serum Annexin A2 was calculated in 59 CRC patients and 44 healthy subjects. Receiver operating characteristic (ROC) curve and logistic regression were utilized to evaluate the diagnostic effectiveness and construct diagnostic model.

RESULTS

Annexin A2 in CRC tissues was slightly higher than in normal adjacent paired tissues (χ2=6.0652, p<0.05). Serum Annexin A2 in CRC patients was significantly lower than in healthy controls (p<0.05). Besides, the levels of serum Annexin A2 were lower in patients with poor tumor differentiation than in well or moderate tumor differentiation (p=0.0111). ROC analysis indicated the diagnostic efficacy of serum Annexin A2 was better than carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA199) for CRC. Furthermore, joint detection of Annexin A2 and CEA had the maximum area under the ROC curve (AUC) in discriminating CRC from healthy controls (AUC 0.931, sensitivity 86.4%, specificity 84.7%, positive predictive value 87.9%, and negative predictive value 82.2%).

CONCLUSIONS

Serum Annexin A2 may be a non-invasive and promising biomarker for the diagnosis of CRC, and the joint detection of Annexin A2 and CEA may have been favorable clinical applied value in the diagnosis of CRC.

FOXQ1 promotes the osteogenic differentiation of bone mesenchymal stem cells via Wnt/β-catenin signaling by binding with ANXA2

BACKGROUND

This study investigated the role of Forkhead box Q1 (FOXQ1) in the osteogenic differentiation of bone mesenchymal stem cells.

METHODS

Mouse bone mesenchymal stem cells (mBMSCs) were transfected with lentivirus to generate Foxq1-overexpressing mBMSCs, Foxq1-suppressed mBMSCs, and mBMSC controls. The activity of osteogenic differentiation was evaluated with alizarin red staining, alkaline phosphatase activity assay, and RT-qPCR. Wnt/β-catenin signaling activities were compared among groups by TOPFlash/FOPFlash assay, immunofluorescence staining, and western blot assay of beta-catenin (CTNNB1). Coimmunoprecipitation mass spectrometry was also carried out to identify proteins binding with FOXQ1.

RESULTS

Our data showed that FOXQ1 expression was positively correlated with the osteogenic differentiation of the mBMSCs. FOXQ1 also promoted the nuclear translocation of CTNNB1 in the mBMSCs, enhancing Wnt/β-catenin signaling, which was also shown to be essential for the osteogenic differentiation-promoting effect of FOXQ1 in the mBMSCs. Annexin A2 (ANXA2) was bound with FOXQ1, and its depletion reversed the promoting effect of FOXQ1 on Wnt/β-catenin signaling.

CONCLUSION

These results showed that FOXQ1 binds with ANXA2, promoting Wnt/β-catenin signaling in bone mesenchymal stem cells, which subsequently promotes osteogenic differentiation.

Important role of annexin A2 (ANXA2) in new blood vessel development in vivo and human triple negative breast cancer (TNBC) growth

Development of new blood vessels in the tumor microenvironment is an essential component of tumor progression during which newly formed blood vessels nourish tumor cells and play a critical role in rapid tumor growth, invasion and metastasis. Nevertheless, how tumor cells develop new blood vessels in the tumor microenvironment (TME) have been enigmatic. Previously, we have shown specific overexpression of ANX A2 in TNBC cells regulates plasmin generation and suspected a role in neoangiogenesis. In this report, we used Matrigel plug model of in vivo angiogenesis and confirmed its role in new blood vessel development. Next, we tested if blocking of ANX A2 in aggressive human breast TME can inhibit angiogenesis and tumor growth in vivo. We showed that aggressive human breast tumor cells growing in nude mice can induce intense neoangiogenesis in the tumor mass. Blocking of ANXA2 significantly inhibited neoangiogenesis and resulted in inhibition of tumor growth. Interestingly, we identified that blocking of ANXA2 significantly inhibited tyrosine phosphorylation (Tyr-P) of ANXA2 implying its involvement in tyrosine signaling pathway and suggesting it may regulate angiogenesis. Taken together, our experimental evidence suggests that ANX A2 could be a novel strategy for disruption of tyrosine signaling and inhibition of neoangiogenesis in breast tumor.

Annexin A2 depletion exacerbates the intracerebral microhemorrhage induced by acute rickettsia and Ebola virus infections

Intracerebral microhemorrhages (CMHs) are small foci of hemorrhages in the cerebrum. Acute infections induced by some intracellular pathogens, including rickettsia, can result in CMHs. Annexin a2 (ANXA2) has been documented to play a functional role during intracellular bacterial adhesion. Here we report that ANXA2-knockout (KO) mice are more susceptible to CMHs in response to rickettsia and Ebola virus infections, suggesting an essential role of ANXA2 in protecting vascular integrity during these intracellular pathogen infections. Proteomic analysis via mass spectrometry of whole brain lysates and brain-derived endosomes from ANXA2-KO and wild-type (WT) mice post-infection with R. australis revealed that a variety of significant proteins were differentially expressed, and the follow-up function enrichment analysis had identified several relevant cell-cell junction functions. Immunohistology study confirmed that both infected WT and infected ANXA2-KO mice were subjected to adherens junctional protein (VE-cadherin) damages. However, key blood-brain barrier (BBB) components, tight junctional proteins ZO-1 and occludin, were disorganized in the brains from R. australis-infected ANXA2-KO mice, but not those of infected WT mice. Similar ANXA2-KO dependent CMHs and fragments of ZO-1 and occludin were also observed in Ebola virus-infected ANXA2-KO mice, but not found in infected WT mice. Overall, our study revealed a novel role of ANXA2 in the formation of CMHs during R. australis and Ebola virus infections; and the underlying mechanism is relevant to the role of ANXA2-regulated tight junctions and its role in stabilizing the BBB in these deadly infections.

Clinicopathological value and underlying molecular mechanism of annexin A2 in 992 cases of thyroid carcinoma

BACKGROUND

Thyroid carcinoma (THCA) is one of the most frequent endocrine cancers and has increasing morbidity. Annexin A2 (ANXA2) has been found to be highly expressed in various cancers; however, its expression level and potential mechanism in THCA remain unknown. This study investigated the clinicopathological value and primary molecular machinery of ANXA2 in THCA.

MATERIAL AND METHODS

Public RNA-sequencing and microarray data were obtained and analyzed with ANXA2 expression in THCA and corresponding non-cancerous thyroid tissue. A Pearson correlation coefficient calculation was used for the acquisition of ANXA2 coexpressed genes, while edgR, limma, and Robust Rank Aggregation were employed for differentially expressed gene (DEG) in THCA. The probable mechanism of ANXA2 in THCA was predicted by gene ontology and pathway enrichment. A dual-luciferase reporter assay was employed to confirm the targeting relationships between ANXA2 and its predicted microRNA (miRNA).

RESULTS

Expression of ANXA2 was significantly upregulated in THCA tissues with a summarized standardized mean difference of 1.09 (P < 0.0001) based on 992 THCA cases and 589 cases of normal thyroid tissue. Expression of ANXA2 was related to pathologic stage. Subsequently, 1442 genes were obtained when overlapping 4542 ANXA2 coexpressed genes with 2248 DEGs in THCA; these genes were mostly enriched in pathways of extracellular matrix-receptor interaction, cell adhesion molecules, and complement and coagulation cascades. MiR-23b-3p was confirmed to target ANXA2 by dual-luciferase reporter assay.

CONCLUSIONS

Upregulated expression of ANXA2 may promote the malignant biological behavior of THCA by affecting the involving pathways or being targeted by miR-23b-3p.

Axon Guidance Molecules Promote Perineural Invasion and Metastasis of Orthotopic Pancreatic Tumors in Mice

BACKGROUND & AIMS

Little is known about mechanisms of perineural invasion (PNI) by pancreatic ductal adenocarcinomas (PDAs) or other tumors. Annexin A2 (ANXA2) regulates secretion of SEMA3D, an axon guidance molecule, which binds and activates the receptor PLXND1 to promote PDA invasion and metastasis. We investigated whether axon guidance molecules promote PNI and metastasis by PDA cells in mice.

METHODS

We performed studies in a dorsal root ganglion (DRG) invasion system, wild-type C57BL/6 mice (controls), mice with peripheral sensory neuron-specific disruption of PlxnD1 (PLAC mice), LSL-KRASG12D/+;LSL-TP53R172H/+;PDX-1-CRE+/+ (KPC) mice, and KPC mice crossed with ANXA2-knockout mice (KPCA mice). PDA cells were isolated from KPC mice and DRG cells were isolated from control mice. Levels of SEMA3D or ANXA2 were knocked down in PDA cells with small hairpin and interfering RNAs and cells were analyzed by immunoblots in migration assays, with DRGs and with or without antibodies against PLXND1. PDA cells were injected into the pancreas of control and PLAC mice, growth of tumors was assessed, and tumor samples were analyzed by histology. DRG cells were incubated with SEMA3D and analyzed by live imaging. We measured levels of SEMA3D and PLXND1 in PDA specimens from patients with PNI and calculated distances between tumor cells and nerves.

RESULTS

DRG cells increase the migration of PDC cells in invasion assays; knockdown of SEMA3D in PDA cells or antibody blockade of PLXND1 on DRG cells reduced this invasive activity. In mice, orthotopic tumors grown from PDA cells with knockdown of SEMA3D, and in PLAC mice, orthotopic tumors grown from PDA cells, had reduced innervation and formed fewer metastases than orthotopic tumors grown from PDA cells in control mice. Increased levels of SEMA3D and PLXND1 in human PDA specimens associated with PNI.

CONCLUSIONS

DRG cells increase the migratory and invasive activities of pancreatic cancer cells, via secretion of SEMA3D by pancreatic cells and activation of PLXND1 on DRGs. Knockdown of SEMA3D and loss of neural PLXND1 reduces innervation of orthotopic PDAs and metastasis in mice. Increased levels of SEMA3D and PLXND1 in human PDA specimens associated with PNI. Strategies to disrupt the axon guidance pathway mediated by SEMA3D and PLXND1 might be developed to slow progression of PDA.

Annexin A2 Enhances the Progression of Colorectal Cancer and Hepatocarcinoma via Cytoskeleton Structural Rearrangements

Annexin A2 (ANXA2) is reported to be associated with cancer development. To investigate the roles ANXA2 plays during the development of cancer, the RNAi method was used to inhibit the ANXA2 expression in caco2 (human colorectal cancer cell line) and SMMC7721 (human hepatocarcinoma cell line) cells. The results showed that when the expression of ANXA2 was efficiently inhibited, the growth and motility of both cell lines were significantly decreased, and the development of the motility relevant microstructures, such as pseudopodia, filopodia, and the polymerization of microfilaments and microtubules were obviously inhibited. The cancer cell apoptosis was enhanced without obvious significance. The possible regulating pathway in the process was also predicted and discussed. Our results suggested that ANXA2 plays important roles in maintaining the malignancy of colorectal and hepatic cancer by enhancing the cell proliferation, motility, and development of the motility associated microstructures of cancer cells based on a possible complicated signal pathway.

Sp1 promotes cell migration and invasion in oral squamous cell carcinoma by upregulating Annexin A2 transcription

Oral squamous cell carcinoma (OSCC) is a common malignant tumor with high metastatic potential in head and neck. Revealing the mechanism of OSCC metastasis will benefit the prognosis and prevention of OSCC. Sp1 is a transcription factor involved in the progression of several tumors. Annexin A2 functions as an oncogene, and there are three putative Sp1 binding sites in the Annexin A2 promoter region. Therefore, we hypothesized that Sp1 could regulate OSCC metastasis by regulating Annexin A2 expression. Quantitative real-time PCR (qRT-PCR) and Western blot were used to evaluate Sp1 or Annexin A2 expression. Transwell assays were used to evaluate the migration and invasion capacity of OSCC cells. Luciferase assays and Chromatin immunoprecipitation assays were used to verify whether Sp1 regulate Annexin A2 at the transcriptional level. We found that the expression of Sp1 increased in OSCC tissues compared to paired adjacent normal tissues, and the overexpression of Sp1 was associated with tumor metastasis. Furthermore, Sp1 promoted cell migration and invasion through Annexin A2. In addition, we verified that Sp1 controls Annexin A2 expression at the transcriptional level and identified the binding sites involved. Our study suggests that Sp1/Annexin A2 expression could be a promising prognostic biomarker and therapeutic target for OSCC metastasis.

High expression of Annexin A2 is associated with DNA repair, metabolic alteration, and worse survival in pancreatic ductal adenocarcinoma

BACKGROUND

Annexin A2 (ANXA2) is a known driver of cancer progression. We investigated what mechanism associates with ANXA2 high expression and its survival impact using a bioinformatic approach in pancreatic ductal adenocarcinoma.

METHODS

Primary pancreatic tumor (n = 185) cohort in The Cancer Genome Atlas and Gene set enrichment analysis were used.

RESULTS

There were no significant associations between ANXA2 expression and clinicopathologic features of the patients investigated. The ANXA2 high tumors enriched some of the known downstream signaling, such as NF-κB (P = .028) and tumor necrosis factor (P = .044) pathways, whereas others, such as angiogenesis or epithelial-mesenchymal transition, were not associated. ANXA2 high expression tumors enriched DNA repair-related gene sets (DNA repair; P = .011, p53 pathway; P = .036) and cell proliferation-related gene sets (MYC targets; P = .041). In addition, new association with metabolism related gene sets, such as glycolysis (P = .016), nucleic acid metabolism (P = .001), and pyrimidine metabolism (P = .004) were identified in the ANXA2 high group. Patients with high ANXA2 expression demonstrated significantly worse disease-free survival (P = .001) and overall survival (P = .014), with high ANXA2 being an independent risk factor.

CONCLUSION

High ANXA2 expression was associated with NF-κB and tumor necrosis factor signaling, DNA repair, cell proliferation, and metabolic alteration and worse prognosis in pancreatic ductal adenocarcinoma.

A combined ANXA2-NDRG1-STAT1 gene signature predicts response to chemoradiotherapy in cervical cancer

BACKGROUND

A better understanding of locally advanced cervical cancer (LACC) is mandatory for further improving the rates of disease control, since a significant proportion of patients still fail to respond or undergo relapse after concurrent chemoradiation treatment (CRT), and survival for these patients has generally remained poor.

METHODS

To identify specific markers of CRT response, we compared pretreatment biopsies from LACC patients with pathological complete response (sensitive) with those from patients showing macroscopic residual tumor (resistant) after neoadjuvant CRT, using a proteomic approach integrated with gene expression profiling. The study of the underpinning mechanisms of chemoradiation response was carried out through in vitro models of cervical cancer.

RESULTS

We identified annexin A2 (ANXA2), N-myc downstream regulated gene 1 (NDRG1) and signal transducer and activator of transcription 1 (STAT1) as biomarkers of LACC patients' responsiveness to CRT. The dataset collected through qPCR on these genes was used as training dataset to implement a Random Forest algorithm able to predict the response of new patients to this treatment. Mechanistic investigations demonstrated the key role of the identified genes in the balance between death and survival of tumor cells.

CONCLUSIONS

Our results define a predictive gene signature that can help in cervical cancer patient stratification, thus providing a useful tool towards more personalized treatment modalities.

P11 Loss-of-Function is Associated with Decreased Cell Proliferation and Neurobehavioral Disorders in Mice

Although depression is associated with anxiety and memory deficit in humans, the molecular mechanisms of the complication remain largely unknown. In this study, we generated P11 knockout mice using CRISPR/Cas9 technology, as well as P11 knockout MEF cell lines, and confirmed depression-like phenotype. We observed that knockout of P11 in MEFs led to a decreased cell proliferation compared with P11+/+ MEFs. Moreover, P11 knockout resulted in a larger cell size, which resulted probably from accumulated F-actin stress fibers. The number of proliferating cells was decreased in the hippocampus of P11 KO mice. We observed anxiety-like disorder in addition to depression phenotype in the knockout mice. In addition, knockout of P11 led to memory deficit in female mice, but not in males. These data indicated that P11 is involved in regulating cell proliferation and cell size. The molecular associations of depression behavior with anxiety and memory deficit suggested a potential approach to improve therapeutic intervention through P11 in these disorders.

Polymorphisms in enterovirus 71 receptors associated with susceptibility and clinical severity

OBJECTIVE

To evaluate the association of enterovirus 71 (EV71) susceptibility and clinical severity with polymorphisms in EV71 receptors, including human scavenger receptor class B member 2 (SCARB2), P-selectin glycoprotein ligand-1 (PSGL-1), and annexin II (ANXA2).

METHODS

We enrolled laboratory-confirmed EV71 cases and healthy age- and gender-matched controls in Taiwan from 2000 to 2012. We detected genetic polymorphisms in SCARB2, PSGL-1, and ANXA2 and correlated the results with EV71 susceptibility and severity.

RESULTS

We collected 599 EV71 cases and 98 controls. Among EV71 patients, the male to female ratio was 1.61, and the mean age was 2.99±2.47 years. For clinical severity, 117 (19.6%) had severe central nervous system involvement with or without cardiopulmonary failure. For outcomes, 46 (7.7%) had sequelae, and 14 (2.3%) died. SCARB2 polymorphisms (rs6824953 and rs11097262) were associated with susceptibility to EV71 infection (OR 1.60, 95% CI 1.07-2.39; and OR 1.64, 95% CI 1.09-2.47, respectively). PSGL-1 polymorphisms (rs7137098 and rs8179137) were significantly associated with severe EV71 infection (OR 1.46, 95% CI 1.1-1.96; and OR 1.47, 95% CI 1.07-2.03, respectively).

CONCLUSIONS

SCARB2 polymorphisms (rs6824953 and rs11097262) might be associated with EV71 susceptibility. PSGL-1 polymorphisms (rs7137098 and rs8179137) were associated with severe EV71 infection.

Biological Effect and Mechanism of the miR-23b-3p/ANXA2 Axis in Pancreatic Ductal Adenocarcinoma

BACKGROUND/AIMS

Accumulating evidence strongly suggests that microRNAs (miRNAs) modulate the expression of known tumor suppressor genes and oncogenes. In the present study, we found that the proliferation and invasion ability of pancreatic ductal adenocarcinoma (PDAC) cells were significantly suppressed by the overexpression of miR-23b-3p. In addition, there are miR-23b-3p binding sites in annexin A2 (ANXA2). Here, we investigated whether miR-23b-3p had an impact on the progression and metastasis of PDAC by targeting ANXA2.

METHODS

Cell proliferation, migration, and invasion, and cell cycle assays were performed to explore the effect of miR-23b-3p on various malignant phenotypes of pancreatic cancer cells. The size of tumors was observed following miR-23b-3p overexpression in an in vivo chick chorioallantoic membrane assay. Dual-luciferase reporter, quantitative real-time PCR, western blot, and immunohistochemical analyses were used to validate the relationship between miR-23b-3p and ANXA2 in vitro.

RESULTS

We observed that miR-23b-3p could bind specifically to the 3' untranslated region of ANXA2 and inhibit its expression. MiR-23b-3p overexpression downregulated the expression of ANXA2 mRNA in PDAC cells and limited the size of tumors or even prevented tumor formation. In addition, there was a negative correlation between miR-23b-3p expression and ANXA2 protein expression in clinical specimens.

CONCLUSION

MiR-23b-3p inhibits the development and progression of PDAC by regulating ANXA2 directly.

ANN1 and ANN2 Function in Post-Phloem Sugar Transport in Root Tips to Affect Primary Root Growth

Annexins are a multigene family of calcium-dependent membrane-binding proteins that play important roles in plant cell signaling. Annexins are multifunctional proteins, and their function in plants is not comprehensively understood. Arabidopsis (Arabidopsis thaliana) annexins ANN1 and ANN2 are 64% identical in their primary structure, and both are highly expressed in seedlings. Here, we showed that ann-mutant seedlings grown in the absence of sugar show decreased primary root growth and altered columella cells in root caps; however, these mutant defects are rescued by Suc, Glc, or Fru. In seedlings grown without sugar, significant up-regulation of photosynthetic gene expression and chlorophyll accumulation was found in ann-mutant cotyledons compared to that in wild type, which indicates potential sugar starvation in the roots of ann-mutant seedlings. Unexpectedly, the overall sugar content of ann-mutant primary roots was significantly higher than that of wild-type roots when grown without sugar. To examine the diffusion of sugar along the entire root to the root tip, we examined the unloading pattern of carboxyfluorescein dye and found that post-phloem sugar transport was impaired in ann-mutant root tips compared to that in wild type. Increased levels of ROS and callose were detected in the root tips of ann-mutant seedlings grown without Suc, the latter of which would restrict plasmodesmal sugar transport to root tips. Our results indicate that ANN1 and ANN2 play an important role in post-phloem sugar transport to the root tip, which in turn indirectly influences photosynthetic rates in cotyledons. This study expands our understanding of the function of annexins in plants.

Heterotetrameric annexin A2/S100A10 (A2t) is essential for oncogenic human papillomavirus trafficking and capsid disassembly, and protects virions from lysosomal degradation

Human papillomavirus (HPV) entry into epithelial cells is independent of canonical endocytic pathways. Upon interaction with host cells, HPV establishes infection by traversing through an endocytic pathway that is clathrin- and caveolin-independent, but dependent on the annexin A2/S100A10 heterotetramer (A2t). We examined the contribution of monomeric annexin A2 (AnxA2) vs. A2t in HPV infection and endocytosis, and further characterized the role of these molecules in protein trafficking. We specifically show that cell surface A2t is not required for HPV attachment, and in the absence of A2t virion internalization remains clathrin-independent. Without A2t, viral progression from early endosomes to multivesicular endosomes is significantly inhibited, capsid uncoating is dramatically reduced, and lysosomal degradation of HPV is accelerated. Furthermore, we present evidence that AnxA2 forms a complex with CD63, a known mediator of HPV trafficking. Overall, the observed reduction in infection is less significant in the absence of S100A10 alone compared to full A2t, supporting an independent role for monomeric AnxA2. More broadly, we show that successful infection by multiple oncogenic HPV types is dependent on A2t. These findings suggest that A2t is a central mediator of high-risk HPV intracellular trafficking post-entry and pre-viral uncoating.

Transbilayer phospholipid movement facilitates the translocation of annexin across membranes

Annexins are cytosolic phospholipid-binding proteins that can be found on the outer leaflet of the plasma membrane. The extracellular functions of annexin include modulating fibrinolysis activity and cell migration. Despite having well-described extracellular functions, the mechanism of annexin transport from the cytoplasmic inner leaflet to the extracellular outer leaflet of the plasma membrane remains unclear. Here, we show that the transbilayer movement of phospholipids facilitates the transport of annexins A2 and A5 across membranes in cells and in liposomes. We identified TMEM16F (also known as anoctamin-6, ANO6) as a lipid scramblase required for transport of these annexins to the outer leaflet of the plasma membrane. This work reveals a mechanism for annexin translocation across membranes which depends on plasma membrane phospholipid remodelling.