Annexin-A1 regulates TLR-mediated IFN-ß production through an interaction with TANK-binding kinase 1.

TLRs play a pivotal role in the recognition of bacteria and viruses. Members of the family recognize specific pathogen sequences to trigger both MyD88 and TRIF-dependent pathways to stimulate a plethora of cells. Aberrant activation of these pathways is known to play a critical role in the development of autoimmunity and cancer. However, how these pathways are entirely regulated is not fully understood. In these studies, we have identified Annexin-A1 (ANXA1) as a novel regulator of TLR-induced IFN-ß and CXCL10 production. We demonstrate that in the absence of ANXA1, mice produce significantly less IFN-ß and CXCL10, and macrophages and plasmacytoid dendritic cells have a deficiency in activation following polyinosinic:polycytidylic acid administration in vivo. Furthermore, a deficiency in activation is observed in macrophages after LPS and polyinosinic:polycytidylic acid in vitro. In keeping with these findings, overexpression of ANXA1 resulted in enhanced IFN-ß and IFN-stimulated responsive element promoter activity, whereas silencing of ANXA1 impaired TLR3- and TLR4-induced IFN-ß and IFN-stimulated responsive element activation. In addition, we show that the C terminus of ANXA1 directly associates with TANK-binding kinase 1 to regulate IFN regulatory factor 3 translocation and phosphorylation. Our findings demonstrate that ANXA1 plays an important role in TLR activation, leading to an augmentation in the type 1 IFN antiviral cytokine response.

Prenatal diagnosis after high chance non-invasive prenatal testing for trisomies 21, 18 and 13, chorionic villus sampling or amniocentesis? - Experience at a district general hospital in the United Kingdom.

The non-invasive prenatal testing (NIPT) analyses cell-free DNA (cfDNA) derived from the placental tissue in the maternal circulation. Though highly sensitive and specific, a major limitation is in cases of confined placental mosaicism (CPM). Whether to perform chorionic villus sampling (CVS) or amniocentesis to confirm a positive NIPT result is controversial. One major drawback of CVS is that cytogenetic diagnosis may not always reflect the true chromosomal make-up of the fetus. This work, therefore, proposes the use of amniocentesis in the presence of normal ultrasound findings, and the option of either CVS or amniocentesis when there are abnormal USS findings.

RNA-Sequencing-Based Transcriptomic Analysis Reveals a Role for Annexin-A1 in Classical and Influenza A Virus-Induced Autophagy.

Influenza viruses have been shown to use autophagy for their survival. However, the proteins and mechanisms involved in the autophagic process triggered by the influenza virus are unclear. Annexin-A1 (ANXA1) is an immunomodulatory protein involved in the regulation of the immune response and Influenza A virus (IAV) replication. In this study, using clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 (CRISPR associated protein 9) deletion of ANXA1, combined with the next-generation sequencing, we systematically analyzed the critical role of ANXA1 in IAV infection as well as the detailed processes governing IAV infection, such as macroautophagy. A number of differentially expressed genes were uniquely expressed in influenza A virus-infected A549 parental cells and A549 ∆ANXA1 cells, which were enriched in the immune system and infection-related pathways. Gene ontology and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway revealed the role of ANXA1 in autophagy. To validate this, the effect of mechanistic target of rapamycin (mTOR) inhibitors, starvation and influenza infection on autophagy was determined, and our results demonstrate that ANXA1 enhances autophagy induced by conventional autophagy inducers and influenza virus. These results will help us to understand the underlying mechanisms of IAV infection and provide a potential therapeutic target for restricting influenza viral replication and infection.

PPARγ Ligand-induced Annexin A1 Expression Determines Chemotherapy Response via Deubiquitination of Death Domain Kinase RIP in Triple-negative Breast Cancers.

Metastatic breast cancer is still incurable so far; new specifically targeted and more effective therapies for triple-negative breast cancer (TNBC) are required in the clinic. In this study, our clinical data have established that basal and claudin-low subtypes of breast cancer (TNBC types) express significantly higher levels of Annexin A1 (ANXA1) with poor survival outcomes. Using human cancer cell lines that model the TNBC subtype, we observed a strong positive correlation between expression of ANXA1 and PPARγ. A similar correlation between these two markers was also established in our clinical breast cancer patients' specimens. To establish a link between these two markers in TNBC, we show de novo expression of ANXA1 is induced by activation of PPARγ both in vitro and in vivo and it has a predictive value in determining chemosensitivity to PPARγ ligands. Mechanistically, we show for the first time PPARγ-induced ANXA1 protein directly interacts with receptor interacting protein-1 (RIP1), promoting its deubiquitination and thereby activating the caspase-8-dependent death pathway. We further identified this underlying mechanism also involved a PPARγ-induced ANXA1-dependent autoubiquitination of cIAP1, the direct E3 ligase of RIP1, shifting cIAP1 toward proteosomal degradation. Collectively, our study provides first insight for the suitability of using drug-induced expression of ANXA1 as a new player in RIP1-induced death machinery in TNBCs, presenting itself both as an inclusion criterion for patient selection and surrogate marker for drug response in future PPARγ chemotherapy trials. Mol Cancer Ther; 16(11); 2528-42. ©2017 AACR.

The regulation of TNFα production after heat and endotoxin stimulation is dependent on Annexin-A1 and HSP70.

Febrile temperatures can induce stress responses which protect cells from damage and can reduce inflammation during infections and sepsis. However, the mechanisms behind the protective functions of heat in response to the bacterial endotoxin LPS are unclear. We have recently shown that Annexin-1 (ANXA1)-deficient macrophages exhibited higher TNFα levels after LPS stimulation. Moreover, we have previously reported that ANXA1 can function as a stress protein. Therefore in this study, we determined if ANXA1 is involved in the protective effects of heat on cytokine levels in macrophages after heat and LPS. Exposure of macrophages to 42 °C for 1 h prior to LPS results in an inhibition of TNFα production, which was not evident in ANXA1(-/-) macrophages. We show that this regulation involves primarily MYD88-independent pathways. ANXA1 regulates TNFα mRNA stability after heat and LPS, and this is dependent on endogenous ANXA1 expression and not exogenously secreted factors. Further mechanistic studies revealed the possible involvement of the heat shock protein HSP70 and JNK in the heat and inflammatory stress response regulated by ANXA1. This study shows that ANXA1, an immunomodulatory protein, is critical in the heat stress response induced after heat and endotoxin stimulation.

Annexin-A1 regulates microRNA-26b* and microRNA-562 to directly target NF-κB and angiogenesis in breast cancer cells.

Annexin 1 (ANXA1) is an endogenous anti-inflammatory protein implicated in cancer. ANXA1 was previously shown to be regulated by hsa-miR-196a. However, whether ANXA1 itself regulates microRNA (miR) expression is unknown. Therefore, we investigated the regulation of miR by ANXA1 in MCF7 breast cancer cells. MCF7-EV (Empty vector) and MCF7-V5 (ANXA1-V5 expressing cells) were subjected to a miR microarray. Microarray analysis revealed a number of miRNAs which were dysregulated in MCF7-V5 cells. 2 novel miRNAs (miR562 and miR26b*) were validated, cloned and functionally characterized. As ANXA1 constitutively activates NF-κB activity to modulate breast cancer metastasis, we found that miR26b* and miR562 directly targeted the canonical NF-κB pathway by targeting the 3' UTR and inhibiting expression of Rel A (p65) and NF-κB1 (p105) respectively. MiR562 inhibited wound healing, which was reversed when ANXA1 was overexpressed. Overexpression of either miR562 or miR26b* in MCF-7 cells enhanced endothelial tube formation when cocultured with human umbilical cord endothelial cells while conversely, treatment of MCF7 cells with either anti-miR562 or anti-miR26b* inhibited endothelial tube formation after co-culture. Further analysis of miR562 revealed that miR562-transfected cell conditioned media enhances endothelial cell tube formation, indicating that miR562 increased angiogenic secreted factors from MCF-7 breast tumor cells. TNFα was increased upon overexpression of miR562, which was reversed when ANXA1 was co-transfected In conclusion, this data suggests that ANXA1-regulated miR26b* and miR562 may play a role in wound healing and tumor-induced endothelial cell tube formation by targeting NF-κB expression and point towards a potential therapeutic target for breast cancer.