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.

Hydrogen peroxide is a neuronal alarmin that triggers specific RNAs, local translation of Annexin A2, and cytoskeletal remodeling in Schwann cells

Schwann cells are key players in neuro-regeneration: They sense "alarm" signals released by degenerating nerve terminals and differentiate toward a proregenerative phenotype, with phagocytosis of nerve debris and nerve guidance. At the murine neuromuscular junction, hydrogen peroxide (H₂O₂) is a key signal of Schwann cells' activation in response to a variety of nerve injuries. Here we report that Schwann cells exposed to low doses of H₂O₂ rewire the expression of several RNAs at both transcriptional and translational levels. Among the genes positively regulated at both levels, we identified an enriched cluster involved in cytoskeleton remodeling and cell migration, with the Annexin (Anxa) proteins being the most represented family. We show that both Annexin A2 (Anxa2) transcript and protein accumulate at the tips of long pseudopods that Schwann cells extend upon H₂O₂ exposure. Interestingly, Schwann cells reply to this signal and to nerve injury by locally translating Anxa2 in pseudopods, and undergo an extensive cytoskeleton remodeling. Our results show that, similarly to neurons, Schwann cells take advantage of local protein synthesis to change shape and move toward damaged axonal terminals to facilitate axonal regeneration.

Annexin A1, Annexin A2, and Dyrk 1B are upregulated during GAS1-induced cell cycle arrest

GAS1 is a pleiotropic protein that has been investigated because of its ability to induce cell proliferation, cell arrest, and apoptosis, depending on the cellular or the physiological context in which it is expressed. At this point, we have information about the molecular mechanisms by which GAS1 induces proliferation and apoptosis; but very few studies have been focused on elucidating the mechanisms by which GAS1 induces cell arrest. With the aim of expanding our knowledge on this subject, we first focused our research on finding proteins that were preferentially expressed in cells arrested by serum deprivation. By using a proteomics approach and mass spectrometry analysis, we identified 17 proteins in the 2-DE protein profile of serum deprived NIH3T3 cells. Among them, Annexin A1 (Anxa1), Annexin A2 (Anxa2), dual specificity tyrosine-phosphorylation-regulated kinase 1B (Dyrk1B), and Eukaryotic translation initiation factor 3, F (eIf3f) were upregulated at transcriptional the level in proliferative NIH3T3 cells. Moreover, we demonstrated that Anxa1, Anxa2, and Dyrk1b are upregulated at both the transcriptional and translational levels by the overexpression of GAS1. Thus, our results suggest that the upregulation of Anxa1, Anxa2, and Dyrk1b could be related to the ability of GAS1 to induce cell arrest and maintain cell viability. Finally, we provided further evidence showing that GAS1 through Dyrk 1B leads not only to the arrest of NIH3T3 cells but also maintains cell viability.

Elevation of p11 in lateral habenula mediates depression-like behavior

The lateral habenula (LHb) is a key brain region involved in the pathophysiology of depression. It is activated by stimuli associated with negative experiences and is involved in encoding aversive signals. Hyperactivity of LHb is found in both rodent models of depression and human patients with depression. However, little is known about the underlying molecular mechanisms. Here we show that in LHb neurons, p11, a multifunctional protein implicated in depression, is significantly upregulated by chronic restraint stress. Knockdown of p11 expression in LHb alleviates the stress-induced depression-like behaviors. Moreover, chronic restraint stress induces bursting action potentials in LHb neurons, which are abolished by p11 knockdown. Overexpression of p11 in dopamine D2 receptor-containing LHb neurons of control mice induces depression-like behaviors. These results have identified p11 in LHb as a key molecular determinant regulating negative emotions, which may help to understand the molecular and cellular basis of depression.

Fatty acids modulate the expression levels of key proteins for cholesterol absorption in Caco-2 monolayer

BACKGROUND

Fatty acids have been shown to modulate intestinal cholesterol absorption in cells and animals, a process that is mediated by several transporter proteins. Of these proteins, Niemann-Pick C1-Like 1 (NPC1L1) is a major contributor to this process. The current study investigates the unknown mechanism by which fatty acids modulate cholesterol absorption.

METHODS

We evaluated the effects of six fatty acids palmitic acid (PAM), oleic acid (OLA), linoleic acid (LNA), arachidonic acid (ARA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on cholesterol uptake and transport in human enterocytes Caco-2 cells, and on the mRNA expression levels of NPC1L1, others proteins (ABCG5, ABCG8, ABCA1, ACAT2, MTP, Caveolin 1, Annexin-2) involved in cholesterol absorption, and SREBP-1 and SREBP-2 that are responsible for lipid metabolism.

RESULTS

The polyunsaturated fatty acids (PUFAs), especially for EPA and DHA, dose-dependently inhibited cholesterol uptake and transport in Caco-2 monolayer, while saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) had no inhibitory effects. EPA and DHA inhibited cholesterol absorption in Caco-2 monolayer might be caused by down-regulating NPC1L1 mRNA and protein levels, which were associated with inhibition of SREBP-1/- 2 mRNA expression levels.

CONCLUSION

Results from this study indicate that functional food containing high PUFAs may have potential therapeutic benefit to reduce cholesterol absorption. Further studies on this topic may provide approaches to control lipid metabolism and to promote health.

Genetic variations in the p11/tPA/BDNF pathway are associated with post stroke depression

BACKGROUND

The effects of BDNF on post stroke depression (PSD) may be influenced by genetic variations in intracellular signal transduction pathways, such as the p11/tPA/BDNF pathway. In this study, we aimed to determine the association of polymorphisms in candidate genes of the gene transduction pathway with PSD, as well as the effects of the interactions between genes in our Chinese sample.

METHODS

Two-hundred-fifty-four Chinese samples with acute ischaemic stroke included 122 PSD patients and 132 nonPSD patients. Sixty-five single nucleotide polymorphisms (SNPs) in six genes (p11, tPA, PAI-1, BDNF, TrkB and p75NTR) of the p11/tPA/BDNF pathway with minor allele frequencies > 5% were successfully genotyped from an initial series of 76 SNPs. The severity of depressive symptoms was assessed by the 17-item Hamilton Depression Rating scale score. Environmental factors were measured with the life events scale and social support rating scale for all patients. SNP and haplotype associations were analysed using gPLINK software. Gene-gene interactions were evaluated with generalized multifactor dimensionality reduction software.

RESULTS

The results showed that TrkB polymorphisms (rs11140793AC genotype, rs7047042CG genotype, rs1221CT genotype, rs2277193TC genotype and rs2277192AG genotype) were significantly associated with PSD. Three haplotypes (AT, GG, and AAT) of TrkB were significantly associated with PSD. Seven haplotypes (GC, AG, ACG, CGC, GCT, ACGC and ACAT) of BDNF were significantly correlated with PSD. We identified significant gene-gene interactions between the p11 (rs11204922 SNP), tPA (rs8178895, rs2020918 SNPs) and BDNF (rs6265, rs2049046, rs16917271, rs727155 SNPs) genes in the PSD group. We also identified significant gene-gene interactions between the BDNF (rs2049046, rs7931247 SNPs) and TrkB (rs7816 SNP) genes with increased occurrence of PSD and sig gene-gene interactions between the BDNF gene (rs6265, rs56164415, rs2049046, rs4923468, rs2883187, rs16917271, rs1491850, rs727155, rs2049048 SNPs) and p75NTR gene (rs2072446, rs11466155) in the PSD group.

CONCLUSION

These findings provides evidence that the TrkB gene, BDNF and TrkB haplotypes, and gene-gene interactions between p11, tPA and BDNF are all associated with PSD, which suggests that genetic variations in the p11/tPA/BDNF pathway may play a central role in regulating the underlying mechanism of PSD.

Annexin A2 links poor myofiber repair with inflammation and adipogenic replacement of the injured muscle

Repair of skeletal muscle after sarcolemmal damage involves dysferlin and dysferlin-interacting proteins such as annexins. Mice and patient lacking dysferlin exhibit chronic muscle inflammation and adipogenic replacement of the myofibers. Here, we show that similar to dysferlin, lack of annexin A2 (AnxA2) also results in poor myofiber repair and progressive muscle weakening with age. By longitudinal analysis of AnxA2-deficient muscle we find that poor myofiber repair due to the lack of AnxA2 does not result in chronic inflammation or adipogenic replacement of the myofibers. Further, deletion of AnxA2 in dysferlin deficient mice reduced muscle inflammation, adipogenic replacement of myofibers, and improved muscle function. These results identify multiple roles of AnxA2 in muscle repair, which includes facilitating myofiber repair, chronic muscle inflammation and adipogenic replacement of dysferlinopathic muscle. It also identifies inhibition of AnxA2-mediated inflammation as a novel therapeutic avenue for treating muscle loss in dysferlinopathy.

Annexin A2 (ANXA2) interacts with nonstructural protein 1 and promotes the replication of highly pathogenic H5N1 avian influenza virus

BACKGROUND

Non-structural protein 1 (NS1) is a multifunctional protein and a crucial regulatory factor in the replication and pathogenesis of avian influenza virus (AIV). Studies have shown that NS1 can interact with a variety of host proteins to modulate the viral life cycle. We previously generated a monoclonal antibody against NS1 protein; In the current research study, using this antibody, we immunoprecipitated host proteins that interact with NS1 to better understand the roles played by NS1 in communications between virus and host.

RESULTS

Co-immunoprecipitation experiments identified annexin A2 (ANXA2) as a target molecule interacting with NS1. Results from confocal laser scanning microscopy indicated that NS1 co-localized with ANXA2 in the cell cytoplasm. Overexpression of ANXA2 significantly increased the titer of H5N1 subtype HPAIV, whereas siRNA-mediated knockdown of ANXA2 markedly inhibited the expression of viral proteins and reduced the progeny virus titer.

CONCLUSIONS

Our results indicate that ANXA2 interacts with NS1 and ANXA2 expression increases HPAIV replication.

Hedgehog signaling stimulates Tenascin C to promote invasion of pancreatic ductal adenocarcinoma cells through Annexin A2

Pancreatic adenocarcinoma (PDA) is characterized by a dense desmoplastic reaction that comprises 60-90% of the tumor, while only 10-40% of the tumor is composed of malignant epithelial cells. This desmoplastic reaction is composed of stromal fibroblast cells, extracellular matrix proteins, and immune cells. Accumulating evidence has suggested that the stromal and epithelial cell compartments interact during the pathogenesis of this disease. Therefore, it is important to identify the signaling pathways responsible for this interaction to better understand the mechanisms by which PDA invades and metastasizes. Here, we show that secreted stromal factors induce invasion of PDA cells. Specifically, hedgehog signaling from the tumor cells induces tenascin C (TnC) secretion from the stromal cells that acts back upon the tumor cells in a paracrine fashion to induce the invasion of PDA cells through its' receptor annexin A2 (AnxA2). Therefore, blocking the interaction between TnC and AnxA2 has the potential to prevent liver metastasis in PDA.

Molecular characterization of pneumococcal surface protein K, a potential pneumococcal vaccine antigen

The pneumococcal capsule is indispensable for pathogenesis in systemic infections; however, many pneumococcal diseases, including conjunctivitis, otitis media, and some systemic infections in immunocompromised patients, are caused by nonencapsulated Streptococcus pneumoniae (NESp). Null capsule clade 1 (NCC1), found in group 2 NESp, expresses pneumococcal surface protein K (PspK) and is becoming prevalent among pneumococcal organisms owing to the widespread use of pneumococcal conjugate vaccines. Despite its clinical importance, the molecular mechanisms underlying the prevalence of NCC1 have not been fully elucidated. Here, we investigated the role of the R3 domain of PspK in the epithelial cell adherence of NCC1. We found that the R3 domain of PspK mediated NCC1 adherence via its direct interaction with the epithelial surface protein annexin A2. Additionally, neutralization with purified recombinant PspK-R3 or rabbit anti-UD:R3 IgG inhibited binding of NESp to lung epithelial cells in vitro. Immunization with the 'repeat' domain of PspK-R3 or PspK-UD:R3 effectively elicited mucosal and systemic immune responses against PspK-R3 and provided protection against nasopharyngeal, lung, and middle ear colonization of NESp in mice. Additionally, we found that rabbit anti-UD:R3 IgG bound to PspC-R1 of the encapsulated TIGR4 strain and that UD:R3 immunization provided protection against nasopharyngeal and lung colonization of TIGR4 and deaths by TIGR4 and D39 in mice. Further studies using 68 pneumococcal clinical isolates showed that 79% of clinical isolates showed cross-reactivity to rabbit anti-UD:R3 IgG. About 87% of serotypes in the 13-valent pneumococcal conjugate vaccine (PCV) and 68% of non-vaccine serotypes were positive for cross-reactivity with rabbit anti-UD:R3 IgG. Thus, the R3 domain of PspK may be an effective vaccine candidate for both NESp and encapsulated Sp.

A Vibrio vulnificus VvpM Induces IL-1β Production Coupled with Necrotic Macrophage Death via Distinct Spatial Targeting by ANXA2

An inflammatory form of phagocyte death evoked by the Gram-negative bacterium Vibrio (V.) vulnificus (WT) is one of hallmarks to promote their colonization, but the virulence factor and infectious mechanism involved in this process remain largely unknown. Here, we identified extracellular metalloprotease VvpM as a new virulence factor and investigated the molecular mechanism of VvpM which acts during the regulation of the inflammatory form of macrophage death and bacterial colonization. Mutation of the vvpM gene appeared to play major role in the prevention of IL-1β production due to V. vulnificus infection in macrophage. However, the recombinant protein (r) VvpM caused IL-1β production coupled with necrotic cell death, which is highly susceptible to the knockdown of annexin A2 (ANXA2) located in both membrane lipid and non-lipid rafts. In lipid rafts, rVvpM recruited NOX enzymes coupled with ANXA2 to facilitate the production of ROS responsible for the epigenetic and transcriptional regulation of NF-κB in the IL-1β promoter. rVvpM acting on non-lipid rafts increased LC3 puncta formation and autophagic flux, which are required for the mRNA expression of Atg5 involved in the autophagosome formation process. The autophagy activation caused by rVvpM induced NLRP3 inflammasome-dependent caspase-1 activation in the promoting of IL-1β production. In mouse models of V. vulnificus infection, the VvpM mutant failed to elevate the level of pro-inflammatory responses closely related to IL-1β production and prevented bacterial colonization. These findings delineate VvpM efficiently regulates two pathogenic pathways that stimulate NF-κB-dependent IL-1β production and autophagy-mediated NLRP3 inflammasome via distinct spatial targeting by ANXA2.

A new cis-acting motif is required for the axonal SMN-dependent Anxa2 mRNA localization

Spinal muscular atrophy (SMA) is caused by mutations and/or deletions of the survival motor neuron gene (SMN1). Besides its function in the biogenesis of spliceosomal snRNPs, SMN might possess a motor neuron specific role and could function in the transport of axonal mRNAs and in the modulation of local protein translation. Accordingly, SMN colocalizes with axonal mRNAs of differentiated NSC-34 motor neuron-like cells. We recently showed that SMN depletion gives rise to a decrease in the axonal transport of the mRNAs encoding Annexin A2 (Anxa2). In this work, we have characterized the structural features of the Anxa2 mRNA required for its axonal targeting by SMN. We found that a G-rich motif located near the 3'UTR is essential for axonal localization of the Anxa2 transcript. We also show that mutations in the motif sequence abolish targeting of Anxa2 reporter mRNAs in axon-like structures of differentiated NSC-34 cells. Finally, localization of both wild-type and mutated Anxa2 reporters is restricted to the cell body in SMN-depleted cells. Altogether, our studies show that this G-motif represents a novel and essential determinant for axonal localization of the Anxa2 mRNA mediated by the SMN complex.

The upregulation of annexin A2 after spinal cord injury in rats may have implication for astrocyte proliferation

Annexin A2 (ANXA2), is a member of the annexin family of proteins that exhibit Ca²⁺-dependent binding to phospholipids. One attractive biological function of ANXA2 is participating in DNA synthesis and cell proliferation. Previous studies have shown that ANXA2 play a role in the development of the central nervous system. However, the biological function of ANXA2 after spinal cord injury (SCI) is still with limited acquaintance. In the present study, we performed a SCI model in adult rats and investigated the dynamic changes of ANXA2 expression in the spinal cord. Western blot analysis indicated a striking expression upregulation of ANXA2 after SCI. Immunohistochemistry further confirmed that ANXA2 immunoactivity was expressed at low levels in normal condition and increased at 5day after SCI. Double immunofluorescence staining prompted that ANXA2 immunoreactivity was found in astrocytes and neurons. Interestingly, ANXA2 expression was increased predominantly in astrocytes. We also examined the expression profiles of proliferating cell nuclear antigen (PCNA), Cyclin D1 and active caspase-3 in the injured spinal cords by western blot. Co-expression of ANXA2/PCNA, ANXA2/Cyclin D1 was detected in glial fibrillary acidic protein. Importantly, double immunofluorescence staining revealed that cell proliferation evaluated by PCNA appeared in many ANXA2-expressing cells and rare caspase-3 was observed in ANXA2-expressing cells after SCI. In addition, ANXA2 knockdown in astrocytes resulted in the increase of PCNA expression after LPS stimulation, showing that ANXA2 inhibited astrocyte proliferation after inflammation. Our data suggested that ANXA2 might play important roles in CNS pathophysiology after SCI.

Disruption of Annexin II /p11 Interaction Suppresses Leukemia Cell Binding, Homing and Engraftment, and Sensitizes the Leukemia Cells to Chemotherapy

The bone marrow microenvironment plays an important role in acute lymphoblastic leukemia (ALL) cell proliferation, maintenance, and resistance to chemotherapy. Annexin II (ANX2) is abundantly expressed on bone marrow cells and complexes with p11 to form ANX2/p11-hetero-tetramer (ANX2T). We present evidence that p11 is upregulated in refractory ALL cell lines and patient samples. A small molecule inhibitor that disrupts ANX2/p11 interaction (ANX2T inhibitor), an anti-ANX2 antibody, and knockdown of p11, abrogated ALL cell adhesion to osteoblasts, indicating that ANX2/p11 interaction facilitates binding and retention of ALL cells in the bone marrow. Furthermore, ANX2T inhibitor increased the sensitivity of primary ALL cells co-cultured with osteoblasts to dexamethasone and vincristine induced cell death. Finally, in an orthotopic leukemia xenograft mouse model, the number of ALL cells homing to the bone marrow was reduced by 40-50% in mice injected with anti-ANX2 antibody, anti-p11 antibody or ANX2T inhibitor compared to respective controls. In a long-term engraftment assay, the percentage of ALL cells in mouse blood, bone marrow and spleen was reduced in mice treated with agents that disrupt ANX2/p11 interaction. These data show that disruption of ANX2/p11 interaction results in reduced ALL cell adhesion to osteoblasts, increased ALL cell sensitization to chemotherapy, and suppression of ALL cell homing and engraftment.

Transcriptional regulation of Annexin A2 promotes starvation-induced autophagy

Autophagy is an important degradation pathway, which is induced after starvation, where it buffers nutrient deprivation by recycling macromolecules in organisms from yeast to man. While the classical pathway mediating this response is via mTOR inhibition, there are likely to be additional pathways that support the process. Here, we identify Annexin A2 as an autophagy modulator that regulates autophagosome formation by enabling appropriate ATG9A trafficking from endosomes to autophagosomes via actin. This process is dependent on the Annexin A2 effectors ARP2 and Spire1. Annexin A2 expression increases after starvation in cells in an mTOR-independent fashion. This is mediated via Jun N-terminal kinase activation of c-Jun, which, in turn, enhances the trans-activation of the Annexin A2 promoter. Annexin A2 knockdown abrogates starvation-induced autophagy, while its overexpression induces autophagy. Hence, c-Jun-mediated transcriptional responses support starvation-induced autophagy by regulating Annexin A2 expression levels.

Semaphorin 3D autocrine signaling mediates the metastatic role of annexin A2 in pancreatic cancer

Most patients with pancreatic ductal adenocarcinoma (PDA) present with metastatic disease at the time of diagnosis or will recur with metastases after surgical treatment. Semaphorin-plexin signaling mediates the migration of neuronal axons during development and of blood vessels during angiogenesis. The expression of the gene encoding semaphorin 3D (Sema3D) is increased in PDA tumors, and the presence of antibodies against the pleiotropic protein annexin A2 (AnxA2) in the sera of some patients after surgical resection of PDA is associated with longer recurrence-free survival. By knocking out AnxA2 in a transgenic mouse model of PDA (KPC) that recapitulates the progression of human PDA from premalignancy to metastatic disease, we found that AnxA2 promoted metastases in vivo. The expression of AnxA2 promoted the secretion of Sema3D from PDA cells, which coimmunoprecipitated with the co-receptor plexin D1 (PlxnD1) on PDA cells. Mouse PDA cells in which SEMA3D was knocked down or ANXA2-null PDA cells exhibited decreased invasive and metastatic potential in culture and in mice. However, restoring Sema3D in AnxA2-null cells did not entirely rescue metastatic behavior in culture and in vivo, suggesting that AnxA2 mediates additional prometastatic mechanisms. Patients with primary PDA tumors that have abundant Sema3D have widely metastatic disease and decreased survival compared to patients with tumors that have relatively low Sema3D abundance. Thus, AnxA2 and Sema3D may be new therapeutic targets and prognostic markers of metastatic PDA.

Proteomic Identification of Target Proteins of Thiodigalactoside in White Adipose Tissue from Diet-Induced Obese Rats

Previously, galectin-1 (GAL1) was found to be up-regulated in obesity-prone subjects, suggesting that use of a GAL1 inhibitor could be a novel therapeutic approach for treatment of obesity. We evaluated thiodigalactoside (TDG) as a potent inhibitor of GAL1 and identified target proteins of TDG by performing comparative proteome analysis of white adipose tissue (WAT) from control and TDG-treated rats fed a high fat diet (HFD) using two dimensional gel electrophoresis (2-DE) combined with MALDI-TOF-MS. Thirty-two spots from a total of 356 matched spots showed differential expression between control and TDG-treated rats, as identified by peptide mass fingerprinting. These proteins were categorized into groups such as carbohydrate metabolism, tricarboxylic acid (TCA) cycle, signal transduction, cytoskeletal, and mitochondrial proteins based on functional analysis using Protein Annotation Through Evolutionary Relationship (PANTHER) and Database for Annotation, Visualization, Integrated Discovery (DAVID) classification. One of the most striking findings of this study was significant changes in Carbonic anhydrase 3 (CA3), Voltage-dependent anion channel 1 (VDAC1), phosphatidylethanolamine-binding protein 1 (PEBP1), annexin A2 (ANXA2) and lactate dehydrogenase A chain (LDHA) protein levels between WAT from control and TDG-treated groups. In addition, we confirmed increased expression of thermogenic proteins as well as reduced expression of lipogenic proteins in response to TDG treatment. These results suggest that TDG may effectively prevent obesity, and TDG-responsive proteins can be used as novel target proteins for obesity treatment.

Annexin A2 is required for the early steps of cytokinesis

Cytokinesis requires the formation of an actomyosin contractile ring between the two sets of sister chromatids. Annexin A2 is a calcium- and phospholipid-binding protein implicated in cortical actin remodeling. We report that annexin A2 accumulates at the equatorial cortex at the onset of cytokinesis and depletion of annexin A2 results in cytokinetic failure, due to a defective cleavage furrow assembly. In the absence of annexin A2, the small GTPase RhoA-which regulates cortical cytoskeletal rearrangement-fails to form a compact ring at the equatorial plane. Furthermore, annexin A2 is required for cortical localization of the RhoGEF Ect2 and to maintain the association between the equatorial cortex and the central spindle. Our results demonstrate that annexin A2 is necessary in the early phase of cytokinesis. We propose that annexin A2 participates in central spindle-equatorial plasma membrane communication.

Increased annexin A2 expression in the placenta of women with acute worsening of preeclampsia

BACKGROUND

The aims of present study were to investigate the expression of Annexin A2 in the placenta of patients with preeclampsia (PE) and correlate these data with acute worsening of clinical symptoms.

METHODS

Placentas were collected from uncomplicated normal pregnancies (n = 9), PE cases without emergency termination of pregnancy (group 1, n = 6), and PE cases with acute worsening of symptoms necessitating immediate pregnancy termination (group 2, n = 7). Immunohistochemistry data were analyzed quantitatively, and placental mRNA expression was measured by Real-time PCR.

RESULTS

Group 2 had a significantly shorter interval between diagnosis and pregnancy termination compared with group 1 (p = 0.002). Birth weight and placental weight in group 2 were significantly lower compared with the normal group (p = 0.006 and p = 0.03, birth weight and placental weight, respectively), whereas there were no differences in gestational age at delivery between the three groups or the severity of high blood pressure and proteinuria between the PE groups. Placental expression of Annexin A2 as determined by immunohistochemistry was significantly higher in both PE groups compared with the uncomplicated pregnancy group (p < 0.001 and p < 0.001, groups 1 and 2, respectively). Placental Annexin A2 mRNA expression was significantly elevated in group 2 compared with the normal group (p = 0.002) but did not change in group 1.

CONCLUSIONS

This study is the first to demonstrate increased placental Annexin A2 mRNA expression during the acute phase of PE. Immunohistochemical staining of placental Annexin A2 was high, regardless of PE phase. These findings suggest that worsening of PE might alter Annexin A2 expression at the transcription level.

[The expression and antibody preparation of S100A10 protein]

OBJECTIVE

To prepare S100A10 protein and its specific polyclonal antibody.

METHODS

The full-length gene fragment of S100A10 was amplified by PCR, and then cloned into pET28a(+) prokaryotic expression vector. After transformation, the vector was induced to express the recombinant (S100A10)(2) protein by IPTG in E.coli BL21 (DE3). The recombinant (S100A10)(2) was then purified by Ni-NTA resin. (S100A10)(2)-specific polyclonal antibody was prepared using the purified recombinant (S100A10)(2) protein as antigen to inoculate rabbit intradermally. The title and specificity of the polyclonal antibody were determined by ELISA and Western blotting.

RESULTS

The study successfully constructed the prokaryotic recombinant expression vector pET28a(+)-(S100A10)(2), and obtained the purified recombinant (S100A10)(2) protein and polyclonal antibody with high titer and specificity.

CONCLUSION

The prokaryotic expression and purification system for S100A10 has been established and polyclonal antibody of (S100A10)(2) been prepared, which provides helpful fools for further researches on S100A10.

Identification of prognosis-related proteins in gingival squamous cell carcinoma by twodimensional gel electrophoresis and mass spectrometry-based proteomics

OBJECTIVES

The aim of this study was to identify differentially expressed proteins in oral squamous carcinoma cells that could be potential prognosis-related cancer biomarkers.

MATERIALS AND METHODS

We compared protein expression patterns from gingival squamous cellc carcinoma (GSCC) tissues and adjacent non-cancerous matched tissues by proteomic analysis using two-dimensional gel electrophoresis coupled to mass spectrometry (2D-PAGE/MS).

RESULTS

Seventeen protein spots were found to be over-expressed and eight were under-expressed in cancerous tissue compared to the normal counterpart. Of these, annexin A2 and ezrin were validated by Western blot. We also demonstrated by immunohistochemistry that POSTN is highly expressed in the neoplastic tissues examined. Among the differentially expressed proteins, we focused our attention on Chloride intracellular channel 1 (CLIC1).

CONCLUSION

The 2D-PAGE/MS-based proteomics appears an efficient approach in detecting and identifying differentially expressed proteins that might function as potential biomarkers and/or molecular targets for early cancer diagnosis and prognosis and that might contribute to a innovative therapeutic strategies in GSCC. However, further validation and functional studies are needed to confirm and to support these promising, still preliminary data.

KEY WORDS

Cancer biomarkers, Oral squamous cell carcinoma, Proteomics.

Annexin A2 in renal cell carcinoma: expression, function, and prognostic significance

OBJECTIVE

Renal cell carcinoma (RCC) is the most lethal genitourinary cancer and intrinsically resistant to chemotherapy, radiotherapy, and hormone therapy. Annexin A2 (Anxa2) is a calcium-dependent phospholipid-binding protein found on various cell types that plays multiple roles in regulating cellular functions. In RCC, Anxa2 expression was correlated with tumor differentiation, clinical outcomes, and the metastatic potential; however, the underlying mechanisms remain obscure. This study investigated the role of Anxa2 in regulating tumorigenesis of RCC.

MATERIALS AND METHODS

Commercial RCC tissue microarray arrays and a kidney cancer quantitative polymerase chain reaction array were used to examine Anxa2 by immunohistochemistry and real-time polymerase chain reaction analysis. Short hairpin (sh)RNA-based lentiviral system technology was used to evaluate the effects of manipulating Anxa2 expression on multiple malignant features of 2 RCC cell lines, A498 and 786-O, and its mechanisms.

RESULTS

(1) The Anxa2 expression level was generally elevated to varying degrees in RCC tissues. In adjacent noncancerous tissues, Anxa2 was mainly expressed in glomeruli and slightly expressed in the cytoplasm of proximal tubules. (2) An increased Anxa2 expression level was found in tissues of clear cell RCC, papillary RCC, and chromophobe RCC, and it was prominently expressed in cancer cell membranes. In addition, the Anxa2 expression level was correlated with poor prognosis. (3) Silencing Anxa2 expression suppressed the abilities of cell migration and invasion, but cell proliferation was less affected. (4) Diminished Anxa2 expression caused alterations in the cell polarity, disrupted the formation of actin filaments, and reduced CXCR4 expression. (5) Inhibition of the Rho/Rock axis restored silencing of Anxa2-mediated suppression of cell motility.

CONCLUSIONS

Overall, our study points out the regulatory function of Anxa2 in RCC cell motility and provides a molecular-based mechanism of Anxa2 positivity in the progression of RCC.

Impaired osteoblast differentiation in annexin A2- and -A5-deficient cells

Annexins are a class of calcium-binding proteins with diverse functions in the regulation of lipid rafts, inflammation, fibrinolysis, transcriptional programming and ion transport. Within bone, they are well-characterized as components of mineralizing matrix vesicles, although little else is known as to their function during osteogenesis. We employed shRNA to generate annexin A2 (AnxA2)- or annexin A5 (AnxA5)-knockdown pre-osteoblasts, and determined whether proliferation or osteogenic differentiation was altered in knockdown cells, compared to pSiren (Si) controls. We report that DNA content, a marker of proliferation, was significantly reduced in both AnxA2 and AnxA5 knockdown cells. Alkaline phosphatase expression and activity were also suppressed in AnxA2- or AnxA5-knockdown after 14 days of culture. The pattern of osteogenic gene expression was altered in knockdown cells, with Col1a1 expressed more rapidly in knock-down cells, compared to pSiren. In contrast, Runx2, Ibsp, and Bglap all revealed decreased expression after 14 days of culture. In both AnxA2- and AnxA5-knockdown, interleukin-induced STAT6 signaling was markedly attenuated compared to pSiren controls. These data suggest that AnxA2 and AnxA5 can influence bone formation via regulation of osteoprogenitor proliferation, differentiation, and responsiveness to cytokines in addition to their well-studied function in matrix vesicles.