Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease with limited treatment methods. Long non-coding RNAs (lncRNAs) have been found involved in tumorigenic and progression. The present study revealed that LINC01133, a fewly reported lncRNA, was one of 16 hub genes that could predict PDAC patients\' prognosis. LINC01133 was over-expressed in PDAC tumors compared to adjacent pancreas and could promote PDAC proliferation and metastasis in vitro and in vivo, as well as inhibit PDAC apoptosis. LINC01133 expression positively correlated to secreted phosphoprotein 1 (SPP1) expression, leading to an enhanced epithelial-mesenchymal transition (EMT) process. LINC01133 bound with actin-related protein 3 (Arp3), the complex reduced SPP1 mRNA degradation which increased SPP1 mRNA level, ultimately leading to PDAC proliferation. This research revealed a novel mechanism of PDAC development and provided a potential prognosis indicator that may benefit PDAC patients.

Mammalian target of rapamycin (mTOR) is a crucial signaling protein regulating a range of cellular events. Numerous studies have reported that the mTOR pathway is related to spermatogenesis in mammals. However, its functions and underlying mechanisms in crustaceans remain largely unknown. mTOR exists as two multimeric functional complexes termed mTOR complex 1 (mTORC1) and mTORC2. Herein, we first cloned ribosomal protein S6 (rpS6, a downstream molecule of mTORC1) and protein kinase C (PKC, a downstream effector of mTORC2) from the testis of Eriocheir sinensis. The dynamic localization of rpS6 and PKC suggested that both proteins may be essential for spermatogenesis. rpS6/PKC knockdown and Torin1 treatment led to defects in spermatogenesis, including germ cell loss, retention of mature sperm and empty lumen formation. In addition, the integrity of the testis barrier (similar to the blood-testis barrier in mammals) was disrupted in the rpS6/PKC knockdown and Torin1 treatment groups, accompanied by changing in expression and distribution of junction proteins. Further study demonstrated that these findings may result from the disorganization of filamentous actin (F-actin) networks, which were mediated by the expression of actin-related protein 3 (Arp3) rather than epidermal growth factor receptor pathway substrate 8 (Eps8). In summary, our study illustrated that mTORC1/rpS6 and mTORC2/PKC regulated spermatogenesis via Arp3-mediated actin microfilament organization in E. sinensis.

The actin 2/3 complex (Arp2/3) regulates actin polymerization and nucleation of actin filaments, is associated with cell motility, and has been shown to play a key role in the invasion and migration of cancer cells. nucleation-promoting factor (NPF) such as N-WASP (neural-WASP famly verprolin-homologous protein family), WAVE (WASP famly verprolin-homologous protein family), and WASH (WASP and Scar homologue) undergo conformational changes upon receipt of multiple upstream signals including Rho family GTPases, cdc42 (Cell division control protein 42 homolog), and phosphatidylinositol 4,5-bisphosphate (PtdIns 4,5 P2) to bind and activate the Arp2/3 complex. Once activated, the Arp2/3 complex forms actin-based membrane protrusions necessary for cancer cells to acquire an invasive phenotype. Therefore, how to influence the invasion and migration of cancer cells by regulating the activity of the Arp2/3 complex has attracted great research interest in recent years. Several studies have explored the effects of phosphorylation modifications of cortactin and several NPFs (Nucleation Promoting Factor) including N-WASP and WAVE on the activity of the Arp2/3 complex and ultimately on cancer cell invasiveness, and have attempted to suggest new strategies for antiinvasive therapy as a result. Other studies have highlighted the potential of targeting genes encoding partial or complete proteins of the Arp2/3 complex as a therapeutic strategy to prevent cancer cell invasion and metastasis. This article reviews the role of the Arp2/3 complex in the development, invasion, and metastasis of different types of cancer and the mechanisms regulating the activity of the Arp2/3 complex.

Spermatogenesis is a complicated process that includes spermatogonia differentiation, spermatocytes meiosis, spermatids spermiogenesis and final release of spermatozoa. Actin-related protein 3 (Arp3) and epidermal growth factor receptor pathway substrate 8 (Eps8) are two actin binding proteins that regulate cell adhesion in seminiferous tubules during mammalian spermatogenesis. However, the functions of these two proteins during spermatogenesis in nonmammalian species, especially Crustacea, are still unknown. Here, we cloned es-Arp3 and es-Eps8 from the testis of Chinese mitten crab Eriocheir sinensis. es-Arp3 and es-Eps8 were located in spermatocytes, spermatids and spermatozoa. Knockdown of es-Arp3 and es-Eps8 in vivo caused morphological changes to seminiferous tubules including delayed spermatozoa release, shedding of germ cells and vacuoles. Filamentous-actin (F-actin) filaments network was disorganized due to deficiency of es-Arp3 and es-Eps8. Accompanying this, four junctional proteins (α-catenin, β-catenin, pinin and ZO1) displayed abnormal expression levels as well as penetrating biotin signals in seminiferous tubules. We also used the Arp2/3 complex inhibitor CK666 to block es-Arp3 activity and supported es-Arp3 knockdown results. In summary, our study demonstrated for the first time that es-Arp3 and es-Eps8 are important for spermatogenesis via regulating microfilament-mediated cell adhesion in Eriocheir sinensis.

Obesity is a major health crisis in the modern society. Studies have shown that the consumption of a high-fat diet (HFD) induces hypothalamic inflammation and leptin resistance, which consequently favours body mass gain. Actin related protein 2/3 complex subunit 1 (ARPC1B), an actin-binding protein, is highly expressed in immune cells. Recent studies have shown that ARPC1B has a certain anti-inflammatory effect. While ARPC1B expression is decreased in the hypothalamus of mice fed a HFD, the role of ARPC1B in HFD-induced obesity remains unclear. Thus, we investigated whether ARPC1B up-regulation in the hypothalamic arcuate nucleus (ARC) could inhibit the development of obesity. Herein, ARPC1B overexpression lentiviral particles were stereotaxically injected into the ARC of male C57BL/6J mice (7 weeks old) fed with HFD. Overexpression of ARPC1B in the hypothalamic ARC attenuated HFD-induced ARC inflammation, reduced body-weight gain and feed efficiency. Furthermore, up-regulation of ARC ARPC1B improved the glucose tolerance and reduced subcutaneous/epididymal fat mass accumulation, which decreased the serum total cholesterol, serum triglyceride and leptin levels. In addition, upon ARPC1B overexpression in the hypothalamic ARC, intraperitoneal injection of leptin increased the phosphorylation level of signal transducer and activator of transcription 3 (STAT3), an important transcription factor for leptin\'s action, in the ARC of obese mice. Accordingly, we suggest that up-regulation of ARPC1B in the hypothalamic ARC may improve the HFD-induced hypothalamic inflammation and leptin resistance. Our findings demonstrate that ARPC1B is a promising target for the treatment of diet-induced obesity.

The blood-brain barrier (BBB) is critical to maintaining central nervous system (CNS) homeostasis. However, the effects of microgravity (MG) on the BBB remain unclear. This study aimed to investigate the influence of simulated MG (SMG) on the BBB and explore its potential mechanism using a proteomic approach. Rats were tail-suspended to simulate MG for 21 days. SMG could disrupt the BBB, including increased oxidative stress levels, proinflammatory cytokine levels, and permeability, damaged BBB ultrastructure, and downregulated tight junctions (TJs) and adherens junctions (AJs) protein expression in the rat brain. A total of 554 differentially expressed proteins (DEPs) induced by SMG were determined based on the label-free quantitative proteomic strategy. The bioinformatics analysis suggested that DEPs were mainly enriched in regulating the cell-cell junction and cell-extracellular matrix biological pathways. The inhibited Ras-related C3 botulinum toxin substrate 1 (Rac1)/Wiskott-Aldrich syndrome protein family verprolin-homologous protein 2 (Wave2)/actin-related protein 3 (Arp3) pathway and the decreased ratio of filamentous actin (F-actin) to globular actin contributed to BBB dysfunction induced by SMG. In the human brain microvascular endothelial cell (HBMECs), SMG increased the oxidative stress levels and proinflammatory cytokine levels, promoted apoptosis, and arrested the cell cycle phase. Expression of TJs and AJs proteins were downregulated and the distribution of F-actin was altered in SMG-treated HBMECs. The key role of the Rac1/Wave2/Arp3 pathway in BBB dysfunction was confirmed in HBMECs with a specific Rac1 agonist. This study demonstrated that SMG induced BBB dysfunction and revealed that Rac1/Wave2/Arp3 could be a potential signaling pathway responsible for BBB disruption under SMG. These results might shed a novel light on maintaining astronaut CNS homeostasis during space travel.

Transendothelial migration (TEM) of neutrophils under blood flow is critical in the inflammatory cascade. However, the role of endothelial plasticity in this process is not fully understood. Therefore, we used an in vitro model to test the dynamics of human polymorphonuclear neutrophil (PMN) TEM across lipopolysaccharide-treated human umbilical vein endothelial cell (HUVEC) monolayers. Interestingly, shRNA-E-selectin knockdown in HUVECs destabilized endothelial junctional integrity by reducing actin branching and increasing stress fiber at cell-cell junctions. This process is accomplished by downregulating the activation of cortactin and Arp2/3, which in turn alters the adhesive function of VE-cadherin, enhancing PMN transmigration. Meanwhile, redundant P-selectins possess overlapping functions in E-selectin-mediated neutrophil adhesion, and transmigration. These results demonstrate, to our knowledge, for the first time, that E-selectins negatively regulate neutrophil transmigration through alterations in endothelial plasticity. Furthermore, it improves our understanding of the mechanisms underlying actin remodeling, and junctional integrity, in endothelial cells mediating leukocyte TEM.

The actin cytoskeleton is extremely dynamic and supports diverse cellular functions in many physiological and pathological processes, including tumorigenesis. However, the mechanisms that regulate the actin-related protein 2/3 (ARP2/3) complex and thereby promote actin polymerization and organization in cancer cells are not well-understood. We previously implicated the proline-rich 11 (PRR11) protein in lung cancer development. In this study, using immunofluorescence staining, actin polymerization assays, and siRNA-mediated gene silencing, we uncovered that cytoplasmic PRR11 is involved in F-actin polymerization and organization. We found that dysregulation of PRR11 expression results in F-actin rearrangement and nuclear instability in non-small cell lung cancer cells. Results from molecular mechanistic experiments indicated that PRR11 associates with and recruits the ARP2/3 complex, facilitates F-actin polymerization, and thereby disrupts the F-actin cytoskeleton, leading to abnormal nuclear lamina assembly and chromatin reorganization. Inhibition of the ARP2/3 complex activity abolished irregular F-actin polymerization, lamina assembly, and chromatin reorganization due to PRR11 overexpression. Notably, experiments with truncated PRR11 variants revealed that PRR11 regulates F-actin through different regions. We found that deletion of either the N or C terminus of PRR11 abrogates its effects on F-actin polymerization and nuclear instability and that deletion of amino acid residues 100-184 or 100-200 strongly induces an F-actin structure called the actin comet tail, not observed with WT PRR11. Our findings indicate that cytoplasmic PRR11 plays an essential role in regulating F-actin assembly and nuclear stability by recruiting the ARP2/3 complex in human non-small cell lung carcinoma cells.

The blood-testis barrier (BTB) separates the seminiferous epithelium into the apical and basal compartments. The BTB has to operate timely and accurately to ensure the correct migration of germ cells, meanwhile maintaining the immunological barrier. Testin was first characterized from primary Sertoli cells, it is a secretory protein and a sensitive biomarker to monitor junctions between Sertoli and germ cells. Till now, the functions of testin on BTB dynamics and the involving mechanisms are unknown. Herein, testin acts as a regulatory protein on BTB integrity. In vitro testin knockdown by RNAi caused significant damage to the Sertoli cell barrier with no apparent changes in the protein levels of several major tight junction (TJ), adhesion junction, and gap junction proteins. Also, testin RNAi caused the diffusion of two TJ structural proteins, occludin and ZO-1, diffusing away from the Sertoli cell surface into the cytoplasm. Association and colocalization between ZO-1 and occludin were decreased after testin RNAi, examined by Co-IP and coimmunofluorescent staining, respectively. Furthermore, testin RNAi induced a dramatic disruption on the arrangement of actin filament bundles and a reduced F-actin/G-actin ratio. The actin regulatory protein ARP3 appeared at the Sertoli cell interface after testin RNAi without its protein level change, whereas overexpressing testin in Sertoli cells showed no effect on TJ barrier integrity. The above findings suggest that besides as a monitor for Sertoli-germ cell junction integrity, testin is also an essential molecule to maintain Sertoli-Sertoli junctions.

The identification of tumor-associated antigens (TAAs) and their corresponding autoantibodies in lung cancer (LC) may expand our vision of cancer immunity. This study aims to screen novel TAAs to distinguish LC from the healthy population.
In our previous study, 35 genes encoding LC-associated TAAs were identified from the serological analysis of recombinant cDNA expression libraries (SEREX), and Oncomine database was further used to identify potential genes in cancer progression. Autoantibody to TAAs were tested by enzyme-linked immunosorbent assay (ELISA) in sera from 1379 participants in validation set and verification set.
Based on analysis of three independent microarrays in Oncomine, ten genes were consistently dysregulated in LC. The sera level and positive frequency of the anti-TOP2A, anti-ACTR3, anti-RPS6KA5 and anti-PSIP1 from LC patients were higher than normal control in validation set. The area under curve (AUC) of anti-TOP2A, anti-ACTR3, anti-RPS6KA5 and anti-PSIP1 was respectively 0.758, 0.787, 0.707, 0.668. The sensitivity of these four autoantibodies for LC detection ranged from 26.63 % to 32.07 % with the specificity over 90 %. Data from the verification set confirmed the results. Except that, the frequency of serum autoantibody against TOP2A (43.3 %) and ACTR3 (50.0 %) was significantly higher in early stage LC than late stage (23.6 % and 22.3 %, respectively).
TOP2A, ACTR3, RPS6KA5 and PSIP1 can elicit humoral immune response in LC and their autoantibodies have relationship with the tumorigenesis of LC. Anti-TOP2A and anti-ACTR3 have the potential to serve as a serological biomarkers in early stage LC.