Integrin signaling and cell growth control

β1 Integrin/FAK signaling regulates interleukin-8 production in human gingival epithelial Ca9-22 cells

OBJECTIVES

Interleukin-8 (IL-8), a proinflammatory factor in human tissues, plays an important role in inflammation. Type IV collagen, a key component of the basement membrane, interacts with integrins, which are primary receptors in the extracellular matrix (ECM). Integrins are essential for the regulation of various cellular behaviors and signal transduction pathways. However, the relationship between type IV collagen, β1 integrin, and gingival epithelial cells is poorly understood. The aim in this study was to elucidate the effect of the interaction between type IV collagen and β1 integrin on IL-8 secretion in human gingival epithelial cells (Ca9-22).

METHODS

Ca9-22 cells were treated with or without type IV collagen, and IL-8 production was assessed using an enzyme-linked immunosorbent assay (ELISA). The role of β1 integrin was investigated using a β1 integrin-neutralizing antibody. Western blotting was performed to measure the phosphorylation levels of the relevant proteins. The effects of the focal adhesion kinase (FAK) inhibitor Y15 and the MEK inhibitor U0126 on β1 integrin/FAK and Erk1/2 MAPK pathways in IL-8 production were evaluated to explore the involvement of these signaling pathways.

RESULTS

β1 integrin induced IL-8 secretion in the Ca9-22 cells by regulating FAK, Erk1/2, and p130Cas proteins. p130Cas was independent of FAK, whereas Erk1/2 functioned downstream of FAK. Inhibition of FAK or Erk1/2 substantially reduced IL-8 secretion, highlighting their pivotal roles in this signaling pathway.

CONCLUSION

β1 integrin promotes IL-8 secretion in Ca9-22 cells via the β1 integrin/FAK/Erk1/2 signaling pathway. These findings elucidate the pathogenesis of periodontitis and provide a foundation for the development of targeted therapeutic strategies.

The Effect of Synthetic Polyamine BPA-C8 on the Fertilization Process of Intact and Denuded Sea Urchin Eggs

Sea urchin eggs are covered with layers of extracellular matrix, namely, the vitelline layer (VL) and jelly coat (JC). It has been shown that sea urchin eggs' JC components serve as chemoattractants or ligands for the receptor on the fertilizing sperm to promote the acrosome reaction. Moreover, the egg's VL provides receptors for conspecific sperm to bind, and, to date, at least two sperm receptors have been identified on the surface of sea urchin eggs. Interestingly, however, according to our previous work, denuded sea urchin eggs devoid of the JC and VL do not fail to become fertilized by sperm. Instead, they are bound and penetratedby multiple sperm, raising the possibility that an alternative pathway independent of the VL-residing sperm receptor may be at work. In this research, we studied the roles of the JC and VL using intact and denuded eggs and the synthetic polyamine BPA-C8. BPA-C8 is known to bind to the negatively charged macromolecular complexes in the cells, such as the JC, VL, and the plasma membrane of echinoderm eggs, as well as to the actin filaments in fibroblasts. Our results showed that, when added to seawater, BPA-C8 significantly repressed the Ca2+ wave in the intact P. lividus eggs at fertilization. In eggs deprived of the VL and JC, BPA-C8 binds to the plasma membrane and increases fibrous structures connecting microvilli, thereby allowing the denuded eggs to revert towards monospermy at fertilization. However, the reduced Ca2+ signal in denuded eggs was nullified compared to the intact eggs because removing the JC and VL already decreased the Ca2+ wave. BPA-C8 does not cross the VL and the cell membrane of unfertilized sea urchin eggs to diffuse into the cytoplasm at variance with the fibroblasts. Indeed, the jasplakinolide-induced polymerization of subplasmalemmal actin filaments was inhibited in the eggs microinjected with BPA-C8, but not in the ones bath-incubated with the same dose of BPA-C8.

Protein Kinase A is a Functional Component of Focal Adhesions

Focal adhesions (FAs) form the junction between extracellular matrix (ECM)-bound integrins and the actin cytoskeleton and also transmit signals that regulate cell adhesion, cytoskeletal dynamics, and cell migration. While many of these signals are rooted in reversible tyrosine phosphorylation, phosphorylation of FA proteins on Ser/Thr residues is far more abundant yet its mechanisms and consequences are far less understood. The cAMP-dependent protein kinase (protein kinase A; PKA) has important roles in cell adhesion and cell migration and is both an effector and regulator of integrin-mediated adhesion to the ECM. Importantly, subcellular localization plays a critically important role in specifying PKA function. Here, we show that PKA is present in isolated FA-cytoskeleton complexes and active within FAs in live cells. Furthermore, using kinase-catalyzed biotinylation of isolated FA-cytoskeleton complexes, we identify fifty-three high-stringency candidate PKA substrates within FAs. From this list, we validate tensin-3 (Tns3) - a well-established molecular scaffold, regulator of cell migration, and component of focal and fibrillar adhesions - as a novel direct substrate for PKA. These observations identify a new pathway for phospho-regulation of Tns3 and, importantly, establish a new and important niche for localized PKA signaling and thus provide a foundation for further investigation of the role of PKA in the regulation of FA dynamics and signaling.

Talin-1 inhibits Smurf1-mediated Stat3 degradation to modulate β-cell proliferation and mass in mice

Insufficient pancreatic β-cell mass and reduced insulin expression are key events in the pathogenesis of diabetes mellitus (DM). Here we demonstrate the high expression of Talin-1 in β-cells and that deficiency of Talin-1 reduces β-cell proliferation, which leads to reduced β-cell mass and insulin expression, thus causing glucose intolerance without affecting peripheral insulin sensitivity in mice. High-fat diet fed exerbates these phenotypes. Mechanistically, Talin-1 interacts with the E3 ligase smad ubiquitination regulatory factor 1 (Smurf1), which prohibits ubiquitination of the signal transducer and activator of transcription 3 (Stat3) mediated by Smurf1, and ablation of Talin-1 enhances Smurf1-mediated ubiquitination of Stat3, leading to decreased β-cell proliferation and mass. Furthermore, haploinsufficiency of Talin-1 and Stat3 genes, but not that of either gene, in β-cell in mice significantly impairs glucose tolerance and insulin expression, indicating that both factors indeed function in the same genetic pathway. Finally, inducible deletion Talin-1 in β-cell causes glucose intolerance in adult mice. Collectively, our findings reveal that Talin-1 functions as a crucial regulator of β-cell mass, and highlight its potential as a therapeutic target for DM patients.

Glycoproteomic analysis of regulatory effects of bisecting N-glycans on N-glycan biosynthesis and protein expressions in human HK-2 cells

Bisecting N-glycan is known to be a metastasis suppressor and plays a regulatory role in the biosynthesis of N-glycans. Previous studies have shown that bisecting N-glycans are capable of modulating both the branching and terminal modifications of glycans. However, these effects have been investigated mainly by glycomic approaches and it remains unclear how they alter when glycans are attached to different glycosites of proteins. Here, we systematically investigated the regulatory roles of bisecting N-glycans in human HK-2 cells using StrucGP, a strategy we developed for structural interpretation of site-specific N-glycans on glycoproteins. The glycoproteomics analysis showed that most of bisecting N-glycans are complex type and often occur in company with core fucosylation. With the overexpression and knockdown of MGAT3, the only enzyme responsible for bisecting N-glycan synthesis, we found that bisecting N-glycans can impact the biosynthesis of N-glycans from multiple aspects, including glycan types, branching, sialylation, fucosylation (different effects for core and terminal fucosylation) as well as the presence of terminal N-acetylglucosamine. Furthermore, gene ontology analysis suggested that most proteins with bisecting N-glycans located in the extracellular region or membrane, where they function mostly in cell adhesion, extracellular matrix regulation and cell signaling. Finally, we showed that overexpression of bisecting N-glycans had a broad impact on the protein expressions of HK-2 cells, involving multiple biological processes. Taken together, our work systematically demonstrated the expression profiles of bisecting N-glycans, and their regulatory effects on the biosynthesis of N-glycans and protein expressions, which provide valuable information for the functional elucidation of bisecting N-glycans.

Endostatin 33 Peptide Is a Deintegrin α6β1 Agent That Exerts Antitumor Activity by Inhibiting the PI3K-Akt Signaling Pathway in Prostate Cancer

BACKGROUND

Prostate cancer (PCa) is the leading cause of death in men and has poor therapeutic outcomes.

METHODS

A novel endostatin 33 peptide was synthesized by adding a specific QRD sequence on the basis of the endostatin 30 peptide (PEP06) with antitumor activity. Then, bioinformatic analysis and subsequent experiments were performed to validate the antitumor function of this endostatin 33 peptide.

RESULTS

We found that the 33 polypeptides significantly inhibited growth, invasion and metastasis and promoted the apoptosis of PCa in vivo or vitro, which is more significant than PEP06 under the same conditions. According to 489 cases from the TCGA data portal, the α6β1 high expression group was closely associated with the poor prognosis (Gleason score, pathological N stage, etc.) of PCa and was mainly enriched in the PI3K-Akt pathway. Subsequently, we demonstrated that endostatin 33 peptide can down-regulate the PI3K-Akt pathway via the targeted inhibition of α6β1, thereby inhibiting the epithelial-mesenchymal transition and matrix metalloproteinase in C42 cell lines.

CONCLUSION

The endostatin 33 peptide can exert antitumor effects by inhibiting the PI3K-Akt pathway, especially in tumors with a high expression of the integrin α6β1 subtype, such as prostate cancer. Therefore, our study will provide a new method and theoretical basis for the treatment of prostate cancer.

Non-Parenchymal Cells and the Extracellular Matrix in Hepatocellular Carcinoma in Non-Alcoholic Fatty Liver Disease

Hepatocellular carcinoma (HCC) in the setting of non-alcoholic fatty liver disease (NAFLD)-related cirrhosis and even in the pre-cirrhotic state is increasing in incidence. NAFLD-related HCC has a poor clinical outcome as it is often advanced at diagnosis due to late diagnosis and systemic treatment response is poor due to reduced immune surveillance. Much of the focus of molecular research has been on the pathological changes in hepatocytes; however, immune cells, hepatic stellate cells, liver sinusoidal endothelial cells and the extracellular matrix may play important roles in the pathogenesis of NAFLD-related HCC as well. Here, we review the role of non-parenchymal cells in the liver in the pathogenesis of HCC in the context of NAFLD-NASH, with a particular focus on the innate and the adaptive immune system, fibrogenesis and angiogenesis. We review the key roles of macrophages, hepatic stellate cells (HSCs), T cells, natural killer (NK) cells, NKT cells and liver sinusoidal endothelial cells (LSECs) and the role of the extracellular matrix in hepatocarcinogenesis within the steatotic milieu.

How Mechanical and Physicochemical Material Characteristics Influence Adipose-Derived Stem Cell Fate

Adipose-derived stem cells (ASCs) are a subpopulation of mesenchymal stem cells. Compared to bone marrow-derived stem cells, they can be harvested with minimal invasiveness. ASCs can be easily expanded and were shown to be able to differentiate into several clinically relevant cell types. Therefore, this cell type represents a promising component in various tissue engineering and medical approaches (e.g., cell therapy). In vivo cells are surrounded by the extracellular matrix (ECM) that provides a wide range of tissue-specific physical and chemical cues, such as stiffness, topography, and chemical composition. Cells can sense the characteristics of their ECM and respond to them in a specific cellular behavior (e.g., proliferation or differentiation). Thus, in vitro biomaterial properties represent an important tool to control ASCs behavior. In this review, we give an overview of the current research in the mechanosensing of ASCs and current studies investigating the impact of material stiffens, topography, and chemical modification on ASC behavior. Additionally, we outline the use of natural ECM as a biomaterial and its interaction with ASCs regarding cellular behavior.

Cell-adhesion Molecules as Key Mechanisms of Tumor Invasion: The Case of Breast Cancer

Cancer is a major health problem worldwide and the second leading cause of death following cardiovascular diseases. Breast cancer is the leading cause of mortality and morbidity among women and one of the most common malignant neoplasms prompt to metastatic disease. In the present review, the mechanisms of the major cell adhesion molecules involved in tumor invasion are discussed, focusing on the case of breast cancer. A non-systematic updated revision of the literature was performed in order to assemble information regarding the expression of the adhesion cell molecules associated with metastasis.

Amyloid precursor protein (APP) and amyloid β (Aβ) interact with cell adhesion molecules: Implications in Alzheimer’s disease and normal physiology

Alzheimer’s disease (AD) is an incurable neurodegenerative disorder in which dysfunction and loss of synapses and neurons lead to cognitive impairment and death. Accumulation and aggregation of neurotoxic amyloid-β (Aβ) peptides generated via amyloidogenic processing of amyloid precursor protein (APP) is considered to play a central role in the disease etiology. APP interacts with cell adhesion molecules, which influence the normal physiological functions of APP, its amyloidogenic and non-amyloidogenic processing, and formation of Aβ aggregates. These cell surface glycoproteins also mediate attachment of Aβ to the neuronal cell surface and induce intracellular signaling contributing to Aβ toxicity. In this review, we discuss the current knowledge surrounding the interactions of cell adhesion molecules with APP and Aβ and analyze the evidence of the critical role these proteins play in regulating the processing and physiological function of APP as well as Aβ toxicity. This is a necessary piece of the complex AD puzzle, which we should understand in order to develop safe and effective therapeutic interventions for AD.

The Dual Functions of a Bracovirus C-Type Lectin in Caterpillar Immune Response Manipulation

Parasitoids are widespread in natural ecosystems and normally equipped with diverse viral factors to defeat host immune responses. On the other hand, parasitoids can enhance the antibacterial abilities and improve the hypoimmunity traits of parasitized hosts that may encounter pathogenic infections. These adaptive strategies guarantee the survival of parasitoid offspring, yet their underlying mechanisms are poorly understood. Here, we focused on Cotesia vestalis, an endoparasitoid of the diamondback moth Plutella xylostella, and found that C. vestalis parasitization decreases the number of host hemocytes, leading to disruption of the encapsulation reaction. We further found that one bracovirus C-type lectin gene, CvBV_28-1, is highly expressed in the hemocytes of parasitized hosts and participates in suppressing the proliferation rate of host hemocytes, which in turn reduces their population and represses the process of encapsulation. Moreover, CvBV_28-1 presents a classical bacterial clearance ability via the agglutination response in a Ca²⁺-dependent manner in response to gram-positive bacteria. Our study provides insights into the innovative strategy of a parasitoid-derived viral gene that has dual functions to manipulate host immunity for a successful parasitism.

Tensin 2-deficient nephropathy - mechanosensitive nephropathy, genetic susceptibility

Tensin 2 (TNS2), a focal adhesion protein, is considered to anchor focal adhesion proteins to β integrin as an integrin adaptor protein and/or serve as a scaffold to facilitate the interactions of these proteins. In the kidney, TNS2 localizes to the basolateral surface of glomerular epithelial cells, i.e., podocytes. Loss of TNS2 leads to the development of glomerular basement membrane lesions and abnormal accumulation of extracellular matrix in maturing glomeruli during the early postnatal stages. It subsequently results in podocyte foot process effacement, eventually leading to glomerulosclerosis. Histopathological features of the affected glomeruli in the middle stage of the disease include expansion of the mesangial matrix without mesangial cell proliferation. In this review, we provide an overview of TNS2-deficient nephropathy and discuss the potential mechanism underlying this mechanosensitive nephropathy, which may be applicable to other glomerulonephropathies, such as CD151-deficient nephropathy and Alport syndrome. The onset of TNS2-deficient nephropathy strictly depends on the genetic background, indicating the presence of critical modifier genes. A better understanding of molecular mechanisms of mechanosensitive nephropathy may open new avenues for the management of patients with glomerulonephropathies.

Effects of forces on chromatin

Chromatin is a unique structure of DNA and histone proteins in the cell nucleus and the site of dynamic regulation of gene expression. Soluble factors are known to affect the chromatin structure and function via activating or inhibiting specific transcription factors. Forces on chromatin come from exogenous stresses on the cell surface and/or endogenous stresses, which are regulated by substrate mechanics, geometry, and topology. Forces on chromatin involve direct (via adhesion molecules, cytoskeleton, and the linker of nucleoskeleton and cytoskeleton complexes) and indirect (via diffusion and/or translocation processes) signaling pathways to modulate levels of chromatin folding and deformation to regulate transcription, which is controlled by histone modifications and depends on magnitude, direction, rate/frequency, duration, and modes of stresses. The rapid force transmission pathway activates multiple genes simultaneously, and the force may act like a "supertranscription factor." The indirect mechanotransduction pathways and the rapid force transmission pathway together exert sustained impacts on the chromatin, the nucleus, and cell functions.

Pinch Loss Ameliorates Obesity, Glucose Intolerance, and Fatty Liver by Modulating Adipocyte Apoptosis in Mice

The mammalian focal adhesion proteins Pinch1/2 activate integrins and promote cell-extracellular matrix adhesion and migration; however, their roles in adipose tissue and metabolism are unclear. Here we find that high-fat diet (HFD) feeding dramatically increases expression of Pinch1/2 proteins in white adipose tissue (WAT) in mice. Furthermore, expression of Pinch1 is largely upregulated in WAT in leptin-deficient ob/ob type 2 diabetic mice and obese humans. While mice with loss of Pinch1 in adipocytes or global Pinch2 do not display any notable phenotypes, deleting Pinch1 in adipocytes and Pinch2 globally significantly decreases body weight and WAT mass, but not brown adipose tissue mass, in HFD-fed, but not normal chow diet-fed, mice. Pinch loss ameliorates HFD-induced glucose intolerance and fatty liver. After HFD challenge, Pinch loss slightly but significantly accelerates energy expenditure. While Pinch loss decreases adipocyte size and alters adipocyte size distribution, it greatly accelerates cell apoptosis primarily in epididymal WAT and to a lesser extent in subcutaneous WAT. In vitro studies demonstrate that Pinch loss accelerates adipocyte apoptosis by activating the Bim/Caspase-8 pathway. In vivo, genetic ablation of Caspase-8 expression in adipocytes essentially abolishes the ameliorating effects of Pinch deficiency on obesity, glucose intolerance, and fatty liver in mice. Thus, we demonstrate a previously unknown function of Pinch in control of adipose mass, glucose, and fat metabolism via modulation of adipocyte apoptosis. We may define a novel target for the prevention and treatment of metabolic diseases, such as obesity and diabetes.

Genomic signatures of artificial selection in the Pacific oyster, Crassostrea gigas

The Pacific oyster, Crassostrea gigas, is an important aquaculture shellfish around the world with great economic and ecological value. Selective breeding programs have been carried out globally to improve production and performance traits, while genomic signatures of artificial selection remain largely unexplored. In China, we performed selective breeding of C. gigas for over a decade, leading to production of several fast‐growing strains. In the present study, we conducted whole‐genome resequencing of 20 oysters from two fast‐growing strains that have been successively selected for 10 generations, and 20 oysters from the two corresponding wild populations. Sequencing depth of >10× was achieved for each sample, leading to identification of over 12.20 million SNPs. The population structures investigated with three independent methods (principal component analysis, phylogenetic tree, and structure) suggested distinct patterns among selected and wild oyster populations. Assessment of the linkage disequilibrium (LD) decay clearly indicated the changes in genetic diversity during selection. Fixation index (F_st) combined with cross‐population composite likelihood ratio (XP‐CLR) allowed for identification of 768 and 664 selective sweeps (encompassing 1042 and 872 genes) tightly linked to selection in the two fast‐growing strains. KEGG enrichment and functional analyses revealed that 33 genes are important for growth regulation, which act as key components of various signaling pathways with close connection and further take part in regulating the process of cell cycle. This work provides valuable information for the understanding of genomic signatures for long‐term selective breeding and will also be important for growth study and genome‐assisted breeding of the Pacific oyster in the future.

Poly(lactide-co-ε-caprolactone) scaffold promotes equivalent tissue integration and supports skin grafts compared to a predicate collagen scaffold

Dermal scarring from motor vehicle accidents, severe burns, military blasts, etc. is a major problem affecting over 80 million people worldwide annually, many of whom suffer from debilitating hypertrophic scar contractures. These stiff, shrunken scars limit mobility, impact quality of life, and cost millions of dollars each year in surgical treatment and physical therapy. Current tissue engineered scaffolds have mechanical properties akin to unwounded skin, but these collagen-based scaffolds rapidly degrade over 2 months, premature to dampen contracture occurring 6-12 months after injury. This study demonstrates a tissue engineered scaffold can be manufactured from a slow-degrading viscoelastic copolymer, poly(ι-lactide-co-ε-caprolactone), with physical and mechanical characteristics to promote tissue ingrowth and support skin-grafts. Copolymers were synthesized via ring-opening polymerization. Solvent casting/particulate leaching was used to manufacture 3D porous scaffolds by mixing copolymers with particles in an organic solvent followed by casting into molds and subsequent particle leaching with water. Scaffolds characterized through SEM, micro-CT, and tensile testing confirmed the required thickness, pore size, porosity, modulus, and strength for promoting skin-graft bioincorporation and dampening fibrosis in vivo. Scaffolds were Oxygen Plasma Treatment and collagen coated to encourage cellular proliferation. Porosity ranging from 70% to 90% was investigated in a subcutaneous murine model and found to have no clinical effect on tissue ingrowth. A swine full-thickness skin wound model confirmed through histology and Computer Planimetry that scaffolds promote skin-graft survival, with or without collagen coating, with equal safety and efficacy as a commercially available tissue engineered scaffold. This study validates a scalable method to create poly(ι-lactide-co-ε-caprolactone) scaffolds with appropriate characteristics and confirms in mouse and swine wound models that the scaffolds are safe and effective at supporting skin-grafts. The results of this study have brought us closer towards developing an alternative technology that supports skin grafts with the potential to investigate long-term hypertrophic scar contractures.

The epidermis-specific cyclin CYCP3;1 is involved in the excess brassinosteroid signaling-inhibited root meristem cell division

Cell division is precisely regulated and highly tissue-specific; studies have suggested that diverse signals in the epidermis, especially the epidermal brassinosteroids (BRs), can regulate root growth. However, the underlying molecular mechanisms that integrate hormonal cues such as BR signaling with other endogenous, tissue-specific developmental programs to regulate epidermal cell proliferation remain unclear. In this study, we used molecular and biochemical approaches, microscopic imaging and genetic analysis to investigate the function and mechanisms of a P-type cyclin in root growth regulation. We found that CYCP3;1, specifically expressed in the root meristem epidermis and lateral root cap, can regulate meristem cell division. Mitotic analyses and biochemical studies demonstrated that CYCP3;1 promotes cell division at the G2-M duration by associating and activating cyclin-dependent kinase B2-1 (CDKB2;1). Furthermore, we found that CYCP3;1 expression was inhibited by BR signaling through BRI1-EMS-SUPPRESSOR1 (BES1), a positive downstream transcription factor in the BR signaling pathway. These findings not only provide a mechanism of how root epidermal-specific regulators modulate root growth, but also reveal why the excess of BRs or enhanced BR signaling inhibits cell division in the meristem to negatively regulate root growth.

Cell-derived decellularized extracellular matrix scaffolds for articular cartilage repair

Articular cartilage repair remains a great clinical challenge. Tissue engineering approaches based on decellularized extracellular matrix (dECM) scaffolds show promise for facilitating articular cartilage repair. Traditional regenerative approaches currently used in clinical practice, such as microfracture, mosaicplasty, and autologous chondrocyte implantation, can improve cartilage repair and show therapeutic effect to some degree; however, the long-term curative effect is suboptimal. As dECM prepared by proper decellularization procedures is a biodegradable material, which provides space for regeneration tissue growth, possesses low immunogenicity, and retains most of its bioactive molecules that maintain tissue homeostasis and facilitate tissue repair, dECM scaffolds may provide a biomimetic microenvironment promoting cell attachment, proliferation, and chondrogenic differentiation. Currently, cell-derived dECM scaffolds have become a research hotspot in the field of cartilage tissue engineering, as ECM derived from cells cultured in vitro has many advantages compared with native cartilage ECM. This review describes cell types used to secrete ECM, methods of inducing cells to secrete cartilage-like ECM and decellularization methods to prepare cell-derived dECM. The potential mechanism of dECM scaffolds on cartilage repair, methods for improving the mechanical strength of cell-derived dECM scaffolds, and future perspectives on cell-derived dECM scaffolds are also discussed in this review.

Roles of Membrane Domains in Integrin-Mediated Cell Adhesion

The composition and organization of the plasma membrane play important functional and regulatory roles in integrin signaling, which direct many physiological and pathological processes, such as development, wound healing, immunity, thrombosis, and cancer metastasis. Membranes are comprised of regions that are thick or thin owing to spontaneous partitioning of long-chain saturated lipids from short-chain polyunsaturated lipids into domains defined as ordered and liquid-disorder domains, respectively. Liquid-ordered domains are typically 100 nm in diameter and sometimes referred to as lipid rafts. We posit that integrin β senses membrane thickness and that mechanical force on the membrane regulates integrin activation through membrane thinning. This review examines what we know about the nature and mechanism of the interaction of integrins with the plasma membrane and its effects on regulating integrins and its binding partners.

Recovery of Encapsulated Adult Neural Progenitor Cells from Microfluidic-Spun Hydrogel Fibers Enhances Proliferation and Neuronal Differentiation

Because of the limitations imposed by traditional two-dimensional (2D) cultures, biomaterials have become a major focus in neural and tissue engineering to study cell behavior in vitro. 2D systems fail to account for interactions between cells and the surrounding environment; these cell-matrix interactions are important to guide cell differentiation and influence cell behavior such as adhesion and migration. Biomaterials provide a unique approach to help mimic the native microenvironment in vivo. In this study, a novel microfluidic technique is used to encapsulate adult rat hippocampal stem/progenitor cells (AHPCs) within alginate-based fibrous hydrogels. To our knowledge, this is the first study to encapsulate AHPCs within a fibrous hydrogel. Alginate-based hydrogels were cultured for 4 days in vitro and recovered to investigate the effects of a 3D environment on the stem cell fate. Post recovery, cells were cultured for an additional 24 or 72 h in vitro before fixing cells to determine if proliferation and neuronal differentiation were impacted after encapsulation. The results indicate that the 3D environment created within a hydrogel is one factor promoting AHPC proliferation and neuronal differentiation (19.1 and 13.5%, respectively); however, this effect is acute. By 72 h post recovery, cells had similar levels of proliferation and neuronal differentiation (10.3 and 8.3%, respectively) compared to the control conditions. Fibrous hydrogels may better mimic the natural micro-environment present in vivo and be used to encapsulate AHPCs, enhancing cell proliferation and selective differentiation. Understanding cell behavior within 3D scaffolds may lead to the development of directed therapies for central nervous system repair and rescue.

Demystifying Circalunar and Diel Rhythmicity in Acropora digitifera under Constant Dim Light

Life on earth has evolved under constant environmental changes; in response to these changes, most organisms have developed an endogenous clock that allows them to anticipate daily and seasonal changes and adapt their biology accordingly. Light cycles synchronize biological rhythms and are controlled by an endogenous clock that is entrained by environmental cues. Light is known to play a key role in the biology of symbiotic corals as they exhibit many biological processes entrained by daily light patterns. In this study, we aimed at determining the effect of constant dim light on coral's perception of diel and monthly cycles. Our results show that under constant dim light corals display a loss of rhythmic processes and constant stimuli by light, which initiates signal transduction that results in an abnormal cell cycle, cell proliferation, and protein synthesis. The results emphasize how constant dim light can mask the biological clock of Acropora digitifera.

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Light entrains many biological processes governed by the endogenous clock

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Constant dim light overrides the biological clock of A. digitifera corals

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Artificial light impacts the processes that allow corals to thrive in our oceans

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The increase of artificial light in coastal areas is a growing threat to coral reefs

Establishment of human trabecular meshwork cell cultures using nontransplantable corneoscleral rims

Human trabecular meshwork (hTM) cell isolation in academic settings utilizes the motile nature of these cells, allowing them to migrate away from the explant and proliferate on distal regions of the culture substrate. Corneoscleral rims used for transplantation are a potential source of explants for the establishment of hTM cell cultures. However, cell isolation and the initiation of primary cell cultures from ocular tissues stored in Optisol-GS medium for an extended period of time (>6 days) has proven difficult, since Optisol-GS remarkably reduces cell viability and cellularity. Therefore, explants obtained from ocular tissues stored in Optisol-GS do not often provide adequate cell yield to initiate primary cell cultures if conventional culture techniques are used. Therefore, the majority of the research on primary hTM cell isolation has been accomplished using donor tissue obtained within 72 h postmortem. The goal of this study was to develop an hTM cell isolation procedure from nontransplantable ocular materials, utilizing the anchorage dependency of TM cells. This procedure yielded functionally viable cells, eficiently dissociated from the trabecular meshwork. Isolated cells demonstrated typical hTM cell characteristics including monolayer formation, contact inhibition, phagocytosis, and responses to glucocorticoid exposure. To the best of our knowledge, this is the first time an expired explant has been utilized in the successful isolation of hTM cells. Our results clearly demonstrate the advantage of increasing the anchor points of hTM cells for enhanced cell migration out from the explants, which have limited cell proliferative capacity.

Inhibitory effect of nintedanib on VEGF secretion in retinal pigment epithelial cells induced by exposure to a necrotic cell lysate

Necrosis is a form of cell death that results in rupture of the plasma membrane and the release of cellular contents, and it can give rise to sterile inflammation in the retina and other tissues. The secretion of vascular endothelial growth factor (VEGF) by retinal pigment epithelial (RPE) cells contributes to retinal homeostasis as well as to pathological angiogenesis. We have now examined the effect of a necrotic cell lysate prepared from human RPE cells (NLR) on the release of VEGF by healthy RPE cells. We found that NLR markedly increased the release of VEGF from RPE cells and that this effect was attenuated by nintedanib, a multiple receptor tyrosine kinase inhibitor, whereas it was unaffected by inhibitors of NF-κB signaling or of caspase-1. NLR also induced the phosphorylation of extracellular signal-regulated kinase (Erk) and signal transducer and activator of transcription 3 (Stat3) in a manner sensitive to inhibition by nintedanib, although inhibitors of Erk and Stat3 signaling pathways did not affect NLR-induced VEGF secretion. In addition, nintedanib attenuated the development of choroidal neovascularization in mice. Our results have thus shown that a necrotic lysate of RPE cells induced VEGF secretion from healthy RPE cells and that this effect was mediated by receptor tyrosine kinase signaling. They therefore suggest that VEGF secretion by healthy RPE cells is a potential therapeutic target for retinal diseases associated with sterile inflammation and pathological angiogenesis.

Different epidermal growth factor receptor signaling pathways in neurons and astrocytes activated by extracellular matrix after spinal cord injury

Spinal cord injury (SCI) is a serious central nervous system (CNS) trauma that results in permanent and severe disability. The extracellular matrix (ECM) can affect the activation of extracellular signal-regulated kinase 1/2 (ERK_1/2) by interacting with the ERK integrin subunits. In this study, we built a model of SCI with glial fibrillary acidic protein-green fluorescent protein (GFAP-GFP) and thymus cell antigen 1-yellow fluorescent protein-H (Thy1-YFPH) in mice that express specific transgenes in their astrocytes or neurons. Then, we collected spinal cord neurons or astrocytes by fluorescence-activated cell sorting (FACS). In this way, we investigated the SCI-induced phosphorylation of ERK_1/2 and epidermal growth factor receptor (EGFR) in neurons and astrocytes, and we discovered that the SCI-induced EGFR signaling pathways differed between neurons and astrocytes. In the present study, we found that the Src-dependent phosphorylation of EGFR induced by SCI occurred only in neurons, not in astrocytes. This phenomenon may be due to the involvement of Thy-1, which promoted the binding between Src and EGFR in neurons after SCI. In addition, the expression of the integrin subunits after SCI differed between neurons and astrocytes. Our present study shows that the EGFR signaling pathway triggered by SCI in neurons differed from the EGFR signaling pathway triggered in astrocytes, a finding that may help to pave the way for clinical trials of therapies that inhibit EGFR signaling pathways after SCI.

Mechanical Durotactic Environment Enhances Specific Glioblastoma Cell Responses

Background: A hallmark of glioblastoma is represented by their ability to widely disperse throughout the brain parenchyma. The importance of developing new anti-migratory targets is critical to reduce recurrence and improve therapeutic efficacy. Methods: Polydimethylsiloxane substrates, either mechanically uniform or presenting durotactic cues, were fabricated to assess GBM cell morphological and dynamical response with and without pharmacological inhibition of NNMII contractility, of its upstream regulator ROCK and actin polymerization. Results: Glioma cells mechanotactic efficiency varied depending on the rigidity compliance of substrates. Morphologically, glioma cells on highly rigid and soft bulk substrates displayed bigger and elongated aggregates whereas on durotactic substrates the same cells were homogeneously dispersed with a less elongated morphology. The durotactic cues also induced a motility change, cell phenotype dependent, and with cells being more invasive on stiffer substrates. Pharmacological inhibition of myosin or ROCK revealed a rigidity-insensitivity, unlike inhibition of microfilament contraction and polymerization of F-actin, suggesting that alternative signalling is used to respond to durotactic cues. Conclusions: The presence of a distinct mechanical cue is an important factor in cell migration. Together, our results provide support for a durotactic role of glioma cells that acts through actomyosin contractility to regulate the aggressive properties of GBM cells.

Recent Insight into the Role of Fibrosis in Nonalcoholic Steatohepatitis-Related Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most widespread tumors in the world and its prognosis is poor because of lack of effective treatments. Epidemiological studies show that non-alcoholic steatohepatitis (NASH) and advanced fibrosis represent a relevant risk factors to the HCC development. However little is known of pathophysiological mechanisms linking liver fibrogenesis to HCC in NASH. Recent advances in scientific research allowed to discover some mechanisms that may represent potential therapeutic targets. These include the integrin signaling, hepatic stellate cells (HSCs) activation, Hedgehog signaling and alteration of immune system. In the near future, knowledge of fibrosis-dependent carcinogenic mechanisms, will help optimize antifibrotic therapies as an approach to prevent and treat HCC in patients with NASH and advanced fibrosis.

Quantitative mass spectrometry to identify protein markers for diagnosis of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a devastating malignancy with a prognosis of <12 months. Even with bans on the use of asbestos in most Western countries, the incidence is still increasing due to the long latency periods between exposure and development of the disease. Diagnosis is often delayed due to invasive biopsies and lack of distinguishable markers. Patients frequently present with pleural effusions months to years before a radiologically detectable mass appears. This study aimed to investigate the proteome of pleural effusions taken from patients with MPM, adenocarcinoma and benign conditions in an attempt to identify a biomarker for early diagnosis. We identified several proteins that may be possible targets and warrant further investigation. Due to the predominance of up regulated proteins involved in VEGF signalling in MPM, we analysed VEGFA levels in effusions and found a strong correlation between VEGFA levels and survival in MPM.

Mitochondrial genome and functional defects in osteosarcoma are associated with their aggressive phenotype

Osteosarcoma (OSA) is an aggressive mesenchymal tumor of the bone that affects children and occurs spontaneously in dogs. Human and canine OSA share similar clinical, biological and genetic features, which make dogs an excellent comparative model to investigate the etiology and pathogenesis of OSA. Mitochondrial (mt) defects have been reported in many different cancers including OSA, although it is not known whether these defects contribute to OSA progression and metastasis. Taking a comparative approach using canine OSA cell lines and tumor tissues we investigated the effects of mtDNA content and dysfunction on OSA biology. OSA tumor tissues had low mtDNA contents compared to the matched non-tumor tissues. We observed mitochondrial heterogeneity among the OSA cell lines and the most invasive cells expressing increased levels of OSA metastasis genes contained the highest amount of mitochondrial defects (reduced mtDNA copies, mt respiration, and expression of electron transport chain proteins). While mitochondria maintain a filamentous network in healthy cells, the mitochondrial morphology in OSA cells were mostly "donut shaped", typical of "stressed" mitochondria. Moreover the expression levels of mitochondrial retrograde signaling proteins Akt1, IGF1R, hnRNPA2 and NFkB correlated with the invasiveness of the OSA cells. Furthermore, we demonstrate the causal role of mitochondrial defects in inducing the invasive phenotype by Ethidium Bromide induced-mtDNA depletion in OSA cells. Our data suggest that defects in mitochondrial genome and function are prevalent in OSA and that lower mtDNA content is associated with higher tumor cell invasiveness. We propose that mt defects in OSA might serve as a prognostic biomarker and a target for therapeutic intervention in OSA patients.

Influence of collagen-based integrin α1 and α2 mediated signaling on human mesenchymal stem cell osteogenesis in three dimensional contexts

Collagen I interactions with integrins α1 and α2 are known to support human mesenchymal stem cell (hMSC) osteogenesis. Nonetheless, elucidating the relative impact of specific integrin interactions has proven challenging, in part due to the complexity of native collagen. In the present work, we employed two collagen-mimetic proteins-Scl2-2 and Scl2-3- to compare the osteogenic effects of integrin α1 versus α2 signaling. Scl2-2 and Scl2-3 were both derived from Scl2-1, a triple helical protein lacking known cell adhesion, cytokine binding, and matrix metalloproteinase sites. However, Scl2-2 and Scl2-3 were each engineered to display distinct collagen-based cell adhesion motifs: GFPGER (binding integrins α1 and α2 ) or GFPGEN (binding only integrin α1 ), respectively. hMSCs were cultured within poly(ethylene glycol) (PEG) hydrogels containing either Scl2-2 or Scl2-3 for 2 weeks. PEG-Scl2-2 gels were associated with increased hMSC osterix expression, osteopontin production, and calcium deposition relative to PEG-Scl2-3 gels. These data indicate that integrin α2 signaling may have an increased osteogenic effect relative to integrin α1 . Since p38 is activated by integrin α2 but not by integrin α1 , hMSCs were further cultured in PEG-Scl2-2 hydrogels in the presence of a p38 inhibitor. Results suggest that p38 activity may play a key role in collagen-supported hMSC osteogenesis. This knowledge can be used toward the rational design of scaffolds which intrinsically promote hMSC osteogenesis. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2594-2604, 2018.

A DISCRETE MATHEMATICAL MODEL FOR SINGLE AND COLLECTIVE MOVEMENT IN AMOEBOID CELLS

In this paper, we develop a new discrete mathematical model for individual and collective cell motility. We introduce a mechanical model for the movement of a cell on a two-dimensional rigid surface to describe and investigate the cell–cell and cell–substrate interactions. The cell cytoskeleton is modeled as a series of springs and dashpots connected in parallel. The cell–substrate attachments and the cell protrusions are also included. In particular, this model is used to describe the directed movement of endothelial cells on a Matrigel plate. We compare the results from our model with experimental data. We show that cell density and substrate rigidity play an important role in network formation.

In Vitro Analysis of Modified Surfaces of Silicone Breast Implants

Background

Although silicone breast implants are well tolerated, local complications such as capsular contracture occur because of insufficient integration with surrounding tissues. In this study, cell behaviour on hydrophilized silicone breast implant foils was analysed qualitatively and quantitatively under in vitro conditions in order to provoke the desired responses in a defined environment.

Methods

Silicone breast implant foils with different surface modifications were tested after 24 hours, 5 days and 7 days. The following modifications of silicone implant foils were tested: Unmodified silicone, silicone after-graft polymerisation for polyacrylic acid (pAAc), silicone-pAAc-fibronectin adsorptive, silicone-pAAC-fibronectin covalent, positive and negative controls. Experiments were conducted using cell culture with murine mouse fibroblasts L-929. Cytotoxicity assays were carried out in direct and indirect contact with cells grown on the material. For the viability test and qualitative analysis of cell proliferation on different foils, both fluoresceine-diacetate and ethidiumbromide were used and in addition the morphologic description of hemalaun-stained cells were used. Quantitative cell analysis was carried out using XTT after resuspension.

Results

Toxic influence on cell cultures could be excluded for coated and uncoated surfaces in contact with dissolved biomaterials. Unmodified silicone surfaces showed poor cell growth in direct contact. We found a gradual improvement of cell morphology, with the spread and proliferation depending on the type of surface modification. Better results were achieved with covalently coupled fibronectin and GRGDS than with pAAc.

Conclusion

Covalent immobilisation of hydrophobic silicone rubber can improve the initial cellbiomaterial interactions that are required to aid the successful development of tissue-like structures.

Integrin β3 plays a novel role in innate immunity in silkworm, Bombyx mori

Integrins are transmembrane receptors that play essential roles in many physiological and pathological processes through cell-to-cell and cell-to-extracellular matrix (ECM) interactions. In the current study, a 2653-bp full-length cDNA of a novel integrin β subunit (designated Bmintegrin β3) was obtained from silkworm hemocytes. Bmintegrin β3 has the typical conserved structure of the integrin β family. The qRT-PCR results showed that Bmintegrin β3 was specifically expressed in the hematological system and that its expression was significantly increased after challenge with different types of PAMPs and bacteria. The recombinant Bmintegrin β3 protein displayed increased aggregation with S. aureus, suggesting that Bmintegrin β3 might directly bind to PAMPs. Interestingly, Bmintegrin β3 knockdown promoted PPO1, PPO2, BAEE, SPH78, SPH125, and SPH127 expression and accelerated the melanization process. Unexpectedly, the expression of genes related to phagocytosis, the Toll pathway, and the IMD pathway was also up-regulated after Bmintegrin β3 knockdown. Thus, Bmintegrin β3 might be a pattern recognition protein (PRP) for PAMPs and might directly bind to bacteria and enhance the phagocytosis activity of hemocytes. Moreover, Bmintegrin β3 and its ligand might negatively regulate the expression of immune-related genes through an unknown mechanism. In summary, our studies provide new insights into the immune functions of Bmintegrin β3 from the silkworm, Bombyx mori.

The role of talin2 in breast cancer tumorigenesis and metastasis

Recent studies show that talin2 has a higher affinity to β-integrin tails and is indispensable for traction force generation and cell invasion. However, its roles in cell migration, cancer cell metastasis and tumorigenesis remain to be determined. Here, we used MDA-MB-231 human breast cancer cells as a model to define the roles of talin2 in cell migration, invasion, metastasis and tumorigenesis. We show here that talin2 knockdown (KD) inhibited cell migration and focal adhesion dynamics, a key step in cell migration, and that talin2 knockout (KO) inhibited cell invasion and traction force generation, the latter is crucial for cell invasion. Re-expression of talin2^WT in talin2-KO cells restored traction force generation and cell invasion, but that of talin2^S339C, a β-integrin-binding deficient mutant, did not. Moreover, talin2 KO (or KD) suppressed tumorigenesis and metastasis in mouse xenograft models. However, surprisingly, re-expression of talin2^WT in talin2-KO cells did not rescue tumorigenesis. Thus, talin2 is required for breast cancer cell migration, invasion, metastasis and tumorigenesis, although exogenous expression of high levels of talin2 could inhibit tumorigenesis.

Model of vascular desmoplastic multispecies tumor growth

We present a three-dimensional nonlinear tumor growth model composed of heterogeneous cell types in a multicomponent-multispecies system, including viable, dead, healthy host, and extra-cellular matrix (ECM) tissue species. The model includes the capability for abnormal ECM dynamics noted in tumor development, as exemplified by pancreatic ductal adenocarcinoma, including dense desmoplasia typically characterized by a significant increase of interstitial connective tissue. An elastic energy is implemented to provide elasticity to the connective tissue. Cancer-associated fibroblasts (myofibroblasts) are modeled as key contributors to this ECM remodeling. The tumor growth is driven by growth factors released by these stromal cells as well as by oxygen and glucose provided by blood vasculature which along with lymphatics are stimulated to proliferate in and around the tumor based on pro-angiogenic factors released by hypoxic tissue regions. Cellular metabolic processes are simulated, including respiration and glycolysis with lactate fermentation. The bicarbonate buffering system is included for cellular pH regulation. This model system may be of use to simulate the complex interactions between tumor and stromal cells as well as the associated ECM and vascular remodeling that typically characterize malignant cancers notorious for poor therapeutic response.

Cross-activating c-Met/β1 integrin complex drives metastasis and invasive resistance in cancer

The molecular underpinnings of invasion, a hallmark of cancer, have been defined in terms of individual mediators but crucial interactions between these mediators remain undefined. In xenograft models and patient specimens, we identified a c-Met/β1 integrin complex that formed during significant invasive oncologic processes: breast cancer metastases and glioblastoma invasive resistance to antiangiogenic VEGF neutralizing antibody, bevacizumab. Inducing c-Met/β1 complex formation through an engineered inducible heterodimerization system promoted features crucial to overcoming stressors during metastases or antiangiogenic therapy: migration in the primary site, survival under hypoxia, and extravasation out of circulation. c-Met/β1 complex formation was up-regulated by hypoxia, while VEGF binding VEGFR2 sequestered c-Met and β1 integrin, preventing their binding. Complex formation promoted ligand-independent receptor activation, with integrin-linked kinase phosphorylating c-Met and crystallography revealing the c-Met/β1 complex to maintain the high-affinity β1 integrin conformation. Site-directed mutagenesis verified the necessity for c-Met/β1 binding of amino acids predicted by crystallography to mediate their extracellular interaction. Far-Western blotting and sequential immunoprecipitation revealed that c-Met displaced α5 integrin from β1 integrin, creating a complex with much greater affinity for fibronectin (FN) than α5β1. Thus, tumor cells adapt to microenvironmental stressors induced by metastases or bevacizumab by coopting receptors, which normally promote both cell migration modes: chemotaxis, movement toward concentrations of environmental chemoattractants, and haptotaxis, movement controlled by the relative strengths of peripheral adhesions. Tumor cells then redirect these receptors away from their conventional binding partners, forming a powerful structural c-Met/β1 complex whose ligand-independent cross-activation and robust affinity for FN drive invasive oncologic processes.

C-reactive protein binds to integrin α2 and Fcγ receptor I, leading to breast cell adhesion and breast cancer progression

C-reactive protein (CRP) is an acute phase protein synthesized upon the inflammatory responses, associated with breast cancer. The process of tumor cell invasion and metastasis involves the adherence of cells to the extracellular matrix via integrin as a receptor for matrix molecules. The present study investigated the role of CRP in the adhesive phenotype of breast cells and the underlying mechanisms. Here, we first showed that CRP induces adhesion of MCF10A human breast epithelial cells through the activation of integrin α2 signaling. Expression of integrin α2 was induced by CRP in which transcription factors c-fos and SP1 may be involved. Binding of CRP with integrin α2 leads to the activation of focal adhesion kinase (FAK), paxillin and ERKs. CRP also binds to an Fcγ receptor Fcγ receptor I (FcγRI), and induces activation of paxillin, FAK and ERKs. Integrin α2 and FAK have crucial roles in the adhesive and invasive phenotypes as well as MMP-9 upregulation induced by CRP in MCF10A cells. Treatment with an inflammatory lipid sphingosine-1-phosphate induced CRP, which may be secreted and exert an autocrine effect by binding to FcγRI and integrin α2. Involvement of CRP in adhesion, invasion, anchorage-independent growth and upregulation of integrin α2, paxillin and FAK was observed in MDA-MB-231 triple-negative human breast cancer (TNBC) cells. Using an in vivo invasion model and an orthotopic mouse tumor model with MDA-MB-231 cells, we showed that CRP has an important role in intravasation and tumor growth in vivo, demonstrating the in vivo relevance of our in vitro results. The present study elucidates a critical molecular basis between CRP, integrin α2 and FcγRI pathways in MCF10A breast cells and MDA-MB-231 TNBC cells, thereby providing useful information on CRP-induced aggressiveness of breast cells in the inflammatory microenvironment.

Systematic Selection of Reference Genes for the Normalization of Circulating RNA Transcripts in Pregnant Women Based on RNA-Seq Data

RNA transcripts circulating in peripheral blood represent an important source of non-invasive biomarkers. To accurately quantify the levels of circulating transcripts, one needs to normalize the data with internal control reference genes, which are detected at relatively constant levels across blood samples. A few reference gene candidates have to be selected from transcriptome data before the validation of their stable expression by reverse-transcription quantitative polymerase chain reaction. However, there is a lack of transcriptome, let alone whole-transcriptome, data from maternal blood. To overcome this shortfall, we performed RNA-sequencing on blood samples from women presenting with preterm labor. The coefficient of variation (CV) of expression levels was calculated. Of 11,215 exons detected in the maternal blood whole-transcriptome, a panel of 395 genes, including PPP1R15B, EXOC8, ACTB, and TPT1, were identified to comprise exons with considerably less variable expression level (CV, 7.75-17.7%) than any GAPDH exon (minimum CV, 27.3%). Upon validation, the selected genes from this panel remained more stably expressed than GAPDH in maternal blood. This panel is over-represented with genes involved with the actin cytoskeleton, macromolecular complex, and integrin signaling. This groundwork provides a starting point for systematically selecting reference gene candidates for normalizing the levels of circulating RNA transcripts in maternal blood.

Immuno-Oncology Integrative Networks: Elucidating the Influences of Osteosarcoma Phenotypes

In vivo and in vitro functional phenotyping characterization was recently obtained with reference to an experimental pan-cancer study of 22 osteosarcoma (OS) cell lines. Here, differentially expressed gene (DEG) profiles were recomputed from the publicly available data to conduct network inference on the immune system regulatory activity across the characterized OS phenotypes. Based on such DEG profiles, and for each phenotype that was analyzed, we obtained coexpression networks and bio-annotations for them. Then, we described the immune-modulated influences in phenotype-specific networks' integrating pathway, transcription factor, and microRNA regulations. Overall, this approach seems suitable for representing heterogeneity in OS tumorigenesis.

Targeting cancer cell integrins using gold nanorods in photothermal therapy inhibits migration through affecting cytoskeletal proteins

Metastasis is responsible for most cancer-related deaths, but the current clinical treatments are not effective. Recently, gold nanoparticles (AuNPs) were discovered to inhibit cancer cell migration and prevent metastasis. Rationally designed AuNPs could greatly benefit their antimigration property, but the molecular mechanisms need to be explored. Cytoskeletons are cell structural proteins that closely relate to migration, and surface receptor integrins play critical roles in controlling the organization of cytoskeletons. Herein, we developed a strategy to inhibit cancer cell migration by targeting integrins, using Arg-Gly-Asp (RGD) peptide-functionalized gold nanorods. To enhance the effect, AuNRs were further activated with 808-nm near-infrared (NIR) light to generate heat for photothermal therapy (PPTT), where the temperature was adjusted not to affect the cell viability/proliferation. Our results demonstrate changes in cell morphology, observed as cytoskeleton protrusions-i.e., lamellipodia and filopodia-were reduced after treatment. The Western blot analysis indicates the downstream effectors of integrin were attracted toward the antimigration direction. Proteomics results indicated broad perturbations in four signaling pathways, Rho GTPases, actin, microtubule, and kinases-related pathways, which are the downstream regulators of integrins. Due to the dominant role of integrins in controlling cytoskeleton, focal adhesion, actomyosin contraction, and actin and microtubule assembly have been disrupted by targeting integrins. PPTT further enhanced the remodeling of cytoskeletal proteins and decreased migration. In summary, the ability of targeting AuNRs to cancer cell integrins and the introduction of PPTT stimulated broad regulation on the cytoskeleton, which provides the evidence for a potential medical application for controlling cancer metastasis.

The molecular basis of talin2's high affinity toward β1-integrin

Talin interacts with β-integrin tails and actin to control integrin activation, thus regulating focal adhesion dynamics and cell migration. There are two talin genes, Tln1 and Tln2, which encode talin1 and talin2, and it is generally believed that talin2 functions redundantly with talin1. However, we show here that talin2 has a higher affinity to β1-integrin tails than talin1. Mutation of talin2 S339 to leucine, which can cause Fifth Finger Camptodactyly, a human genetic disease, completely disrupted its binding to β–integrin tails. Also, substitution of talin1 C336 with Ser enhanced the affinity of talin1, whereas substitution of talin2 S339 with Cys diminished that of talin2. Further computational modeling analysis shows that talin2 S339 formed a hydrogen bond with E353, which is critical for inducing key hydrogen bonds between talin2 N326 and β1-integrin R760, and between talin2 K327 and β1-integrin D759. Mutation at any of these residues significantly diminished the interaction of talin2 with β1- integrin tails. These hydrogen bonds were not observed in talin1/β1-integrin, but did exist in talin1^C336S/β1-integrin complex. These results suggest that talin2 S339 forms a hydrogen bond with E353 to mediate its high affinity to β1-integrin.

Integrin α8 Is Abundant in Human, Rat, and Mouse Trophoblasts

OBJECTIVE

Integrins exert regulatory functions in placentogenesis. Null mutation of certain integrin α subunits leads to placental defects with subsequent fetal growth restriction or embryonic lethality in mice. So far, the placental role of α8 integrin remains to be determined.

METHODS

Localization of α8 integrin and its ligands, fibronectin (FN) and osteopontin (OPN), was studied by immunohistochemistry in human, rat, and mouse placenta. The vascularization of the placental labyrinth layer of α8 integrin-deficient mice was determined by CD31 staining. In humans, α8 integrin expression was assessed via real-time polymerase chain reaction in healthy placentas, in the placental pathologies such as intrauterine growth restriction (IUGR), preeclampsia, and HELLP-syndrome (hemolysis, elevated liver enzymes, low platelet count), as well as in primary extravillous trophoblasts (EVT) and villous trophoblasts.

RESULTS

In humans, α8 integrin was detected in first and third trimester syncytiotrophoblast and EVT. Although OPN showed the same localization, FN was observed in EVT only. No expressional changes in α8 integrin were detected in the placental pathologies studied. Rodent placenta showed α8 integrin expression in giant cells and in the labyrinth layer. The localization of OPN and FN, however, showed species-specific differences. Knockout of α8 integrin in mice did not cause IUGR, despite some reduction in labyrinth layer vascularization.

CONCLUSION

α8 Integrin is expressed in functional placental compartments among its ligands, OPN and/or FN, across species. Although this may point to a regulatory role in trophoblast function, our data from α8 integrin-deficient mice indicated only mild placental pathology. Thus, the lack of placental α8 integrin seems to be largely compensated for.

The Characteristics Of Human Bone-Derived Cells (HBDCS) during osteogenesis in vitro

BACKGROUND

The primary human bone-derived cell culture technique is used as a model to study human osteogenesis. Compared to cell line cultures, primary osteoprogenitor and osteoblast cultures provide more complex information about osteogenesis, bone remodeling and regeneration than cell line cultures.

METHODS

In this study, we isolated human bone-derived cells (HBDCs) and promoted their differentiation into osteoblasts. The following parameters were evaluated: cell number and viability, total protein expression, alkaline phosphatase activity, collagenous matrix production and osteogenic genes expression, i.e., gene coding for type I collagen and alkaline phosphatase.

RESULTS

It was proved the results show that HBDCs intensively proliferate during the first 7 days of culture followed by differentiation accompanied by an increase in alkaline phosphatase activity. Moreover, it was observed that during the differentiation of HBDCs, the expression of integrin β1 increased.

CONCLUSIONS

The process was also accompanied by changes in cell shape and rearrangement of the actin cytoskeleton and focal contacts containing FAK and the integrin β1 subunit. We suggest that the β1 integrin subunit may be a suitable new target in studies of the differentiation of primary human osteoblasts in culture.

Promotion of Adipogenesis of 3T3-L1 Cells on Protein Adsorption-Suppressing Poly(2-methoxyethyl acrylate) Analogs

Stem cell differentiation is an important issue in regenerative medicine and tissue engineering. It has been reported that cell shape is one of the factors that determine the lineage commitment of mesenchymal stem cells (MSCs). Therefore, the substrates have been developed to control their shapes. Recently, we found that poly(2-methoxyethyl acrylate) (PMEA) analogs can control tumor cell shape through the alteration of protein adsorption. Here, the adipogenesis of an adipocyte-progenitor cell, 3T3-L1 cells, was attempted; adipogenesis was to be regulated by surfaces coated with PMEA analogs through the control of their shape. The adipogenesis of 3T3-L1 cells was promoted on the surfaces coated with PMEA and its analogs, PMe3A and PMe2A. Evident focal adhesions were hardly observed on these surfaces, suggesting that integrin signal activation was suppressed. Additionally, actin assembly and cell spreading were suppressed on these surfaces. Therefore, the surfaces coated with PMEA analogs are expected to be suitable surfaces to regulate adipogenesis through the suppression of cell spreading. Additionally, we found that protein adsorption correlated with actin assembly and adipogenesis.

Regulation of Integrin α6 Recycling by Calcium-independent Phospholipase A2 (iPLA2) to Promote Microglia Chemotaxis on Laminin

Microglia are the immune effector cells that are activated in response to pathological changes in the central nervous system. Microglial activation is accompanied by the alteration of integrin expression on the microglia surface. However, changes of integrin expression upon chemoattractant (ADP) stimulation still remain unknown. In this study, we investigated whether ADP induces the alteration of integrin species on the cell surface, leading to changes in chemotactic ability on different extracellular matrix proteins. Flow cytometry scans and on-cell Western assays showed that ADP stimulation induced a significant increase of α6 integrin-GFP, but not α5, on the surface of microglia cells. Microglia also showed a greater motility increase on laminin than fibronectin after ADP stimulation. Time lapse microscopy and integrin endocytosis assay revealed the essential role of calcium-independent phospholipase A₂ activity for the recycling of α6 integrin-GFP from the endosomal recycling complex to the plasma membrane. Lack of calcium-independent phospholipase A₂ activity caused a reduced rate of focal adhesion formation on laminin at the leading edge. Our results suggest that the alteration of integrin-mediated adhesion may regulate the extent of microglial infiltration into the site of damage by controlling their chemotactic ability.

Fabrication and Application of Photocrosslinked, Nanometer-Scale, Physically Adsorbed Films for Tissue Culture Regeneration

This study describes the development and cell culture application of nanometer thick photocrosslinkable thermoresponsive polymer films prepared by physical adsorption. Two thermoresponsive polymers, poly(N-isopropylacrylamide (NIPAm)-co-acrylamidebenzophenone (AcBzPh)) and poly(NIPAm-co-AcBzPh-co-N-tertbutylacrylamide) are investigated. Films are prepared both above and below the polymers' lower critical solution temperatures (LCSTs) and cross-linked, to determine the effect, adsorption preparation temperature has on the resultant film. The films prepared at temperatures below the LCST are smoother, thinner, and more hydrophilic than those prepared above. Human pulmonary microvascular endothelial cell (HPMEC) adhesion and proliferation are superior on the films produced below the polymers LCST compared to those produced above. Cells sheets are detached by simply lowering the ambient temperature to below the LCST. Transmission electron, scanning electron, and light microscopies indicate that the detached HPMEC sheets maintain their integrity.

HTLV-1 Viral Factor HBZ Induces CCR4 to Promote T-cell Migration and Proliferation

Human T-cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia-lymphoma (ATL) and other inflammatory diseases in infected individuals. However, a complete understanding of how HTLV-1 transforms T cells is lacking. Expression of the chemokine receptor CCR4 on ATL cells and HTLV-1-infected cells suggested the hypothesis that CCR4 may mediate features of ATL and inflammatory diseases caused by HTLV-1. In this study, we show that the constitutively expressed HTLV-1 bZIP factor (HBZ) encoded by HTLV-1 is responsible for inducing CCR4 and its ability to promote T-cell proliferation and migration. Ectopic expression of HBZ was sufficient to stimulate expression of CCR4 in human and mouse T cells. Conversely, HBZ silencing in ATL cell lines was sufficient to inhibit CCR4 expression. Mechanistic investigations showed that HBZ induced GATA3 expression in CD4(+) T cells, thereby activating transcription from the CCR4 promoter. In an established air pouch model of ATL, we observed that CD4(+) T cells of HBZ transgenic mice (HBZ-Tg mice) migrated preferentially to the pouch, as compared with those in nontransgenic mice. Migration of CD4(+) T cells in HBZ-Tg mice was inhibited by treatment with a CCR4 antagonist. Proliferating (Ki67(+)) CD4(+) T cells were found to express high levels of CCR4 and CD103. Further, CD4(+) T-cell proliferation in HBZ-Tg mice was enhanced by coordinate treatment with the CCR4 ligands CCL17 and 22 and with the CD103 ligand E-cadherin. Consistent with this finding, we found that ATL cells in clinical skin lesions were frequently positive for CCR4, CD103, and Ki67. Taken together, our results show how HBZ activates CCR4 expression on T cells to augment their migration and proliferation, two phenomena linked to HTLV-1 pathogenesis. Cancer Res; 76(17); 5068-79. ©2016 AACR.

Synthetic hydrogel supports the function and regeneration of artificial ovarian tissue in mice

Many prepubertal girls and young women suffer from premature ovarian insufficiency induced by chemotherapy given for treatment of cancer and autoimmune diseases. Autotransplantation of cryopreserved ovarian tissue could restore the lost ovarian endocrine function and fertility. Unfortunately, tissue ischemia, inconsistent graft quality and the risk of reintroducing malignant cells may stand in the way of the clinical translation of this approach. To address these risks and limitations, we engineered an artificial ovarian tissue from immature follicles using a synthetic hydrogel, poly(ethylene glycol) vinyl sulfone (PEG-VS), as a supportive matrix. Enzymatically isolated follicles from 6–7-day-old mice ovaries were encapsulated in 7% PEG-VS hydrogels modified with 0.5 mmol/l RGD and crosslinked with a trifunctional matrix metalloproteinase-sensitive peptide. PEG hydrogels with the encapsulated follicles were orthotopically implanted into ovariectomised mice to investigate whether PEG hydrogel supports folliculogenesis and steroidogenesis in vivo. After 30 days, grafts revealed multiple fully developed antral follicles and corpora lutea, which corresponded with regular ovulation cycles and follicle-stimulating hormone (FSH) levels. The elevated levels of FSH, caused by bilateral ovariectomy, were reversed by the implanted follicles and maintained at physiological levels for 60 days. Importantly, primordial and primary follicles still represented 60% of the follicular pool, demonstrating selective recruitment of primordial follicles into the growing pool. Functioning blood vessels in the grafts 30 and 60 days after implantation proved the capability of PEG hydrogels to undergo graft remodelling and revascularisation. Our results demonstrate that PEG hydrogels with encapsulated immature ovarian follicles successfully functioned as an artificial ovarian tissue for 60 days in vivo.

Enhancement of Wound Healing by Non-Thermal N2/Ar Micro-Plasma Exposure in Mice with Fractional-CO2-Laser-Induced Wounds

Micro-plasma is a possible alternative treatment for wound management. The effect of micro-plasma on wound healing depends on its composition and temperature. The authors previously developed a capillary-tube-based micro-plasma system that can generate micro-plasma with a high nitric oxide-containing species composition and mild working temperature. Here, the efficacy of micro-plasma treatment on wound healing in a laser-induced skin wound mouse model was investigated. A partial thickness wound was created in the back skin of each mouse and then treated with micro-plasma. Non-invasive methods, namely wound closure kinetics, optical coherence tomography (OCT), and laser Doppler scanning, were used to measure the healing efficiency in the wound area. Neo-tissue growth and the expressions of matrix metallopeptidase-3 (MMP-3) and laminin in the wound area were assessed using histological and immunohistochemistry (IHC) analysis. The results show that micro-plasma treatment promoted wound healing. Micro-plasma treatment significantly reduced the wound bed region. The OCT images and histological analysis indicates more pronounced tissue regrowth in the wound bed region after micro-plasma treatment. The laser Doppler images shows that micro-plasma treatment promoted blood flow in the wound bed region. The IHC results show that the level of laminin increased in the wound bed region after micro-plasma treatment, whereas the level of MMP-3 decreased. Based on these results, micro-plasma has potential to be used to promote the healing of skin wounds clinically.