alpha3beta1 integrin promotes cell survival via multiple interactions between 14-3-3 isoforms and proapoptotic proteins

Hepatic Sinusoid Capillarizate via IGTAV/FAK Pathway Under High Glucose

The incidence of diabetic patients with non-alcoholic fatty liver disease (NAFLD) is continuously increasing worldwide. However, the specific mechanisms of NAFLD patients with diabetes are still not clear. Recent studies have indicated that integrins play an important role in NAFLD. In this study, we considered the relationship between integrin αv (IGTAV)/FAK pathway and sinusoidal capillarization. We investigated the difference between the expression of IGTAV, laminin (LN), focal adhesion kinase (FAK), and phosphor-FAK protein in human liver sinusoidal endothelial cells (HLSECs) to explore the specific mechanisms of the diseases of NAFLD with diabetes under high glucose. We cultured and identified the HLSECs and constructed the recombinant lentivirus vector with IGTAV shRNA by quantitative real-time PCR (qRT-PCR) to silence the IGTAV gene. Cells were divided into groups of 25 mmol/L glucose and 25 mmol/L mannitol. We measured the protein levels of IGTAV, LN, FAK, and phosphor-FAK by western blot at 2 h, 6 h, and 12 h before and after IGTAV gene silencing. The lentivirus vector was successfully constructed with IGTAV shRNA. The HLSECs under high glucose were observed by scanning electron microscope. SPSS19.0 was used for statistical analysis. High glucose significantly increased the expression of IGTAV, LN, and phosphor-FAK protein in HLSECs; the shRNA IGTAV could effectively inhibit the expression of phosphor-FAK and LN at 2 h and 6 h. Inhibition of the phosphor-FAK could effectively decrease the expression of LN in HLSECs at 2 h and 6 h under high glucose. Inhibition of IGTAV gene of HLSECs under high glucose could improve hepatic sinus capillarization. Inhibition of IGTAV and phosphor-FAK decreased the expression of LN. High glucose led to hepatic sinus capillarization via IGTAV/ FAK pathway.

Tissue-Engineered Models of the Human Brain: State-of-the-Art Analysis and Challenges

Neurological disorders affect billions of people across the world, making the discovery of effective treatments an important challenge. The evaluation of drug efficacy is further complicated because of the lack of in vitro models able to reproduce the complexity of the human brain structure and functions. Some limitations of 2D preclinical models of the human brain have been overcome by the use of 3D cultures such as cell spheroids, organoids and organs-on-chip. However, one of the most promising approaches for mimicking not only cell structure, but also brain architecture, is currently represented by tissue-engineered brain models. Both conventional (particularly electrospinning and salt leaching) and unconventional (particularly bioprinting) techniques have been exploited, making use of natural polymers or combinations between natural and synthetic polymers. Moreover, the use of induced pluripotent stem cells (iPSCs) has allowed the co-culture of different human brain cells (neurons, astrocytes, oligodendrocytes, microglia), helping towards approaching the central nervous system complexity. In this review article, we explain the importance of in vitro brain modeling, and present the main in vitro brain models developed to date, with a special focus on the most recent advancements in tissue-engineered brain models making use of iPSCs. Finally, we critically discuss achievements, main challenges and future perspectives.

From the Matrix to the Nucleus and Back: Mechanobiology in the Light of Health, Pathologies, and Regeneration of Oral Periodontal Tissues

Among oral tissues, the periodontium is permanently subjected to mechanical forces resulting from chewing, mastication, or orthodontic appliances. Molecularly, these movements induce a series of subsequent signaling processes, which are embedded in the biological concept of cellular mechanotransduction (MT). Cell and tissue structures, ranging from the extracellular matrix (ECM) to the plasma membrane, the cytosol and the nucleus, are involved in MT. Dysregulation of the diverse, fine-tuned interaction of molecular players responsible for transmitting biophysical environmental information into the cell's inner milieu can lead to and promote serious diseases, such as periodontitis or oral squamous cell carcinoma (OSCC). Therefore, periodontal integrity and regeneration is highly dependent on the proper integration and regulation of mechanobiological signals in the context of cell behavior. Recent experimental findings have increased the understanding of classical cellular mechanosensing mechanisms by both integrating exogenic factors such as bacterial gingipain proteases and newly discovered cell-inherent functions of mechanoresponsive co-transcriptional regulators such as the Yes-associated protein 1 (YAP1) or the nuclear cytoskeleton. Regarding periodontal MT research, this review offers insights into the current trends and open aspects. Concerning oral regenerative medicine or weakening of periodontal tissue diseases, perspectives on future applications of mechanobiological principles are discussed.

Enhanced integrin affinity and neural differentiation of induced pluripotent stem cells using Ln5-P4-grafted amphiphilic solid lipid nanoparticles

Amphiphilic solid lipid nanoparticles (ASLNs) with surface PPFLMLLKGSTR peptide (Ln5-P4) (Ln5-P4/ASLNs) were prepared to load nerve growth factor (NGF) and retinoic acid (RA) and to guide the differentiation of induced pluripotent stem cells (iPSCs) toward neurons. Beeswax (BW) and lecithin played predominant roles in microemulsion and in the average diameter, zeta potential, encapsulation efficiency of NGF and RA and release kinetics of NGF- and RA-loaded Ln5-P4/ASLNs (Ln5-P4/NGF-RA-ASLNs). An increasing BW weight percentage from 0% to 75% decreased the particle size and zeta potential along with improved encapsulation efficiency of RA and NGF with enhanced positive expression of β-tubulin III to 93.72% in cultured cells. Strong affinity of Ln5-P4/NGF-RA-ASLNs to α₃β₁ integrin expressed on iPSCs facilitated internalization of Ln5-P4/NGF-RA-ASLNs. The capability of Ln5-P4/NGF-RA-ASLNs to induce neuronal differentiation was much higher than that of free NGF-ASLNs and RA-ASLNs, as visualized using immunochemical staining. Flow cytometry analysis indicated that Ln5-P4 on NGF-RA-ASLNs promoted the uptake of NGF and RA by iPSCs and accelerated neuronal production. Ln5-P4/NGF-RA-ASLNs are a promising colloidal delivery system to generate mature neurons from iPSCs and can be potential for treating neurodegenerative disease and nerve injury in regeneration medicine.

Knockdown of the α5 laminin chain affects differentiation of colorectal cancer cells and their sensitivity to chemotherapy

The interaction of tumor cells with the extracellular matrix (ECM) may affect the rate of cancer progression and metastasis. One of the major components of ECM are laminins, the heterotrimeric glycoproteins consisting of α-, β-, and γ-chains (αβγ). Laminins interact with their cell surface receptors and, thus, regulate multiple cellular processes. In this work, we demonstrate that shRNA-mediated knockdown of the α5 laminin chain results in Wnt- and mTORC1-dependent partial dedifferentiation of colorectal cancer cells. Furthermore, we showed that this dedifferentiation involved activation of ER-stress signaling, pathway promoting the sensitivity of cells to 5-fluorouracil.

14-3-3ζ promotes gliomas cells invasion by regulating Snail through the PI3K/AKT signaling

14-3-3ζ has been reported to function as critical regulators of diverse cellular responses. However, the role of 14-3-3ζ in gliomas progression remains largely unknown. The expression level of 14-3-3ζ and Snail was detected by Western blot analysis and quantitative polymerase chain reaction in different grades of human gliomas. The effect of 14-3-3ζ on gliomas progression was measured using cell migration and invasion assay, the colony formation experiment, and CCK-8 assay. The effect of 14-3-3ζ on PI3K/AKT/Snail signaling protein expression levels was tested by Western blotting. Firstly, 14-3-3ζ was often up-regulated in high-grade gliomas relative to low-grade gliomas, and this overexpression was significantly related to tumor size, Karnofsky Performance Scale score and weaker disease-free survival. Secondly, the overexpression of 14-3-3ζ promoted gliomas cells proliferation, migration, and invasion. Conversely, the knockdown of 14-3-3ζ suppressed gliomas cells proliferation, migration, and invasion. Furthermore, subsequent mechanistic studies showed that 14-3-3ζ could activate PI3K/AKT/Snail signaling pathway to facilitate gliomas cells proliferation, migration, and invasion. This study shows that the overexpression of 14-3-3ζ can promote remarkably gliomas cells proliferation, migration, and invasion by regulating the Snail protein expression through activating PI3K/AKT signaling, and it may serve as a potential prognostic marker and therapeutic target for gliomas.

Nitric oxide prevents H2O2-induced apoptosis in SK-N-MC human neuroblastoma cells

Nitric oxide (NO) is a cellular signaling molecule in many physiological and pathological processes including neuroprotector. Here we examined the antiapoptotic effect of NO in SK-N-MC cells. H2O2 treatment (10-200 μM) induced cell death in a dose-dependent manner and pretreatment of cells with 100 μM S-nitroso-N-acetylpenicillamine (SNAP), an NO donor, attenuated the occurrence of H2O2-induced cell death. DAPI staining showed H2O2-induced nuclear fragmentation and NO treatment suppressed it. NO inhibited the proteolytic activation of caspase-3 and mitochondrial cytochrome c release. Treatment of soluble guanylyl cyclase inhibitor ODQ decreased the protective effect of SNAP on H2O2-treated cells and increased caspase 3-like enzyme activity and activation, cytochrome c release, PARP cleavage, and DNA fragmentation, indicating that cGMP is a key mediator in NO-mediated antiapoptosis. The cGMP analog 8-Br-cGMP blocked H2O2-induced apoptotic cell death; reduction of caspase-3 enzyme, cytochrome c release, and caspase-8 and -9. These preventive effects of SNAP and 8-Br-cGMP were suppressed by PKG inhibitor KT5823. Levels of PKGI, PKGII, and p-VASP proteins were increased by SNAP and 8-Br-cGMP and suppressed by KT5823 treatment. These results indicate that PKG is a downstream signal mediator in the suppression of apoptosis by NO and cGMP. Akt activation was inhibited the PI3K inhibitors LY294002 and Wortmannin, resulting in the inhibition of cell viability and increase of cytochrome c release. SNAP induced phosphorylation of Akt and Bad and then increased the interactions between 14-3-3β and p-Bad. These data suggest that the NO suppresses H2O2-induced SK-N-MC cell apoptosis by suppressing apoptosis signal mediating the interaction between 14-3-3β and Bad phosphorylation via PKG/PI3K/Akt.

Peptide coatings enhance keratinocyte attachment towards improving the peri-implant mucosal seal

There is a critical need for preventing peri-implantitis as its prevalence has increased and dental implants lack features to prevent it. Research strategies to prevent peri-implantitis have focused on modifying dental implants to incorporate different antimicrobial agents. An alternative strategy consists of barring the expansion of the biofilm subgingivally by forming a long-lasting permucosal seal between the soft tissue and the implant surface. Here, we innovatively biofunctionalized titanium with bioinspired peptide coatings to strengthen biological interactions between epithelial cells and the titanium surface. We selected laminin 332- and ameloblastin-derived peptides (Lam, Ambn). Laminin 332 participates in the formation of hemidesmosomes by keratinocytes and promotes epithelial attachment around teeth; and ameloblastin, an enamel derived protein, is involved in tissue regeneration events following disruption of the periodontium. Lam, Ambn or combinations of both peptides were covalently immobilized on titanium discs. Successful immobilization of the peptides was confirmed by contact angle goniometry, X-ray photoelectron spectroscopy and fluorescent labelling of the peptides. Additionally, we confirmed the mechanical and thermochemical stability of the peptides on Ti substrates. Proliferation and hemidesmosome formation of human keratinocytes (TERT-2/OKF-6) were assessed by immunofluorescence labelling. The peptide-coated surfaces increased cell proliferation for up to 48 h in culture compared to control surfaces. Most importantly, formation of hemidesmosomes by keratinocytes was significantly increased on surfaces coated with Ambn + Lam peptides compared to control (p < 0.01) and monopeptide coatings (p < 0.005). Together, these results support the Ambn + Lam multipeptide coating as a promising candidate for inducing a permucosal seal around dental implants.

YAP/TAZ Activation as a Target for Treating Metastatic Cancer

Yes-Associated Protein (YAP) and Transcriptional Co-activator with PDZ-binding Motif (TAZ) have both emerged as important drivers of cancer progression and metastasis. YAP and TAZ are often upregulated or nuclear localized in aggressive human cancers. There is abundant experimental evidence demonstrating that YAP or TAZ activation promotes cancer formation, tumor progression, and metastasis. In this review we summarize the evidence linking YAP/TAZ activation to metastasis, and discuss the roles of YAP and TAZ during each step of the metastatic cascade. Collectively, this evidence strongly suggests that inappropriate YAP or TAZ activity plays a causal role in cancer, and that targeting aberrant YAP/TAZ activation is a promising strategy for the treatment of metastatic disease. To this end, we also discuss several potential strategies for inhibiting YAP/TAZ activation in cancer and the challenges each strategy poses.

Integrin αvβ5 inhibition protects against ischemia-reperfusion-induced lung injury in an autophagy-dependent manner

Integrin αvβ5 mediates pulmonary endothelial barrier function and acute lung injury (LI), but its roles in cell apoptosis and autophagy are unclear. Thus, the aims of this study were to investigate the significance of αvβ5 in ischemia-reperfusion (I/R)-induced apoptosis and LI and to explore the relationship between αvβ5 and autophagy. Human pulmonary microvascular endothelial cells (HPMVECs) were pretreated with an αvβ5-blocking antibody (ALULA) and challenged with oxygen-glucose deprivation/oxygen-glucose restoration, which mimics I/R; then, cellular autophagy and apoptosis were detected, and cell permeability was assessed. In vivo, mice were pretreated with the autophagy inhibitor chloroquine (CLQ), followed by treatment with ALULA. The mice then underwent operative lung I/R. LI was assessed by performing a pathological examination, calculating the wet/dry lung weight ratio and detecting the bronchial alveolar lavage fluid (BALF) protein concentration. αvβ5 inhibition promoted HPMVEC autophagy under I/R in vitro, alleviated cell permeability, decreased the apoptosis ratio, and activated caspase-3 expression. These outcomes were significantly diminished when autophagy was inhibited with a small-interfering RNA construct targeting autophagy-related gene 7 (siATG7). Moreover, ALULA pretreatment alleviated I/R-induced LI (I/R-LI), which manifested as a decreased wet/dry lung weight ratio, an altered BALF protein concentration, and lung edema. Preinhibiting autophagy with CLQ, however, eliminated the protective effects of ALULA on I/R-LI. Therefore, inhibiting αvβ5 effectively ameliorated I/R-induced endothelial cell apoptosis and I/R-LI. This process was dependent on improved autophagy and its inhibitory effects on activated caspase-3.

Neuronal production from induced pluripotent stem cells in self-assembled collagen-hyaluronic acid-alginate microgel scaffolds with grafted GRGDSP/Ln5-P4

Self-assembled microgel functionalized with peptides was developed and applied to regenerate neurons from induced pluripotent stem cells (iPSCs). Collagen (COL), hyaluronic acid (HA), and alginate (ALG) were modified with methacrylic anhydride (MA), photocrosslinked for patterned particles, grafted with GRGDSP and Ln5-P4, and self-assembled to integrate the microgel into three-dimensional scaffolds. Physicochemical assessments revealed that the ternary microgel scaffolds had an optimal chemical composition at COLMA:HAMA:ALGMA=1:2:1. In fabricating cell-laden constructs, modified GRGDSP/Ln5-P4 in linear self-assembled scaffolds could significantly improve the entrapment efficiency and viability of iPSCs. In addition, GRGDSP/Ln5-P4 in the microgel constructs triggered the differentiation of iPSCs toward neurons, since the percentage of neurite-like cells could be higher than 98% after induction of nerve growth factor. Self-assembled microgel comprising COLMA, HAMA, ALGMA, and GRGDSP/Ln5-P4 may be promising in producing mature neural lineage from iPSCs, to provide better treatment for damaged nervous tissue.

Peptide-Tethered Hydrogel Scaffold Promotes Recovery from Spinal Cord Transection via Synergism with Mesenchymal Stem Cells

Spinal cord injury (SCI) is one of the most devastating injuries. Treatment strategies for SCI are required to overcome comprehensive issues. Implantation of biomaterial scaffolds and stem cells has been demonstrated to be a promising strategy. However, a comprehensive recovery effect is difficult to achieve. In the comprehensive treatment process, the specific roles of the implanted scaffolds and of stem cells in combined strategy are usually neglected. In this study, a peptide-modified scaffold is developed based on hyaluronic acid and an adhesive peptide PPFLMLLKGSTR. Synchrotron radiation micro computed tomography measurement provides insights to the three-dimensional inner topographical property and perspective porous structure of the scaffold. The modified scaffold significantly improves cellular survival and adhesive growth of mesenchymal stem cells during 3D culture in vitro. After implantation in transected spinal cord, the modified scaffold and mesenchymal stems are found to function in synergy to restore injured spinal cord tissue, with respective strengths. Hindlimb motor function scores exhibit the most significant impact of the composite implant at 2 weeks post injury, which is the time secondary injury factors begin to take hold. Investigation on the secondary injury factors including inflammatory response and astrocyte overactivity at 10 days post injury reveals the possible underlying reason. Implants of the scaffold, cells, and especially the combination of both elicit inhibitory effects on these adverse factors. The study develops a promising implant for spinal cord tissue engineering and reveals the roles of the scaffold and stem cells. More importantly, the results provide the first understanding of the bioactive peptide PPFLMLLKGSTR concerning its functions on mesenchymal stem cells and spinal cord tissue restoration.

14-3-3ζ promotes lung cancer cell invasion by increasing the Snail protein expression through atypical protein kinase C (aPKC)/NF-κB signaling

14-3-3ζ has been identified as a putative oncogene in several cancers, including non-small cell lung cancer (NSCLC). However, the mechanisms underlying its functions remain undefined. In this study, we show that overexpression of 14-3-3ζ was frequently detected in lung adenocarcinoma (LuAC) tissues and was significantly associated with lymph node metastasis and poor outcome. Functional studies demonstrated that 14-3-3ζ promoted migration and invasion in A549 cells, both of which were effectively inhibited when 14-3-3ζ was silenced with short hairpin RNA (shRNA). Furthermore, 14-3-3ζ-mediated invasion of cancer cells was found to upregulate Snail through the activation of atypical protein kinase C (aPKC). Activation of aPKCζ mediates this effect by stimulating NF-κB signaling. Our results identify a specific pathway by which 14-3-3ζ induces tumor invasion and provide insight into potential therapeutic approaches to target 14-3-3ζ-associated lung adenocarcinoma.

Analysis of protein expression in periodontal pocket tissue: a preliminary study

Background

The periodontal disease is caused by a set of inflammatory disorders characterized by periodontal pocket formation that lead to tooth loss if untreated. The proteomic profile and related molecular conditions of pocket tissue in periodontally-affected patients are not reported in literature. To characterize the proteomic profile of periodontally-affected patients, their interproximal periodontal pocket tissue was compared with that of periodontally-healthy patients. Pocket-associated and healthy tissue samples, harvested during surgical therapy, were treated to extract the protein content. Tissues were always collected at sites where no periodontal-pathogenic bacteria were detectable. Proteins were separated using two-dimensional gel electrophoresis and identified by liquid chromatography/mass spectrometry. After identification, four proteins were selected for subsequent Western Blot quantitation both in pathological and healty tissues.

Results

A significant unbalance in protein expression between healthy and pathological sites was recorded. Thirty-two protein spots were overall identified, and four proteins (S100A9, HSPB1, LEG7 and 14-3-3) were selected for Western blot analysis of both periodontally-affected and healthy patients. The four selected proteins resulted over-expressed in periodontal pocket tissue when compared with the corresponding tissue of periodontally-healthy patients. The results of Western blot analysis are congruent with the defensive and the regenerative reaction of injured periodontal tissues.

Conclusions

The proteomic analysis was performed for the first time directly on periodontal pocket tissue. The proteomic network highlighted in this study enhances the understanding of periodontal disease pathogenesis necessary for specific therapeutic strategies setting.

Label-free quantitative proteomic analysis of the YAP/TAZ interactome

The function of an individual protein is typically defined by protein-protein interactions orchestrating the formation of large complexes critical for a wide variety of biological processes. Over the last decade the analysis of purified protein complexes by mass spectrometry became a key technique to identify protein-protein interactions. We present a fast and straightforward approach for analyses of interacting proteins combining a Flp-in single-copy cellular integration system and single-step affinity purification with single-shot mass spectrometry analysis. We applied this protocol to the analysis of the YAP and TAZ interactome. YAP and TAZ are the downstream effectors of the mammalian Hippo tumor suppressor pathway. Our study provides comprehensive interactomes for both YAP and TAZ and does not only confirm the majority of previously described interactors but, strikingly, revealed uncharacterized interaction partners that affect YAP/TAZ TEAD-dependent transcription. Among these newly identified candidates are Rassf8, thymopoetin, and the transcription factors CCAAT/enhancer-binding protein (C/EBP)β/δ and core-binding factor subunit β (Cbfb). In addition, our data allowed insights into complex stoichiometry and uncovered discrepancies between the YAP and TAZ interactomes. Taken together, the stringent approach presented here could help to significantly sharpen the understanding of protein-protein networks.

Components of cell-matrix linkage as potential new markers for prostate cancer

Prostate cancer is one of the most common tumor diseases worldwide. Often being non-aggressive, prostate tumors in these cases do not need immediate treatment. However, about 20% of diagnosed prostate cancers tend to metastasize and require treatment. Existing diagnostic methods may fail to accurately recognize the transition of a dormant, non-aggressive tumor into highly malignant prostate cancer. Therefore, new diagnostic tools are needed to improve diagnosis and therapy of prostate carcinoma. This review evaluates existing methods to diagnose prostate carcinoma, such as the biochemical marker prostate-specific antigen (PSA), but also discusses the possibility to use the altered expression of integrins and laminin-332 in prostate carcinomas as diagnostic tools and therapeutic targets of prostate cancer.

The effect of a laminin-5-derived peptide coated onto chitin microfibers on re-epithelialization in early-stage wound healing

Considerable effort has been directed towards regenerating defective tissues using tissue-engineering methods. Recently, peptides have been recognized as a valuable scientific tool in the field of tissue-engineering. The PPFLMLLKGSTR motif of the human laminin-5 alpha3 chain has been previously reported to promote keratinocyte survival; however, the in vivo effects of the PPFLMLLKGSTR motif have not yet been studied. These studies raised the hypothesis that a laminin-5-derived peptide can promote wound healing by accelerating re-epithelialization in vivo. To examine this hypothesis, we applied chitin microfibrous matrices coated with the PPFLMLLKGSTR motif in both rat and rabbit full-thickness cutaneous wound models. Compared with vehicle-treated and peptide-treated cutaneous wounds, the application significantly promoted early-stage wound healing by accelerating re-epithelialization, notably reduced inflammatory cell infiltration, and prominently enhanced fibroblast proliferation. These findings support our hypothesis that the PPFLMLLKGSTR motif acts as a very effective wound healing accelerator by enhancing re-epithelialization.

Reduced aquaporin3 expression and survival of keratinocytes in the depigmented epidermis of vitiligo

Activation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway is critical for the survival of differentiating cells and depends on the E-cadherin-catenin complex. In an earlier study we showed impaired PI3K/AKT activation in vitiliginous keratinocytes (KCs). Recently, aquaporin3 (AQP3) has been reported to co-accumulate with E-cadherin in forming cell-to-cell contacts. Therefore, we examined the expression of AQP3 in vitiliginous KCs and the role of AQP3 in KC survival and differentiation by comparing downstream signaling molecules. AQP3 protein expression was significantly decreased in the depigmented epidermis compared with the normally pigmented epidermis of patients with vitiligo. Transfection of cultured normal human KCs with AQP3 small interfering RNA (siRNA) reduced the expression levels of phosphorylated PI3K, E-cadherin, beta-catenin, and gamma-catenin, regardless of the calcium concentration. These downstream signaling molecules were also decreased in the depigmented epidermis. The results of immunoprecipitation and double staining confirmed colocalization of AQP3 with E-cadherin, as well as an active role of AQP3 in E-cadherin expression of cell-to-cell contacts. Moreover, AQP3 knockdown induced no increase in differentiating markers at high calcium concentrations and reduced survival of KCs, suggesting that reduced AQP3 in vitiliginous KCs might be responsible for their reduced survival.