Protective effects of nordalbergin against LPS-induced endotoxemia through inhibiting MAPK/NF-κB signaling pathway, NLRP3 inflammasome activation, and ROS production.

OBJECTIVE: Nordalbergin is a coumarin extracted from Dalbergia sissoo DC. To date, the biological effects of nordalbergin have not been well investigated. To investigate the anti-inflammatory responses and the anti-oxidant abilities of nordalbergin using lipopolysaccharide (LPS)-activated macrophages and LPS-induced sepsis mouse model. MATERIALS AND METHODS: Production of nitrite oxide (NO), prostaglandin E2 (PGE2), pro-inflammatory cytokines (tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-1ß), reactive oxygen species (ROS), tissue damage and serum inflammatory markers, and the activation of the NLRP3 inflammasome were examined. RESULTS: Our results indicated that nordalbergin reduced the production of NO and pro-inflammatory cytokines in vitro and ex vivo. Nordalbergin also suppressed iNOS and cyclooxygenase-2 expressions, decreased NF-κB activity, and attenuated MAPKs signaling pathway activation by decreasing JNK and p38 phosphorylation by LPS-activated J774A.1 macrophages. Notably, nordalbergin diminished NLRP3 inflammasome activation via repressing the maturation of IL-1ß and caspase-1 and suppressing ROS production by LPS/ATP- and LPS/nigericin-activated J774A.1 macrophages. Furthermore, nordalbergin exhibited protective effects against the infiltration of inflammatory cells and also inhibited the levels of organ damage markers (AST, ALT, BUN) by LPS-challenged mice. CONCLUSION: Nordalbergin possesses anti-inflammatory effects in macrophage-mediated innate immune responses, alleviates ROS production, decreases NLRP3 activation, and exhibits protective effects against LPS-induced tissue damage in mice.

MCL1 inhibition: a promising approach to augment the efficacy of sorafenib in NSCLC through ferroptosis induction.

Ferroptosis, an iron-dependent form of regulated cell death, plays a crucial role in modulating the therapeutic response in non-small cell lung cancer (NSCLC) patients. Studies have identified the signal transducer and activator of transcription 3 (STAT3) and myeloid cell leukemia-1 (MCL1) as potential targets for sorafenib, which exhibits activities in inducing ferroptosis. However, the role of STAT3-MCL1 axis in sorafenib-induced ferroptosis in NSCLC is still unclear. This study provided evidence that ferroptosis is a critical driver of sorafenib-induced cell death in NSCLC, supported by the accumulation of lipid peroxidation products, indicative of oxidative stress-induced cell death. Additionally, both in vitro and in vivo experiments showed that ferroptosis contributed to a significant portion of the anti-cancer effects elicited by sorafenib in NSCLC. The noticeable accumulation of lipid peroxidation products in sorafenib-treated mice underscored the significance of ferroptosis as a contributing factor to the therapeutic response of sorafenib in NSCLC. Furthermore, we identified the involvement of the STAT3/MCL1 axis in sorafenib-induced antitumor activity in NSCLC. Mechanistically, sorafenib inhibited endogenous STAT3 activation and downregulated MCL1 protein expression, consequently unleashing the ferroptosis driver BECN1 from the BECN1-MCL1 complex. Conversely, there is an augmented association of BECN1 with the catalytic subunit of system Xc-, SLC7A11, whose activity to import cystine and alleviate lipid peroxidation is hindered upon its binding with BECN1. Notably, we found that MCL1 upregulation correlated with ferroptosis resistance in NSCLC upon sorafenib treatment. Our findings highlight the importance of sorafenib-triggered ferroptosis in NSCLC and offer a novel strategy to treat advanced NSCLC patients: by downregulating MCL1 and, in turn, predispose NSCLC cells to ferroptosis.

Microglia-mediated drug substance transfer promotes chemoresistance in brain tumors: insights from an in vitro co-culture model using GCV/Tk prodrug system.

BACKGROUND: It is well known that tumor-associated macrophages (TAMs) play essential roles in brain tumor resistance to chemotherapy. However, the detailed mechanisms of how TAMs are involved in brain tumor resistance are still unclear and lack a suitable analysis model. METHODS: A BV2 microglial cells with ALTS1C1 astrocytoma cells in vitro co-culture system was used to mimic the microglia dominating tumor stroma in the tumor invasion microenvironment and explore the interaction between microglia and brain tumor cells. RESULTS: Our result suggested that microglia could form colonies with glioma cells under high-density culturing conditions and protect glioma cells from apoptosis induced by chemotherapeutic drugs. Moreover, this study demonstrates that microglia could hijack drug substances from the glioma cells and reduce the drug intensity of ALTS1C1 via direct contact. Inhibition of gap junction protein prevented microglial-glioma colony formation and microglia-mediated chemoresistance. CONCLUSIONS: This study provides novel insights into how glioma cells acquire chemoresistance via microglia-mediated drug substance transferring, providing a new option for treating chemo-resistant brain tumors.

Tumor-Derived Membrane Vesicles Restrain Migration in Gliomas By Altering Collective Polarization.

Mechanobiology is a cornerstone in physiology. However, its role in biomedical applications remains considerably undermined. In this study, we employed cell membrane vesicles (CMVs), which are currently being used as nanodrug carriers, as tactile cues for mechano-regulation of collective cell behaviors. Gliomas, which are among the most resilient brain tumors and have a low patient survival rate, were used as the cell model. We observed that mechanical responses due to the application of glioma- or microglia-derived CMVs resulted in the doubling of the traction stress of glioma cell collectives with a 10-fold increase in the CMV concentration. Glioma-CMVs constrained cell protrusions and hindered their collective migration, with the migration speed of such cells declining by almost 40% compared to the untreated cells. We speculated that the alteration of collective polarization leads to migration speed changes, and this phenomenon was elucidated using the cellular Potts model. In addition to intracellular force modulation and cytoskeletal reorganization, glioma-CMVs altered drug diffusion within glioma spheroids by downregulating the mechano-signaling protein YAP-1 while also marginally enhancing the associated apoptotic events. Our results suggest that glioma-CMVs can be applied as an adjuvant to current treatment approaches to restrict tumor invasion and enhance the penetration of reagents within tumors. Considering the broad impact of mechano-transduction on cell functions, the regulation of cell mechanics through CMVs can provide a foundation for alternative therapeutic strategies.

Evaluating the biological effectiveness of boron neutron capture therapy by using microfluidics-based pancreatic tumor spheroids.

Background: The recent success of boron neutron capture therapy (BNCT) for cancer treatment has attracted considerable attention. Because irradiated neutrons penetrate deep into solid tumor tissue, BNCT efficacy is strongly influenced by cell pathophysiology in tumors. The tumor microenvironment critically influences tumor pathophysiology, but its effects on BNCT remain unexplored. Methods: We used a pancreatic tumor as a model to develop a high-throughput 3D tumor spheroid platform for evaluating BNCT efficacy under different microenvironment conditions. We expanded our system to serve as a transwell-like device in order to investigate the influence of stromal fibroblasts in the tumor microenvironment. Results: With the use of the proposed microfluidic chip and a laboratory pipette, more than 40 spheroids with controllable diameters (standard deviation <10%) could be cultured on a chip for more than 10 days. The response to BNCT from each spheroid can be monitored in real time. By using pancreatic tumor spheroids of two different diameters, we found that large spheroids, characterized by more hypoxic microenvironments, exhibited lower BNCT susceptibility. The cells in the hypoxic region expressed the HIF1-α signal, which is crucial in many therapeutic resistance signal pathways. In addition, the heterogeneous presence of stemness markers (Oct-4, Sox-2, and CD 44) implied that the underlying BNCT resistance mechanism was sophisticated. In the presence of fibroblasts, we found an association between ß-catenin nuclear translocation and BNCT resistance; membrane contacts from fibroblasts were found to be indispensable for translocation activation. Conclusions: In summary, by means of easily accessible microfluidic engineering, we developed tumor spheroids to recapture the pathophysiological characteristics of pancreatic tumors. Our data suggest that hypoxia and fibrosis can reduce BNCT efficacy in pancreatic cancer treatment. Considering the growing requirement for drug screening in personalized medicine, our findings and the developed method are expected to improve the fundamental understanding of BNCT and facilitate broad applications of BNCT in clinical settings.

Identification of Prognostic Genes in Gliomas Based on Increased Microenvironment Stiffness.

With a median survival time of 15 months, glioblastoma multiforme is one of the most aggressive primary brain cancers. The crucial roles played by the extracellular matrix (ECM) stiffness in glioma progression and treatment resistance have been reported in numerous studies. However, the association between ECM-stiffness-regulated genes and the prognosis of glioma patients remains to be explored. Thus, using bioinformatics analysis, we first identified 180 stiffness-dependent genes from an RNA-Seq dataset, and then evaluated their prognosis in The Cancer Genome Atlas (TCGA) glioma dataset. Our results showed that 11 stiffness-dependent genes common between low- and high-grade gliomas were prognostic. After validation using the Chinese Glioma Genome Atlas (CGGA) database, we further identified four stiffness-dependent prognostic genes: FN1, ITGA5, OSMR, and NGFR. In addition to high-grade glioma, overexpression of the four-gene signature also showed poor prognosis in low-grade glioma patients. Moreover, our analysis confirmed that the expression levels of stiffness-dependent prognostic genes in high-grade glioma were significantly higher than in low-grade glioma, suggesting that these genes were associated with glioma progression. Based on a pathophysiology-inspired approach, our findings illuminate the link between ECM stiffness and the prognosis of glioma patients and suggest a signature of four stiffness-dependent genes as potential therapeutic targets.

Tissue Architecture Influences the Biological Effectiveness of Boron Neutron Capture Therapy in In Vitro/In Silico Three-Dimensional Self-Assembly Cell Models of Pancreatic Cancers.

Pancreatic cancer is a leading cause of cancer death, and boron neutron capture therapy (BNCT) is one of the promising radiotherapy techniques for patients with pancreatic cancer. In this study, we evaluated the biological effectiveness of BNCT at multicellular levels using in vitro and in silico models. To recapture the phenotypic characteristic of pancreatic tumors, we developed a cell self-assembly approach with human pancreatic cancer cells Panc-1 and BxPC-3 cocultured with MRC-5 fibroblasts. On substrate with physiological stiffness, tumor cells self-assembled into 3D spheroids, and the cocultured fibroblasts further facilitated the assembly process, which recapture the influence of tumor stroma. Interestingly, after 1.2 MW neutron irradiation, lower survival rates and higher apoptosis (increasing by 4-fold for Panc-1 and 1.5-fold for BxPC-3) were observed in 3D spheroids, instead of in 2D monolayers. The unexpected low tolerance of 3D spheroids to BNCT highlights the unique characteristics of BNCT over conventional radiotherapy. The uptake of boron-containing compound boronophenylalanine (BPA) and the alteration of E-cadherin can partially contribute to the observed susceptibility. In addition to biological effects, the probability of induced α-particle exposure correlated to the multicellular organization was speculated to affect the cellular responses to BNCT. A Monte Carlo (MC) simulation was also established to further interpret the observed survival. Intracellular boron distribution in the multicellular structure and related treatment resistance were reconstructed in silico. Simulation results demonstrated that the physical architecture is one of the essential factors for biological effectiveness in BNCT, which supports our in vitro findings. In summary, we developed in vitro and in silico self-assembly 3D models to evaluate the effectiveness of BNCT on pancreatic tumors. Considering the easy-access of this 3D cell-assembly platform, this study may not only contribute to the current understanding of BNCT but is also expected to be applied to evaluate the BNCT efficacy for individualized treatment plans in the future.

Sorting of cadherin-catenin-associated proteins into individual clusters.

The cytoplasmic tails of classical cadherins form a multiprotein cadherin-catenin complex (CCC) that constitutes the major structural unit of adherens junctions (AJs). The CCC in AJs forms junctional clusters, "E clusters," driven by cis and trans interactions in the cadherin ectodomain and stabilized by α-catenin-actin interactions. Additional proteins are known to bind to the cytoplasmic region of the CCC. Here, we analyze how these CCC-associated proteins (CAPs) integrate into cadherin clusters and how they affect the clustering process. Using a cross-linking approach coupled with mass spectrometry, we found that the majority of CAPs, including the force-sensing protein vinculin, interact with CCCs outside of AJs. Accordingly, structural modeling shows that there is not enough space for CAPs the size of vinculin to integrate into E clusters. Using two CAPs, scribble and erbin, as examples, we provide evidence that these proteins form separate clusters, which we term "C clusters." As proof of principle, we show, by using cadherin ectodomain monoclonal antibodies (mAbs), that mAb-bound E-cadherin forms separate clusters that undergo trans interactions. Taken together, our data suggest that, in addition to its role in cell-cell adhesion, CAP-driven CCC clustering serves to organize cytoplasmic proteins into distinct domains that may synchronize signaling networks of neighboring cells within tissues.

Dynamically and Spatially Controllable Albumin-Based Hydrogels for the Prevention of Postoperative Adhesion.

Since the degree of severity and the geometry of wounds vary, it is necessary to prepare an antiadhesive hydrogel that possesses dynamically controllable material properties, exhibits biodegradability, and possesses drug-releasing properties. Injectable, oxygen peroxide-sensitive, and photo-cross-linkable hydrogels that permit in situ dynamic and spatial control of their physicochemical properties were synthesized for the prevention of postoperative adhesion. Albumin is the most abundant protein in blood serum and serves as a carrier for several molecules that exhibit poor water solubility. It is therefore a suitable biomaterial for the fabrication of hydrogels since it presents a low risk of life-threatening complications and does not require immunosuppressive therapy for preventing graft rejection. The physicochemical properties of this hydrogel can then be spatially postadjusted via transdermal exposure to light to release drugs, depending on what is required for the injury. A significant reduction in postoperative peritoneal adhesion was observed in an animal model involving severe sidewall and bowel abrasions. This study demonstrated that the fabricated dually cross-linked, albumin-based hydrogels have great potential in such applications because they showed a low immune response, easy handling, full wound coverage, and tunable biodegradability. Precise spatial and controllable drug-release profiles may also be achieved via in situ transdermal post-tuning of the biomaterials, depending on the injury.

Reactive Oxygen Species and Inflammatory Responses of Macrophages to Substrates with Physiological Stiffness.

Macrophages play essential roles in innate immunity and their functions can be activated by different signals at pathological sites. Concerning changes in the rigidity of the microenvironment as a disease progresses, the influence of stiffened substrates on macrophage physiology remains elusive. In this study, to evaluate the effect of stiffened substrates on macrophages, we used J774A.1 cells as the macrophage model to investigate its mechanoinflammation responses using engineered polymeric substrates with various physiological rigidities (approximately 0.6 to 100 kPa). Under lipopolysaccharide (LPS) and adenosine triphosphate (ATP) stress, approximately 4-fold higher cytoplasmic reactive oxygen species (ROS) were triggered in cells on the softer substrate, compared with cells on the stiff substrates. The enhanced ROS response was found to be regulated mainly by NADPH oxidase. Moreover, mitochondrial ROS (mtROS), a crucial intracellular ROS source, are produced in response to substrate rigidity. The results showed higher mtROS production when cells were grown on a soft substrate with LPS/ATP stimuli, and the mechano-mtROS alteration was eliminated by Rho kinase inhibitor Y-27632. We suggest that substrate rigidity can coincide with LPS/ATP in regulating the ROS generation of macrophages. As a result of the pivotal role of ROS in regulating inflammation, increased NLRP-3 inflammasome formation and higher NO secretion (an approximately 300% increase) were observed with macrophages grown on soft substrates. Although no substantial genomic distinction was identified in our experiments, based on the phenotypic and functional results, softer substrates prime macrophages toward the proinflammatory (M1)-like phenotype. In summary, this study demonstrated the mechanosensitive inflammatory response of macrophages and the alteration of ROS, as secondary inflammation signals, may contribute to the functional status of macrophages. These findings not only provide an alternative interpretation of the functional transitions of macrophages influenced by substrate rigidity but may also support the manipulation of the inflammatory responses of macrophages via physical microenvironment modifications.

Aldolase triggers metabolic reprogramming in colorectal cancer in hypoxia and stiff desmoplastic microenvironments.

Colorectal cancer (CRC) progression is highly associated with desmoplasia. Aerobic glycolysis is another distinct feature that appears during the CRC phase of the adenoma-carcinoma sequence. However, the interconnections between the desmoplastic microenvironment and metabolic reprogramming remain largely unexplored. In our in vitro model, we investigated the compounding influences of hypoxia and substrate stiffness, two critical physical features of desmoplasia, on the CRC metabolic shift by using engineered polyacrylamide gels. Unexpectedly, we found that compared to cells on a soft gel (approximately 1.5 kPa, normal tissue), cells on a stiff gel (approximately 8.7 kPa, desmoplastic tissue) exhibited reduced glucose uptake and glycolysis under both normoxia and hypoxia. In addition, the increasing substrate stiffness activated focal adhesion kinase (FAK)/phosphoinositide 3-kinase signaling, but not the mitochondrial respiratory inhibitor HIF-1α. However, the presence of aldolase B (ALDOB) reversed the CRC metabolic response to mechanosignaling; enhanced glucose uptake (approximately 1.5-fold) and aerobic glycolysis (approximately 2- to 3--fold) with significantly decreased mitochondrial oxidative phosphorylation. ALDOB also changed the response of CRC traction force, which is related to tumor metastasis, under hypoxia/normoxia. In summary, our data suggest a counter influence of hypoxia and substrate stiffness on glucose uptake, and ALDOB upregulation can reverse this, which drives hypoxia and stiff substrate to enhance the CRC aerobic glycolysis synergistically. The results not only highlight the potential impacts on metabolic reprogramming led by physical alterations in the microenvironment, but also extend our understanding of the essential role of ALDOB in CRC progression from a biophysical perspective.

Corylin inhibits LPS-induced inflammatory response and attenuates the activation of NLRP3 inflammasome in microglia.

BACKGROUND: Inflammation has been found to be associated with many neurodegenerative diseases, including Parkinson's and dementia. Attenuation of microglia-induced inflammation is a strategy that impedes the progression of neurodegenerative diseases. METHODS: We used lipopolysaccharide (LPS) to simulate murine microglia cells (BV2 cells) as an experimental model to mimic the inflammatory environment in the brain. In addition, we examined the anti-inflammatory ability of corylin, a main compound isolated from Psoralea corylifolia L. that is commonly used in Chinese herbal medicine. The production of nitric oxide (NO) by LPS-activated BV2 cells was measured using Griess reaction. The secretion of proinflammatory cytokines including tumor necrosis factor (TNF-α), interleukin-1ß (IL-1ß) and interleukin-6 (IL-6) by LPS-activated BV2 cells was analyzed using enzyme-linked immunosorbent assay (ELISA). The expression of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3), apoptosis-associated speck-like protein containing a caspase-activation and recruitment domain (ASC), caspase-1, IL-1ß and mitogen-activated protein kinases (MAPKs) in LPS-activated BV2 cells was examined by Western blot. RESULTS: Our experimental results demonstrated that corylin suppressed the production of NO and proinflammatory cytokines by LPS-activated BV2 cells. In addition, corylin inhibited the expression of iNOS and COX-2, attenuated the phosphorylation of ERK, JNK and p38, decreased the expression of NLRP3 and ASC, and repressed the activation of caspase-1 and IL-1ß by LPS-activated BV2 cells. CONCLUSION: Our results indicate the anti-inflammatory effects of corylin acted through attenuating LPS-induced inflammation and inhibiting the activation of NLRP3 inflammasome in LPS-activated BV2 cells. These results suggest that corylin might have potential in treating brain inflammation and attenuating the progression of neurodegeneration diseases.

Unexpected dose response of HaCaT to UVB irradiation.

Application of high-dosage UVB irradiation in phototherapeutic dermatological treatments present health concerns attributed to UV-exposure. In assessing UV-induced photobiological damage, we investigated dose-dependent effects of UVB irradiation on human keratinocyte cells (HaCaT). Our study implemented survival and apoptosis assays and revealed an unexpected dose response wherein higher UVB-dosage induced higher viability. Established inhibitors, such as AKT- (LY294002), PKC- (Gö6976, and Rottlerin), ERK- (PD98059), P38 MAPK- (SB203580), and JNK- (SP600125), were assessed to investigate UV-induced apoptotic pathways. Despite unobvious contributions of known signaling pathways in dose-response mediation, microarray analysis identified transcriptional expression of UVB-response genes related to the respiratory-chain. Observed correlation of ROS-production with UVB irradiation potentiated ROS as the underlying mechanism for observed dose responses. Inability of established pathways to explain such responses suggests the complex nature underlying UVB-phototherapy response.

Superhydrophobic graphene-based sponge as a novel sorbent for crude oil removal under various environmental conditions.

Mechanical recovery of oils using oil sorbents is one of the most important approaches to manage marine oil spills. However, the properties of the oils spilled into sea are influenced by external environmental conditions. In this study, we present a graphene-based (GB) sponge as a novel sorbent for crude oil removal and compare its performance with that of a commercial sorbent sheet under various environmental parameters. The GB sponge with excellent superhydrophobic and superoleophilic characteristics is demonstrated to be an efficient sorbent for crude oils, with high sorption capacity (up to 85-95 times its weight) and good reusability. The crude-oil-sorption capacity of our GB sponge is remarkably higher (about 4-5 times) than that of the commercial sheet and most other previously reported sponge sorbents. Moreover, several challenging environmental conditions were examined for their effects on the sorption performance, including the weathering time of oils, seawater temperature, and turbulence (wave effect). The results show that the viscosity of the oil increased with increasing weathering time or decreasing temperature; therefore, the sorption rate seemed to decrease with longer weathering times and lower temperatures. Turbulence can facilitate inner sorption and promote higher oil sorption. Our results indicate that the extent of the effects of weather and other environmental factors on crude oil should be considered in the assessment of the effective adsorption capacity and efficiency of sorbents. The present work also highlights the widespread potential applications of our GB sponge in marine spilled-oil cleanup and hydrophobic solvent removal.

RNA-seq transcriptome analysis of breast cancer cell lines under shikonin treatment.

Shikonin is a naphthoquinone isolated from the dried root of Lithospermum erythrorhizon, an herb used in Chinese medicine. Although several studies have indicated that shikonin exhibits antitumor activity in breast cancer, the mechanism of action remains unclear. In the present study, we performed transcriptome analysis using RNA-seq and explored the mechanism of action of shikonin in regulating the growth of different types of breast cancer cells. The IC50 of shikonin on MCF-7, SKBR-3 and MDA-MB-231 cells were 10.3 µΜ, 15.0 µΜ, 15.0 µΜ respectively. Our results also demonstrated that shikonin arrests the progression of cell cycle and induces apoptosis in MDA-MB-231 cells. Using RNA-seq transcriptome analysis, we found 38 common genes that significantly express in different types of breast cancer cells under shikonin treatment. In particular, our results indicated that shikonin induces the expression of dual specificity phosphatase (DUSP)-1 and DUSP2 in both RNA and protein levels. In addition, shikonin also inhibits the phosphorylation of JNK and p38, the downstream signaling molecules of DUSP1 and DUSP2. Therefore, our results suggest that shikonin induces the expression of DUSP1 and DUSP2 which consequently switches off JNK and p38 MAPK pathways and causes cell cycle arrest and apoptosis in breast cancer cells.

Corylin protects LPS-induced sepsis and attenuates LPS-induced inflammatory response.

Corylin is a main compound isolated from Psoralea corylifolia L. (Fabaceae). A variety of pharmacological effects such as antioxidant, anti-proliferation, and anti-inflammatory properties of corylin have been reported. Nevertheless, the effect of corylin in microbial infection and sepsis remains unclear. In the present study, we investigated the anti-inflammatory effects of corylin. Our experimental results demonstrated that corylin inhibited the production of TNF-α, IL-6 and NO by both LPS-activated RAW 264.7 cells and LPS-activated murine peritoneal macrophages. Moreover, corylin suppressed the expression levels of iNOS and COX-2, reduced the production of PGE2 and HMGB1, blocked the translocation of HMGB1 from the nucleus to cytosol, and decreased the phosphorylation of MAPKs in LPS-activated RAW 264.7 cells as well as suppressed the activity of NF-κB in LPS-activated J-Blue cells. In addition, the administration of corylin reduced the production of NO and TNF-α, decreased LPS-induced liver damage markers (AST and ALT) and kidney damage markers (BUN and CRE), attenuated infiltration of inflammatory cells and tissue damage of lung, liver and kidney, and enhanced the survival rate of LPS-challenged mice. Taken together, these results show the anti-inflammatory properties of corylin on LPS-induced inflammation and sepsis. Corylin could potentially be a novel anti-inflammatory and immunosuppressive drug candidate in the treatment of sepsis and septic shock.

Microgrooved Surface Modulates Neuron Differentiation in Human Embryonic Stem Cells.

Stem cell-based therapies have drawn intensive attention in the neuronal regenerative fields. Several studies have revealed that stem cells can serve as an inexhaustible source for neurons for transplantation therapies. However, generation of neurons and directionality has not yet been fully investigated. Herein, we investigate the mechanical ramifications of surface topography on human embryonic cell differentiation. Microgrooved surfaces with various pitches were applied to modulate the neuron differentiation. Our protocol showed that neuron differentiation increased as grove pitch decreased. The results indicated that 2 µm microgrooves can improve neuron growth by ~1.7-fold. Our results indicate the importance of mechanotransduction on neuronal differentiation and highlight the feasibility of manipulating the neuronal differentiation with surface topography, providing new perspectives for accommodating clinical transplantation.

α-Catenin-mediated cadherin clustering couples cadherin and actin dynamics.

The function of the actin-binding domain of α-catenin, αABD, including its possible role in the direct anchorage of the cadherin-catenin complex to the actin cytoskeleton, has remained uncertain. We identified two point mutations on the αABD surface that interfere with αABD binding to actin and used them to probe the role of α-catenin-actin interactions in adherens junctions. We found that the junctions directly bound to actin via αABD were more dynamic than the junctions bound to actin indirectly through vinculin and that recombinant αABD interacted with cortical actin but not with actin bundles. This interaction resulted in the formation of numerous short-lived cortex-bound αABD clusters. Our data suggest that αABD clustering drives the continuous assembly of transient, actin-associated cadherin-catenin clusters whose disassembly is maintained by actin depolymerization. It appears then that such actin-dependent αABD clustering is a unique molecular mechanism mediating both integrity and reassembly of the cell-cell adhesive interface formed through weak cis- and trans-intercadherin interactions.

Nicotine alters mucin rheological properties.

Tobacco smoke exposure, the major cause of chronic obstructive pulmonary disease (COPD), instigates a dysfunctional clearance of thick obstructive mucus. However, the mechanism underlying the formation of abnormally viscous mucus remains elusive. We investigated whether nicotine can directly alter the rheological properties of mucin by examining its physicochemical interactions with human airway mucin gels secreted from A549 lung epithelial cells. Swelling kinetics and multiple particle tracking were utilized to assess mucin gel viscosity change when exposed to nicotine. Herein we show that nicotine (≤50 nM) significantly hindered postexocytotic swelling and hydration of released mucins, leading to higher viscosity, possibly by electrostatic and hydrophobic interactions. Moreover, the close association of nicotine and mucins allows airway mucus to function as a reservoir for prolonged nicotine release, leading to correlated pathogenic effects. Our results provide a novel explanation for the maltransport of poorly hydrated mucus in smokers. More importantly, this study further indicates that even low-concentration nicotine can profoundly increase mucus viscosity and thus highlights the health risks of secondhand smoke exposure.

Aggregation, dissolution, and stability of quantum dots in marine environments: importance of extracellular polymeric substances.

There is an increasing concern that a considerable fraction of engineered nanoparticles (ENs), including quantum dots (QDs), will eventually find their way into the marine environment and have negative impacts on plankton. As ENs enter the ocean, they will encounter extracellular polymeric substances (EPS) from microbial sources before directly interacting with plankton cells. In this study, EPS harvested from four phytoplankton species, Amphora sp., Dunaliella tertiolecta, Phaeocystis globosa, and Thalassiosira pseudonana, were examined for potential interactions with CdSe nonfunctionalized and functionalized (carboxyl- and amine-) QDs in artificial seawater. Our results show that EPS do not reduce the solubility of QDs but rather decrease their stability. The degradation rate of QDs was positively correlated to the protein composition of EPS (defined by the ratio of protein/carbohydrate). Two approaches showed significant inhibition to the degradation of carboxyl-functionalized QDs: (1) the presence of an antioxidant, such as N-acetyl cysteine, and (2) absence of light. Owing to the complexity in evaluating integrated effects of QDs intrinsic properties and the external environmental factors that control the stability of QDs, conclusions must be based on a careful consideration of all these factors when attempting to evaluate the bioavailability of QDs and other ENs in the marine environments.