S-vacancy-assisted fast charge transport and oriented ReS2 growth in twin crystal ZnxCd1-xS: an atomic-level heterostructure for dual-functional photocatalytic conversion.

The achievement of dual-functional photocatalytic technology requires a photocatalyst with accelerated charge flow and purposeful active-site arrangement. In this study, we developed an oriented embedding strategy to induce ReS2 growth at the S vacancy in twin-crystal Zn0.5Cd0.5S solid solution (Sv-ZCS), obtaining an atomic-level heterostructure (ReS2/Sv-ZCS). The electronic structure calculations demonstrate that the charge density of the Zn atom around the S vacancy is higher than for other Zn atoms and the introduced S vacancy establishes a high-speed channel for electron transport via formed Zn-S-Re bonds at the interface between ReS2 and Sv-ZCS. Photogenerated electrons and holes gathered on Re atoms and Sv-ZCS, respectively, which achieves spatial charge separation and separated arrangement for redox sites. As a result, the optimized ReS2/Sv-ZCS heterostructure possesses high efficiency of electron injection (2.6-fold) and charge separation (8.44-fold), as well as excellent conductivity capability (20.16-fold). The photocatalytic performance of the ReS2/Sv-ZCS composite exhibits highly improved dual-functional activity with simultaneous H2 evolution and selective oxidation of benzyl alcohol. The reaction rate of benzaldehyde and H2 evolution reaches 125 mmol gcat-1 h-1 and 159 mmol gcat-1 h-1, which is the highest efficiency achieved so far for simultaneous coproduction of H2 fuel and organic chemicals on ReS2-based composites. This work enriches the application of ReS2-modified composites in a dual-functional photoredox system and also gives insight into the role of defects in electronic structure modification and activity improvement.

Attracting adolescents to become doctors and nurses: differential importance of personal and environmental factors in 61 economies.

BACKGROUND: Doctors and nurses play a fundamental role in maintaining global health systems and achieving universal health care coverage. However, significant shortages persist, and little is known about the popularity of these careers among young people in various economies or the relative impact of personal inputs and contextual factors. METHODS: Using data from the large-scale Programme of International Student Assessment (PISA) 2018, we showed the recent distribution of adolescents' medical (doctor) and nursing career expectations in 61 economies. With multilevel logistic and hierarchical linear regression, we examined the relative importance of economic indicators, health work conditions, and personal background factors in affecting adolescents' health career expectations. RESULTS: Approximately 11% of adolescents expected to be doctors in each economy, while only 2% expected to be nurses. Adolescents were attracted to health professions mainly by system-level favourable conditions (accounting for 1/3 variance), including (a) government health expenditure beyond that expected gross domestic product (GDP); (b) a safe working environment for doctors in wealthy nations; and (c) high salaries for nurses in less-developed economies. In contrast, adolescents' background (gender, social status, and academic ability) was less influential, explaining only 10% of the differences. CONCLUSIONS: In the technological and digital era, high-ability students are equally competitive for emerging careers other than doctors and nurses. In developing countries, a high salary package and societal respect are enough to attract adolescents to nursing careers. In contrast, for developed countries, extra expenditures beyond regular GDP allocation and a safe work environment are crucial in attracting adolescents to become doctors. Salary may effectively attract international-trained doctors and nurses, but the work environment will likely emerge as an essential factor in retaining migrants in their positions. TRIAL REGISTRATION NUMBER: No human participants were involved in this study.

p300 Acetyltransferase Is a Cytoplasm-to-Nucleus Shuttle for SMAD2/3 and TAZ Nuclear Transport in Transforming Growth Factor ß-Stimulated Hepatic Stellate Cells.

Nuclear translocation of mothers against decapentaplegic homolog 2/3 (SMAD2/3), core transcription factors of transforming growth factor ß (TGF-ß) signaling, is critical for hepatic stellate cell (HSC) differentiation into metastasis-promoting myofibroblasts. SMAD2/3 have multiple coactivators, including WW domain-containing transcription regulator protein 1 (WWTR1 or TAZ) and p300 acetyltransferase. In the nucleus, TAZ binds to SMAD2/3 to prevent SMAD2/3 nuclear export. However, how TAZ and SMAD2/3 enter the nucleus remains poorly understood because neither contains a nuclear localization signal (NLS), an amino acid sequence tagging proteins for nuclear transport. p300 is an NLS-containing large scaffold protein, so we hypothesized that SMAD2/3 and TAZ may undergo nuclear import through complexing with p300. Coimmunoprecipitation, immunofluorescence, and nuclear fractionation assays revealed that TGF-ß1 promoted binding of SMAD2/3 and TAZ to p300 and that p300 inactivation disrupted TGF-ß1-mediated SMAD2/3 and TAZ nuclear accumulation. Deleting the p300 NLS blocked TGF-ß1-induced SMAD2/3 and TAZ nuclear transport. Consistently, p300 inactivation suppressed TGF-ß1-mediated HSC activation and transcription of genes encoding tumor-promoting factors, such as connective tissue growth factor, Tenascin C, Periostin, platelet-derived growth factor C, and fibroblast growth factor 2, as revealed by microarray analysis. Chromatin immunoprecipitation-real-time quantitative PCR showed that canonical p300-mediated acetylation of histones also facilitated transcription in response to TGF-ß1 stimulation. Interestingly, although both TGF-ß1-mediated and stiffness-mediated HSC activation require p300, comparison of gene expression data sets revealed that transcriptional targets of TGF-ß1 were distinct from those of stiffness-p300 mechanosignaling. Lastly, in tumor/HSC coinjection and intrasplenic tumor injection models, targeting p300 of activated-HSC/myofibroblasts by C646, short hairpin RNA, or cre-mediated gene disruption reduced tumor and liver metastatic growth in mice. Conclusion: p300 facilitates TGF-ß1-stimulated HSC activation by both noncanonical (cytoplasm-to-nucleus shuttle for SMAD2/3 and TAZ) and canonical (histone acetylation) mechanisms. p300 is an attractive target for inhibiting HSC activation and the prometastatic liver microenvironment.

Vasodilator-stimulated phosphoprotein promotes activation of hepatic stellate cells by regulating Rab11-dependent plasma membrane targeting of transforming growth factor beta receptors.

UNLABELLED: Liver microenvironment is a critical determinant for development and progression of liver metastasis. Under transforming growth factor beta (TGF-ß) stimulation, hepatic stellate cells (HSCs), which are liver-specific pericytes, transdifferentiate into tumor-associated myofibroblasts that promote tumor implantation (TI) and growth in the liver. However, the regulation of this HSC activation process remains poorly understood. In this study, we tested whether vasodilator-stimulated phosphoprotein (VASP) of HSCs regulated the TGF-ß-mediated HSC activation process and tumor growth. In both an experimental liver metastasis mouse model and cancer patients, colorectal cancer cells reaching liver sinusoids induced up-regulation of VASP and alpha-smooth muscle actin (α-SMA) in adjacent HSCs. VASP knockdown in HSCs inhibited TGF-ß-mediated myofibroblastic activation of HSCs, TI, and growth in mice. Mechanistically, VASP formed protein complexes with TGF-ß receptor II (TßRII) and Rab11, a Ras-like small GTPase and key regulator of recycling endosomes. VASP knockdown impaired Rab11 activity and Rab11-dependent targeting of TßRII to the plasma membrane, thereby desensitizing HSCs to TGF-ß1 stimulation. CONCLUSIONS: Our study demonstrates a requirement of VASP for TGF-ß-mediated HSC activation in the tumor microenvironment by regulating Rab11-dependent recycling of TßRII to the plasma membrane. VASP and its effector, Rab11, in the tumor microenvironment thus present therapeutic targets for reducing TI and metastatic growth in the liver.

PDGF receptor-α promotes TGF-ß signaling in hepatic stellate cells via transcriptional and posttranscriptional regulation of TGF-ß receptors.

Platelet-derived growth factor (PDGF) and transforming growth factor-ß (TGF-ß) signaling are required for hepatic stellate cell (HSC) activation under pathological conditions such as liver metastatic tumor growth. These two signaling pathways are functionally divergent; PDGF signaling promotes proliferation and migration of HSCs, and TGF-ß induces transdifferentiation of quiescent HSCs into myofibroblasts. Although PDGF signaling is implicated in TGF-ß-mediated epithelial mesenchymal transition of tumor cells, the role of PDGF receptors in TGF-ß activation of HSCs has not been investigated. Here we report that PDGF receptor-α (PDGFR-α) is required for TGF-ß signaling of cultured human HSCs although HSCs express both PDGF-α and -ß receptors. PDGFR-α knockdown inhibits TGF-ß-induced phosphorylation and nuclear accumulation of SMAD2 with no influence on AKT or ERK phosphorylation associated with noncanonical TGF-ß signaling. PDGFR-α knockdown suppresses TGF-ß receptor I (TßRI) but increases TßRII gene transcription. At the protein level, PDGFR-α is recruited to TßRI/TßRII complexes by TGF-ß stimulation. PDGFR-α knockdown blocks TGF-ß-mediated internalization of TßRII and induces accumulation of TßRII at the plasma membrane, thereby inhibiting TGF-ß phosphorylation of SMAD2. Functionally, knockdown of PDGFR-α reduces paracrine effects of HSCs on colorectal cancer cell proliferation and migration in vitro. In mice and patients, colorectal cancer cell invasion of the liver induces upregulation of PDGFR-α of HSCs. In summary, our finding that PDGFR-α knockdown inhibits SMAD-dependent TGF-ß signaling by repressing TßRI transcriptionally and blocking endocytosis of TGF-ß receptors highlights a convergence of PDGF and TGF-ß signaling for HSC activation and PDGFR-α as a therapeutic target for liver metastasis and other settings of HSC activation.

MT1-MMP prevents growth inhibition by three dimensional fibronectin matrix.

The extracellular microenvironment plays a key role in regulation of cellular functions and growth control. We show here that membrane-type 1 matrix metalloproteinase (MT1-MMP) acts as a growth promoter in confluent culture. When MT1-MMP was silenced in HT1080 fibrosarcoma cells, cells created three dimensional (3D) fibronectin matrix in a confluent culture, and growth of cells embedded within it was retarded. Formation of 3D fibronectin matrix initiated by MT1-MMP silencing was impeded by knockdown of either FN or integrin ß1, which resulted in restoration of cell growth. When cells in 3D fibronectin matrix were treated with integrin ß1 inhibitory antibody, cells underwent S phase entry. These results suggest that MT1-MMP prevents growth suppression by 3D fibronectin matrix, which is mediated through integrin ß1.

Shedding of kidney injury molecule-1 by membrane-type 1 matrix metalloproteinase.

Co-expression of membrane-type 1 matrix metalloproteinase (MT1-MMP) with kidney injury molecule-1 (KIM-1) in HEK293T cells resulted in cleavage and shedding of KIM-1 ectodomain. Analysis of cleavage products using KIM-1 mutants localized cleavage site at the juxtamembrane region. HT1080 cells were stably transfected with expression plasmid for KIM-1 or its mutant with deletion of the juxtamembrane region (Asp(261)-Gly(295)) to establish HT/KIM-1 or HT/ΔKIM-1 cells, respectively. KIM-1 protein appeared on cell surface at low level in HT/KIM-1 cells, and accumulated by the treatment with MMP inhibitor BB-94 or small interfering RNA (siRNA) to MT1-MMP, indicating that MT1-MMP is involved in cleavage and shedding of KIM-1. In contrast, HT/ΔKIM-1 cells expressed KIM-1 protein at high level regardless of BB-94 or siRNA treatment. Cells expressing high level KIM-1 protein exhibited phagocytosis of Escherichia coli and reduced cell adhesion and spreading on collagen-coated plate compared with KIM-1 negative cells. Control HT1080 and HT/KIM-1 cells showed significantly higher invasive growth in collagen gel, cell migration on collagen-coated plate and liver metastasis in chick embryo than HT/ΔKIM-1 cells. These results suggest that KIM-1 negatively regulates cellular function mediated through interaction with collagen, and MT1-MMP abrogates it through the cleavage and shedding of KIM-1.

Cleavage of hepatocyte growth factor activator inhibitor-1 by membrane-type MMP-1 activates matriptase.

Co-expression of membrane-type 1 (MT1)-MMP with hepatocyte growth factor activator inhibitor-1 (HAI-1) in HEK293T cells resulted in cleavage of HAI-1 to produce three fragments. Recombinant MT1-MMP was shown to cleave HAI-1 protein in vitro. Hepatocyte growth factor activator inhibitor-1 was initially identified as the cognate inhibitor of matriptase, a transmembrane serine protease that processes urokinase-type plasminogen activator (uPA). Co-expression of HAI-1 with matriptase suppressed matriptase protease activity, and co-expression of MT1-MMP with them resulted in recovery of matriptase activity by stimulating shedding of HAI-1 fragments. Matriptase protein was detected in squamous carcinoma-derived HSC-4 cells, however, matriptase protease activity was undetectable. Transfection of siRNA for HAI-1 enhanced serine protease activity, which was suppressed by cotransfection of matriptase siRNA. Collagen-gel culture or treatment with concanavalin A (ConA) of HSC-4 cells enhanced MT1-MMP activity, which induced shedding of HAI-1 fragments and conversely stimulated uPA activation by these cells. Serine protease activity, including uPA activation of cells treated with ConA, was abrogated by downregulation of either matriptase or MT1-MMP through the transfection of each siRNA. These results suggest that MT1-MMP induced by collagen-gel culture or ConA treatment causes cleavage and shedding of HAI-1 protein, which allows activation of matriptase in HSC-4 cells. HSC-4 cells showed a characteristic invasive growth by forming vacuole-like structures in collagen gel, which was suppressed by transfection of siRNA for either MT1-MMP or matriptase, suggesting that activation of matriptase through the cleavage of HAI-1 is one of the MT1-MMP multifunctions essential for invasive growth of HSC-4 cells.