Superconducting diode effect and interference patterns in kagome CsV3Sb5.

The interplay among frustrated lattice geometry, non-trivial band topology and correlation yields rich quantum states of matter in kagome systems1,2. A series of recent members in this family, AV3Sb5 (A = K, Rb or Cs), exhibit a cascade of symmetry-breaking transitions3, involving the 3Q chiral charge ordering4-8, electronic nematicity9,10, roton pair density wave11 and superconductivity12. The nature of the superconducting order is yet to be resolved. Here we report an indication of dynamic superconducting domains with boundary supercurrents in intrinsic CsV3Sb5 flakes. The magnetic field-free superconducting diode effect is observed with polarity modulated by thermal histories, suggesting that there are dynamic superconducting order domains in a spontaneous time-reversal symmetry-breaking background. Strikingly, the critical current exhibits double-slit superconductivity interference patterns when subjected to an external magnetic field. The characteristics of the patterns are modulated by thermal cycling. These phenomena are proposed as a consequence of periodically modulated supercurrents flowing along certain domain boundaries constrained by fluxoid quantization. Our results imply a time-reversal symmetry-breaking superconducting order, opening a potential for exploring exotic physics, for example, Majorana zero modes, in this intriguing topological kagome system.

Alkaline phosphatase downregulation promotes lung adenocarcinoma metastasis via the c-Myc/RhoA axis.

BACKGROUND: Lung adenocarcinoma (LUAD) metastasis significantly reduces patient survival; hence inhibiting the metastatic ability of lung cancer cells will greatly prolong patient survival. Alkaline phosphatase (ALPL), a homodimeric cell surface phosphohydrolase, is reported to play a controversial role in prostate cancer and ovarian cancer cell migration; however, the function of ALPL in LUAD and the related mechanisms remain unclear. METHODS: TCGA database was used to analysis the expression of ALPL, and further verification was performed in a cohort of 36 LUAD samples by qPCR and western blot. Soft-agar assay, transwell assay and lung metastasis assay were employed to detect the function of ALPL in LUAD progression. The qPCR, luciferase promoter reporter assay and western blot were used to clarify the molecular mechanisms of ALPL in promoting metastasis in LUAD. RESULTS: ALPL was downregulated in LUAD, and the disease-free survival rate of patients with low ALPL was significantly reduced. Further studies showed that overexpression of ALPL in LUAD cell lines did not significantly affect cell proliferation, but it did significantly attenuate lung metastasis in a mouse model. ALPL downregulation in LUAD led to a decrease in the amount of phosphorylated (p)-ERK. Because p-ERK promotes the classical c-Myc degradation pathway, the decrease in p-ERK led to the accumulation of c-Myc and therefore to an increase in RhoA transcription, which enhanced LUAD cell metastasis. CONCLUSION: ALPL specially inhibits the metastasis of LUAD cells by affecting the p-ERK/c-Myc/RhoA axis, providing a theoretical basis for the targeted therapy of clinical LUAD.

Zinc Toxicity and Iron-Sulfur Cluster Biogenesis in Escherichia coli.

While zinc is an essential trace metal in biology, excess zinc is toxic to organisms. Previous studies have shown that zinc toxicity is associated with disruption of the [4Fe-4S] clusters in various dehydratases in Escherichia coli Here, we report that the intracellular zinc overload in E. coli cells inhibits iron-sulfur cluster biogenesis without affecting the preassembled iron-sulfur clusters in proteins. Among the housekeeping iron-sulfur cluster assembly proteins encoded by the gene cluster iscSUA-hscBA-fdx-iscX in E. coli cells, the scaffold IscU, the iron chaperone IscA, and ferredoxin have strong zinc binding activity in cells, suggesting that intracellular zinc overload inhibits iron-sulfur cluster biogenesis by binding to the iron-sulfur cluster assembly proteins. Mutations of the conserved cysteine residues to serine in IscA, IscU, or ferredoxin completely abolish the zinc binding activity of the proteins, indicating that zinc can compete with iron or iron-sulfur cluster binding in IscA, IscU, and ferredoxin and block iron-sulfur cluster biogenesis. Furthermore, intracellular zinc overload appears to emulate the slow-growth phenotype of the E. coli mutant cells with deletion of the iron-sulfur cluster assembly proteins IscU, IscA, and ferredoxin. Our results suggest that intracellular zinc overload inhibits iron-sulfur cluster biogenesis by targeting the iron-sulfur cluster assembly proteins IscU, IscA, and ferredoxin in E. coli cells.IMPORTANCE Zinc toxicity has been implicated in causing various human diseases. High concentrations of zinc can also inhibit bacterial cell growth. However, the underlying mechanism has not been fully understood. Here, we report that zinc overload in Escherichia coli cells inhibits iron-sulfur cluster biogenesis by targeting specific iron-sulfur cluster assembly proteins. Because iron-sulfur proteins are involved in diverse physiological processes, the zinc-mediated inhibition of iron-sulfur cluster biogenesis could be largely responsible for the zinc-mediated cytotoxicity. Our finding provides new insights on how intracellular zinc overload may inhibit cellular functions in bacteria.

Congenital hypodysfibrinogenemia associated with a novel deletion of three residues (γAla289_Asp291del) in fibrinogen.

Hypodysfibrinogenemia is the least frequently reported congenital fibrinogen disorder, characterized by both quantity and quality defects of fibrinogen. In this study, we investigated the molecular basis of hypodysfibrinogenemia in a Chinese family. Functional fibrinogen was measured by Clauss method, and the antigenic fibrinogen was measured by immunoturbidimetry assay. All the exons and exon-intron boundaries of fibrinogen genes (FGA, FGB and FGG) were analysed by direct DNA sequencing. To further evaluate its molecular and functional characterizations, fibrinogen was purified from the plasma of propositus, then SDS-PAGE, fibrin polymerization, clot lysis, and electron microscopy scanning were all performed. The propositus showed a slight decrease of immunologic fibrinogen (1.52 g/L) but dramatically reduced functional fibrinogen (0.3 g/L). DNA sequencing revealed a novel heterozygous CCTTTGATG deletion in the exon 8 of FGG, leading to the deletion of Ala289, Phe290, and Asp291 in fibrinogen γ-chain. The polymerization of the fibrinogen from the propositus was markedly impaired, with prolonged lag period and decreased final turbidity. The fibrinogen clottability showed a reduced fraction of participating clot formation. While the clot lysis showed normal. Scanning electron microscopy revealed that the fibers of the propositus were thicker than normal, with larger pores and curlier meshworks. We conclude that γAla289_Asp291del is responsible for the hypodysfibrinogenemia in this case.

Lithium Ion Intercalation-Induced Metal-Insulator Transition in Inclined-Standing Grown 2D Non-Layered Cr2S3 Nanosheets.

Gate-controlled ionic intercalation in the van der Waals gap of 2D layered materials can induce novel phases and unlock new properties. However, this strategy is often unsuitable for densely packed 2D non-layered materials. The non-layered rhombohedral Cr2S3 is an intrinsic heterodimensional superlattice with alternating layers of 2D CrS2 and 0D Cr1/3. Here an innovative chemical vapor deposition method is reported, utilizing strategically modified metal precursors to initiate entirely new seed layers, yields ultrathin inclined-standing grown 2D Cr2S3 nanosheets with edge instead of face contact with substrate surfaces, enabling rapid all-dry transfer to other substrates while ensuring high crystal quality. The unconventional ordered vacancy channels within the 0D Cr1/3 layers, as revealed by cross-sectional scanning transmission electron microscope, permitting the insertion of Li+ ions. An unprecedented metal-insulator transition, with a resistance modulation of up to six orders of magnitude at 300 K, is observed in Cr2S3-based ionic field-effect transistors. Theoretical calculations corroborate the metallization induced by Li-ion intercalation. This work sheds light on the understanding of growth mechanism, structure-property correlation and highlights the diverse potential applications of 2D non-layered Cr2S3 superlattice.

Thermoelectric Properties of n-Type Bi4O4SeX2 (X = Cl, Br).

The multiple anion superlattice Bi4O4SeCl2 has been reported to exhibit extremely low thermal conductivity along the stacking c-axis, making it a promising material for thermoelectric applications. In this study, we investigate the thermoelectric properties of Bi4O4SeX2 (X = Cl, Br) polycrystalline ceramics with different electron concentrations by adjusting the stoichiometry. Despite optimizing the electric transport, the thermal conductivity remained ultra-low and approached the Ioffe-Regel limit at high temperatures. Notably, our findings demonstrate that non-stoichiometric tuning is a promising approach for enhancing the thermoelectric performance of Bi4O4SeX2 by refining its electric transport, resulting in a figure of merit of up to 0.16 at 770 K.

Achieving Ferroelectricity in a Centrosymmetric High-Performance Semiconductor by Strain Engineering.

Phase engineering by strain in 2D semiconductors is of great importance for a variety of applications. Here, a study of the strain-induced ferroelectric (FE) transition in bismuth oxyselenide (Bi2 O2 Se) films, a high-performance (HP) semiconductor for next-generation electronics, is presented. Bi2 O2 Se is not FE at ambient pressure. At a loading force of ≳400 nN, the piezoelectric force responses exhibit butterfly loops in magnitude and 180° phase switching. By carefully ruling out extrinsic factors, these features are attributed to a transition to the FE phase. The transition is further supported by the appearance of a sharp peak in optical second-harmonic generation under uniaxial strain. In general, solids with paraelectrics at ambient pressure and FE under strain are rare. The FE transition is discussed using first-principles calculations and theoretical simulations. The switching of FE polarization acts as a knob for Schottky barrier engineering at contacts and serves as the basis for a memristor with a huge on/off current ratio of 106 . This work adds a new degree of freedom to HP electronic/optoelectronic semiconductors, and the integration of FE and HP semiconductivity paves the way for many exciting functionalities, including HP neuromorphic computing and bulk piezophotovoltaics.

Commensurate Stacking Phase Transitions in an Intercalated Transition Metal Dichalcogenide.

Intercalation and stacking-order modulation are two active ways in manipulating the interlayer interaction of transition metal dichalcogenides (TMDCs), which lead to a variety of emergent phases and allow for engineering material properties. Herein, the growth of Pb-intercalated TMDCs-Pb(Ta1+x Se2 )2 , the first 124-phase, is reported. Pb(Ta1+x Se2 )2 exhibits a unique two-step first-order structural phase transition at around 230 K. The transitions are solely associated with the stacking degree of freedom, evolving from a high-temperature (high-T) phase with ABC stacking and R3m symmetry to an intermediate phase with AB stacking and P3m1, and finally to a low-temperature (low-T) phase again with R3msymmetry, but with ACB stacking. Each step involves a rigid slide of building blocks by a vector [1/3, 2/3, 0]. Intriguingly, gigantic lattice contractions occur at the transitions on warming. At low-T, bulk superconductivity with Tc  ≈ 1.8 K is observed. The underlying physics of the structural phase transitions are discussed from first-principle calculations. The symmetry analysis reveals topological nodal lines in the band structure. The results demonstrate the possibility of realizing higher-order metal-intercalated phases of TMDCs and advance the knowledge of polymorphic transitions, and may inspire stacking-order engineering in TMDCs and beyond.

Lupeol inhibits migration and invasion of colorectal cancer cells by suppressing RhoA-ROCK1 signaling pathway.

Metastasis is the main cause of death in colorectal cancer (CRC) patients. However, current treatment options for CRC metastasis are very limited. Lupeol, a triterpene that is widely found in vegetables and fruits, has been reported to possess the cancer-preventive and anti-inflammatory functions. However, the roles of Lupeol in the migration and invasion of colorectal cancer remain unclear. Here, we evaluated the effect of Lupeol treatment on colorectal cancer cell lines, HCT116 and SW620, and delineated its underlying mechanisms. Our results showed that Lupeol induced a dose-dependent inhibition of HCT116 and SW620 cells viability, measured by CCK8 assay. Wound healing and Transwell migration and invasion assays revealed that Lupeol significantly suppressed the migration and invasion of CRC cells. Using laser confocal microscope, we observed that the pseudopods and protrusions of HCT116 and SW620 cells decreased and disrupted after treatment with Lupeol. In addition, the quantitative real-time PCR and Western blotting results showed that Lupeol downregulated the expression of RhoA and RhoC, and their downstream effectors ROCK1, Cofilin, p-MLC, and the associated regulatory protein Cyclin A2. Interestingly, the migration and invasion capacity of CRC cells was reduced after RhoA knockdown. And there were no additional changes in CRC cells with RhoA knockdown to treat with Lupeol. These findings demonstrate that Lupeol can suppress the migration and invasion of colorectal cancer cells by remodeling the actin cytoskeleton via RhoA-ROCK1 pathway inhibition, which may provide an effective anti-metastatic agent for CRC patients.

FH535 inhibits proliferation and migration of colorectal cancer cells by regulating CyclinA2 and Claudin1 gene expression.

Wnt signaling pathway plays a major role in the progression of colorectal cancer (CRC). Small molecules which can cut off this signal transduction can be promising anti-cancer drugs for CRC therapy. Therefore, we aimed to investigate the mechanisms of FH535, an inhibitor of the Wnt signaling pathway, on inhibiting proliferation and migration of colorectal cancer cells DLD-1 and SW620. We found that FH535 could significantly suppress the growth of DLD-1 and SW620 cells in a concentration-dependent and time-dependent manner. The results of cell cycle tests showed that FH535 could significantly induce G2/M arrest in colorectal cancer cells. Transwell and Wound-healing assays revealed that FH535 notably inhibited cell migration. Moreover, we found that FH535 down-regulated ß-catenin and CyclinA2 expressions while up-regulating Claudin-1 expression at both mRNA and protein levels, which may contribute to the FH535-induced inhibitory effect on proliferation and migration in human colorectal cancer cells. Our study revealed that FH535 inhibited proliferation and migration of colorectal cancer cells by regulating CyclinA2 and Claudin1 gene expression, which enriches regulatory network of FH535 and may contribute to being promising anti-cancer drugs for CRC therapy.

KMT2A histone methyltransferase contributes to colorectal cancer development by promoting cathepsin Z transcriptional activation.

Accumulating evidence supports the notion that epigenetic modifiers are abnormal in carcinogenesis and have a fundamental role in cancer progression. Among these aberrant epigenetic modifiers, the function of histone methyltransferase KMT2A in somatic tumors is not well known. By analyzing KMT2A expression in patient tissues, we demonstrated that KMT2A was overexpressed in colorectal cancer tissues in comparison with adjacent normal tissues and its expression was positively correlated with cancer stages. In KMT2A-knockdown HCT116 and DLD1 cells, cell invasion and migration were consequently suppressed. In addition, KMT2A depletion effectively suppressed cancer metastasis in vivo. Mechanistically, cathepsin Z (CTSZ) was demonstrated to be an important downstream gene of KMT2A. Further studies showed that p65 could recruit KMT2A on the promoter region of the downstream gene CTSZ and knockdown of p65 could reduce the KMT2A on the promoter of CTSZ. Finally, our present study revealed that KMT2A epigenetically promotes cancer progression by targeting CTSZ, which has specific functions in cancer invasion and metastasis.

Lupeol inhibits growth and migration in two human colorectal cancer cell lines by suppression of Wnt-ß-catenin pathway.

BACKGROUND: Lupeol, a triterpene isolated from various herbal plants, possesses an anti-inflammatory function and has been proposed as a candidate for anticancer agents. The purpose of this research was to investigate the effect of lupeol on the viability, apoptosis, cell-cycle distribution, and migration of colorectal cancer cell lines and its molecular mechanism. METHODS: Lupeol was assessed for its anticancer effect using two human colorectal cancer cell lines: SW480 and HCT116. These cells were treated with lupeol, and their viability, apoptosis, migration, and cycle distribution were detected by CCK8, flow cytometry, and the transwell method. Quantitative PCR, Western blot, and immunofluorescence were applied to detect the expressions of CTNNB1, TCF4, cMYC, CCND1, CLDN1, and CCNA2. RESULTS: Lupeol suppressed cell viability and migration and induced cellular apoptosis of both cell lines, with increased p53 and decreased Bcl2 protein levels (P<0.05). Cell cycles of both lupeol-treated cell lines were arrested in the S phase (P<0.05). Quantitative PCR and Western blot analyses showed significantly reduced expressions of CTNNB1, TCF4, and downstream genes of the Wnt-ß-catenin pathway, including the cell-cycle-regulated genes of cMYC and CCND1 of both cell lines upon lupeol treatment (P<0.05). mRNA and protein levels of CLDN1 decreased in HCT116 cells, plus the expression of CCNA2 mRNA and protein decreased in SW480 cells (P<0.05). Immunofluorescence analysis confirmed decreased expression of Wnt-ß-catenin signaling. CONCLUSION: Our findings indicate that lupeol effectively inhibits proliferation and migration and induces apoptosis and cell-cycle arrest of two colorectal cell lines by inactivation of the Wnt-ß-catenin signaling pathway and downregulation of cMYC, CCND1, CCNA2, and CLDN1, thereby making it a promising anticancer candidate.

[DNA damage, Bcl-2, Bax expression and ultrastructure change in spermatogenic cell of mice exposed to cadmium].

OBJECTIVE: To study DNA damage, Bcl-2 and Bax expression, and ultrastructure change in spermatogenic cell of mice by cadmium exposure. METHODS: Twenty-four male mice were divided into 4 groups: 3 groups treated with cadmium chloride of 1, 5, 10 micromol x kg(-1) x d(-1) i.p. respectively for 5 days, and one normal saline control group. The DNA damage of spermatogenic cell by single-cell gel electrophoresis technology was detected. The expression positive rate of Bcl-2, Bax protein in spermatogenic cell by the immunohistochemical method was assayed, and the ultrastructural change of spermatogenic cell by the transmission electron microscope was observed. RESULTS: DNA damage rates of of spermatogenic cell in 1, 5, 10 micromol/kg cadmium chloride groups were higher than that of normal group (P < 0.001). Bcl-2 protein expression positive rates were lower than that of normal group (P < 0.001). Bax protein positive expression rate in 5 micromol/kg group was higher than those in normal group, and 1, 10 micromol/kg groups. The ultrastructure of karyotis, karyotheca, mitochondria, endoplasmic reticulum in three treated groups had different degree of damage and the degree of ultrastructural change was increasing with rising concentration of cadmium. CONCLUSION: Cadmium exposure will cause the DNA break, Bcl-2 and Bax protein abnormal expression and ultrastructural change in spermatogenic cell.

Drosophila perlecan regulates intestinal stem cell activity via cell-matrix attachment.

Stem cells require specialized local microenvironments, termed niches, for normal retention, proliferation, and multipotency. Niches are composed of cells together with their associated extracellular matrix (ECM). Currently, the roles of ECM in regulating niche functions are poorly understood. Here, we demonstrate that Perlecan (Pcan), a highly conserved ECM component, controls intestinal stem cell (ISC) activities and ISC-ECM attachment in Drosophila adult posterior midgut. Loss of Pcan from ISCs, but not other surrounding cells, causes ISCs to detach from underlying ECM, lose their identity, and fail to proliferate. These defects are not a result of a loss of epidermal growth factor receptor (EGFR) or Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling activity but partially depend on integrin signaling activity. We propose that Pcan secreted by ISCs confers niche properties to the adjacent ECM that is required for ISC maintenance of stem cell identity, activity, and anchorage to the niche.