Neuroprotective effects of 1‐O‐hexyl‐2,3,5‐trimethylhydroquinone on ischaemia/reperfusion‐induced neuronal injury by activating the Nrf2/HO‐1 pathway

1‐O‐Hexyl‐2,3,5‐trimethylhydroquinone (HTHQ), a lipophilic phenolic agent, has an antioxidant activity and reactive oxygen species (ROS) scavenging property. However, the role of HTHQ on cerebral ischaemic/reperfusion (I/R) injury and the underlying mechanisms remain poorly understood. In the present study, we demonstrated that HTHQ treatment ameliorated cerebral I/R injury in vivo, as demonstrated by the decreased infarct volume ration, neurological deficits, oxidative stress and neuronal apoptosis. HTHQ treatment increased the levels of nuclear factor erythroid 2–related factor 2 (Nrf2) and its downstream antioxidant protein, haeme oxygenase‐1 (HO‐1). In addition, HTHQ treatment decreases oxidative stress and neuronal apoptosis of PC12 cells following hypoxia and reperfusion (H/R) in vitro. Moreover, we provided evidence that PC12 cells were more vulnerable to H/R‐induced oxidative stress after si‐Nrf2 transfection, and the HTHQ‐mediated protection was lost in PC12 cells transfected with siNrf2. In conclusion, these results suggested that HTHQ possesses neuroprotective effects against oxidative stress and apoptosis after cerebral I/R injury via activation of the Nrf2/HO‐1 pathway.     

lncRNA NR2F1‐AS1 promotes breast cancer angiogenesis through activating IGF‐1/IGF‐1R/ERK pathway

Long non‐coding RNAs (lncRNAs) take various effects in cancer mostly through sponging with microRNAs (miRNAs). lncRNA NR2F1‐AS1 is found to promote tumour progression in hepatocellular carcinoma, endometrial cancer and thyroid cancer. However, the role of lncRNA NR2F1‐AS1 in breast cancer angiogenesis remains unknown. In this study, we found lncRNA NR2F1‐AS1 was positively related with CD31 and CD34 in breast cancer through Pearson's correlation analysis, while lncRNA NR2F1‐AS1 transfection promoted human umbilical vascular endothelial cell (HUVEC) tube formation. In breast cancer cells, lncRNA NR2F1‐AS1 enhanced the HUVEC proliferation, tube formation and migration ability through tumour‐conditioned medium (TCM). In zebrafish model, lncRNA NR2F1‐AS1 increased the breast cancer cell‐related neo‐vasculature and subsequently promoted the breast cancer cell metastasis. In mouse model, lncRNA NR2F1‐AS1 promoted the tumour vessel formation, increased the micro vessel density (MVD) and then induced the growth of primary tumour. Mechanically, lncRNA NR2F1‐AS1 increased insulin‐like growth factor‐1 (IGF‐1) expression through sponging miRNA‐338‐3p in breast cancer cells and then activated the receptor of IGF‐1 (IGF‐1R) and extracellular signal‐regulated kinase (ERK) pathway in HUVECs. These results indicated that lncRNA NR2F1‐AS1 could promote breast cancer angiogenesis through IGF‐1/IGF‐1R/ERK pathway.     

Study of Thermal Decomposition of Li1‐x(Ni1/3Mn1/3Co1/3)0.9O2 Using In‐Situ High‐Energy X‐Ray Diffraction

Safety has been a major technological concern hindering the deployment of lithium‐ion batteries for automobile applications. We investigated the decomposition mechanism of delithiated cathode materials at thermal abuse conditions using Li_1.1[Ni_1/3Mn_1/3Co_1/3]_0.9O₂ as a model cathode material. An in‐situ high‐energy X‐ray diffraction technique was established as an alternative to conventional thermal analysis techniques like differential scanning calorimetry and accelerating rate calorimetry. The X‐ray diffraction data revealed that the thermal decomposition pathway of delithiated Li_1‐x[Ni_1/3Mn_1/3Co_1/3]_0.9O₂ strongly depended on the exposed chemical environment, like solvents and lithium salts. A phase transformation of dry delithiated Li_1‐x[Ni_1/3Mn_1/3Co_1/3]_0.9O₂ was observed at about 278 °C, and its onset temperature was reduced to about 197°C with the presence of the electrolyte. It is suggested that the reduction in thermal stability is possibly related to proton intercalation into the delithiated material.     

PTRN‐1/CAMSAP promotes CYK‐1/formin‐dependent actin polymerization during endocytic recycling

Cargo sorting and membrane carrier initiation in recycling endosomes require appropriately coordinated actin dynamics. However, the mechanism underlying the regulation of actin organization during recycling transport remains elusive. Here we report that the loss of PTRN‐1/CAMSAP stalled actin exchange and diminished the cytosolic actin structures. Furthermore, we found that PTRN‐1 is required for the recycling of clathrin‐independent cargo hTAC‐GFP. The N‐terminal calponin homology (CH) domain and central coiled‐coils (CC) region of PTRN‐1 can synergistically sustain the flow of hTAC‐GFP. We identified CYK‐1/formin as a binding partner of PTRN‐1. The N‐terminal GTPase‐binding domain (GBD) of CYK‐1 serves as the binding interface for the PTRN‐1 CH domain. The presence of the PTRN‐1 CH domain promoted CYK‐1‐mediated actin polymerization, which suggests that the PTRN‐1‐CH:CYK‐1‐GBD interaction efficiently relieves autoinhibitory interactions within CYK‐1. As expected, the overexpression of the CYK‐1 formin homology domain 2 (FH2) substantially restored actin structures and partially suppressed the hTAC‐GFP overaccumulation phenotype in ptrn‐1 mutants. We conclude that the PTRN‐1 CH domain is required to stimulate CYK‐1 to facilitate actin dynamics during endocytic recycling.     

UVA influenced the SIRT1‐miR‐27a‐5p‐SMAD2‐MMP1/COL1/BCL2 axis in human skin primary fibroblasts

Both SIRT1 and UVA radiation are involved in cellular damage processes such as apoptosis, senescence and ageing. MicroRNAs (miRNAs) have been reported to be closely related to UV radiation, as well as to SIRT1. In this study, we investigated the connections among SIRT1, UVA and miRNA in human skin primary fibroblasts. Our results showed that UVA altered the protein level of SIRT1 in a time point–dependent manner. Using miRNA microarray, bioinformatics analysis, we found that knocking down SIRT1 could cause up‐regulation of miR‐27a‐5p and the latter could down‐regulate SMAD2, and these results were verified by qRT‐PCR or Western blot. Furthermore, UVA radiation (5 J/cm²), knocking down SIRT1 or overexpression of miR‐27a‐5p led to increased expression of MMP1, and decreased expressions of COL1 and BCL2. We also found additive impacts on MMP1, COL1 and BCL2 under the combination of UVA radiation + Sirtinol (SIRT1 inhibitor), or UVA radiation + miR‐27a‐5p mimic. SIRT1 activator resveratrol could reverse damage changes caused by UVA radiation. Besides, absent of SIRT1 or overexpression of miR‐27a‐5p increased cell apoptosis and induced cell arrest in G2/M phase. Taken together, these results demonstrated that UVA could influence a novel SIRT1‐miR‐27a‐5p‐SMAD2‐MMP1/COL1/BCL2 axis in skin primary fibroblasts, and may provide potential therapeutic targets for UVA‐induced skin damage.     

3‐Cl‐AHPC inhibits pro‐HGF maturation by inducing matriptase/HAI‐1 complex formation

Matriptase is an epithelia‐specific membrane‐anchored serine protease, and its dysregulation is highly related to the progression of a variety of cancers. Hepatocyte growth factor activator inhibitor‐1 (HAI‐1) inhibits matriptase activity through forming complex with activated matriptase. The balance of matriptase activation and matriptase/HAI‐1 complex formation determines the intensity and duration of matriptase activity. 3‐Cl‐AHPC, 4‐[3‐(1‐adamantyl)‐4‐hydroxyphenyl]‐3‐chlorocinnamic acid, is an adamantly substituted retinoid‐related molecule and a ligand of retinoic acid receptor γ (RARγ). 3‐Cl‐AHPC is of strong anti‐cancer effect but with elusive mechanisms. In our current study, we show that 3‐Cl‐AHPC time‐ and dose‐ dependently induces matriptase/HAI‐1 complex formation, leading to the suppression of activated matriptase in cancer cells and tissues. Furthermore, 3‐Cl‐AHPC promotes matriptase shedding but without increasing the activity of shed matriptase. Moreover, 3‐Cl‐AHPC inhibits matriptase‐mediated cleavage of pro‐HGF through matriptase/HAI‐1 complex induction, resulting in the suppression of pro‐HGF‐stimulated signalling and cell scattering. Although 3‐Cl‐AHPC binds to RARγ, its induction of matriptase/HAI‐1 complex is not RARγ dependent. Together, our data demonstrates that 3‐Cl‐AHPC down‐regulates matriptase activity through induction of matriptase/HAI‐1 complex formation in a RARγ‐independent manner, providing a mechanism of 3‐Cl‐AHPC anti‐cancer activity and a new strategy to inhibit abnormal matriptase activity via matriptase/HAI‐1 complex induction using small molecules.     

1‐Aminobenzocyclobutene‐1‐phosphonic Acid and Related Compounds as Inhibitors of Phenylalanine Ammonia‐Lyase

Five new geminal aminocycloalkanephosphonic acids ( 4 – 8 ) containing both an aromatic ring and a cycloalkane ring were synthesized and evaluated as potential inhibitors of buckwheat phenylalanine ammonia‐lyase (PAL). Within the set of compounds which are related to 2‐aminoindane‐2‐phosphonic acid (AIP, 3 ), a known powerful inhibitor of PAL, racemic 1‐aminobenzocyclobutene‐1‐phosphonic acid ( 4 ), was six times weaker than AIP as an in vitro inhibitor of buckwheat PAL, but six times stronger than AIP as an in vivo inhibitor of phenylalanine‐derived anthocyanin synthesis in buckwheat.     

Nitric oxide‐mediated regulation of ‐amyloid clearance via alterations of MMP‐9/TIMP‐1

Fibrillar amyloid plaques are largely composed of amyloid‐beta (Aβ) peptides that are metabolized into products, including Aβ1‐16, by proteases including matrix metalloproteinase 9 (MMP‐9). The balance between production and degradation of Aβ proteins is critical to amyloid accumulation and resulting disease. Regulation of MMP‐9 and its endogenous inhibitor tissue inhibitor of metalloproteinase (TIMP)‐1 by nitric oxide (NO) has been shown. We hypothesize that nitric oxide synthase (NOS2) protects against Alzheimer's disease pathology by increasing amyloid clearance through NO regulation of MMP‐9/TIMP‐1 balance. We show NO‐mediated increased MMP‐9/TIMP‐1 ratios enhanced the degradation of fibrillar Aβ in vitro, which was abolished when silenced for MMP‐9 protein translation. The in vivo relationship between MMP‐9, NO and Aβ degradation was examined by comparing an Alzheimer's disease mouse model that expresses NOS2 with a model lacking NOS2. To quantitate MMP‐9 mediated changes, we generated an antibody recognizing the Aβ1‐16 fragment, and used mass spectrometry multi‐reaction monitoring assay for detection of immunoprecipitated Aβ1‐16 peptides. Aβ1‐16 levels decreased in brain lysates lacking NOS2 when compared with strains that express human amyloid precursor protein on the NOS2 background. TIMP‐1 increased in the APPSwDI/NOS2^?/? mice with decreased MMP activity and increased amyloid burden, thereby supporting roles for NO in the regulation of MMP/TIMP balance and plaque clearance.     

Growth cone neuropilin‐1 mediates collapsin‐1/sema III facilitation of antero‐ and retrograde axoplasmic transport

Collapsin‐1/SemaIII, a member of the semaphorin family, has been implicated in axonal pathfinding as a repulsive guidance cue. Cellular and molecular mechanisms by which collapsin‐1 exerts its action are not fully understood. Collapsin‐1 induces growth cone collapse via a pathway which may include neuropilin‐1, a cell‐surface collapsin‐1 binding protein, as well as intracellular CRMP‐62 and heterotrimeric G proteins. We previously identified a second action of collapsin‐1, the facilitation of antero‐ and retrograde axoplasmic transport. This response occurs via a mechanism distinct from that causing growth cone collapse. To investigate the possible involvement of neuropilin‐1 in the action of collapsin‐1 on axoplasmic transport, we produced a soluble neuropilin‐1 (sNP‐1) lacking the transmembrane and intracellular region. sNP‐1 progressively displaced the dose–response curve for collapsin‐1 to induce growth cone collapse to higher concentrations. sNP‐1 also inhibited collapsin‐1‐induced augmentation of both antero‐ and retrograde axoplasmic transport. Furthermore, an anti‐neuropilin‐1 antibody blocked the collapsin‐induced axoplasmic transport. These results together indicate that neuropilin‐1 mediates collapsin‐1 action on axoplasmic transport. To visualize collapsin‐1 binding to endogenous neuropilin‐1, we used a truncated collapsin‐1–alkaline phosphatase fusion protein (CAP‐4). CAP‐4 stains the growth cone, neurite, and cell body. However, local application of collapsin‐1 to growth cone but to neither neurite nor cell body promotes axoplasmic transport. Thus, growth cone NP‐1 mediates the facilitatory action of collapsin‐1 on antero‐ and retrograde axoplasmic transport. © 1999 John Wiley & Sons, Inc. J Neurobiol 39: 579–589, 1999     

SREBP‐1c,Pdx‐1, and GLP‐1R involved in palmitate–EPA regulated glucose‐stimulated insulin secretion in INS‐1 cells

Impairment of glucose‐stimulated insulin secretion (GSIS) caused by glucolipotoxicity is an essential feature in type 2 diabetes mellitus (T2DM). Palmitate and eicosapentaenoate (EPA), because of their lipotoxicity and protection effect, were found to impair or restore the GSIS in beta cells. Furthermore, palmitate was found to up‐regulate the expression level of sterol regulatory element‐binding protein (SREBP)‐1c and down‐regulate the levels of pancreatic and duodenal homeobox (Pdx)‐1 and glucagon‐like peptide (GLP)‐1 receptor (GLP‐1R) in INS‐1 cells. To investigate the underlying mechanism, the lentiviral system was used to knock‐down or over‐express SREBP‐1c and Pdx‐1, respectively. It was found that palmitate failed to suppress the expression of Pdx‐1 and GLP‐1R in SREBP‐1c‐deficient INS‐1 cells. Moreover, down‐regulation of Pdx‐1 could cause the low expression of GLP‐1R with/without palmitate treatment. Additionally, either SREBP‐1c down‐regulation or Pdx‐1 over‐expression could partially alleviate palmitate‐induced GSIS impairment. These results suggested that sequent SREBP‐1c‐Pdx‐1‐GLP‐1R signal pathway was involved in the palmitate‐caused GSIS impairment in beta cells. J. Cell. Biochem. 111: 634–642, 2010. © 2010 Wiley‐Liss, Inc.     

Long non‐coding RNA AFAP1‐AS1/miR‐320a/RBPJ axis regulates laryngeal carcinoma cell stemness and chemoresistance

AFAP1‐AS1 is a long non‐coding RNA that is associated with tumorigenesis and poor prognosis in a variety of cancers. We have been suggested that AFAP1‐AS1 increases tumorigenesis in laryngeal carcinoma specifically by enhancing stemness and chemoresistance. We assessed AFAP1‐AS1 expression in human laryngeal specimens, paired adjacent normal tissues and human HEp‐2 cells. Indeed, we found not only that AFAP1‐AS1 was up‐regulated in laryngeal carcinoma specimens and cells, but also that stemness‐associated genes were overexpressed. Silencing of AFAP1‐AS1 promoted HEp‐2 cell chemoresistance under cisplatin treatment. Expression of AFAP1‐AS1 was increased in drug‐resistant Hep‐2 cells. We then probed the mechanism of AFAP1‐AS1 activity and determined that miR‐320a was a potential molecular target of AFAP1‐AS1. Luciferase reporter and qRT‐PCR assays of AFAP1‐AS1 and miR‐320a levels in human specimens and cell cultures indicated that AFAP1‐AS1 negatively regulates miR‐320a. To discover the molecular mechanism of miR‐320a, we again used the DIANA Tools algorithm to predict its genetic target, RBPJ. After cloning the 3′‐untranslated regions (3′‐UTR) of RBPJ into a luciferase reporter, we determined that miR‐320a did in fact reduce RBPJ mRNA and protein levels. Ultimately, we determined that AFAP1‐AS1 increases RBPJ expression by negatively regulating miR‐320a and RBPJ overexpression rescues stemness and chemoresistance inhibited by AFAP1‐AS1 silencing. Taken together, these results suggest that AFAP1‐AS1 can serve as a prognostic biomarker in laryngeal carcinoma and that miR‐320a has the potential to improve standard therapeutic approaches to the disease, especially for cases in which cancer cell stemness and drug resistance present significant barriers to effective treatment.