Platelet activation with unfractionated heparin at therapeutic concentrations and comparisons with a low-molecular-weight heparin and with a direct thrombin inhibitor

BACKGROUND

The growing use of heparin in acute thrombotic disorders, coupled with the availability of many new antithrombotic agents, emphasizes the need for adequate characterization of the platelet effects of the various anticoagulants. Controversial platelet effects have been reported with heparin (eg, enhanced platelet activation in vitro with high doses and no such effect in vivo at therapeutic doses). This study examined platelet receptor activation and platelet aggregation at therapeutic concentrations of unfractionated heparin (UFH), of enoxaparin, a low-molecular-weight heparin, and of argatroban, a direct thrombin inhibitor.

METHODS AND RESULTS

Platelet P-selectin (CD62) and activated GP IIb/IIIa (PAC-1) expression on platelet membrane was quantified in whole blood as well as platelet aggregation in platelet-rich plasma in 43 patients with unstable angina before and during treatment with UFH or enoxaparin. Studies were also carried out in blood of seven normal volunteers after addition ex vivo of UFH (0.25 U/mL), enoxaparin (0.25 U/mL), argatroban (1 ng/mL), and normal saline. UFH in patients with unstable angina increased the percentage of circulating platelets positive to PAC-1 from 2.7+/-1.7% to 4.4+/-3.4% (P<.05) and to CD62 from 1.6+/-0.9% to 2.7+/-1.5% (P<.01). Platelets were also hyperresponsive to stimulation with ADP and with the thrombin-receptor agonist peptide. Aggregation to ADP increased from 6.8+/-4.6% to 11.2+/-7.0% and to TRAP from 5.2+/-3.5% to 11.1+/-6.0% (P<.001). The addition of UFH to blood of normal volunteers resulted also in activation of GP IIb/IIIa receptors, expression of P-selectin, and enhanced platelet aggregation. Enoxaparin had only minor effects on platelet activation in vivo and ex vivo, and argatroban, evaluated ex vivo, had no detectable effects.

CONCLUSIONS

Therapeutic concentrations of UFH are associated with platelet activation.

Dynamic distribution of chemoattractant receptors in living cells during chemotaxis and persistent stimulation

While the localization of chemoattractant receptors on randomly oriented cells has been previously studied by immunohistochemistry, the instantaneous distribution of receptors on living cells undergoing directed migration has not been determined. To do this, we replaced cAR1, the primary cAMP receptor of Dictyostelium, with a cAR1-green fluorescence protein fusion construct. We found that this chimeric protein is functionally indistinguishable from wild-type cAR1. By time-lapse imaging of single cells, we observed that the receptors remained evenly distributed on the cell surface and all of its projections during chemotaxis involving turns and reversals of polarity directed by repositioning of a chemoattractant-filled micropipet. Thus, cell polarization cannot result from a gradient-induced asymmetric distribution of chemoattractant receptors. Some newly extended pseudopods at migration fronts showed a transient drop in fluorescence signals, suggesting that the flow of receptors into these zones may slightly lag behind the protrusion process. Challenge with a uniform increase in chemoattractant, sufficient to cause a dramatic decrease in the affinity of surface binding sites and cell desensitization, also did not significantly alter the distribution profile. Hence, the induced reduction in binding activity and cellular sensitivity cannot be due to receptor relocalization. The chimeric receptors were able to "cap" rapidly during treatment with Con A, suggesting that they are mobile in the plane of the cell membrane. This capping was not influenced by pretreatment with chemoattractant.

Resveratrol enhances proliferation and osteoblastic differentiation in human mesenchymal stem cells via ER-dependent ERK1/2 activation

In the present study, we investigated the in vitro effect of resveratrol (RSVL), a polyphenolic phytoestrogen, on cell proliferation and osteoblastic maturation in human bone marrow-derived mesenchymal stem cell (HBMSC) cultures. RSVL (10(-8)-10(-5) M) increased cell growth dose-dependently, as measured by [(3)H]-thymidine incorporation, and stimulated osteoblastic maturation as assessed by alkaline phosphatase (ALP) activity, calcium deposition into the extracellular matrix, and the expression of osteoblastic markers such as RUNX2/CBFA1, Osterix and Osteocalcin in HBMSCs cell cultures. Further studies found that RSVL (10(-6)M) resulted in a rapid activation of both extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK) signaling in HBMSCs cultures. The effects of RSVL were mimicked by 17beta-estrodial (10(-8) M) and were abolished by estrogen receptor (ER) antagonist ICI182780. An ERK1/2 pathway inhibitor, PD98059, significantly attenuated RSVL-induced ERK1/2 phosphorylation, consistent with the reduction of cell proliferation and osteoblastic differentiation as well as expression of osteoblastic markers. In contrast, SB203580, a p38 MAPK pathway blocker, blocked RSVL-induced p38 phosphorylation, but resulted in an increase of cell proliferation and a more osteoblastic maturation. These data suggest that RSVL stimulates HBMSCs proliferation and osteoblastic differentiation through an ER-dependent mechanism and coupling to ERK1/2 activation.

Importin beta mediates nuclear translocation of Smad 3

Smad proteins are intracellular mediators of transforming growth factor-beta (TGF-beta) and related cytokines. Although ligand-induced nuclear translocation of Smad proteins is clearly established, the pathway mediating this import is yet to be determined. We previously identified a nuclear localization signal (NLS) in the N-terminal region of Smad 3, the major Smad protein involved in TGF-beta signal transduction. This basic motif (Lys(40-)Lys-Leu-Lys-Lys(44)), conserved among all the pathway-specific Smad proteins, is required for Smad 3 nuclear import in response to ligand. Here we studied the nuclear import pathway of Smad 3 mediated by this NLS. We demonstrate that the isolated Smad 3 MH1 domain displays significant specific binding to importin beta, which is diminished or eliminated by mutations in the NLS. Full-size Smad 3 exhibits weak but specific binding to importin beta, which is enhanced after phosphorylation by the type I TGF-beta receptor. In contrast, no interaction was observed between importin alpha and Smad 3 or its MH1 domain, indicating that nuclear translocation of Smad proteins may occur through direct binding to importin beta. We propose that activation of all of the pathway-specific Smad proteins (Smads 1, 2, 3, 5, 8, and 9) exposes the conserved NLS motif, which then binds directly to importin beta and triggers nuclear translocation.

Etoposide and cisplatin versus paclitaxel and carboplatin with concurrent thoracic radiotherapy in unresectable stage III non-small cell lung cancer: a multicenter randomized phase III trial

Background

The optimal chemotherapy regimen administered currently with radiation in patients with stage III non-small cell lung cancer (NSCLC) remains unclear. A multicenter phase III trial was conducted to compare the efficacy of concurrent thoracic radiation therapy with either etoposide/cisplatin (EP) or carboplatin/paclitaxel (PC) in patients with stage III NSCLC.

Patients and methods

Patients were randomly received 60-66 Gy of thoracic radiation therapy concurrent with either etoposide 50 mg/m2 on days 1-5 and cisplatin 50 mg/m2 on days 1 and 8 every 4 weeks for two cycles (EP arm), or paclitaxel 45 mg/m2 and carboplatin (AUC 2) on day 1 weekly (PC arm). The primary end point was overall survival (OS). The study was designed with 80% power to detect a 17% superiority in 3-year OS with a type I error rate of 0.05.

Results

A total of 200 patients were randomized and 191 patients were treated (95 in the EP arm and 96 in the PC arm). With a median follow-up time of 73 months, the 3-year OS was significantly higher in the EP arm than that of the PC arm. The estimated difference was 15.0% (95% CI 2.0%-28.0%) and P value of 0.024. Median survival times were 23.3 months in the EP arm and 20.7 months in the PC arm (log-rank test P = 0.095, HR 0.76, 95%CI 0.55-1.05). The incidence of Grade ≥2 radiation pneumonitis was higher in the PC arm (33.3% versus 18.9%, P = 0.036), while the incidence of Grade ≥3 esophagitis was higher in the EP arm (20.0% versus 6.3%, P = 0.009).

Conclusion

EP might be superior to weekly PC in terms of OS in the setting of concurrent chemoradiation for unresectable stage III NSCLC.

Trial registration ID

NCT01494558.

Children's support for elderly parents in urban and rural China: results from a national survey

This study examines the factors that determine adult children's financial support for elderly parents, using data from the China Survey on Support Systems for the Elderly conducted in 1992. The findings support the hypotheses of need-based transfers. In both urban and rural areas, children's financial transfers to their elderly parents are based on the parents' need, and familial support compensates for inequalities in elderly persons' access to public resources. The data also suggest that elderly support is an outcome of short- and long-term arrangements between generations. Elderly Chinese, especially those in urban areas, have short-term exchanges with their adult children, providing housing or other services and receiving financial support in return. Also, adult children's support for elderly parents may be a repayment of parental investment made in them earlier.

A novel oncogenic role for the miRNA-506-514 cluster in initiating melanocyte transformation and promoting melanoma growth

Malignant melanoma is the most aggressive form of skin cancer and its incidence has doubled in the last two decades. It represents only 4% of skin cancer cases per year, but causes as many as 74% of skin cancer deaths. Early detection of malignant melanoma is associated with survival rates of up to 90%, but later detection (stage III to stage IV) is associated with survival rates of only 10%. Dysregulation of microRNA (miRNA) expression has been linked to tumor development and progression by functioning either as a tumor suppressor, an oncogene or a metastasis regulator in multiple cancer types. To understand the role of miRNA in the pathogenesis of malignant melanoma and identify biomarkers of metastasis, miRNA expression profiles in skin punches from 33 metastatic melanoma patients and 14 normal healthy donors were compared. We identified a cluster of 14 miRNAs on the X chromosome, termed the miR-506-514 cluster, which was consistently overexpressed in nearly all melanomas tested (30-60 fold, P<0.001), regardless of mutations in N-ras or B-raf. Inhibition of the expression of this cluster as a whole, or one of its sub-clusters (Sub-cluster A) consisting of six mature miRNAs, led to significant inhibition of cell growth, induction of apoptosis, decreased invasiveness and decreased colony formation in soft agar across multiple melanoma cell lines. Sub-cluster A of the miR-506-514 cluster was critical for maintaining the cancer phenotype, but the overexpression of the full cluster was necessary for melanocyte transformation. Our results provide new insights into the functional role of this miRNA cluster in melanoma, and suggest new approaches to treat or diagnose this disease.

A distinct nuclear localization signal in the N terminus of Smad 3 determines its ligand-induced nuclear translocation

Smad proteins are intracellular mediators of transforming growth factor beta (TGF-beta) and related cytokines and undergo ligand-induced nuclear translocation. Here we describe the identification of a nuclear localization signal (NLS) in the N-terminal region of Smad 3, the major Smad protein involved in TGF-beta signaling. An NLS-like basic motif (Lys(40)-Lys-Leu-Lys-Lys(44)), conserved among all pathway-specific Smad proteins, not only is responsible for constitutive nuclear localization of the isolated Smad 3 MH1 domain but also is crucial for Smad 3 nuclear import in response to ligand. Mutations in this motif completely abolished TGF-beta-induced nuclear translocation but had no impact on ligand-induced phosphorylation of Smad 3, complex formation with Smad 4, or specific binding to DNA. Hence Smad 3 proteins with NLS mutations are dominant-negative inhibitors of TGF-beta-induced transcriptional activation. Smad 4, which cannot translocate into the nucleus in the absence of Smad 3 or another pathway-specific Smad, contains a Glu in place of the last Lys in this motif. Smad 3 harboring the same mutation (K44E) does not undergo ligand-induced nuclear import. Conversely, the isolated Smad 4 MH1 domain does not accumulate in the nucleus but becomes nuclear enriched when Glu(49) is replaced with Lys. We propose that this highly conserved five-residue NLS motif determines ligand-induced nuclear translocation of all pathway-specific Smads.

miR-21, miR-17 and miR-19a induced by phosphatase of regenerating liver-3 promote the proliferation and metastasis of colon cancer

Background:

Phosphatase of regenerating liver-3 (PRL-3) is an oncogene known to promote tumour metastasis, especially in colorectal cancer (CRC). Here, we demonstrate that the miR-21, miR-17 and miR-19a expressions induced by PRL-3 are involved in the proliferation and metastasis of colon cancer.

Methods:

Microarray analysis and quantitative reverse-transcription polymerase chain reactions (qRT–PCR) were used to investigate the changes in miRNA expression due to the overexpression of PRL-3. Transwell chamber invasion assays, CCK-8 proliferation assays and RNA interference assays were used to explore the effects of PRL-3 on miR-21, miR-17 and miR-19a expression in colon cancer cells. Immunohistochemistry and qRT–PCR were performed in colon cancer tissues to evaluate the expression of PRL-3, signal transducer and activator of transcription 3 (STAT3), miR-21, miR-17 and miR-19a.

Results:

Our study demonstrated that the overexpression of PRL-3 in colon cancer cells induced the expression of miR-21, miR-17 and miR-19a by activating STAT3. Subsequently, these microRNAs contributed to the increased proliferation and invasiveness of the colon cancer cells. Positive correlations between PRL-3 and these microRNAs were also observed in matched primary colon cancer tissues and metastatic lesions.

Conclusion:

miR-21, miR-17 and miR-19a induced by PRL-3 contribute to the proliferation and invasion of colon cancer.

Nucleocytoplasmic shuttling of Smad1 conferred by its nuclear localization and nuclear export signals

Smad1 mediates signaling by bone morphogenetic proteins (BMPs). In the resting state, Smad1 is found in both the nucleus and cytosol. BMP addition triggers Smad1 serine phosphorylation, binding of Smad4, and its accumulation in the nucleus. Mutations in the Smad1 N-terminal basic nuclear localization signal (NLS)-like motif, conserved among all Smad proteins, eliminated its ligand-induced nuclear translocation without affecting its other functions, including DNA binding and complex formation with Smad4. Addition of leptomycin B, an inhibitor of nuclear export, induced rapid nuclear accumulation of Smad1, whereas overexpression of CRM1, the receptor for nuclear export, resulted in Smad1 re-localization to the cytoplasm and inhibition of BMP-induced nuclear accumulation. Thus, in addition to the NLS, Smad1 also contains a functional nuclear export signal (NES). We identified a leucine-rich NES motif in the C terminus of Smad1; its disruption led to constitutive Smad1 nuclear distribution. Reporter gene activation assays demonstrated that both the NLS and NES are required for optimal transcriptional activation by Smad1. Despite its constitutive nuclear accumulation, a Smad1 NES mutant did not display higher basal reporter gene activity. We conclude that Smad1 is under constant nucleocytoplasmic shuttling conferred by its NLS and NES; nuclear accumulation after ligand-induced phosphorylation represents a change in the balance of the activities of these opposing signals and is essential for transcriptional activation.

Constitutive NOS expression in cultured endothelial cells is elevated by fluid shear stress

The role of chronic fluid shear stress on endothelial constitutive nitric oxide synthase (cNOS) levels may have an important role in vessel diameter control. We subjected primary human umbilical vein endothelial cells (HUVEC) or bovine aortic endothelial cells (BAEC, passages 2-14) to steady laminar shear stress. In both cell types, the intracellular level of cNOS was elevated within 3 h of flow exposure at 25 dyn/cm2 and remained elevated at 6 and 12 h of flow exposure, compared with stationary controls, as indicated by digital immunofluorescence microscopy. Shear stress exposure for 6 h caused a 2.2 +/- 0.3- and 2.8 +/- 0.3-fold elevation of cNOS protein levels in BAEC (n = 3, P < 0.01) and HUVEC (n = 3, P < 0.01), respectively, in the presence or absence of 1 microM dexamethasone. Dexamethasone suppresses induction of the inducible NOS gene, indicating that cNOS was elevated by fluid shear stress. Flow exposure at 4 dyn/cm2 caused no enhancement of cNOS levels in either cell type. The flow induction of the cNOS protein levels was not blocked by preincubation of BAEC with 100-400 microM of NG-nitro-L-arginine methyl ester, indicating that flow-induced NO (or guanosine 3',5'-cyclic monophosphate) was not involved in the elevation of cNOS levels. Protein kinase C inhibitor H-7 (10 microM) had no effect on induction of NOS protein in BAEC exposed to 25 dyn/cm2. The cNOS mRNA levels were found to be elevated by two- to threefold in BAEC after 6 or 12 h of flow exposure at either 4 or 25 dyn/cm2, and this induction of NOS mRNA occurred in the presence of dexamethasone. The elevation of cNOS levels by chronic flow exposure may provide a mechanism for chronic regulation of vessel diameter by endothelial response to prevailing blood flow.

Characterization of a novel transplantable orthotopic rat bladder transitional cell tumour model

An animal tumour model that mimics the human counterpart is essential for preclinical evaluation of new treatment modalities. The objective of this study was to develop and characterize such a model. To accomplish this, the established AY-27 rat bladder transitional cell carcinoma (TCC) cell line was transplanted orthotopically into Fischer CDF344 female rats. AY-27 TCC cells were grown in monolayer cell culture and instilled intravesically as single cell suspensions into bladders that had been conditioned with mild acid washing. Tumour growth was assessed weekly by subjecting the rats to magnetic resonance imaging (MRI). At intervals following implantation and MRI tumour detection, the animals were sacrificed for necropsy, histological examination and immunocytochemical studies. Flow cytometry was also performed for detection of Fas or Fas-ligand expression on AY-27 cells. The overall tumour establishment was 95% (97/102 rats) at 12-50 days, while in a subgroup of animals sacrificed at 16 days, 80 out of 82 animals (97%) developed TCC, the majority of which was superficial. Tumour stage was assessed by gross pathology and light microscopy. Histological examination of the tumour specimens confirmed the presence of grade II-III TCC. Immunocytochemistry confirmed that the tumour model maintained the features of TCC. The changes seen on MRI correlated well with the extent of tumour invasion identified histologically. Patchy carcinoma in situ could be detected histologically 12-13 days post-inoculation, and progressed to papillary tumour or invasive disease thereafter. Neither Fas nor Fas-ligand was expressed on AY-27 cells. The orthotopic AY-27 TCC model is highly reproducible and is ideal for preclinical studies on experimental intravesical therapies.

Shear stress induction of the endothelial nitric oxide synthase gene is calcium-dependent but not calcium-activated

Arterial levels of shear stress (25 dynes/cm2) can elevate constitutive endothelial nitric oxide synthase (eNOS) gene expression in cultured endothelial cells (Ranjan et al., 1995). By PhosphorImaging of Northern blots, we report that the eNOS/glyceraldehyde 3-phosphate dehydrogenase (GAPDH) messenger RNA (mRNA) ratio in bovine aortic endothelial cells (BAEC) increased by 4.8- and 7.95-fold after 6-hr shear stress exposure of 4 and 25 dynes/cm2, respectively. Incubation of BAEC with dexamethasone (1 microM) had no effect on shear stress induction of eNOS mRNA. Buffering of intracellular calcium in BAEC with bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid, tetra(acetoxymethyl)-ester (BAPTA/AM) reduced shear stress induction of eNOS mRNA by 70%. Yet, stimulation of BAEC with ionomycin (0.1-1.0 microM) for 6-24 hr to elevate intracellular calcium had no effect on eNOS mRNA. These studies indicated that the shear stress induction of eNOS mRNA was a calcium-dependent, but not calcium-activated, process. Shear stress was a very potent and rapid inducer of the eNOS mRNA, which could not be mimicked with phorbol myristrate acetate or endotoxin. Inhibition of tyrosine kinases with genistein (10 microM) or tyrphostin B46 (10 microM) or inhibition of G-protein signaling with guanosine 5'-O-(2-thiodiphosphate) (GDP-betaS) (600 microM, 6-hr preincubation) did not block the shear stress elevation of eNOS mRNA.

Preclinical assessment of hypocrellin B and hypocrellin B derivatives as sensitizers for photodynamic therapy of cancer: progress update

Hypocrellins are perylenequinone pigments with substantial absorption in the red spectral region and high singlet oxygen yield. They are available in pure monomeric form and may be derivatized to optimize properties of red light absorption, tissue biodistribution and toxicity. In vitro screening of synthetic derivatives of the naturally occurring compound, hypocrellin B (HB), for optimal properties of cyto-(dark) toxicity and phototoxicity resulted in selection of three compounds for preclinical evaluation: HBEA-R1 (ethanolaminated HB), HBBA-R2 (butylaminated HB) and HBDP-R1 [2-(N,N-dimethylamino)-propylamine-HB]. Extinction coefficients at 630 nm (epsilon 630) are 6230, 6190 and 4800, respectively; and 1O2 quantum yields, phi, 0.60, 0.32 and 0.42. Intracellular uptake is essentially complete within 2 h (HBEA-R1, HBBA-R2) and 20 h (HBDP-R1). Greatest uptake is associated with lysosomes and Golgi. The HBEA-R1 and HBBA-R2 elicit phototoxicity in vitro primarily via the type II mechanism, with some type I activity under stringently hypoxic conditions. Transcutaneous phototherapy with HBEA-R1 permanently ablates EMT6/Ed tumors growing in the flanks of Balb/c mice, with minimal cutaneous effects. The HBBA-R2 does not elicit mutagenic activity in strains TA98 and TA100 of Salmonella typhimurium. Further development of selected hypocrellin derivatives as photosensitizers for photodynamic therapy is warranted.

Hepatitis B virus X protein downregulates expression of the miR-16 family in malignant hepatocytes in vitro

BACKGROUND

Hepatitis B virus X protein (HBx) is involved in the initiation and progression of hepatocellular carcinoma (HCC) by regulating the host protein-coding genes. In this study, we showed that HBx altered the expression of microRNAs (miRNAs) to promote proliferation and transformation in malignant hepatocytes in vitro.

METHODS

miRNA microarray and quantitative reverse-transcription polymerase chain reactions (qRT-PCRs) were performed to identify miRNAs that were differentially regulated by HBx in HCC cells. Protein, mRNA, and miRNA expression analyses; cell cycle and apoptosis analyses; loss/gain-of-function analysis; and luciferase reporter assays were performed to delineate the consequences of miR-16 family repression in HepG2 cells.

RESULTS

Hepatitis B virus X protein induced widespread deregulation of miRNAs in HepG2 cells, and the downregulation of the miR-16 family was reproducible in HepG2, SK-HEP-1, and Huh7 cells. CCND1, a target of the miR-16 family, was derepressed by HBx in HepG2 cells. c-Myc mediated the HBx-induced repression of miR-15a/16 in HepG2 cells. Ectopically expressed miR-15a/16 suppressed the proliferation, clonogenicity, and anchorage-independent growth of HBx-expressing HepG2 cells by arresting them in the G1 phase and inducing apoptosis, whereas reduced expression of miR-16 accelerated the growth and cell-cycle progression of HepG2 cells.

CONCLUSIONS

Hepatitis B virus X protein altered the in vitro expression of miRNAs in host malignant hepatocytes, particularly downregulating the miR-16 family. Repression of miR-15a/16 is c-Myc mediated and is required for the HBx-induced transformation of HepG2 cells in vitro. Therefore, miR-16 family may serve as a therapeutic target for hepatitis B virus (HBV)-associated HCC.

Design and synthesis of Pfmrk inhibitors as potential antimalarial agents

The synthesis and inhibitory activities of 10 potential inhibitors of Pfmrk, a Plasmodium falciparum cyclin-dependent protein kinase, are described. The most potent inhibitor is a 3-phenyl-quinolinone compound with an IC(50) value of 18 microM. It is the first compound reported to inhibit Pfmrk at the micro molar range.

The suppression of ox-LDL-induced inflammatory cytokine release and apoptosis of HCAECs by long non-coding RNA-MALAT1 via regulating microRNA-155/SOCS1 pathway

BACKGROUND

Atherosclerosis is a chronic inflammatory disease. Accumulating evidence suggests that long non-coding RNAs (lncRNAs) and microRNAs have emerged as critical regulators of atherosclerosis; however, whether they have crosstalk on this issue remains elusive. Here, we investigated the potential associations between lncRNA-MALAT1 and miR-155 on the regulation of atherosclerosis.

METHODS

Quantitative real-time PCR was employed to assess the expression of MALAT1, IL-6 and IL-8. ELISA was performed to measure the secretion of IL-6 and IL-8. MTT assay was used to determine the proliferation of Human Coronary Artery Endothelial Cells (HCAECs). Flow cytometry was used to measure the cell apoptosis. Western blot was used to assess the expression of apoptosis-related proteins and the phosphorylation of STAT1 and STAT3.

RESULTS

We found that the pro-inflammatory cytokine release and the apoptosis of HCAECs were elevated upon ox-LDL treatment, while MALAT1 expression was also up regulated. Knocking down of MALAT1 boosted ox-LDL-induced cytokine release and apoptosis of HCAECs. The binding site of miR-155 in MALAT1 sequence was confirmed by dual luciferase assay. Furthermore, miR-155 inhibition significantly repressed ox-LDL mediated inflammation and apoptosis of HCAECs via SOCS1. At last, we found that MALAT1 could suppress the inflammatory cytokine release and cell apoptosis via sponging miR-155 to increase SOCS1 level, which in turn restrained JAK-STAT pathway.

CONCLUSION

In summary, this study revealed the mechanisms by which MALAT1 worked as a putative atherosclerosis suppressor via miR-155 and SOCS1. Therefore, modulation of MALAT1/miR-155/SOCS1 axis might alleviate the inflammation persisted in atherosclerosis.

CSE1 and CSE2, two new genes required for accurate mitotic chromosome segregation in Saccharomyces cerevisiae

By monitoring the mitotic transmission of a marked chromosome bearing a defective centromere, we have identified conditional alleles of two genes involved in chromosome segregation (cse). Mutations in CSE1 and CSE2 have a greater effect on the segregation of chromosomes carrying mutant centromeres than on the segregation of chromosomes with wild-type centromeres. In addition, the cse mutations cause predominantly nondisjunction rather than loss events but do not cause a detectable increase in mitotic recombination. At the restrictive temperature, cse1 and cse2 mutants accumulate large-budded cells, with a significant fraction exhibiting aberrant binucleate morphologies. We cloned the CSE1 and CSE2 genes by complementation of the cold-sensitive phenotypes. Physical and genetic mapping data indicate that CSE1 is linked to HAP2 on the left arm of chromosome VII and CSE2 is adjacent to PRP2 on chromosome XIV. CSE1 is essential and encodes a novel 109-kDa protein. CSE2 encodes a 17-kDa protein with a putative basic-region leucine zipper motif. Disruption of CSE2 causes chromosome missegregation, conditional lethality, and slow growth at the permissive temperature.

Distinct effects of recombinant tenascin-C domains on neuronal cell adhesion, growth cone guidance, and neuronal polarity

Using a set of recombinantly expressed proteins, distinct domains of the mouse extracellular matrix glycoprotein tenascin-C, hereafter called tenascin, have been identified to confer adhesion, anti-adhesion, and changes in morphology of neuronal cells. In short-term adhesion assays (1 hr), cerebellar and hippocampal neurons adhered to several domains, encompassing the fibronectin type III-like (FN III) repeats 1-2 and 6-8, as well as to the alternatively spliced FN III repeats and to tenascin itself. Although no short-term adhesion to the EGF repeats containing fragment could be detected under the conditions used, it was anti-adhesive for neuronal cell bodies and repellent for growth cone advance and neuritogenesis. FN III repeats 3-5 were repellent only for growth cones but not for neuronal cell bodies. Neurite outgrowth promoting activities at early stages and induction of a polarized neuronal morphology at later stages of differentiation were associated with the EGF repeats and the FN III repeats 6-8. These observations suggest differential effects of particular domains of the tenascin molecule on distinct cellular compartments, i.e., cell body, axon and dendrite, and existence of multiple neuronal receptors with distinct intracellular signaling features.

Functional cloning of the proto-oncogene brain factor-1 (BF-1) as a Smad-binding antagonist of transforming growth factor-beta signaling

Using the plasminogen activator inhibitor (PAI) promoter to drive the expression of a reporter gene (mouse CD2), we devised a system to clone negative regulators of the transforming growth factor-beta (TGF-beta) signaling pathway. We infected a TGF-beta-responsive cell line (MvLu1) with a retroviral cDNA library, selecting by fluorescence-activated cell sorter single cells displaying low PAI promoter activity in response to TGF-beta. Using this strategy we cloned the proto-oncogene brain factor-1 (BF-1). BF-1 represses the PAI promoter in part by associating with both unphosphorylated Smad3 (in the cytoplasm) and phosphorylated Smad3 (in the nucleus), thus preventing its binding to DNA. BF-1 also associates with Smad1, -2, and -4; the Smad MH2 domain binds to BF-1, and the C-terminal segment of BF-1 is uniquely and solely required for binding to Smads. Further, BF-1 represses another TGF-beta-induced promoter (p15), it up-regulates a TGF-beta-repressed promoter (Cyclin A), and it reverses the growth arrest caused by TGF-beta. Our results suggest that BF-1 is a general inhibitor of TGF-beta signaling and as such may play a key role during brain development.