Endothelin-1 activates p38 mitogen-activated protein kinase via endothelin-A receptor in rat myocardial cells

In myocardial cells (MCs), endothelin-1 (ET-1) exerts various effects such as hypertrophy, and causes cellular injury. Long-term treatment with an endothelin-A (ET_A) receptor antagonist improves the survival of rats with heart failure, suggesting that myocardial endothelin system contributes to the progression of heart failure. p38 mitogen-activated kinase (MAPK) is a member of the MAPK family and activated by several forms of environmental stresses. We show here the effect of ET-1 on p38 MAPK activation and the role of ET-1-activated p38 MAPK on morphological changes in MCs. ET-1-stimulated p38 MAPK phosphorylation was detectable within 2 min and maximal at 5 min and was concentration dependent. The maximum effect was obtained at 10 nM. An ET_A receptor antagonist, BQ-123, but not an endothelin-B receptor antagonist, BQ-788, inhibited these reactions. A p38 MAPK inhibitor, SB203580, failed to inhibit the morphological changes associated with ET-1-induced myocardial cell hypertrophy. These results indicate that p38 MAPK is activated by ET-1 but does not contribute to the development of ET-1-induced myocardial cell hypertrophy.     

Isolation of a new potent cytotoxic pigment along with indigotin from the pathogenic basidiomycetous fungus Schizophyllum commune

An indole derivative, schizocommunin, was isolated along with indigotin (indigo), indirubin, isatin, and tryptanthrin, from the liquid culture medium in which a culture of Schizophyllum commune, isolated from the bronchus of a human patient with allergic bronchopulmonary mycosis, had been grown. The structure of schizocommunin was established by spectroscopic investigation. Schizocommunin showed the strong cytotoxicity against murine lymphoma cells. The assignments of the ¹H- and ¹³C-NMR signals of indigotin were also listed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Association of a cellular 21-kDa transmembrane protein (VAP21) with enveloped viruses.

We reported previously that the rabies virions contained a 21-kDa cellular transmembrane protein (referred to as VAP21) as a minor component (Sagara, J. et al, Microbiol. Immunol. 41(12): 947-955, 1997). In this study, we further examined the possible interactions of VAP21 with other enveloped viruses, including the vesicular stomatitis virus (VSV; negative-stranded RNA virus), Sindbis virus (positive-stranded RNA virus) and herpes simplex virus type 1 (HSV-1; double-stranded DNA virus). An immunoblot analysis demonstrated that all of these enveloped viruses contained VAP21 in the virion as a minor component. Immunoprecipitation studies suggested that VAP21 was associated with certain viral proteins in the cell, such as the matrix (M) protein of VSV, a capsid protein of Sindbis virus, and at least a capsid protein (VP5) of HSV-1. The association was disrupted by treatment with 0.5% sodium dodecyl sulfate, but resistant to the treatment with 1% NP-40 plus 1% deoxycholate. These results suggest that: 1) VAP21 is not primarily associated with the viral transmembrane glycoprotein but rather with the internal viral protein, and, 2) this association would cause the efficient incorporation of VAP21 into the virion.     

Intracellular behavior of rabies virus matrix protein (M) is determined by the viral glycoprotein (G).

To investigate the nature and intracellular behavior of the matrix (M) protein of an avirulent strain (HEP-Flury) of rabies virus, we cloned and sequenced the cDNA of the protein. Using expression vectors pZIP-NeoSV(X)1 and pCDM8, the cDNA was transfected to animal cells (BHK-21 and COS-7) with or without coexpression of viral glycoprotein (G). When M protein alone was expressed in the cells, it displayed homogeneous distribution in the whole cell including the nucleus. In contrast, coexpression with G protein resulted in the abolishment of nuclear distribution of M antigen, and both of the antigens displayed a colocalized distribution in the cell, especially at the cellular membrane as seen in the virus-infected cells, while the distribution of G antigen was not affected by coexpressed M antigen. Immunoprecipitation studies revealed that M protein was coprecipitated with G protein by anti-G antibody, and vice versa, although cross-linking with dithiobis(succinimidyl propionate) was necessary for coprecipitation because of their easier dissociation in the presence of sodium deoxycholate. These results suggest that M protein intimately associates with G protein, which may affect or regulate the behavior (e.g., intracellular localization) of M protein. Studies with deletion mutants of M protein indicate that an internal region around the amino acids from 115 to 151 is essential for the M protein to preserve its binding ability to G protein.     

Negative association between asthma and variants of CC16(CC10) on chromosome 11q13 in British and Japanese populations

The gene encoding Clara cell-derived inflammatory molecule CC16 has been cited as a candidate gene for atopic asthma on chromosome 11q13. A genetic association study was performed with variants of the CC16 gene on chromosome 11q13 in relation to asthma in British (n=275) and Japanese (n=300) populations. No significant association was found between asthma and CC16 genotypes, irrespective of atopic status in these two populations. These data suggest that CC16 might not be the major locus for asthma on 11q13. Received: 22 December 1997 / Accepted: 9 February 1998     

Human Brain Capillary Endothelium: Modulation of K+ Efflux and K+, Ca2+ Uptake by Endothelin

This report describes K⁺ efflux, K⁺ and Ca²⁺ uptake responses to endothelins (ET-1 and ET-3) in cultured endothelium derived from capillaries of human brain (HBEC). ET-1 dose dependently increased K⁺ efflux, K⁺ and Ca²⁺ uptake in these cells. ET-1 stimulated K⁺ efflux occurred prior to that of K⁺ uptake. ET-3 was ineffective. The main contributor to the ET-1 induced K⁺ uptake was ouabain but not bumetanide-sensitive (Na⁺-K⁺-ATPase and Na⁺-K⁺-Cl^– cotransport activity, respectively). All tested paradigms of ET-1 effects in HBEC were inhibited by selective antagonist of ET_A but not ET_B receptors and inhibitors of phospholipase C and receptor-operated Ca²⁺ channels. Activation of protein kinase C (PKC) decreased whereas inhibition of PKC increased the ET-1 stimulated K⁺ efflux, K⁺ and Ca²⁺ uptake in HBEC. The results indicate that ET-1 affects the HBEC ionic transport systems through activation of ET_A receptors linked to PLC and modulated by intracellular Ca²⁺ mobilization and PKC.     

The 21-kDa Polypeptide (VAP21) in the Rabies Virion Is a CD99-Related Host Cell Protein

In our monoclonal antibody (MAb) stocks prepared against the BHK-21 cell antigens, two (#11875 and 28276) recognized a 21-kDa polypeptide (referred to as VAP21) which is efficiently incorporated into the rabies virion. By using these MAbs, we isolated the cDNA clones that encoded a polypeptide of 144 amino acids from our BHK-21 cell cDNA library. Based on the following evidence, the cDNA was assumed to encode a full-length sequence of VAP21 antigen: i) expression of the cDNA in animal cells resulted in the production of a polypeptide recognized by the two MAbs, and its electrophoretic mobility was the same as that of authentic VAP21 antigen; and ii) immunization with the products from the cDNA-transformed E. coli cells raised specific antibodies in rabbits that recognized a 21-kDa polypeptide in the virion. From the deduced amino acid sequence, it is suggested that the VAP21 antigen has a molecular structure of type-I transmembrane protein containing characteristic proline-rich and glycine-rich regions in its ectodomain. Homology searches resulted in finding homologous sequences (totally about 40% homology) in the human MIC2 gene product (CD99; 32-kDa) of T lymphocytes. These results suggest that the VAP21 antigen in the rabies virion is a cellular CD99-related transmembrane protein.     

Effectiveness of weekly subcutaneous recombinant human erythropoietin administration for chemotherapy-induced anemia

The effects of weekly subcutaneousrecombinant human erythropoietin (r-hEPO)administration on anemia during chemotherapy includingcisplatin and 5-fluorouracil in patients with head andneck carcinomas were examined. Weekly subcutaneousr-hEPO administration in cancer patients has not beeninvestigated previously. Patients were treated withr-hEPO 100 IU/kg (2 patients), 200 IU/kg (6 patients),or 400 IU/kg (5 patients), or placebo, andeffectiveness was evaluated by monitoring hemoglobinconcentration changes after administration for 8weeks. Hemoglobin concentrations in all 3 r-hEPOdosage groups were higher than that in the controlgroup during chemotherapy. All r-hEPO doses producedimprovements in the anemia induced by chemotherapy;however, the 400 IU/kg dose was most effective. Therequirement for blood transfusions decreased inpatients receiving r-hEPO therapy, and no significantside-effects were associated with r-hEPOadministration. These results suggest thatchemotherapy-induced anemia can be prevented by weeklysubcutaneous r-hEPO administration.     

Induction of Differentiation and Apoptosis in Human Promyelocytic Leukemia HL60 Cell Line by a New Type of Steroids

Mer-NF8054X is a new type of steroid whose structure has been established as 11-oxo-18, 22-cycloergosta-6, 8(14)-diene-3β, 5β, 9β, 23S-tetraol (an 18, 22-cycloergostane), which has been reported to have antifungal activity againstAspergillus fumigatus.However, other biological activities are unknown. Herein, we reported that Mer-NF8054X inhibited cell growth of HL60 human leukemia cells, when used either singly or in combination with retinoic acid (RA). In addition, Mer-NF8054X alone induced differentiation and apoptosis of HL60 cells. The induction of differentiation of HL60 cells by Mer-NF8054X was synergistic in combination with RA. On the other hand, Emesterone A, an analogue of Mer-NF8054X which is missing a hydroxy residue from the third position, showed much lower activity than Mer-NF8054X on the inhibition of cell growth and the induction of cell differentiation and apoptosis. However, Emesterone B, an analogue of Emesterone A which is missing a hydroxy residue from the fifth position, showed higher activity than Emesterone A but lower activity than Mer-NF8054X when examined for the inhibition of cell growth and the induction of cell differentiation and apoptosis. These results suggested that Mer-NF8054X and its analogs may be a new type of differentiation inducing agent. The hydroxy residue at the third position or fifth position in Mer-NF8054X may be necessary, but not essential, for inhibition of growth and induction of both differentiation and apoptosis of HL60 cells. In addition, Mer-NF8054X enhanced the differentiation of HL60 cells induced by RA. Based on these results, Mer-NF8054X may have utility in the clinic in combination with RA for leukemia patients.