Overexpression of Adhesion Molecule L1 in NG108-15 Neuroblastoma × Glioma Hybrid Cells Enhances Dibutyryl Cyclic AMP-Induced Neurite Outgrowth and Functional Synapse Formation with Myotubes

Abstract: The role of adhesion molecule L1 in synapse formation was examined by transient transfection of L1 cDNA in neuroblastoma × glioma hybrid NG108-15 cells. L1 overexpression was found in ∼50% of the transfected NG108-15 cell population. Neurite outgrowth induced by 0.25 m M dibutyryl cyclic AMP (cAMP) was much greater in L1-transfected NG108-15 cells than that in nontransfected and mock-transfected cells. The proportion of cells with neurites and the number of neurites per cells were increased in L1-transfected cells after 2 days of dibutyryl cAMP treatment. The proportion of cells with branched neurites and the average length of neurites were higher at day 4. A significantly higher rate of synapse formation with myotubes was apparent in the late phase of coculture (days 4–7) in L1-transfected cells than in control cells. The miniature end-plate potential frequency in myotubes was the same for the three types of NG108-15 cells. These results show that overexpression of L1 in NG108-15 cells facilitates synaptic connections by enhancing branching and elongation of neurites induced with dibutyryl cAMP, rather than by increasing probability of acetylcholine release.     

Distribution of endothelin-converting enzyme-1 and neutral endopeptidase in human endometrium.

The expression of endothelin-1 (ET-1), which has been proposed to have a potential autocrine/paracrine role, varies during the menstrual cycle, and therefore, ET-1 may be involved in the cyclic change of the human endometrium. However, neither the synthesis nor the degradation of ET-1 in the endometrium has been determined in detail. We investigated endothelin-converting enzyme-1 (ECE-1), which converts big-ET-1 to active ET-1, and neutral endopeptidase (NEP), which cleaves and inactivates ET-1 in human endometrium in vivo and in vitro. Western blot analysis demonstrated that the change in the expression of ECE-1 during the menstrual cycle differed from that of NEP in the endometrium. ECE-1 was expressed by endometrial epithelial cells, whereas NEP was predominantly expressed by stromal cells in vivo and in vitro. In conclusion, our results suggest that spacio-temporal expression of two endopeptidases, ECE-1 and NEP, involved in the synthesis and degradation of ET-1, might regulate ET-1 action in human endometrium.     

(2S,2'R)-analogue of LG190178 is a major active isomer

Vitamin D receptor (VDR) ligands are therapeutic agents for the treatment of psoriasis, osteoporosis, and secondary hyperparathyroidism. VDR ligands also show immense potential as therapeutic agents for autoimmune diseases and cancers of the skin, prostate, colon, and breast as well as leukemia. LG190178 is a novel non-secosteroidal ligand for VDR. We synthesized and evaluated stereoisomers of LG190178 and found that only an (2S,2'R)-analogue of LG190178 (YR301) had strong activity.     

G-CSF prevents cardiac remodeling after myocardial infarction by activating the Jak-Stat pathway in cardiomyocytes

Granulocyte colony-stimulating factor (G-CSF) was reported to induce myocardial regeneration by promoting mobilization of bone marrow stem cells to the injured heart after myocardial infarction, but the precise mechanisms of the beneficial effects of G-CSF are not fully understood. Here we show that G-CSF acts directly on cardiomyocytes and promotes their survival after myocardial infarction. G-CSF receptor was expressed on cardiomyocytes and G-CSF activated the Jak/Stat pathway in cardiomyocytes. The G-CSF treatment did not affect initial infarct size at 3 d but improved cardiac function as early as 1 week after myocardial infarction. Moreover, the beneficial effects of G-CSF on cardiac function were reduced by delayed start of the treatment. G-CSF induced antiapoptotic proteins and inhibited apoptotic death of cardiomyocytes in the infarcted hearts. G-CSF also reduced apoptosis of endothelial cells and increased vascularization in the infarcted hearts, further protecting against ischemic injury. All these effects of G-CSF on infarcted hearts were abolished by overexpression of a dominant-negative mutant Stat3 protein in cardiomyocytes. These results suggest that G-CSF promotes survival of cardiac myocytes and prevents left ventricular remodeling after myocardial infarction through the functional communication between cardiomyocytes and noncardiomyocytes.     

Measurement of adenylyl cyclase by separating cyclic AMP on silica gel thin-layer chromatography

A procedure for isolation of cyclic AMP (cAMP) by thin-layer chromatography on silica gel is described. One-dimensional ascending chromatograms were developed using [H(2)O/C(2)H(5)OH/NH(4)HCO(3) (30%:70%:0.2M)] as the mobile phase. This procedure separated [32P]cAMP from other radioactive metabolites of [32P]ATP in up to 19 samples on one sheet (20 x 10 cm) over 40-60 min at room temperature (21 degrees C). This simple and rapid isolation method provides a novel and convenient technique for the assay of adenylyl cyclase.     

Correlation between expression of oncogene products and resistance to anticancer drugs in cultured ovarian cancer cell lines

Despite recent advances in the application of chemotherapy to ovarian cancer, the development of alternative therapies that retain activity against drug-resistant-tumors remains a high priority. We analyzed a number of cultured ovarian cancer cell lines of different tissue types for the presence or absence of sensitivity to various anticancer drugs as well as expression patterns of oncogene products (erbB-2, EGFR, bcl-2). As a result, we identified oncogene products that were related to resistance. Using 9 cultured cell lines of ovarian cancers (serous, mucinous, endometrioid, clear, undifferentiated), sensitivities to anticancer drugs were investigated using the MTT assay. The phenotypes of oncogene products expressed by the above cultured cell lines were analyzed by Western blotting. The oncogene products involved in resistance to anticancer drugs were identified by multivariate analysis. Positive correlation between the resistance to anticancer drugs and the oncogene products was obtained by multivariate analysis for (a) CDDP and erbB-2 (b) x p-16 and erbB-2, and (c) MMC and EGFR. Correlation between resistance to anticancer drugs and expression of certain oncogene products was obtained in ovarian cancers, suggesting that sensitivity to anticancer drugs could be predicated prior to chemotherapy.     

Subtype-specific coupling with ADP-ribosyl cyclase of metabotropic glutamate receptors in retina,cervical superior ganglion and NG108-15 cells

Cyclic ADP-ribose (cADP-ribose) is a putative second messenger or modulator. However, the role of cADP-ribose in the downstream signals of the metabotropic glutamate receptors (mGluRs) is unclear. Here, we show that glutamate stimulates ADP-ribosyl cyclase activity in rat or mouse crude membranes of retina via group III mGluRs or in superior cervical ganglion via group I mGluRs. The retina of mGluR6-deficient mice showed no increase in the ADP-ribosyl cyclase level in response to glutamate. GTP enhanced the initial rate of basal and glutamate-stimulated cyclase activity. GTP-gamma-S also stimulated basal activity. To determine whether the coupling mode of mGluRs to ADP-ribosyl cyclase is a feature common to individual cloned mGluRs, we expressed each mGluR subtype in NG108-15 neuroblastoma x glioma hybrid cells. The glutamate-induced stimulation of the cyclase occurs preferentially in NG108-15 cells over-expressing mGluRs1, 3, 5, and 6. Cells expressing mGluR2 or mGluRs4 and 7 exhibit inhibition or no coupling, respectively. Glutamate-induced activation or inhibition of the cyclase activity was eliminated after pre-treatment with cholera or pertussis toxin, respectively. Thus, the subtype-specific coupling of mGluRs to ADP-ribosyl cyclase via G proteins suggests that some glutamate-evoked neuronal functions are mediated by cADP-ribose.     

Long-term induction of beta-CGRP mRNA in rat lungs by allergic inflammation

Calcitonin gene-related peptide (CGRP) is one of the major neuropeptides released from sensory nerve endings and neuroendocrine cells of the lung. Two CGRP isoforms, alpha-and beta-CGRP, have been identified in rats and humans, but no studies have attempted to reveal direct evidence of differences in action or location of these isoforms in allergic inflammation (AI). We investigated mRNA expressions of alpha-and beta-CGRP in lungs, nodose ganglia (NG), and dorsal root ganglia (DRG) of an animal model for AI of the airways, utilizing a model created by sensitizing Brown Norway (BN) rats with ovalbumin (OVA). By semiquantitative RT-PCR analysis, long-lasting enhanced expression of the beta-CGRP mRNA was shown in the lungs of the AI rats (14.5-fold enhancement at 6 hr, 8.1-fold at 24 hr, and 3.7-fold at 120 hr after OVA-challenge compared to the level in the lungs of phosphate-buffered saline (PBS)-challenged control rats). In contrast, the mRNA expression of the alpha-CGRP in AI lungs showed only a transient increase after OVA-challenge (2.7-fold at 6 hr) followed by a lower level of expression (0.5-fold at 48 hr and 0.6-fold at 120 hr). The mRNA expressions of both isoforms in NG, but not in DRG, were transiently up-regulated at 6 hr after antigen challenge. In situ RT-PCR in combination with immunohistochemical analysis revealed that beta-CGRP was expressed in neuroendocrine cells in clusters (termed neuroepithelial bodies [NEBs]) in AI lungs. These results indicate that the long-term induction of beta-CGRP in NEBs may play an important role in pulmonary AI such as bronchial asthma.