Cysteine-containing leukotrienes (cysteinyl-LTs) are potent bronchoconstrictors and play a key role in asthma. We found that histamine and LTD, markedly constrict strips of human bronchi (HB) with similar efficacy. However, in human airway smooth-muscle (HASM) cells, LTD(4), at variance with histamine, elicited only a small, transient change in intracellular calcium ion concentration. HASM cells express both Ca(2+)-dependent and -independent isoforms of protein kinase C (PKC) (i.e., PKC-alpha and PKC-epsilon). Western blot analysis showed that PKC-alpha is activated by histamine and, to a lesser extent, by LTD(4), whereas only LTD(4) translocates PKC-epsilon. This translocation was specifically inhibited by the LTD4 antagonist pobilukast. Phorbol-dibutyrate ester (PDBu) (a PKC activator) contracted HE strips to the same extent in the presence as in the absence of extra- and intracellular Ca(2+). In the absence of Ca(2+), LTD(4) contracted HB strips to the same extent as did PDBu, suggesting the involvement of a Ca(2+)-independent PKC in LTD(4)-mediated signal transduction. PDBu-induced desensitization and the PKC inhibitor H7 abolished the slow and sustained LTD(4)-triggered contraction of HE strips in the absence of Ca(2+), although H7 did not greatly affect the response in the presence of the ion. Thus, in human airways, we identified a novel LTD(4) transduction mechanism linked to bronchial smooth-muscle contraction, which is partly independent of Ca(2+) and involves the activation of PKC-epsilon.

Leukotriene D(4)-induced activation of smooth-muscle cells from human bronchi is partly Ca(2+)-independent / M. Accomazzo, G. Rovati, T. Vigano, A. Hernandez, A. Bonazzi, M. Bolla, F. Fumagalli, S. Viappiani, E. Galbiati, S. Ravasi, C. Albertoni, M. Di Luca, A. Caputi, P. Zannini, G. Chiesa, A. Villa, S. Doglia, G. Folco, S. Nicosia. - In: AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE. - ISSN 1073-449X. - 163:1(2001), pp. 266-272.

Leukotriene D(4)-induced activation of smooth-muscle cells from human bronchi is partly Ca(2+)-independent

M. Accomazzo;G. Rovati;S. Viappiani;S. Ravasi;M. Di Luca;G. Folco;
2001

Abstract

Cysteine-containing leukotrienes (cysteinyl-LTs) are potent bronchoconstrictors and play a key role in asthma. We found that histamine and LTD, markedly constrict strips of human bronchi (HB) with similar efficacy. However, in human airway smooth-muscle (HASM) cells, LTD(4), at variance with histamine, elicited only a small, transient change in intracellular calcium ion concentration. HASM cells express both Ca(2+)-dependent and -independent isoforms of protein kinase C (PKC) (i.e., PKC-alpha and PKC-epsilon). Western blot analysis showed that PKC-alpha is activated by histamine and, to a lesser extent, by LTD(4), whereas only LTD(4) translocates PKC-epsilon. This translocation was specifically inhibited by the LTD4 antagonist pobilukast. Phorbol-dibutyrate ester (PDBu) (a PKC activator) contracted HE strips to the same extent in the presence as in the absence of extra- and intracellular Ca(2+). In the absence of Ca(2+), LTD(4) contracted HB strips to the same extent as did PDBu, suggesting the involvement of a Ca(2+)-independent PKC in LTD(4)-mediated signal transduction. PDBu-induced desensitization and the PKC inhibitor H7 abolished the slow and sustained LTD(4)-triggered contraction of HE strips in the absence of Ca(2+), although H7 did not greatly affect the response in the presence of the ion. Thus, in human airways, we identified a novel LTD(4) transduction mechanism linked to bronchial smooth-muscle contraction, which is partly independent of Ca(2+) and involves the activation of PKC-epsilon.
Settore BIO/14 - Farmacologia
http://ajrccm.atsjournals.org/content/163/1/266.long
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/180081
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