Mechanisms of bradykinin-induced contraction in human fetal lung fibroblasts

L. Petecchia, F. Sabatini, C. Usai, S. Carnevali, M. Ognibene, C. Vanni, A. Eva, L. M. Fabbri, G. A. Rossi, F. L M Ricciardolo

Research output: Contribution to journalArticlepeer-review

Abstract

Bradykinin (BK) induces fibroblast contraction but the structural changes and intracellular mechanisms involved have not been completely explored. We stimulated HFL-1 fibroblasts with BK to assess: 1) fibroblast contractility; 2) the role of α-smooth muscle actin (SMA) in contraction by small interfering RNA (siRNA); 3) α-SMA protein expression; 4) α-SMA and F-actin structure; 5) intracellular calcium concentration ([Ca 2+]i); and 6) phosphorylated myosin light-chain (pMLC) and MLC kinase (MLCK) expression. BK triggered concentration- and time-dependent fibroblast gel contraction in conjunction with α-SMA over expression, but not in α-SMA-siRNA-treated cells. BK also increased α-SMA + and F-actin+ cell number and stress fibre polymerisation (detectable at 5-60 min). These BK-induced changes were associated with an increase in [Ca2+]i, which peaked within 15 s, and activation of pMLC, which was detectable at 5-60 min. No MLCK content modification was observed. The different manifestations of the BK-induced fibroblast activation were downregulated at different levels (25-100%) by HOE140, a specific BK B2 receptor (B2R) antagonist and by the Ca2+ chelator, EGTA. Thus, BK-induced fibroblast contraction, associated with differentiation into α-SMA+ myofibroblasts, is mediated through the activation of the B2R and involves the Ca2+/calmodulin pMLC-dependent pathway. Copyright

Original languageEnglish
Pages (from-to)655-664
Number of pages10
JournalEuropean Respiratory Journal
Volume36
Issue number3
DOIs
Publication statusPublished - Sep 2010

Keywords

  • α-smooth muscle actin
  • Calcium
  • Contraction
  • Fibroblasts
  • Myosin phosphorylation

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine

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