title: Biomechanical regulation of hedgehog signaling in vascular smooth muscle cells in vitro and in vivo.
abstract: Hedgehog (Hh) signaling has recently been shown to be both responsive to mechanical loading in vitro and to control vascular development in vivo. We investigated the role of cyclic strain and pulsatile flow in modulating Hh signaling and growth of adult rat vascular smooth muscle cells (SMC) in culture. Exposure of SMC to defined equibiaxial cyclic strain (0% and 10% stretch, 60 cycles/min, for 24 h) significantly decreased sonic hedgehog (Shh) and patched 1 (Ptc1) expression while concurrently inhibiting Gli(2)-dependent promoter activity and mRNA expression, respectively. Cyclic strain significantly decreased SMC proliferation (cell counts and proliferating cell nuclear antigen expression) concomitant with a marked increase in SMC apoptosis (fluorescence-activated cell sorter analysis, acridine orange staining of apoptotic nuclei and Bax/Bcl-x(L) ratio). These strain-induced changes in proliferation and apoptosis were significantly attenuated following addition of either recombinant Shh (3.5 microg/ml) or overexpression of the Notch 3 intracellular domain (Notch IC). Further studies using a perfused transcapillary culture system demonstrated a significant decrease in Hh signaling in SMC following exposure of cells to increased pulsatile flow concomitant with a decrease in proliferation and an increase in apoptosis. Finally, the pulsatile flow-induced decreases in Hh signaling were validated in vivo following flow-induced rat carotid arterial remodeling after 28 days. These data suggest that Hh expression is diminished by biomechanical stimulation in vitro and in vivo and thus may play a fundamental role in arterial remodeling and atherogenesis in vivo.
authors.affiliation: Faculty of Science and Health, Vascular Health Research Centre, Dublin City University, Glasnevin, Dublin 9, Ireland.
authors.forename: David
authors.initials: D
authors.lastname: Morrow
authors.forename: Catherine
authors.initials: C
authors.lastname: Sweeney
authors.forename: Yvonne A
authors.initials: YA
authors.lastname: Birney
authors.forename: Shaunta
authors.initials: S
authors.lastname: Guha
authors.forename: Nora
authors.initials: N
authors.lastname: Collins
authors.forename: Philip M
authors.initials: PM
authors.lastname: Cummins
authors.forename: Ronan
authors.initials: R
authors.lastname: Murphy
authors.forename: Dermot
authors.initials: D
authors.lastname: Walls
authors.forename: Eileen M
authors.initials: EM
authors.lastname: Redmond
authors.forename: Paul A
authors.initials: PA
authors.lastname: Cahill
mesh_terms: D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D049109:Cell Proliferation; D053823:Hedgehog Proteins / Q000378:metabolism* / Q000494:pharmacology; D051741:Kruppel-Like Transcription Factors / Q000235:genetics; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D000071656:Receptor, Notch3; D011956:Receptors, Cell Surface / Q000378:metabolism; D051880:Receptors, Notch / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology*; D013314:Stress, Mechanical; D000075746:Zinc Finger Protein Gli2
chemical_list: C000618551:Gli2 protein, mouse; D053823:Hedgehog Proteins; D051741:Kruppel-Like Transcription Factors; C498556:Notch3 protein, rat; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; C000606240:Ptch1 protein, mouse; C000606239:Ptch1 protein, rat; D012333:RNA, Messenger; D000071656:Receptor, Notch3; D011956:Receptors, Cell Surface; D051880:Receptors, Notch; D011994:Recombinant Proteins; C465570:Shh protein, mouse; D000075746:Zinc Finger Protein Gli2