Markers of airway smooth muscle cell phenotype .
Halayko, Andrew J., Hassan Salari, Xuefei Ma, and Newman L. Stephens.
Department of Physiology, University of Manitoba, 770 Bannatyne
Avenue, Winnipeg, MB, Canada, R3E 0W3, Inspiraplex, 3650 rue St
-Urbain, Montreal, PQ, Canada and Department of Medicine, University
of British Columbia, Vancouver, BC, Canada
APStracts 3:0013L, 1996.
Airways smooth muscle plays a principal role in the pathogenesis of
asthma. Primary cultures are being used to investigate airways
myocyte proliferation and cellular pathways regulating contraction.
Airways smooth muscle cells (SMCs) modulate from a contractile to a
non-contractile phenotype in culture but no systematic study of the
concomitant changes in expression of cytocontractile and cytoskeletal
proteins has been reported. We measured temporal changes in protein
marker expression of canine tracheal SMCs in primary culture using
specific antibodies and cDNA probes. Immunoblot analysis revealed
when cells became proliferative after five days of culture, the
content of smooth muscle myosin heavy chain (sm-MHC), calponin, sm
-[alpha]-actin and desmin diminished by >75%; myosin light chain
kinase, h-caldesmon and [beta]-tropomyosin had also decreased
significantly (p<0.05). Northern blots revealed that mRNA levels
for sm-MHC and sm-[alpha]-actin were also significantly reduced in
proliferative SMCs. Conversely, immunoblotting demonstrated the
content of non-muscle myosin heavy chain, l-caldesmon, vimentin,
[alpha]/[beta]-protein kinase C and CD44 to be increased 1 to 6-fold
as cells became proliferative. The content of sm-MHC and sm-[alpha]
-actin protein increased post-confluence suggesting that cultured
airway SMCs are capable of phenotypic plasticity. Marker protein
contents were also compared, by immunoblot assay, between SMCs
dissociated from trachealis or pulmonary arterial media.
Cytocontractile protein content was higher in the trachea, which
shortens faster than the pulmonary artery. The identification of
these markers provides tools for assessing the phenotype of airways
SMCs in culture and the airways of asthmatic patients.
Received 29 June 1995; accepted in final form 12 January 1996.
APS Manuscript Number L204-5.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 January 96