Inhibition of glycogen synthase kinase-3beta is sufficient for airway smooth muscle hypertrophy.
We examined the role of glycogen synthase kinase-3beta (GSK-3beta) inhibition in airway smooth muscle hypertrophy, a structural change found in patients with severe asthma. LiCl, SB216763, and specific small interfering RNA (siRNA) against GSK-3beta, each of which inhibit GSK-3beta activity or expression, increased human bronchial smooth muscle cell size, protein synthesis, and expression of the contractile proteins alpha-smooth muscle actin, myosin light chain kinase, smooth muscle myosin heavy chain, and SM22. Similar results were obtained following treatment of cells with cardiotrophin (CT)-1, a member of the interleukin-6 superfamily, and transforming growth factor (TGF)-beta, a proasthmatic cytokine. GSK-3beta inhibition increased mRNA expression of alpha-actin and transactivation of nuclear factors of activated T cells and serum response factor. siRNA against eukaryotic translation initiation factor 2Bepsilon (eIF2Bepsilon) attenuated LiCl- and SB216763-induced protein synthesis and expression of alpha-actin and SM22, indicating that eIF2B is required for GSK-3beta-mediated airway smooth muscle hypertrophy. eIF2Bepsilon siRNA also blocked CT-1- but not TGF-beta-induced protein synthesis. Infection of human bronchial smooth muscle cells with pMSCV GSK-3beta-A9, a retroviral vector encoding a constitutively active, nonphosphorylatable GSK-3beta, blocked protein synthesis and alpha-actin expression induced by LiCl, SB216763, and CT-1 but not TGF-beta. Finally, lungs from ovalbumin-sensitized and -challenged mice demonstrated increased alpha-actin and CT-1 mRNA expression, and airway myocytes isolated from ovalbumin-treated mice showed increased cell size and GSK-3beta phosphorylation. These data suggest that inhibition of the GSK-3beta/eIF2Bepsilon translational control pathway contributes to airway smooth muscle hypertrophy in vitro and in vivo. On the other hand, TGF-beta-induced hypertrophy does not depend on GSK-3beta/eIF2B signaling.
Deng
Huan
H
Department of Pediatrics and Communicable Diseases, University of Michigan, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA.
Dokshin
Gregoriy A
GA
Lei
Jing
J
Goldsmith
Adam M
AM
Bitar
Khalil N
KN
Fingar
Diane C
DC
Hershenson
Marc B
MB
Bentley
J Kelley
JK
D000818:Animals; D001249:Asthma / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D001980:Bronchi / Q000201:enzymology* / Q000473:pathology; D016207:Cytokines / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020717:Eukaryotic Initiation Factor-2B / Q000235:genetics / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D006984:Hypertrophy / Q000208:ethnology / Q000235:genetics; D007211:Indoles / Q000494:pharmacology; D018021:Lithium Chloride / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D051379:Mice; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D009130:Muscle, Smooth / Q000201:enzymology* / Q000473:pathology; D014176:Protein Biosynthesis / Q000187:drug effects / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics
D016207:Cytokines; D004791:Enzyme Inhibitors; D020717:Eukaryotic Initiation Factor-2B; D007211:Indoles; D008301:Maleimides; D009124:Muscle Proteins; D034741:RNA, Small Interfering; C417521:SB 216763; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D038362:Glycogen Synthase Kinase 3; D018021:Lithium Chloride