Nogo-B regulates migration and contraction of airway smooth muscle cells by decreasing ARPC 2/3 and increasing MYL-9 expression.
BACKGROUND
Abnormal proliferation, apoptosis, migration and contraction of airway smooth muscle (ASM) cells in airway remodeling in asthma are basically excessive repair responses to a network of inflammatory mediators such as PDGF, but the mechanisms of such responses remain unclear. Nogo-B, a member of the reticulum family 4(RTN4), is known to play a key role in arteriogenesis and tissue repair. Further studies are needed to elucidate the role of Nogo-B in airway smooth muscle abnormalities.


METHODS
A mouse model of chronic asthma was established by repeated OVA inhalation and subjected to Nogo-B expression analysis using immunohistochemistry and Western Blotting. Then, primary human bronchial smooth muscle cells (HBSMCs) were cultured in vitro and a siRNA interference was performed to knockdown the expression of Nogo-B in the cells. The effects of Nogo-B inhibition on PDGF-induced HBSMCs proliferation, migration and contraction were evaluated. Finally, a proteomic analysis was conducted to unveil the underlying mechanisms responsible for the function of Nogo-B.


RESULTS
Total Nogo-B expression was approximately 3.08-fold lower in chronic asthmatic mice compared to naïve mice, which was obvious in the smooth muscle layer of the airways. Interference of Nogo-B expression by siRNA resulted nearly 96% reduction in mRNA in cultured HBSMCs. In addition, knockdown of Nogo-B using specific siRNA significantly decreased PDGF-induced migration of HBSMCs by 2.3-fold, and increased the cellular contraction by 16% compared to negative controls, but had limited effects on PDGF-induced proliferation. Furthermore, using proteomic analysis, we demonstrate that the expression of actin related protein 2/3 complex subunit 5 (ARPC 2/3) decreased and, myosin regulatory light chain 9 isoform a (MYL-9) increased after Nogo-B knockdown.


CONCLUSIONS
These data define a novel role for Nogo-B in airway remodeling in chronic asthma. Endogenous Nogo-B, which may exert its effects through ARPC 2/3 and MYL-9, is necessary for the migration and contraction of airway smooth muscle cells.
Department of Respiratory Diseases, ChangHai Hospital, Second Military Medical University, Shanghai 200433, China.
Wujian
W
Xu
Weijun
W
Hong
Yan
Y
Shao
Yunye
Y
Ning
Zailong
Z
Cai
Qiang
Q
Li
D051376:Actin-Related Protein 2-3 Complex / Q000378:metabolism*; D056151:Airway Remodeling; D000818:Animals; D001249:Asthma / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology; D000077214:Becaplermin; D015153:Blotting, Western; D016084:Bronchoconstriction; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D004195:Disease Models, Animal; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008840:Microfilament Proteins / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism; D009185:Myelin Proteins / Q000235:genetics / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D018994:Myosin Light Chains / Q000378:metabolism*; D000070798:Nogo Proteins; D010047:Ovalbumin; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D040901:Proteomics; D020574:Proto-Oncogene Proteins c-sis; D034622:RNA Interference; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection
C517043:ARPC3 protein, human; D051376:Actin-Related Protein 2-3 Complex; D008840:Microfilament Proteins; D009124:Muscle Proteins; D009185:Myelin Proteins; D018994:Myosin Light Chains; D000070798:Nogo Proteins; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; C000603199:RTN4 protein, human; C000603201:Rtn4 protein, mouse; C051615:transgelin; D000077214:Becaplermin; D010047:Ovalbumin
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