Spleen tyrosine kinase mediates BEAS-2B cell migration and proliferation and human rhinovirus-induced expression of vascular endothelial growth factor and interleukin-8.
Spleen tyrosine kinase (Syk) is an immunoregulatory tyrosine kinase that was identified originally in leukocytes. It is a key regulator of innate immunity as well as hematopoietic cell differentiation and proliferation. A role for Syk in regulating normal cellular functions in nonhematopoietic cells is increasingly recognized. We have shown previously robust Syk expression in airway epithelium, where it regulates the early inflammatory response to human rhinovirus (HRV) infections, and HRV cell entry by clathrin-mediated endocytosis. To test the hypothesis that Syk plays a role in modulating airway epithelial cell proliferation, migration, and production of vascular endothelial growth factor and interleukin-8, we studied the BEAS-2B human bronchial epithelial cell line and primary human airway epithelia from normal and asthmatic donors using Syk-specific pharmacologic inhibitors and small interfering RNA. Using an in vitro "wounding" model, we demonstrated significant impairment of "wound" closure after treatment with the Syk inhibitors N4-(2,2-dimethyl-3-oxo-4H-pyrid[1,4]oxazin-6-yl)-5-fluoro-N2-(3,4,5-trimethoxyphenyl)-2,4-pyrimidinediamine (R406) and 2-[7-(3,4-dimethoxyphenyl)-imidazo[1,2-c]pyrimidin-5-ylamino]-nicotinamide dihydrochloride (BAY61-3606), overexpression of the kinase-inactive Syk(K396R) mutant, and Syk knockdown by small interfering RNA. HRV infection also impaired wound healing, an effect that was partly Syk-dependent because wound healing was impaired further when HRV infection occurred in the presence of Syk inhibition. Further investigation of potential regulatory mechanisms revealed that inhibition of Syk suppressed HRV-induced vascular endothelial growth factor expression while promoting the activation of caspase-3, a mediator of epithelial cell apoptosis. Together, these results indicate that Syk plays a role in promoting epithelial cell proliferation and migration, while mitigating the effects of apoptosis.
Division of Respirology and Multi-Organ Transplantation Programme, University Health Network, Department of Medicine, University of Toronto, Toronto, Ontario, Canada.
Xiaomin
X
Wang
Mirek
M
Mychajlowycz
Christine
C
Lau
Carlos
C
Gutierrez
Jeremy A
JA
Scott
Chung-Wai
CW
Chow
D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001249:Asthma / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology* / Q000821:virology; D015870:Gene Expression / Q000187:drug effects; D016209:Interleukin-8 / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D034741:RNA, Small Interfering / Q000235:genetics; D020545:Respiratory Mucosa / Q000166:cytology; D012229:Rhinovirus; D000072377:Syk Kinase; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D014945:Wound Healing / Q000187:drug effects
D016209:Interleukin-8; D047908:Intracellular Signaling Peptides and Proteins; D047428:Protein Kinase Inhibitors; D034741:RNA, Small Interfering; D042461:Vascular Endothelial Growth Factor A; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; D053148:Caspase 3