Human astrocytes express the interleukin (IL)-4 receptor alpha chain (IL-4R alpha) in vitro and in vivo but mechanisms governing astrocyte IL-4R alpha expression have not been established. We hypothesized that epidermal growth factor (EGF) and IL-4, agents that profoundly affect astrocyte proliferation, might also alter IL-4R alpha expression. Exposure to EGF for 24 h enhanced IL-4R alpha mRNA levels; in contrast, IL-4 yielded no increase. Immunoblotting demonstrated that EGF but not IL-4 increased astrocyte IL-4R alpha protein after 2--4 days of exposure. Similarly, EGF but not IL-4 strongly activated phosphorylation of p42/p44 extracellular regulated kinase isoforms, a reaction blocked by the mitogen-activated protein kinase (MAPK) inhibitor, PD98059. PD98059 also blocked EGF-stimulated DNA synthesis but not IL-4R alpha mRNA levels, while antibody to the EGF receptor (erbB1) blocked both EGF effects. Data suggest that astrocyte IL-4R alpha expression is upregulated by EGF but not by IL-4 in an EGF-receptor-dependent manner and that mechanisms are independent of MAPK activation.
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http://dx.doi.org/10.1006/cimm.2001.1768 | DOI Listing |
Front Immunol
November 2024
Eli Lilly and Company, Indianapolis, IN, United States.
Int Immunopharmacol
December 2024
Qyuns Therapeutics Co., Ltd., Taizhou, Jiangsu, China. Electronic address:
Biomed Pharmacother
June 2024
State Key Laboratory of Natural Medicines, Ministry of Education, the Engineering Research Center of Synthetic Polypeptide Drug Discovery and Evaluation of Jiangsu Province, Department of Marine Pharmacy, China Pharmaceutical University, Nanjing 211198, China; The Engineering Research Center of Synthetic Peptide Drug Discovery and Evaluation of Jiangsu Province, China Pharmaceutical University, Nanjing 210009, China. Electronic address:
Cancer Sci
July 2024
Department of Clinical Laboratory, The 4th Hospital of Harbin Medical University, Harbin, China.
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