Molecular mechanisms for the release of chemokines from human leukemic mast cell line (HMC)-1 cells activated by SCF and TNF-α: roles of ERK, p38 MAPK, and NF-κB


Prof C. W. K. Lam
Department of Chemical Pathology
The Chinese University of Hong Kong
Prince of Wales Hospital
Hong Kong


Background:  Mast cells play pivotal roles in IgE-mediated airway inflammation and other mast cell-mediated inflammation by activation and chemoattraction of inflammatory cells.

Objective:  We investigated the intracellular signaling mechanisms regulating chemokine release from human mast cell line-1 (HMC-1) cells activated by stem cell factor (SCF) or tumor necrosis factor (TNF)-α.

Methods:  Chemokine gene expressions were assessed by reverse transcription-polymerase chain reaction, while the releases of chemokines were determined by flow cytometry or enzyme-linked immunosorbent assay (ELISA). To elucidate the intracellular signal transduction regulating the chemokine expression, phosphorylated-extracellular signal-regulated kinase (ERK), phosphorylated-p38 mitogen-activated protein kinase (MAPK) and nuclear translocated nuclear factor (NF)-κB-DNA binding were quantitatively assessed by ELISA.

Results:  Either SCF or TNF-α could induce release from HMC-1 cells of interleukin (IL)-8, monocyte chemoattractant protein (MCP)-1, regulated upon activation normal T-cell expressed and secreted (RANTES), and I-309, while SCF and TNF-α induced release of macrophage inflammatory protein (MIP)-1β and interferon-γ-inducible protein-10 (IP-10), respectively. Using various selective inhibitors for signaling molecules, we found that the inductions of IL-8, MCP-1, and I-309 were mediated by either SCF-activated ERK or TNF-α-activated p38 MAPK, while the induction of IP-10 by TNF-α was mediated by both activated p38 MAPK and NF-κB. The induction of RANTES by SCF or TNF-α was mediated by ERK and NF-κB, respectively, and SCF induced MIP-1β release was mediated by ERK.

Conclusion:  The above results therefore elucidated the different intracellular signaling pathways regulating the release of different chemokines from SCF and TNF-α-activated mast cells, thereby shedding light for the immunopathological mechanisms of mast cell-mediated diseases.