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Coordinate activation of endogenous p38alpha, beta, gamma, and delta by inflammatory stimuli
1Department of Immunology, The Scripps Research Institute, La Jolla, California 92037, USA. cfearns@scripps.edu
Abstract:
The p38 family of mitogen-activated protein kinases is believed to mediate a variety of leukocyte responses to pro-inflammatory stimuli. There are four members of the p38 family, and although activation of the different members has been studied in transiently transfected cells much less is known about activation of the endogenous p38s, particularly in myeloid lineage cells. To investigate activation of endogenous p38s, we have made monoclonal antibodies specific for each p38 and have used these antibodies to study p38 activation by pro-inflammatory stimuli in several human monocytic cell lines. Without stimulation endogenous p38alpha kinase activity was readily detectable, whereas that of p38beta, gamma, and delta was barely measurable. In response to inflammatory stimuli, we observed a time- and dose-dependent activation of all four p38s. The kinetics of activation of each of the p38s were similar for each stimulus used, suggesting a common upstream activation pathway. Simultaneous activation of the p38s suggests that all four may be important in inflammation.
Insights
The study investigated the activation of endogenous p38 kinases in myeloid cells. Results show all four p38 isoforms (p38alpha, p38beta, p38gamma, and p38delta) are activated by inflammatory stimuli, suggesting a common pathway.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- The p38 kinase family plays a crucial role in mediating leukocyte responses to pro-inflammatory stimuli.
- While activation of transfected p38 members is studied, endogenous p38 activation in myeloid cells remains less understood.
Purpose of the Study:
- To investigate the activation of endogenous p38 isoforms (p38alpha, p38beta, p38gamma, p38delta) in human monocytic cell lines.
- To characterize the response of endogenous p38 kinases to pro-inflammatory stimuli.
Main Methods:
- Development of specific monoclonal antibodies for each p38 isoform.
- Utilizing these antibodies to study p38 activation in human monocytic cell lines upon stimulation.
- Assessing kinase activity of endogenous p38 isoforms under basal and stimulated conditions.
Main Results:
- Basal kinase activity was readily detectable for p38alpha, but barely measurable for p38beta, p38gamma, and p38delta.
- Pro-inflammatory stimuli induced time- and dose-dependent activation of all four endogenous p38 isoforms.
- The activation kinetics for all p38 isoforms were similar across different stimuli, indicating a shared upstream pathway.
Conclusions:
- All four endogenous p38 isoforms are activated by inflammatory stimuli in myeloid lineage cells.
- A common upstream activation pathway likely regulates the p38 family.
- The simultaneous activation suggests all four p38 isoforms may play significant roles in inflammatory processes.