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Activation and proliferation of the isolated microglia by colony stimulating factor-1 and possible involvement of
M Sawada1, A Suzumura, H Yamamoto
1Division of Cell Biology, School of Medicine, Fujita-Gakuen Health University, Toyoake, Japan.
Abstract:
Microglia were isolated from primary mixed brain cell culture of normal newborn mice and then cultivated. They were able to be maintained in vitro for 1-2 months, but incorporated little [3H]thymidine under normal culture conditions. When treated with the conditioned medium of L929 mouse fibroblast cells as a crude CSF-1 (mouse macrophage-colony stimulating factor) or purified CSF-1, microglia showed morphological changes and increased in both cell number and [3H]thymidine uptake. In addition, crude CSF-1 increased lysosomal enzyme activity and superoxide anion formation of microglia up to 2 and 3.8 fold as control value, respectively. These effects of CSF-1 were not observed in the purified astrocyte culture. Purified microglia had CSF-1 receptors which were recognized by the anti-CSF-1 receptor antibody that arose from a peptide of a product of proto-oncogene, c-fms. 12-O-Tetradecanoylphorbol-13-acetate (TPA) also increased microglia cell number and their biochemical activities, suggesting the possible involvement of protein kinase C activation. Protein kinase inhibitors, such as staurosporine or H-7, inhibited the effects of both CSF-1 and TPA. These results indicate that microglia may be regulated in its biochemical and proliferation activities by CSF-1 and that this may occur via activation of protein kinase C.
Insights
Mouse microglia proliferation and biochemical activity are regulated by macrophage-colony stimulating factor (CSF-1). CSF-1 activates protein kinase C, influencing microglia
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglia are key immune cells in the central nervous system.
- Their proliferation and activation are crucial for brain health and disease.
- Understanding microglia regulation is vital for developing targeted therapies.
Purpose of the Study:
- To investigate the role of macrophage-colony stimulating factor (CSF-1) in regulating microglia.
- To explore the signaling pathways involved in CSF-1-mediated microglia activation.
- To determine if CSF-1 affects microglia proliferation and biochemical functions.
Main Methods:
- Isolation and in vitro cultivation of primary mouse microglia.
- Treatment with crude or purified CSF-1 and assessment of [3H]thymidine uptake.
- Measurement of lysosomal enzyme activity and superoxide anion formation.
- Analysis of CSF-1 receptor expression using anti-CSF-1 receptor antibody.
- Investigation of 12-O-tetradecanoylphorbol-13-acetate (TPA) and protein kinase inhibitors.
Main Results:
- CSF-1 significantly increased microglia cell number, [3H]thymidine uptake, lysosomal enzyme activity, and superoxide anion formation.
- These effects were specific to microglia and not observed in astrocytes.
- Microglia express CSF-1 receptors, consistent with the proto-oncogene c-fms.
- TPA also enhanced microglia proliferation and biochemical activities, suggesting protein kinase C involvement.
- Protein kinase inhibitors (staurosporine, H-7) blocked the effects of both CSF-1 and TPA.
Conclusions:
- CSF-1 is a key regulator of microglia proliferation and biochemical activities.
- CSF-1 signaling in microglia may involve the activation of protein kinase C.
- These findings provide insights into the molecular mechanisms controlling microglia function.