Abstract
Activation of glial cells has been observed in neurodegenerative diseases including Alzheimer’s disease (AD). Aggregation of amyloid β (Aβ) is profusely observed as characteristic pathology in AD brain. In our previous study using microglial cell line BV-2, tissue-type transglutaminase (TG2) was found to be involved in phagocytosis (Kawabe et al., in Neuroimmunomodulation 22(4):243–249, 2015; Kawabe et al., Neurochem Res 2017). In the present study, we examined whether TG2 and milk fat globule EGF factor 8 protein (MFG-E8), an adaptor protein promotes macrophage to engulf apoptotic cells, were involved in Aβ endocytosis. When the neuronal/glial mixed culture was stimulated freshly prepared Aβ1−42 for 3 days, the incorporation of Aβ was observed by immunofluorescence staining technique in Iba-1-positive microglia. Cystamine, a broad competitive inhibitor of TGs, suppressed it. When aggregated Aβ was added to the mixed culture, the immunoreactivity of MFG-E8 surrounding Aβ was observed, and then followed by microglial endocytosis. Using western blotting technique, MFG-E8 was detected in cell lysate of astrocyte culture, and was also detected in the medium. When microglia culture was incubated with astrocyte conditioned medium, MFG-E8 levels in microglia tended to increase. It is likely that microglia might utilize MFG-E8 released from astrocytes as well as that expressed in themselves in order to endocytose Aβ aggregation. Furthermore, we confirmed that MFG-E8 could bind with TG2 in microglia culture by immunoprecipitate technique. These results suggest that microglia might uptake Aβ as a complex of aggregated Aβ/MFG-E8/TG2.
| Original language | English |
|---|---|
| Pages (from-to) | 1-9 |
| Number of pages | 9 |
| Journal | Neurochemical Research |
| DOIs | |
| Publication status | Accepted/In press - May 3 2017 |
| Externally published | Yes |
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Keywords
- Amyloid β
- Astrocyte
- MFG-E8
- Microglia
- Transglutaminase 2
ASJC Scopus subject areas
- Biochemistry
- Cellular and Molecular Neuroscience
Cite this
Microglia Endocytose Amyloid β Through the Binding of Transglutaminase 2 and Milk Fat Globule EGF Factor 8 Protein. / Kawabe, Kenji; Takano, Katsura; Moriyama, Mitsuaki; Nakamura, Yoichi.
In: Neurochemical Research, 03.05.2017, p. 1-9.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Microglia Endocytose Amyloid β Through the Binding of Transglutaminase 2 and Milk Fat Globule EGF Factor 8 Protein
AU - Kawabe, Kenji
AU - Takano, Katsura
AU - Moriyama, Mitsuaki
AU - Nakamura, Yoichi
PY - 2017/5/3
Y1 - 2017/5/3
N2 - Activation of glial cells has been observed in neurodegenerative diseases including Alzheimer’s disease (AD). Aggregation of amyloid β (Aβ) is profusely observed as characteristic pathology in AD brain. In our previous study using microglial cell line BV-2, tissue-type transglutaminase (TG2) was found to be involved in phagocytosis (Kawabe et al., in Neuroimmunomodulation 22(4):243–249, 2015; Kawabe et al., Neurochem Res 2017). In the present study, we examined whether TG2 and milk fat globule EGF factor 8 protein (MFG-E8), an adaptor protein promotes macrophage to engulf apoptotic cells, were involved in Aβ endocytosis. When the neuronal/glial mixed culture was stimulated freshly prepared Aβ1−42 for 3 days, the incorporation of Aβ was observed by immunofluorescence staining technique in Iba-1-positive microglia. Cystamine, a broad competitive inhibitor of TGs, suppressed it. When aggregated Aβ was added to the mixed culture, the immunoreactivity of MFG-E8 surrounding Aβ was observed, and then followed by microglial endocytosis. Using western blotting technique, MFG-E8 was detected in cell lysate of astrocyte culture, and was also detected in the medium. When microglia culture was incubated with astrocyte conditioned medium, MFG-E8 levels in microglia tended to increase. It is likely that microglia might utilize MFG-E8 released from astrocytes as well as that expressed in themselves in order to endocytose Aβ aggregation. Furthermore, we confirmed that MFG-E8 could bind with TG2 in microglia culture by immunoprecipitate technique. These results suggest that microglia might uptake Aβ as a complex of aggregated Aβ/MFG-E8/TG2.
AB - Activation of glial cells has been observed in neurodegenerative diseases including Alzheimer’s disease (AD). Aggregation of amyloid β (Aβ) is profusely observed as characteristic pathology in AD brain. In our previous study using microglial cell line BV-2, tissue-type transglutaminase (TG2) was found to be involved in phagocytosis (Kawabe et al., in Neuroimmunomodulation 22(4):243–249, 2015; Kawabe et al., Neurochem Res 2017). In the present study, we examined whether TG2 and milk fat globule EGF factor 8 protein (MFG-E8), an adaptor protein promotes macrophage to engulf apoptotic cells, were involved in Aβ endocytosis. When the neuronal/glial mixed culture was stimulated freshly prepared Aβ1−42 for 3 days, the incorporation of Aβ was observed by immunofluorescence staining technique in Iba-1-positive microglia. Cystamine, a broad competitive inhibitor of TGs, suppressed it. When aggregated Aβ was added to the mixed culture, the immunoreactivity of MFG-E8 surrounding Aβ was observed, and then followed by microglial endocytosis. Using western blotting technique, MFG-E8 was detected in cell lysate of astrocyte culture, and was also detected in the medium. When microglia culture was incubated with astrocyte conditioned medium, MFG-E8 levels in microglia tended to increase. It is likely that microglia might utilize MFG-E8 released from astrocytes as well as that expressed in themselves in order to endocytose Aβ aggregation. Furthermore, we confirmed that MFG-E8 could bind with TG2 in microglia culture by immunoprecipitate technique. These results suggest that microglia might uptake Aβ as a complex of aggregated Aβ/MFG-E8/TG2.
KW - Amyloid β
KW - Astrocyte
KW - MFG-E8
KW - Microglia
KW - Transglutaminase 2
UR - http://www.scopus.com/inward/record.url?scp=85018448875&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85018448875&partnerID=8YFLogxK
U2 - 10.1007/s11064-017-2284-y
DO - 10.1007/s11064-017-2284-y
M3 - Article
C2 - 28466190
AN - SCOPUS:85018448875
SP - 1
EP - 9
JO - Neurochemical Research
JF - Neurochemical Research
SN - 0364-3190
ER -