Title:All-trans Retinoic Acid Increased Transglutaminase 2 Expressions in BV-2 Cells
and Cultured Astrocytes
Volume: 17
Author(s): Katsura Takano-Kawabe*, Tatsuhiko Izumo, Tomoki Minamihata Minamihata and Mitsuaki Moriyama
Affiliation:
- Laboratory of Integrative Physiology in Veterinary Sciences, Osaka Metropolitan University, Osaka, Japan
Keywords:
All-trans retinoic acid, Microglia, Astrocyte, Transglutaminase, Amyloid β, Cystamine.
Abstract:
Background:
Activation of microglia and astrocytes has been observed in Alzheimer’s disease (AD). Transglutaminase 2 (TG2) is reported to be activated in AD
and involved in cell proliferation, differentiation, and inflammation. Moreover, amyloid β (Aβ) aggregation is detected as a characteristic
pathology in the AD brain, and is known to be a substrate of TG2. All-trans retinoic acid (ATRA) can modify cell proliferation and differentiation,
and is reported to have therapeutic effects on AD pathology.
Objective:
We aimed to assess the effects of ATRA in microglia and astrocytes on TG2 expression and glial functions.
Methods:
After treatment with ATRA, TG2 expression and TG activity were assayed in both murine microglia BV-2 cells and cultured rat brain astrocytes.
Endocytosis activity in BV-2 cells and Aβ aggregation by astrocytes conditioned medium were also assessed.
Results:
In both BV-2 cells and cultured astrocytes, ATRA increased TG2 expression and TG activity. The increase was blocked by AGN194310, an RA
receptor antagonist. ATRA enhanced the endocytosis activity in BV-2 cells, and the addition of AGN194310 reversed it. The addition of
cystamine, a competitive TG inhibitor, also reduced ATRA-enhanced endocytosis activity. On the other hand, Aβ aggregation was potentiated by
ATRA-treated astrocytes conditioned medium compared to control astrocytes conditioned medium.
Conclusion:
These results suggest that ATRA increased TG2 expression and TG activity via RA receptor in microglia and astrocytes. ATRA-enhanced TGs
might be involved in phagocytosis and Aβ aggregation. Adequate control of TGs expression and function in microglia and astrocytes can be an
important factor in AD pathology.
