Annexin III implicated in the microglial response to motor nerve injury.
To identify proteins implicated in peripheral nerve regeneration, we performed two-dimensional polyacrylamide gel electrophoresis and subsequent mass spectrometry analysis using nerve-injured hypoglossal nuclei of rat. We have identified annexin III (ANX III/ANX A3) as an induced protein after rat hypoglossal nerve injury. ANX III is known as a Ca2+-dependent phospholipid-binding protein, but its physiological function is mostly unknown. By in situ hybridization and immunohistochemistry, we demonstrated that ANX III expression was induced specifically in activated (axotomy-stimulated) microglia after nerve injury. ANX III was the most prominent ANX expressed in microglia of the major ANX family members (ANX I-VI). Hybridization signals for other ANX mRNAs (II, IV, V, and VI) were mainly observed in neuronal cells, and no significant hybridization signal for ANX I mRNA was detected in hypoglossal nuclei. In cultured microglia, ATP treatment induced ANX III translocation to the ruffling membrane where F-actin was accumulated. Further in vitro studies revealed that ANX III was not secreted and had F-actin binding activity in a Ca2+-dependent manner. These results suggest that ANX III may be a Ca2+-dependent mediator between phospholipids and F-actin in microglia stimulated by peripheral nerve injury.
Konishi
Hiroyuki
H
Department of Anatomy and Neurobiology, Osaka City University, Graduate School of Medicine, Asahimachi, Osaka 545-8585, Japan.
Namikawa
Kazuhiko
K
Kiyama
Hiroshi
H
D000199:Actins / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D017318:Annexin A3 / Q000235:genetics / Q000378:metabolism*; D001369:Axons / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D005911:Gliosis / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D007002:Hypoglossal Nerve / Q000166:cytology / Q000378:metabolism; D020437:Hypoglossal Nerve Diseases / Q000378:metabolism / Q000503:physiopathology; D061228:Hypoglossal Nerve Injuries; D008297:Male; D017628:Microglia / Q000378:metabolism*; D009046:Motor Neurons / Q000378:metabolism*; D009416:Nerve Regeneration / Q000502:physiology*; D059348:Peripheral Nerve Injuries; D010525:Peripheral Nerves / Q000166:cytology / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D012333:RNA, Messenger; D051381:Rats; D017208:Rats, Wistar; D015854:Up-Regulation / Q000502:physiology
D000199:Actins; D010743:Phospholipids; D012333:RNA, Messenger; D017318:Annexin A3