Inhibiting cell cycle progression reduces reactive astrogliosis initiated by scratch injury in vitro and by cerebral ischemia in vivo.
Astrogliosis occurs in a variety of neuropathological disorders and injuries, and excessive astrogliosis can be devastating to the recovery of neuronal function. In this study, we asked whether reactive astrogliosis can be suppressed in the lesion area by cell cycle inhibition and thus have therapeutic benefits. Reactive astrogliosis induced in either cultured astrocytes by hypoxia or scratch injury, or in a middle cerebral artery occlusion (MCAO) ischemia model were combined to address this issue. In the cultured astrocytes, hypoxia induced a cell cycle activation that was associated with upregulation of the proliferating cell nuclear marker (PCNA). Significantly, the cell cycle inhibitor, olomoucine, inhibited hypoxia-induced cell cycle activation by arresting the cells at G1/S and G2/M in a dose-dependent manner and also reversed hypoxia-induced upregulation of PCNA. Also in the cultured astrocytes, scratch injury induced reactive astrogliosis, such as hypertrophy and an increase in BrdU(+) astrocytes, both of which were ameliorated by olomoucine. In the MCAO ischemia mouse model, dense reactive glial fibrillary acidic protein and PCNA immunoreactivity were evident at the boundary zone of focal cerebral ischemia at days 7 and 30 after MCAO. We found that intraperitoneal olomoucine administration significantly inhibited these astrogliosis-associated changes. To demonstrate further that cell cycle regulation impacts on astrogliosis, cyclin D1 gene knockout mice (cyclin D1(-/-)) were subjected to ischemia, and we found that the percentage of Ki67-positive astrocytes in these mice was markedly reduced in the boundary zone. The number of apoptotic neurons and the lesion volume in cyclin D1(-/-) mice also decreased as compared to cyclin D1(+/+) and cyclin D1(+/-) mice at days 3, 7, and 30 after local cerebral ischemia. Together, these in vitro and in vivo results strongly suggest that astrogliosis can be significantly affected by cell cycle inhibition, which therefore emerges as a promising intervention to attenuate reactive glia-related damage to neuronal function in brain pathology.
Zhu
Zhou
Z
Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China.
Zhang
Qiang
Q
Yu
Zhiyuan
Z
Zhang
Liang
L
Tian
Daishi
D
Zhu
Suiqiang
S
Bu
Bitao
B
Xie
Minjie
M
Wang
Wei
W
D000704:Analysis of Variance; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000276:immunology* / Q000473:pathology; D001930:Brain Injuries / Q000276:immunology* / Q000473:pathology; D002545:Brain Ischemia / Q000276:immunology* / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects / Q000276:immunology* / Q000502:physiology; D016923:Cell Death / Q000187:drug effects / Q000276:immunology / Q000502:physiology; D002478:Cells, Cultured; D019938:Cyclin D1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005911:Gliosis / Q000276:immunology* / Q000473:pathology / Q000517:prevention & control; D019394:Ki-67 Antigen / Q000032:analysis; D007701:Kinetin / Q000494:pharmacology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D020768:Middle Cerebral Artery; D051381:Rats; D017208:Rats, Wistar; D018709:Statistics, Nonparametric; D014947:Wounds and Injuries / Q000276:immunology / Q000473:pathology
D004791:Enzyme Inhibitors; D019394:Ki-67 Antigen; D019938:Cyclin D1; C090046:olomoucine; D007701:Kinetin