Microglia shape adult hippocampal neurogenesis through apoptosis-coupled phagocytosis.
In the adult hippocampus, neuroprogenitor cells in the subgranular zone (SGZ) of the dentate gyrus give rise to newborn neuroblasts. However, only a small subset of these cells integrates into the hippocampal circuitry as mature neurons at the end of a 4 week period. Here, we show that the majority of the newborn cells undergo death by apoptosis in the first 1 to 4 days of their life, during the transition from amplifying neuroprogenitors to neuroblasts. These apoptotic newborn cells are rapidly cleared out through phagocytosis by unchallenged microglia present in the adult SGZ niche. Phagocytosis by the microglia is efficient and undeterred by increased age or inflammatory challenge. Our results suggest that the main critical period of newborn cell survival occurs within a few days of birth and reveal a new role for microglia in maintaining the homeostasis of the baseline neurogenic cascade.
Sierra
Amanda
A
Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA. amanda.sierrasaavedra@gmail.com
Encinas
Juan M
JM
Deudero
Juan J P
JJ
Chancey
Jessica H
JH
Enikolopov
Grigori
G
Overstreet-Wadiche
Linda S
LS
Tsirka
Stella E
SE
Maletic-Savatic
Mirjana
M
D000818:Animals; D017209:Apoptosis; D006624:Hippocampus / Q000166:cytology*; D051379:Mice; D008822:Mice, Transgenic; D058953:Neural Stem Cells / Q000166:cytology; D055495:Neurogenesis; D010587:Phagocytosis