THESIS
2020
xi, 109 pages : illustrations (chiefly color) ; 30 cm
Abstract
Microglia are predominant immune cells resident in central nervous system (CNS) and
play numerous functions for maintaining CNS homeostasis and participating in immune
responses locally. In zebrafish, there are at least two waves of hematopoiesis
contributing to microglia. RBI derived primitive microglia colonize in brain at
embryonic stage and they are gradually replaced by VDA derived definitive microglia
during development until adulthood. Microglia are long been believed to be maintained
by self-renew without contribution from circulation in physiological conditions.
However, the mechanisms for microglia maintenance are still largely unknown. Here,
we firstly established the visible conditional knockout method with high efficiency to
achieve spatiotemporal inactivation of p...[
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Microglia are predominant immune cells resident in central nervous system (CNS) and
play numerous functions for maintaining CNS homeostasis and participating in immune
responses locally. In zebrafish, there are at least two waves of hematopoiesis
contributing to microglia. RBI derived primitive microglia colonize in brain at
embryonic stage and they are gradually replaced by VDA derived definitive microglia
during development until adulthood. Microglia are long been believed to be maintained
by self-renew without contribution from circulation in physiological conditions.
However, the mechanisms for microglia maintenance are still largely unknown. Here,
we firstly established the visible conditional knockout method with high efficiency to
achieve spatiotemporal inactivation of pu.1. This method was based on intron-targeting
non homologous end joining (NHEJ)-mediated knockin of large fragment into genome
and we generated the visible conditional knockout pu.1
KI allele. Next, we demonstrated
that pu.1 was critical for definitive microglia long-term maintenance. Inactivation of
pu.1 in microglia reduced their proliferation rate and led them gradually replaced by
wild type microglia. Finally, we figured out that pu.1 and spi-b played redundant roles
for microglia short-term survival. This mechanism was conserved in both primitive and
definitive microglia. Taken together, our works provided a useful platform for zebrafish
genetic study and gave new insights into functions of pu.1 and spi-b for microglia
maintenance.
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