| Summary: | 碩士 === 國立臺灣大學 === 生命科學系 === 105 === Autotaxin (Atx), a secreted form of lysophospholipase D, is present in most body fluids. Atx is vital for different developmental processes. Loss of Atx causes vascular and neural defects and embryonic lethality at E9.5 in mice. However, how Atx affects neural development in vivo remains largely unclear mainly due to the difficulty of studying early development in mammals. To address this point, I used translucent zebrafish embryos as a model. I observed that atx expressed in neural tissues from 11 to 36 hours post fertilization (hpf), corresponding to the period of early neural development. Knockdown of atx with morpholino caused defects in formation of midbrain-hindbrain boundary (MHB) and brain ventricles in 24-hpf embryos. I further examined midbrains of atx morphants by cryosection at various developmental stages and observed that neural tube and midline formation were severely affected. It suggests that the Atx loss of function cause defects in neural cell migration toward the midline during neurulation. Knockdown of atx by MO is known to inhibit the formation of Küpffer vesicle, left-right asymmetry and subsequent cardiac looping in zebrafish. These defects may secondarily interfere with neurulation. To avoid this complication, I generated a neural-specific CRISPR construct targeting atx driven by a gfap promoter and successfully disrupted atx in neural tissue. I found brain and neural tube defects similar to atx morphants in the 48 hpf F0 embryos-injected with the atx-targeting plasmid. The formation of neural tube midline was severely delayed or malformed. Taken together, I unequivocally demonstrate the specific role of Atx in the neural tube formation and brain development in zebrafish. Further investigation using this model could help to elucidate the regulation of neural tube formation by Atx.
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