背景:在斑马鱼中脑,GABA能神经元从位于内侧纵向束(nMLF)核中的前体发育而来。然而,强调nMLFGABA能神经元产生的确切机制知之甚少。
结果:nMLF中GABA能神经元共表达转录因子tal2,gata2a,gata3和nkx1.2磅Nodal相关基因和shh信号是nMLFGABA能神经元前体分化所必需的。Tal2对于nMLFGABA能神经发生很重要。破坏Tal2,胚胎在nMLF中完全缺乏GABA合成酶谷氨酸脱羧酶67基因(gad67)表达细胞,和整个nkx1.2lb表达细胞在中脑。尽管间脑和/或nMLF中几乎所有表达tal2的细胞都是gata2a-和gata3-阳性,同时敲除gata2a和gata3不影响tal2或gad67表达。
结论:在斑马鱼中脑,表达tal2,gata2a,和/或gata3彼此独立。gata2a和gata3的功能对于nMLF中GABA能神经元的生成是不必要的。这表明导致nMLFGABA能神经元产生的调节基因的功能连接在小鼠和斑马鱼之间已经分歧。
In the zebrafish midbrain, GABAergic neurons develop from precursors located in the nucleus of the medial longitudinal fasciculus (nMLF). However, the precise mechanisms that underline generation of the nMLF GABAergic neuron are poorly understood.
GABAergic neurons in the nMLF co-express transcription factors tal2, gata2a, gata3, and nkx1.2lb. The Nodal-related gene and shh signaling are required for differentiation of nMLF GABAergic neuron precursors. Tal2 is important for nMLF GABAergic neurogenesis. Disruption of Tal2, embryos completely lack the GABA-synthesizing enzyme glutamic acid decarboxylase 67 gene (gad67) expressing cells in the nMLF, and the whole nkx1.2lb expressing cells in the midbrain. Although almost all tal2-expressing cells in the diencephalon and/or nMLF are gata2a- and gata3-positive, simultaneous knockdown of gata2a and gata3 does not affect either tal2 or gad67 expression.
In the zebrafish midbrain, expression of tal2, gata2a, and/or gata3 is independent of each other. The function of gata2a and gata3 is dispensable for generation of GABAergic neuron in the nMLF. This suggests that the functional connections of the regulatory genes leading to generation of nMLF GABAergic neurons have diverged between mouse and zebrafish.