de Melo Jimmy, Qiu Xiangguo, Du Guoyan, Cristante Leah, Eisenstat David D
Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Manitoba R3E 0V9, Canada.
J Comp Neurol. 2003 Jun 23;461(2):187-204. doi: 10.1002/cne.10674.
Distal-less homeobox genes are expressed in the developing forebrain. We assessed Dlx gene expression in the developing and adult mouse retina. Dlx1 and Dlx2 are detected in retinal neuroprogenitors by embryonic day (E) 12.5 (Eisenstat et al. [1999] J. Comp. Neurol. 217-237). At E13.5, the expression of four homeodomain proteins, DLX2, BRN3b, PAX6, and CHX10, define distinct yet overlapping domains in the retinal neuroepithelium. By postnatal day (P) 0, DLX2 is expressed in the neuroblastic layer and the ganglion cell layer (GCL) consisting of ganglion and displaced amacrine cells. DLX1 expression resembles DLX2 to P0 but decreases postnatally. In the adult, DLX2 is localized to ganglion, amacrine, and horizontal cells as determined by coexpression with retinal cell-specific markers. There is coincident expression of DLX2 with gamma-aminobutyric acid (GABA), glutamic acid decarboxylase (GAD)65, and GAD67 in the inner nuclear layer (INL) and GCL. In the adult, DLX2 is coexpressed with BRN3b in ganglion cells; PAX6 in amacrine, horizontal, and ganglion cells; and Chx10 in some bipolar cells. We predict that a combinatorial code of these homeobox genes and others specify retinal cell fate. Our results support a possible role for Dlx1 and Dlx2 in inner retinal development and in the terminal differentiation and/or maintenance of INL interneurons and ganglion cells in the adult. The correlation of DLX2 with GABA expression in the mouse retina closely mirrors the relationship of DLX2 to GABAergic neuronal differentiation in the embryonic forebrain, including neocortex, olfactory bulb and hippocampus, signifying a conservation of function of Dlx genes in the developing central nervous system.
远端缺失同源框基因在发育中的前脑中表达。我们评估了发育中和成年小鼠视网膜中Dlx基因的表达。在胚胎第12.5天（E12.5）时，可在视网膜神经祖细胞中检测到Dlx1和Dlx2（艾森斯塔特等人，[1999年]《比较神经学杂志》217 - 237页）。在E13.5时，四种同源结构域蛋白DLX2、BRN3b、PAX6和CHX10的表达在视网膜神经上皮中定义了不同但重叠的区域。到出生后第0天（P0），DLX2在由神经节细胞和移位无长突细胞组成的神经母细胞层和神经节细胞层（GCL）中表达。DLX1的表达在P0之前与DLX2相似，但出生后会减少。在成年小鼠中，通过与视网膜细胞特异性标记物共表达确定，DLX2定位于神经节细胞、无长突细胞和水平细胞。在成年小鼠的内核层（INL）和GCL中，DLX2与γ-氨基丁酸（GABA）、谷氨酸脱羧酶（GAD）65和GAD67共表达。在成年小鼠中，DLX2在神经节细胞中与BRN3b共表达；在无长突细胞、水平细胞和神经节细胞中与PAX6共表达；在一些双极细胞中与Chx10共表达。我们预测这些同源框基因和其他基因的组合密码决定视网膜细胞命运。我们的结果支持Dlx1和Dlx2在成年小鼠视网膜内层发育以及INL中间神经元和神经节细胞的终末分化和/或维持中可能发挥的作用。DLX2与小鼠视网膜中GABA表达的相关性紧密反映了DLX2与胚胎前脑（包括新皮层、嗅球和海马体）中GABA能神经元分化的关系，这表明Dlx基因在发育中的中枢神经系统中功能保守。
