Roles of Tbx21 in mitral/tufted cells

为了探索Tbx21和Tbr2在小鼠嗅球二尖瓣/簇生细胞中的功能作用，我使用基因打靶策略分析了它们的功能丧失表型。Tbx21基因敲除小鼠表现出再生的嗅觉神经元对嗅球的支配略有延迟，但二尖瓣/簇状细胞的发育大体正常。相反，Tbr2在二尖瓣/簇状细胞中的缺失导致发育调控基因的表达变化和二尖瓣/簇状细胞树突形态的异常，从而导致与嗅球抑制性中间神经元相互作用的缺陷。这些结果表明，Tbr2对二尖瓣/簇状细胞的正确分化以及嗅球内神经元的连接都是必需的。Tbx21和Tbr21在二尖瓣/簇生细胞中具有不同的功能。

To explore the functional roles of Tbx21 and Tbr2 in mitral/tufted cells in the mouse olfactory bulb, I analyzed their loss-of-function phenotypes using gene-targeting strategy. Tbx21 konckout mice showed a slight delay of regenerated olfactory sensory neurons to innervate the olfactory bulb, but the development of mitral/tufted cells was grossly normal. In contrast, loss of Tbr2 in mitral/tufted cells resulted in expressional changes of developmentally-regulated genes and abnormalities in dendritic morphology of mitral/tufted cells, which led to defects in interactions with inhibitory interneurons in the olfactory bulb. These results demonstrate that Tbr2 is required for proper differentiation of mitral/tufted cells as well as neuronal wiring in the olfactory bulb. It is also revealed that Tbx21 and Tbr21 have different functions in mitral/tufted cells.