Abstract：
The zebrafish retina possesses tremendous regenerative potential. Müller glia underlie retinal regeneration through their ability to reprogram and generate multipotent neuronal progenitors that re-differentiate into lost neurons. Many factors required for Müller glia reprogramming and proliferation have been identified; however, we know little about the epigenetic and transcriptional regulation of these genes during regeneration. Here, we determined whether transcriptional regulation by members of the Bromodomain (Brd) family is required for Müller glia-dependent retinal regeneration. Our data demonstrate that three brd genes were expressed in Müller glia upon injury. brd2a and brd2b were expressed in all Müller glia and brd4 was expressed only in reprogramming Müller glia. Utilizing (+)-JQ1, a pharmacological inhibitor of Brd function, we demonstrate that transcriptional regulation by Brds plays a critical role in Müller glia reprogramming and regeneration. (+)-JQ1 treatment prevented cell cycle re-entry of Müller glia and the generation of neurogenic progenitors. Modulating the (+)-JQ1 exposure window, we identified the first 48 h post-injury as the time-period during which Müller glia reprogramming occurs. (+)-JQ1 treatments after 48 h post-injury had no effect on the re-differentiation of UV cones, indicating that Brd function is required only for Müller glia reprogramming and not subsequent specification/differentiation events. Brd inhibition also prevented the expression of reprogramming genes like ascl1a and lepb in Müller glia, but not effector genes like mmp9, nor did it affect microglial recruitment after injury. These results demonstrate that transcriptional regulation by Brds plays a critical role during Müller glia-dependent retinal regeneration in zebrafish.
摘要：
斑马鱼视网膜具有巨大的再生潜力。Müller神经胶质通过其重新编程和产生多能神经元祖细胞的能力来支撑视网膜再生，这些神经元祖细胞重新分化为丢失的神经元。已经确定了Müllerglia重编程和增殖所需的许多因素；但是，我们对再生过程中这些基因的表观遗传和转录调控知之甚少。这里,我们确定了布罗莫结构域（Brd）家族成员的转录调控是否是Müller胶质细胞依赖性视网膜再生所必需的。我们的数据表明，损伤后Müller胶质细胞中表达了三个brd基因。brd2a和brd2b在所有Müller胶质细胞中表达，brd4仅在重编程Müller胶质细胞中表达。利用(+)-JQ1，一种Brd功能的药理抑制剂，我们证明了Brds的转录调控在Müller胶质细胞重编程和再生中起着关键作用。（）-JQ1处理阻止了Müller神经胶质的细胞周期重新进入和神经源性祖细胞的生成。调制(+)-JQ1曝光窗口,我们将伤后的前48小时确定为Müllerglia重编程发生的时间段.（+）-JQ1治疗后48小时后，对紫外线视锥细胞的再分化没有影响，表明仅Müllerglia重编程需要Brd函数，而不是后续的规范/区分事件。Brd抑制还阻止了Müller胶质细胞中重编程基因如ascl1a和lepb的表达，但不是像mmp9这样的效应基因，也不影响损伤后的小胶质细胞募集。这些结果表明，Brds的转录调控在斑马鱼Müller胶质细胞依赖性视网膜再生中起着至关重要的作用。
