A bHLH-Based Feedback Loop Restricts Vascular Cell Proliferation in Plants
A bHLH-Based Feedback Loop Restricts Vascular Cell Proliferation in Plants
复制标题
DOI：
10.1016/j.devcel.2015.10.022
复制
发表时间：
2015-11-23
影响因子：
11.8
通讯作者：
Blazquez, Miguel A.
中科院分区：
文献类型：
--
作者：
Vera-Sirera, Francisco;De Rybel, Bert;Blazquez, Miguel A.
在多细胞生物体中，控制组织尺寸需要精确的有丝分裂活性的定量调节。在植物中，细胞是固定的，组织大小是通过控制细胞分裂方向和有丝分裂速率来实现的。bHLH转录因子异源二聚体由单核细胞靶蛋白5（TMO 5）和孤独高速公路（LHVV）形成，是血管宽度增加分裂的中心调节因子。一个重要的未回答的问题是，它的活动是如何限制指定血管组织的尺寸。在这里，我们确定了一个监管网络，限制TMO 5/LHW活动。我们发现，热精胺合酶ACAULIS 5拮抗TMO 5/LHW活性，促进积累的SAC 51样（SACL）bHLH转录因子。SACL蛋白与LHW异源二聚化，因此可能与TMO 5/LHW相互作用竞争，阻止TMO 5/LHW靶基因的激活，并抑制由过量TMO 5/LHW活性引起的过度增殖。这些发现连接了两个迄今为止完全不同的途径，并提供了定量控制血管组织生长的机制的理解。
Control of tissue dimensions in multicellular organisms requires the precise quantitative regulation of mitotic activity. In plants, where cells are immobile, tissue size is achieved through control of both cell division orientation and mitotic rate. The bHLH transcription factor heterodimer formed by TARGET OF MONOPTEROS5 (TMO5) and LONESOME HIGHWAY (LHVV) is a central regulator of vascular width-increasing divisions. An important unanswered question is how its activity is limited to specify vascular tissue dimensions. Here we identify a regulatory network that restricts TMO5/LHW activity. We show that thermospermine synthase ACAULIS5 antagonizes TMO5/LHW activity by promoting the accumulation of SAC51-LIKE (SACL) bHLH transcription factors. SACL proteins heterodimerize with LHW therefore likely competing with TMO5/LHW interactions prevent activation of TMO5/LHW target genes, and suppress the over-proliferation caused by excess TMO5/LHW activity. These findings connect two thus-far disparate pathways and provide a mechanistic understanding of the quantitative control of vascular tissue growth.