当前位置: X-MOL 学术Science › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Abl and Canoe/Afadin mediate mechanotransduction at tricellular junctions
Science ( IF 56.9 ) Pub Date : 2020-11-26 , DOI: 10.1126/science.aba5528
Huapeng H Yu 1 , Jennifer A Zallen 1
Affiliation  

Tension where multiple cells meet Cells exist in varying environments and must respond to specific stimuli. During development, epithelial cells need to rapidly reorganize under tension without compromising epithelial integrity. Yu et al. demonstrate that Drosophila epithelial cells achieve this by transiently stabilizing adhesion at tricellular junctions where three cells meet (see the Perspective by Raghavan and Vasioukhin). The conserved adhesion regulator Canoe/Afadin is recruited to tricellular junctions under tension within seconds and dissociates when tension is released through a mechanism that requires Abl-dependent tyrosine phosphorylation. These results identify an in vivo mechanotransduction pathway that dynamically couples tricellular adhesion with physiological forces, allowing cells to rapidly modulate their behavior in response to mechanical changes in their environment. Science, this issue p. eaba5528; see also p. 1036 A force-responsive mechanism stabilizes tricellular adhesion under tension during epithelial remodeling in Drosophila embryos. INTRODUCTION The ability to sense and respond to mechanical force is an intrinsic property of cells that is critical for normal cell function and often deregulated in disease. Mechanical forces induce changes in protein conformation, localization, activity, and posttranslational modification in vitro. An outstanding question is how mechanical signals modulate protein function and cell behavior in response to the physiological forces encountered by cells in living organisms. Tyrosine phosphorylation has long been recognized to be enriched at adherens junctions, which detect and transmit forces between epithelial cells, and can be directly enhanced by mechanical forces in vitro. However, whether mechanical forces influence tyrosine kinase signaling in vivo, and the consequences of this regulation for cell behavior, are not known. RATIONALE An important step in the development of epithelial organs is the remodeling of cell adhesion in response to mechanical forces, which transforms epithelial sheets into diverse structures. Tricellular junctions (TCJs) where three cells meet are dynamically assembled and disassembled during cell rearrangement and are predicted to be sites of increased tension during epithelial remodeling, providing an opportunity to investigate how cells respond to mechanical forces. However, the mechanisms that allow tricellular junctions to rapidly remodel under tension without disrupting epithelial continuity are not well understood. Identifying and characterizing proteins that localize to tricellular junctions under tension can provide insight into the mechanotransduction pathways that modulate cell adhesion in response to mechanical forces in vivo. RESULTS Using time-lapse imaging and a method to directly visualize tyrosine phosphorylation in living embryos, we found that tyrosine phosphorylation is increased at tricellular junctions in a tension-dependent fashion during Drosophila convergent extension. By screening a library of tagged proteins, we identified Canoe as a tyrosine-phosphorylated protein that localizes to tricellular junctions under tension. Canoe recruitment to tricellular junctions dynamically correlated with changes in myosin localization, and Canoe rapidly dissociated from tricellular junctions when tension was released by laser ablation. The enrichment of Canoe at tricellular junctions required Abl-dependent tyrosine phosphorylation of Canoe at Y1987, a conserved site in the Canoe actin-binding domain. Decreasing Abl expression or mutating this tyrosine to an unphosphorylatable amino acid significantly reduced Canoe enrichment at tricellular junctions and disrupted tricellular adhesion in vivo. To determine whether the dynamic recruitment of Canoe to tricellular junctions is important for cell rearrangement, we developed a “vertex trap” method to constitutively target Venus-tagged Canoe to tricellular junctions independently of mechanical inputs. Stably anchoring Canoe at tricellular junctions aberrantly stabilized adhesion at four-way vertices and arrested cell rearrangement. These results suggest that Canoe levels dynamically modulate the strength of cell adhesion at tricellular junctions to facilitate cell rearrangement. CONCLUSION These results identify a mechanotransduction pathway that dynamically couples tricellular adhesion with mechanical forces during epithelial remodeling. Canoe recruitment to tricellular junctions requires actomyosin contractility and Abl-dependent phosphorylation of a conserved tyrosine in the Canoe actin-binding domain. Loss of Canoe disrupts tricellular adhesion, and increasing Canoe levels at tricellular junctions slows or arrests cell rearrangement, influencing the rate of epithelial remodeling. In one model, Canoe could act as a mechanosensor, physically stretching under tension to expose a phosphorylation site for Abl. Alternatively, tension could enhance Abl activity or generate a unique configuration of actin or other molecules at tricellular junctions that is recognized by Canoe. Tricellular junctions influence many processes required for epithelial development and homeostasis, including cell rearrangement, cell division, stem cell self-renewal, and barrier function. A better understanding of the composition, organization, and dynamic properties of tricellular junctions will provide insight into how these structures sense and integrate mechanical forces in epithelia. Regulation of tricellular adhesion by tension requires Canoe and the Abl tyrosine kinase. (Top) Localization of phosphotyrosine (white), Canoe-Venus (green), and myosin-mCherry (red) in the Drosophila embryo. (Bottom) Canoe localization at tricellular junctions is enhanced by Abl and cytoskeletal tension. This force-sensitive mechanism is important for cell adhesion and epithelial remodeling. Epithelial structure is generated by the dynamic reorganization of cells in response to mechanical forces. Adherens junctions transmit forces between cells, but how cells sense and respond to these forces in vivo is not well understood. We identify a mechanotransduction pathway involving the Abl tyrosine kinase and Canoe/Afadin that stabilizes cell adhesion under tension at tricellular junctions in the Drosophila embryo. Canoe is recruited to tricellular junctions in response to actomyosin contractility, and this mechanosensitivity requires Abl-dependent phosphorylation of a conserved tyrosine in the Canoe actin-binding domain. Preventing Canoe tyrosine phosphorylation destabilizes tricellular adhesion, and anchoring Canoe at tricellular junctions independently of mechanical inputs aberrantly stabilizes adhesion, arresting cell rearrangement. These results identify a force-responsive mechanism that stabilizes tricellular adhesion under tension during epithelial remodeling.

中文翻译:

Abl 和 Canoe/Afadin 在三细胞连接处介导机械转导

多个细胞相遇的张力 细胞存在于不同的环境中,必须对特定的刺激做出反应。在发育过程中,上皮细胞需要在不损害上皮完整性的情况下在张力下快速重组。余等人。证明果蝇上皮细胞通过在三个细胞相遇的三细胞连接处瞬时稳定粘附来实现这一点(参见 Raghavan 和 Vasioukhin 的观点)。保守的粘附调节剂 Canoe/Afadin 在张力下在几秒钟内被募集到三细胞连接处,并在张力通过需要依赖于 Abl 的酪氨酸磷酸化的机制释放时解离。这些结果确定了一种体内机械转导途径,该途径将三细胞粘附与生理力动态耦合,允许细胞快速调节其行为以响应其环境的机械变化。科学,这个问题 p。eaba5528; 另见第 1036 在果蝇胚胎的上皮重塑过程中,力响应机制可稳定张力下的三细胞粘附。引言 感知和响应机械力的能力是细胞的固有特性,它对正常细胞功能至关重要,并且在疾病中经常失调。机械力在体外诱导蛋白质构象、定位、活性和翻译后修饰的变化。一个突出的问题是机械信号如何调节蛋白质功能和细胞行为以响应生物体中细胞遇到的生理力。长期以来,人们一直认为酪氨酸磷酸化在粘附连接处富集,它检测和传递上皮细胞之间的力,并且可以通过体外机械力直接增强。然而,机械力是否影响体内酪氨酸激酶信号传导,以及这种调节对细胞行为的影响,尚不清楚。基本原理 上皮器官发育的一个重要步骤是响应机械力的细胞粘附重塑,这将上皮层转化为不同的结构。三个细胞相遇的三细胞连接 (TCJ) 在细胞重排过程中动态组装和分解,预计在上皮重塑过程中是张力增加的部位,为研究细胞如何对机械力做出反应提供了机会。然而,允许三细胞连接在张力下快速重塑而不破坏上皮连续性的机制尚不清楚。识别和表征在张力下定位于三细胞连接处的蛋白质可以深入了解在体内响应机械力而调节细胞粘附的机械转导途径。结果使用延时成像和直接可视化活胚胎中酪氨酸磷酸化的方法,我们发现在果蝇会聚延伸期间,三细胞连接处的酪氨酸磷酸化以张力依赖性方式增加。通过筛选标记蛋白库,我们将 Canoe 鉴定为一种酪氨酸磷酸化蛋白,在张力下定位于三细胞连接处。Canoe 募集到三细胞连接处与肌球蛋白定位的变化动态相关,当激光消融释放张力时,Canoe 从三细胞连接处迅速分离。Canoe 在三细胞连接处的富集需要 Canoe 在 Y1987 的 Abl 依赖性酪氨酸磷酸化,这是 Canoe 肌动蛋白结合域中的一个保守位点。减少 Abl 表达或将该酪氨酸突变为不可磷酸化的氨基酸,可显着降低三细胞连接处的 Canoe 富集并破坏体内三细胞粘附。为了确定 Canoe 到三细胞连接处的动态募集是否对细胞重排很重要,我们开发了一种“顶点陷阱”方法,独立于机械输入,将带有金星标记的 Canoe 组成性地靶向三细胞连接。在三细胞连接处稳定锚定 Canoe 异常稳定了四向顶点的粘附并阻止了细胞重排。这些结果表明 Canoe 水平动态调节三细胞连接处的细胞粘附强度,以促进细胞重排。结论这些结果确定了在上皮重塑过程中将三细胞粘附与机械力动态耦合的机械转导途径。Canoe 募集到三细胞连接需要肌动蛋白收缩性和 Canoe 肌动蛋白结合域中保守酪氨酸的 Abl 依赖性磷酸化。Canoe 的丧失会破坏三细胞粘附,增加三细胞连接处的 Canoe 水平会减缓或阻止细胞重排,影响上皮重塑的速度。在一个模型中,独木舟可以充当机械传感器,在张力下进行物理拉伸以暴露 Abl 的磷酸化位点。或者,张力可以增强 Abl 活性或在 Canoe 识别的三细胞连接处产生独特的肌动蛋白或其他分子构型。三细胞连接影响上皮发育和体内平衡所需的许多过程,包括细胞重排、细胞分裂、干细胞自我更新和屏障功能。更好地了解三细胞连接的组成、组织和动态特性,将有助于深入了解这些结构如何感知和整合上皮细胞中的机械力。通过张力调节三细胞粘附需要独木舟和 Abl 酪氨酸激酶。(上)果蝇胚胎中磷酸酪氨酸(白色)、Canoe-Venus(绿色)和肌球蛋白-mCherry(红色)的定位。(底部)Abl 和细胞骨架张力增强了三细胞连接处的独木舟定位。这种力敏感机制对于细胞粘附和上皮重塑很重要。上皮结构是由细胞响应机械力的动态重组产生的。粘附连接在细胞之间传递力,但细胞如何在体内感知和响应这些力尚不清楚。我们确定了涉及 Abl 酪氨酸激酶和 Canoe/Afadin 的机械转导通路,可在果蝇胚胎的三细胞连接处稳定张力下的细胞粘附。Canoe 被招募到三细胞连接处以响应肌动蛋白收缩性,并且这种机械敏感性需要 Canoe 肌动蛋白结合域中保守酪氨酸的 Abl 依赖性磷酸化。阻止 Canoe 酪氨酸磷酸化会破坏三细胞粘附,并且独立于机械输入将 Canoe 锚定在三细胞连接处会异常稳定粘附,阻止细胞重排。这些结果确定了一种力响应机制,可以在上皮重塑过程中稳定张力下的三细胞粘附。
更新日期:2020-11-26
down
wechat
bug