Characterization of Plakophilin 4 as a key regulator of Rho signaling in epidermal keratinocytes

Plakophilin 4 作为表皮角质形成细胞 Rho 信号传导关键调节因子的表征

• 批准号: 511657520
• 负责人: Professorin Dr. Mechthild Hatzfeld
• 金额: --
• 依托单位: Arbeitsgruppe Pathobiochemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/511657520?language=en
• 关键词: Characterization; Plakophilin; key; regulator; Rho

Plakophilin 4 (PKP4, p0071) is a protein of adherens junctions (AJ) whose expression is restricted to the basal cells of the epidermis, whereas the related p120 is expressed in all keratinocytes regardless of their degree of differentiation. In addition, PKP4 is known to affect Rho-signaling in cytokinesis. To better understand the functions of PKP4, we generated a model system consisting of a wild-type (WT), a PKP4 knockout (PKP4-KO), and a "rescue" cell line (re-expression of PKP4 in the PKP4-KO line). Using this model system, we have performed preliminary studies of PKP4 function showing that loss of PKP4 leads to massive changes in actin cytoskeleton organization with increased stress fibers but decreased cortical actin. This correlates with decreased tension and changes in cell contacts. The goal of the proposed project is to uncover the molecular mechanisms underlying these changes. The focus will be on the role of PKP4 in the regulation of Rho GTPases, in particular RhoA. First, the influence of PKP4 on the local activity of Rho GTPases will be determined. In addition, we will investigate how PKP4 modulates the activity of Rho GTPases via interactions with upstream regulators. For this purpose, a subset of guanine-exchange factors (GEF) and GTPase activating proteins (GAP) were selected for a detailed characterization. Finally, downstream effects will be characterized in terms of actomyosin organization, myosin activity and generation of tissue tension. Mechanosignaling in turn controls proliferation and differentiation via Hippo/YAP/TAZ activity. The data generated in this project will improve our understanding how proliferation and delamination of basal keratinocytes is controlled. This has implications for various skin diseases in which the balance between proliferation and differentiation is disturbed, as well as for changes in skin aging and/or stem cell maintenance.

Plakophilin 4（PKP 4，p0071）是粘附连接（AJ）的蛋白质，其表达限于表皮的基底细胞，而相关的p120在所有角质形成细胞中表达，而不管其分化程度如何。此外，已知PKP 4影响胞质分裂中的Rho信号传导。为了更好地理解PKP 4的功能，我们产生了由野生型（WT）、PKP 4敲除（PKP 4-KO）和“拯救”细胞系（在PKP 4-KO系中重新表达PKP 4）组成的模型系统。使用这个模型系统，我们已经进行了初步的研究PKP 4功能显示，PKP 4的损失导致大量的变化，肌动蛋白细胞骨架组织与应力纤维增加，但皮质肌动蛋白减少。这与张力降低和细胞接触的变化有关。该项目的目标是揭示这些变化背后的分子机制。重点将是PKP 4在Rho GTP酶，特别是RhoA的调节中的作用。首先，将确定PKP 4对Rho GTP酶的局部活性的影响。此外，我们将研究PKP 4如何通过与上游调控因子的相互作用来调节Rho GTP酶的活性。为此目的，选择鸟嘌呤交换因子（GEF）和GTP酶激活蛋白（GAP）的一个子集进行详细表征。最后，下游效应的特点是肌动球蛋白组织，肌球蛋白活性和组织张力的产生。机械信号传导进而通过Hippo/雅普/TAZ活性控制增殖和分化。在这个项目中产生的数据将提高我们的理解如何增殖和分层的基底角质形成细胞的控制。这对其中增殖和分化之间的平衡被扰乱的各种皮肤疾病以及皮肤老化和/或干细胞维持的变化具有影响。