Crosstalk between peroxisomes, endoplasmic reticulum and endosomes during polar growth and development in fungi

过氧化物酶体、内质网和核内体等细胞器一直被认为是具有不同功能的封闭区室。过氧化物酶体参与初级和次级代谢以及活性氧（ROS）信号传导，而核内体充当大分子长距离运输的多用途平台。然而，最近的进展表明，细胞器是相当动态的结构，彼此之间有很强的相互作用。例如，在真菌细胞中，过氧化物酶体和内体之间的紧密分子联系通过显示早期内体的微管依赖性运输将过氧化物酶体分布在整个菌丝中而建立。此外，脂滴（LD）和ER片段通过这些内体转运。同时，LD、内体和过氧化物酶体的形成和动力学依赖于ER。值得注意的是，编码septins的mRNA是早期内体的额外重要货物。实验数据支持这样一种模型，其中胞膜蛋白mRNA在内体的细胞质表面的局部翻译促进胞膜蛋白寡聚体组装和更高级结构的形成。在这里，我们建议调查（i）过氧化物酶体在极性生长和发育过程中的生物学功能，（ii）mRNA运输和过氧化物酶体，ER和内体的串扰之间的潜在功能联系。为了提供对这些方面的广泛看法，我们的团队由真菌生物学专家组成，使用已建立的模型系统，如玉米黑粉菌，构巢曲霉，粗糙脉孢菌和鹅柄孢菌。遗传，生物化学和细胞生物学方法将结合起来，以确定细胞器动力学的分子机制和基本组成部分。通过比较不同真菌模型中细胞器之间的串扰，我们将揭示基本的、进化上保守的过程，以及适应不同真菌生活方式的特定机制。所获得的结果将是细胞生物学家的普遍兴趣，所获得的知识可以应用于提高次级代谢产物的生产和开发新的杀菌剂。

Cell organelles like peroxisomes, the endoplasmic reticulum (ER) and endosomes have long been considered as confined compartments with distinct isolated functions. Peroxisomes participate in primary and secondary metabolism as well as in Reactive Oxygen Species (ROS) signaling, whereas endosomes serve as multipurpose platforms for long distance transport of macromolecules. However, recent advances show that organelles are rather dynamic structures that heavily interact with each other. For example, a close molecular link between peroxisomes and endosomes was established in fungal cells by showing that microtubule-dependent transport of early endosomes distributes peroxisomes throughout hyphae. In addition, lipid droplets (LDs) and ER segments are transported by these endosomes. At the same time, the formation and dynamics of LDs, endosomes, and peroxisomes depend on the ER. Remarkably, mRNAs encoding septins are an additional important cargo for early endosomes. Experimental data support a model in which local translation of septin mRNAs at the cytoplasmic surface of endosomes promotes septin oligomer assembly and formation of higher-order structures. Here, we propose to investigate (i) the biological function of peroxisomes during polar growth and development, (ii) a potential functional link between mRNA transport and the crosstalk of peroxisomes, ER and endosomes. To provide a broad view on these aspects our team consists of fungal biology experts using established model systems such as Ustilago maydis, Aspergillus nidulans, Neurospora crassa and Podospora anserina. Genetic, biochemical and cell biological approaches will be combined to identify molecular mechanisms and essential components in organelle dynamics. By comparing the crosstalk between organelles in different fungal models, we will uncover fundamental, evolutionary conserved processes, as well as specific mechanisms adapted to the life styles of different fungi. Obtained results will be of general interest for cell biologists and the gained knowledge can be applied to improve the production of secondary metabolites and to develop novel fungicides.